MONZEN Hajime

    Kindai University Hospital Professor
Last Updated :2024/03/24

Researcher Information

URL

Research funding number

  • 10611593

J-Global ID

Research Interests

  • 核医学   医学物理学   放射線防護   放射線治療   癌   トランスレーショナルリサーチ   

Research Areas

  • Energy / Quantum beam science
  • Life sciences / Radiology
  • Life sciences / Radiology

Academic & Professional Experience

  • 2021/04 - Today  Kindai UniversityProfessor
  • 2014/04 - 2021/03  Kindai UniversityGraduate school of medical scienciesAssociate professor
  • 2011/04 - 2014/03  Kyoto University医学(系)研究科(研究院)特定准教授
  • 1991/04 - 2011/03  日本赤十字社 大津赤十字病院放射線科部
  • 2001 - 2002  Minnesota UniversityDepartment of Radiation Oncologyvisiting fellow

Association Memberships

  • JAPAN RADIOISOTOPE ASSOCIATION   JAPANESE SOCIETY FOR RADIATION ONCOLOGY   JAPANESE SOCIETY OF RADIOLOGICAL TECHNOLOGY   JAPAN SOCIETY OF MEDICAL PHYSICS   日本放射線技師会   

Published Papers

  • Takuya Uehara; Yasumasa Nishimura; Kazuki Ishikawa; Masahiro Inada; Kenji Matsumoto; Hiroshi Doi; Hajime Monzen; Yukinori Matsuo
    Journal of radiation research 2024/01 
    The present study aimed to evaluate whether an adapted plan with Ethos™ could be used for pharyngeal cancer. Ten patients with pharyngeal cancer who underwent chemoradiotherapy with available daily cone-beam computed tomography (CBCT) data were included. Simulated treatments were generated on the Ethos™ treatment emulator using CBCTs every four to five fractions for two plans: adapted and scheduled. The simulated treatments were divided into three groups: early (first-second week), middle (third-fourth week), and late (fifth-seventh week) periods. Dose-volume histogram parameters were compared for each period between the adapted and scheduled plans in terms of the planning target volume (PTV) (D98%, D95%, D50% and D2%), spinal cord (Dmax and D1cc), brainstem (Dmax) and ipsilateral and contralateral parotid glands (Dmedian and Dmean). The PTV D98%, D95% and D2% of the adapted plan were significantly higher than those of the scheduled plans in all periods, except for D98% in the late period. The adapted plan significantly reduced the spinal cord Dmax and D1cc compared with the scheduled plan in all periods. Ipsilateral and contralateral parotid glands Dmean of the adapted plan were lower than those of scheduled plan in the late period. In conclusion, the present study revealed that the adapted plans could maintain PTV coverage while reducing the doses to organs at risk in each period compared with scheduled plans.
  • Yuya Yanagi; Kazuki Kubo; Takaaki Ito; Kenji Nakamura; Makoto Hirata; Hiroshi Doi; Hajime Monzen
    Cureus Springer Science and Business Media LLC 2168-8184 2023/10
  • Katsuya Okuhata; Hajime Monzen; Yasunori Nakamura; Go Takai; Keiji Nagano; Kenji Nakamura; Kazuki Kubo; Makoto Hosono
    Annals of nuclear medicine 2023/08 
    OBJECTIVE: The purpose of this study is to determine the dose reduction of different shielding materials at various distances from a 177Lu photon radiation source. METHODS: Two protective aprons with lead equivalent thicknesses of 0.25 mm and 0.35 mm and tungsten-containing rubber (TCR) were used as shielding materials. A vial containing 177Lu was sealed in a lead container so that a narrow beam went out through a 3 mm-diameter hole. The dose rate was measured at distances of 0, 10, 50, 100, and 200 cm from the source using a NaI scintillation survey meter to obtain the rate of dose reduction. TCR was tested with thicknesses ranging from 0.3 to 1.0 mm at 0.1 mm intervals and from 1.0 to 4.0 mm at 0.5 mm intervals. RESULTS: At distances of 0, 10, 50, 100, and 200 cm, the dose reduction for the lead equivalent thickness of 0.25 mm were 32.7%, 54.5%, 93.1%, 97.9%, and 99.6%, respectively; and for the lead equivalent thickness of 0.35 mm were 53.4%, 70.6%, 95.6%, 98.9%, and 99.6%, respectively. Without any shielding, the dose rate decreased by 34.4% at 10 cm and by 88.8% at 50 cm from the radiation source. The dose reduction for the TCR thickness of 3.5 mm was 89.8% at 0 cm and 93.3% at 10 cm. The TCR thickness of 0.4 mm provided a dose reduction comparable to or greater than that of the 0.25 mm lead equivalent, whereas the TCR thickness of 1.0 mm or greater provided a dose reduction comparable to that of the 0.35 mm lead equivalent. CONCLUSIONS: Achieving a reduction of 95% or more requires the 0.25 mm lead equivalent for a distance of 100 cm, the 0.35 mm lead equivalent for 50 cm, the TCR thickness of 0.3 mm for 100 cm, or the TCR thickness of 0.9 mm for 50 cm. Without wearing a protective apron, a reduction of approximately 95% is observed at distances greater than 100 cm. These findings would be useful for medical staff engaging in related activities.
  • 【肝胆膵癌に対する放射線治療:2023 Update】膵癌 膵NENに対するペプチド受容体放射性核種療法(PRRT)
    細野 眞; 李 在俊; 立野 沙織; 福田 隼己; 石田 奈緒子; 植原 拓也; 稲田 正浩; 松浦 知弘; 土井 啓至; 中松 清志; 門前 一; 松尾 幸憲
    肝胆膵 (株)アークメディア 87 (1) 79 - 84 0389-4991 2023/07
  • Ito T; Monzen H; Kubo K; Kosaka H; Yanagi Y; Sakai Y; Inada M; Doi H; Nishimura Y
    Reports of Practical Oncology and Radiotherapy VM Media Group sp. z o.o 28 (3) 399 - 406 1507-1367 2023/06 [Refereed]
  • Yoshihiro Ueda; Jun-Ichi Fukunaga; Tatsuya Kamima; Yumiko Shimizu; Kazuki Kubo; Hiroshi Doi; Hajime Monzen
    Physical and engineering sciences in medicine 2023/05 
    PURPOSE: To evaluate whether knowledge-based volumetric modulated arc therapy plans for prostate cancer with a multi-institution model (broad model) are clinically useful and effective as a standardization method. METHODS: A knowledge-based planning (KBP) model was trained with 561 prostate VMAT plans from five institutions with different contouring and planning policies. Five clinical plans at each institution were reoptimized with the broad and single institution model, and the dosimetric parameters and relationship between Dmean and the overlapping volume (rectum or bladder and target) were compared. RESULTS: The differences between the broad and single institution models in the dosimetric parameters for V50, V80, V90, and Dmean were: rectum; 9.5% ± 10.3%, 3.3% ± 1.5%, 1.7% ± 1.6%, and 3.6% ± 3.6%, (p < 0.001), bladder; 8.7% ± 12.8%, 1.5% ± 2.6%, 0.7% ± 2.4%, and 2.7% ± 4.6% (p < 0.02), respectively. The differences between the broad model and clinical plans were: rectum; 2.4% ± 4.6%, 1.7% ± 1.7%, 0.7% ± 2.4%, and 1.5% ± 2.0%, (p = 0.004, 0.015, 0.112, and 0.009) bladder; 2.9% ± 5.8%, 1.6% ± 1.9%, 0.9% ± 1.7%, and 1.1% ± 4.8%, (p < 0.018), respectively. Positive values indicate that the broad model has a lower value. Strong correlations were observed (p < 0.001) in the relationship between Dmean and the rectal and bladder volume overlapping with the target in the broad model (R = 0.815 and 0.891, respectively). The broad model had the smallest R2 of the three plans. CONCLUSIONS: KBP with the broad model is clinically effective and applicable as a standardization method at multiple institutions.
  • Kenji Nakamura; Hajime Monzen; Kazuki Kubo; Hiroyuki Kosaka; Takaaki Ito; Yusuke Sakai; Yuya Yanagi; Yasumasa Nishimura
    Physics in Medicine & Biology IOP Publishing 68 (10) 105007 - 105007 0031-9155 2023/05 
    Abstract Objective. The purpose of this study was to develop a new bolus (HM bolus), with tissue equivalence, transparency, reusability, and free shaping at approximately 40 °C for excellent adhesion, and to evaluate the feasibility of clinically using this bolus as an ideal bolus. Approach. We summarized the advantages and disadvantages of existing boluses. To evaluate dose characteristics, a vinyl gel sheet bolus (Gel bolus) and HM bolus placed on a water-equivalent phantom were used to obtain the percentage depth dose (PDD) of electron (6 MeV, 9 MeV) and photon (4 MV, 6 MV) beams. The average dose difference of the HM bolus and Gel bolus was calculated. The Gel bolus, a soft rubber bolus (SR bolus), and HM bolus were placed in adherence to a pelvic phantom. CT images taken after shaping and 1, 2, and 3 weeks after shaping were used to evaluate the adhesion and reproducibility using air gap and dice similarity coefficient (DSC). Main results. The average dose difference for electron beams was 0.16% ± 0.79% and photon beams was 0.06% ± 0.34%, both within 1% of the PDD results. The HM bolus showed the same build-up effect and dose characteristics as the Gel bolus. The mean air gap values for the Gel bolus, SR bolus, and HM bolus were 96.02 ± 43.77 cm3, 34.93 ± 21.44 cm3, and 4.40 ± 1.50 cm3, respectively. The mean DSC values compared to initial images for the Gel bolus, SR bolus, and HM bolus were 0.363 ± 0.035, 0.556 ± 0.042, and 0.837 ± 0.018, respectively. Excellent adhesion was observed in the CT simulation and during the treatment period. Significance. The HM bolus has unique features, such as tissue equivalence, transparency, reusability, and free shaping for excellent adhesion, and is thus an ideal bolus for use in clinical cases.
  • Wada Y; Monzen H; Ishida N; Ri A; Tatsuno S; Uehara T; Inada M; Doi H; Nakamatsu K; Hosono M; Nishimura Y
    Medical Dosimetry 48 (3) 193 - 196 2023/05 [Refereed]
  • Yusuke Sakai; Hajime Monzen; Yoshiki Takei; Hiroyuki Kosaka; Kenji Nakamura; Yuya Yanagi; Kazuki Wakabayashi; Makoto Hosono; Yasumasa Nishimura
    48 (2) 189 - 194 2023/04 [Refereed]
  • Kenji Matsumoto; Hajime Monzen; Kazuki Kubo; Masakazu Otsuka; Hidekazu Nambu; Yasumasa Nishimura
    Cureus 15 (3) e36493  2023/03 
    This study aims to determine the feasibility of using a new O-ring linear accelerator (Halcyon, Varian Medical Systems, CA, USA) to perform treatment planning using volumetric modulated arc therapy (VMAT) for craniospinal irradiation (CSI). A 20-year-old male patient with leukemia was selected. The planning target volume (PTV) was contoured to include the entire contents of the brain and spinal canal. The PTV margin was 10 mm applied to the clinical target volume (CTV). VMAT (RapidArc, Varian Medical Systems, CA, USA) planning was performed using four isocenter with five arcs, two full rotation arcs to cover the brain and upper part of the spinal cord, and one full rotation arc for the lower part of the spinal cord. The plan was created using the auto-feathering photon optimizer calculation of the planning system. The conformity index (CI) and heterogeneity index (HI) as well as dose-volume histograms of organs at risk (OAR) were evaluated. The patient position of ±3.0 mm in the craniocaudal direction was moved in to simulate the effect of treatment inaccuracy. The total treatment time was also measured. The CI and HI were 1.09 and 8.44, respectively. The mean dose (PTV) was 105.5%, and the mean dose (OARs) was lower than the planning dose constraints. Simulations with a patient position shift of ±3.0 mm resulted in an error of less than ±10.0% of the planned dose to the spinal cord. The total treatment time was within 15 minutes. VMAT planning for CSI with Halcyon achieved high conformality, uniform dose distribution, low dose to the surrounding normal tissues, and reduced treatment time.
  • Hiroyuki Kosaka; Mikoto Tamura; Shota Hattori; Hajime Monzen
    Radiation Protection Dosimetry Oxford University Press (OUP) 0144-8420 2023/01 
    Abstract This study aims to measure the shielding effect of a novel tungsten rubber sheet (TRS) on the exposure of male gonads to ionizing radiation during upper abdominal and abdominal plus pelvic computed tomography (CT) examinations. The air kerma at the gonad with and without shielding was measured using an anthropomorphic body phantom. Gonads were shielded using: (1) 360° wrap with TRS (0.5-mm thick) and (2) 180° wrap with TRS. The air kerma at a position of male gonads in a pelvic scan was 21.8 mGy, even when the gonads were in the off-axis range. The TRS reduced the dose to the male gonads in abdominal plus pelvic CT examinations by 61% and 38% for the 360° and 180° TRS wrap, respectively.
  • Katsuya Okuhata; Mitsugu Fujita; Kenji Nakamura; Yuya Yanagi; Yusuke Sakai; Kazuki Kubo; Hiroyuki Kosaka; Hajime Monzen
    Cureus 15 (1) e34287  2023/01 
    Background Coronavirus disease 2019 and other viruses are transmissible by aerosols and droplets from infected persons. This study aimed to develop a portable device that can trap droplets and deactivate viruses, and verify whether the device in an enclosed room can suction droplets and sanitize them using a filter and an ultraviolet-C (UVC) light-emitting diode. Materials and methods The portable device was evaluated by placing it 50 cm away from the droplet initiation point. A particle image velocimetry laser dispersed into a sheet form was used to visualize the droplets splashed on the irradiated sagittal plane and captured using a charge-coupled device camera at 60 frames per second. The images were overlaid and calculated to determine the percentage of the droplets beyond the portable device. Droplets with a particle size larger than 50 µm that dispersed and were deposited more than 100 cm away were measured using a water-sensitive paper. The effect of UVC sanitization on viruses captured by a high-efficiency particulate air (HEPA) filter was determined using a plaque assay. Results The percentage of droplets was 13.4% and 1.1% with the portable device OFF and ON, respectively, indicating a 91.8% reduction. The deposited droplets were 86 pixels and 26 pixels with the portable device OFF and ON, respectively, indicating a 68.7% reduction. The UVC deactivated more than 99% of the viruses on the HEPA filter surface in 5 minutes. Conclusions Our novel portable device can suck and fall the dispersed droplets, and an active virus was not observed on the exhaust side.
  • Yusuke Sakai; Hajime Monzen; Mikoto Tamura; Kenji Nakamura; Yasumasa Nishimura
    Physical and engineering sciences in medicine 2022/12 
    To clarify the dosimetric characteristics of a real-time variable shape rubber-containing tungsten (STR) bolus in a clinical plan and investigate the efficacy of the STR bolus in photon radiotherapy for keloids and other superficial tumors. A 5 mm gel bolus or 1 mm STR bolus was placed on a solid water phantom. Tangential irradiation was performed using a TomoTherapy Radixact-X9 and 6 MV X-ray flattening-filter-free beam, and the surface dose was measured with radiochromic film. Clinical-like plans (TomoDirect; TD and TomoHelical; TH) were applied with the same geometry and the dose distributions were measured. The increase in surface dose by the build-up effect and backscatter was 37.7% and 8.0% for the gel bolus, and 40.5% and 26.4% for the STR bolus, respectively. In the TD and TH plans, the increase in surface dose was 27.4% and 48.3% for the gel bolus, and 39.0% and 63.2% for the STR bolus. Similary, changes in the sagittal plane dose were - 3.9% and 6.1% for the gel bolus, and - 6.3% and 6.9% for the STR bolus. The STR bolus effectively increased the surface dose by the build-up effect and backscatter in photon radiotherapy for keloids and other superficial tumors.
  • Tomohiro Sagawa; Yoshihiro Ueda; Haruhi Tsuru; Tatsuya Kamima; Shingo Ohira; Mikoto Tamura; Masayoshi Miyazaki; Hajime Monzen; Koji Konishi
    Journal of applied clinical medical physics 24 (2) e13836  2022/11 
    OBJECTIVE: Dosimetric potential of knowledge-based RapidPlan planning model trained with HyperArc plans (Model-HA) for brain metastases has not been reported. We developed a Model-HA and compared its performance with that of clinical volumetric modulated arc therapy (VMAT) plans. METHODS: From 67 clinical stereotactic radiosurgery (SRS) HyperArc plans for brain metastases, 47 plans were used to build and train a Model-HA. The other 20 clinical HyperArc plans were recalculated in RapidPlan system with Model-HA. The model performance was validated with the 20 plans by comparing dosimetric parameters for normal brain tissue between clinical plans and model-generated plans. The 20 clinical conventional VMAT-based SRS or stereotactic radiotherapy plans (CL-VMAT) were reoptimized with Model-HA (RP) and HyperArc system (HA), respectively. The dosimetric parameters were compared among three plans (CL-VMAT vs. RP vs. HA) in terms of planning target volume (PTV), normal brain excluding PTVs (Brain - PTV), brainstem, chiasm, and both optic nerves. RESULTS: In model validation, the optimization performance of Model-HA was comparable to that of HyperArc system. In comparison to CL-VMAT, there were no significant differences among three plans with respect to PTV coverage (p > 0.17) and maximum dose for brainstem, chiasm, and optic nerves (p > 0.40). RP provided significantly lower V20 Gy , V12 Gy , and V4 Gy for Brain - PTV than CL-VMAT (p < 0.01). CONCLUSION: The Model-HA has the potential to significantly reduce the normal brain dose of the original VMAT plans for brain metastases.
  • Mikoto Tamura; Yoshihiro Ueda; Jun-Ichi Fukunaga; Tatsuya Kamima; Yumiko Shimizu; Yuta Muraki; Kazuki Kubo; Kiyoshi Nakamatsu; Makoto Hosono; Hajime Monzen
    Anticancer research 42 (11) 5305 - 5314 2022/11 
    BACKGROUND/AIM: This study evaluated the impact of knowledge-based plan (KBP) model improvement on plan complexity and delivery accuracy in volumetric modulated arc therapy (VMAT) for prostate cancer at multiple institutions. MATERIALS AND METHODS: Five institutions created the first KBP model before April 2017 and subsequently devised a new model (second model) based on feedback from the first KBP and the efforts of planners after April 2019. The dose-volume histogram (DVH) parameters were validated for two prostate cancer cases between the first and second KBPs. Plan complexity metrics, of the modulation complexity score for VMAT (MCSv), closed leaf score (CLS), small aperture score (SAS), and leaf travel (LT), were compared. The delivery accuracy metrics of γ pass rate and point dose discrepancy (plan vs. measurement) at isocenter were also compared. RESULTS: There were no significant differences in DVH parameters between the KBPs. Conversely, V50% of the rectum and bladder was reduced in 6/10 and 8/10 patients, respectively, and these variations were also converged from the first KBP to the second KBP. The mean±1SDs of MCSv, CLS, SAS20mm, and LT (first KBP vs. second KBP) were 0.27±0.033 vs. 0.26±0.044, 0.062±0.032 vs. 0.14±0.091, 0.59±0.048 vs. 0.70±0.14, and 411.91±32.08 mm vs. 548.33±127.50 mm, respectively. The delivery accuracy did not differ, whereas MCSv was moderately correlated with the point dose discrepancy. CONCLUSION: Multi-leaf collimator motion could be more complex with KBP model improvement, which had the potential to deteriorate the delivery accuracy.
  • Y. Nakamura; H. Monzen; M. Tamura; H. Kosaka; K. Kijima; Y. Nishimura
    Radiography Elsevier BV 28 (4) 912 - 918 1078-8174 2022/11
  • Kazuki Kubo; Mikoto Tamura; Kenji Matsumoto; Masakazu Otsuka; Hajime Monzen
    Journal of applied clinical medical physics e13807  2022/10 
    Independent monitor unit verification (MUV) methods for the dynamic beam-flattening (DBF) technique have not been established. The purpose of this study was to clarify whether MU values for the DBF technique can be calculated using in-air and in-water output ratios (Sc and Scp ). Sc and Scp were measured in the DBF mode, and the phantom scatter factor (Sp ) was calculated. The difference between calculated and planned MUs with square and rectangle fields and clinical plans for different treatment sites was also evaluated. Sc values for the 4 × 4 to 24 × 24 cm2 fields of the distal multi-leaf collimator (MLC) layer at 2-cm intervals were 0.887, 0.815, 0.715, 0.716, 0.611, 0.612, 0.511, 0.373, 0.374, 0.375, and 0.374, respectively. No collimator exchange effect was observed. Sc also depends slightly on the field size of the distal MLC layer. If the distal-MLC-layered field size was less than 20% of the corresponding MLC sequence size in the proximal MLC layer, Sc was affected by >1%, which was compensated using a correction factor (CF). Sp increased as the field sizes of the MLC sequence and distal MLC leaves increased. MUs calculated using measured Sc , Sp , and CF for square and rectangle fields agreed with planned MUs within ±1.2%. A larger difference (-1.5%) between calculated and planned MUs was observed for clinical plans, whereas differences in MUs were within 2 MU for most fields (56 out of 64 fields). MU calculation for the DBF technique can be performed with Sc , Sp , and CF for independent MUV.
  • Yuya Yanagi; Hajime Monzen; Mikoto Tamura; Masakazu Otsuka; Yasumasa Nishimura
    Journal of applied clinical medical physics 23 (10) e13791  2022/10 
    PURPOSE: To determine the thickness of a soft variable shape tungsten rubber (STR) as a lung compensating filter in total body irradiation. METHODS: A tough water (TW) phantom and tough lung (TL) phantom were used as water and lung-equivalent phantoms. The TW with a thickness of 3 cm simulating the thoracic wall was used (upper layer). The TW or TL with a thickness from 1 to 15 cm (1 cm increments) was placed beneath the upper layer (middle layer). The TW with a thickness of 5 cm simulating the mediastinum was placed beneath the middle layer (lower layer), and a farmer ionization chamber was placed beneath this layer. The relative doses of a 10 MV X-rays were then measured. The TL was compensated in 1 mm increments from 1 to 11 mm of the STR, and the thickness of the STR at the same dose of TW (water equivalent) was obtained. RESULTS: The compensating ability of STR increased as the thickness of the TL increased, and an STR with a thickness of 1 mm reduced the dose by 2%-4%, depending on the thickness of lung. The STR thickness as an equivalent dose of TW per cm of TL was approximately linear, and the thickness was 0.62 mm/cm of TL. CONCLUSION: The STR can be used as a lung compensating filter for a water equivalent dose with 0.62 mm of STR per cm of lung.
  • Jun-Ichi Fukunaga; Mikoto Tamura; Yoshihiro Ueda; Tatsuya Kamima; Yumiko Shimizu; Yuta Muraki; Kiyoshi Nakamatsu; Hajime Monzen
    Scientific reports 12 (1) 15282 - 15282 2022/09 
    We established a multi-institution model (big model) of knowledge-based treatment planning with over 500 treatment plans from five institutions in volumetric modulated arc therapy (VMAT) for prostate cancer. This study aimed to clarify the efficacy of using a large number of registered treatment plans for sharing the big model. The big model was created with 561 clinically approved VMAT plans for prostate cancer from five institutions (A: 150, B: 153, C: 49, D: 60, and E: 149) with different planning strategies. The dosimetric parameters of planning target volume (PTV), rectum, and bladder for two validation VMAT plans generated with the big model were compared with those from each institutional model (single-institution model). The goodness-of-fit of regression lines (R2 and χ2 values) and ratios of the outliers of Cook's distance (CD) > 4.0, modified Z-score (mZ) > 3.5, studentized residual (SR) > 3.0, and areal difference of estimate (dA) > 3.0 for regression scatter plots in the big model and single-institution model were also evaluated. The mean ± standard deviation (SD) of dosimetric parameters were as follows (big model vs. single-institution model): 79.0 ± 1.6 vs. 78.7 ± 0.5 (D50) and 0.13 ± 0.06 vs. 0.13 ± 0.07 (Homogeneity Index) for the PTV; 6.6 ± 4.0 vs. 8.4 ± 3.6 (V90) and 32.4 ± 3.8 vs. 46.6 ± 15.4 (V50) for the rectum; and 13.8 ± 1.8 vs. 13.3 ± 4.3 (V90) and 39.9 ± 2.0 vs. 38.4 ± 5.2 (V50) for the bladder. The R2 values in the big model were 0.251 and 0.755 for rectum and bladder, respectively, which were comparable to those from each institution model. The respective χ2 values in the big model were 1.009 and 1.002, which were closer to 1.0 than those from each institution model. The ratios of the outliers in the big model were also comparable to those from each institution model. The big model could generate a comparable VMAT plan quality compared with each single-institution model and therefore could possibly be shared with other institutions.
  • Katsuya Okuhata; Kenta Kijima; Kenji Nakamura; Yuya Yanagi; Hajime Monzen
    Anticancer research 42 (9) 4411 - 4415 2022/09 
    BACKGROUND/AIM: We aimed to clarify the TomoTherapy irradiation method for accurate dose delivery to the postoperative ear keloid with minimal exposure. MATERIALS AND METHODS: An electron beam of Elekta synergy and static and helical photon beams of TomoTherapy were delivered to the auricle and lobe of an anthropomorphic phantom compensated using a soft rubber bolus. The doses to the ear surface and the eyeballs and thyroid were measured using radiochromic film and glass dosimeters, respectively. RESULTS: Using static, helical, and electron beams, the respective doses to the ear surface were 97.9%, 103.0%, and 91.7% of the prescribed dose; the respective doses to the thyroid were 0.6, 0.8, and 2.4 cGy; the respective doses to the left eyeball were 3.3, 6.9, and 2.7 cGy. CONCLUSION: The static beam of the TomoTherapy can be safely used for treating ear keloids, while ensuring target dose. The helical photon beam spreads out the low-dose exposure.
  • Hironori Akiyama; Ken Yoshida; Tadashi Takenaka; Tadayuki Kotsuma; Koji Masui; Hajime Monzen; Iori Sumida; Yutaka Tsujimoto; Mamoru Miyao; Hiroki Okumura; Taiju Shimbo; Hideki Takegawa; Naoya Murakami; Koji Inaba; Tairo Kashihara; Zoltán Takácsi-Nagy; Nikolaos Tselis; Hideya Yamazaki; Eiichi Tanaka; Keiji Nihei; Yoshiko Ariji
    Journal of contemporary brachytherapy 14 (1) 87 - 95 2022/02 
    PURPOSE: The purpose of this study was to evaluate the effect of a lead block for alveolar bone protection in image-guided high-dose-rate interstitial brachytherapy for tongue cancer. MATERIAL AND METHODS: We treated 6 patients and delivered 5,400 cGy in 9 fractions using a lead block. Effects of lead block (median thickness, 4 mm) on dose attenuation by distance were visually examined using TG-43 formalism-based dose distribution curves to determine whether or not the area with the highest dose is located in the alveolar bone, where there is a high-risk of infection. Dose re-calculations were performed using TG-186 formalism with advanced collapsed cone engine (ACE) for inhomogeneity correction set to cortical bone density for the whole mandible and alveolar bone, water density for clinical target volume (CTV), air density for outside body and lead density, and silastic density for lead block and its' silicon replica, respectively. RESULTS: The highest dose was detected outside the alveolar bone in five of the six cases. For dose-volume histogram analysis, median minimum doses delivered per fraction to the 0.1 cm3 of alveolar bone (D0.1cm3 TG-43, ACE-silicon, and ACE-lead) were 344.3 (range, 262.9-427.4) cGy, 336.6 (253.3-425.0) cGy, and 169.7 (114.9-233.3) cGy, respectively. D0.1cm3 ACE-lead was significantly lower than other parameters. No significant difference was observed between CTV-related parameters. CONCLUSIONS: The results suggested that using a lead block for alveolar bone protection with a thickness of about 4 mm, can shift the highest dose area to non-alveolar regions. In addition, it reduced D0.1cm3 of alveolar bone to about half, without affecting tumor dose.
  • Shota Hattori; Hajime Monzen; Mikoto Tamura; Hiroyuki Kosaka; Yasunori Nakamura; Yasumasa Nishimura
    Journal of applied clinical medical physics 23 (3) e13532  2022/01 
    PURPOSE: The efficiency of protective equipment for the brain has not been verified at the left anterior oblique (LAO) position, which is commonly used in clinical procedures. The purpose of this study was to investigate radiation exposure of the brain in interventional radiology (IR) and the shielding ability of a new protective flap. METHODS: We made a flap that combined a protective cap with a left lateral face shield. The flap was made of tungsten-containing rubber (TCR). An anthropomorphic head phantom was placed at the physician's position, and air kerma rates (μGy/min and μGy/15s) were measured by electronic dosimeter at three locations: the surface of the left side of the head, and the left and right temporal lobes with the protective cap and the flap in fluoroscopy and cine modes. The X-ray tube was at the lower left side of the physician, and its angles were LAO60 and LAO60CAU40. The tube voltage (95-125 kV), tube current (4.7-732 mA), and air kerma rate (27.8-1078 mGy/min) were automatically adjusted by the X-ray system. We obtained the cap and the flap shielding efficiencies. RESULTS: In cine mode at LAO60CAU40, the shielding efficiencies on the surface of the left side of the head and left temporal lobe with the cap were 92.6% and 5.1%, respectively, and the corresponding shielding efficiencies with the flap were 92.5% and 86.1%, respectively. The flap can reduce radiation exposure of the brain more than the cap alone. CONCLUSIONS: At the left anterior oblique in interventional radiology, the flap can reduce exposure to the brain.
  • HARUHI TSURU; YOSHIHIRO UEDA; MIKOTO TAMURA; HAJIME MONZEN; SHINGO OHIRA; AKIRA MASAOKA; SHOUKI INUI; KOJI KONISHI; JUNICHI FUKUNAGA; HIROKAZU MIZUNO; MASAYOSHI MIYAZAKI; MASAHIKO KOIZUMI
    In Vivo Anticancer Research USA Inc. 36 (2) 687 - 693 0258-851X 2022
  • Takuya Uehara; Hajime Monzen; Mikoto Tamura; Masahiro Inada; Masakazu Otsuka; Hiroshi Doi; Kenji Matsumoto; Yasumasa Nishimura
    Radiation Oncology Springer Science and Business Media LLC 16 (1) 2021/12 
    Abstract Background The use of total body irradiation (TBI) with linac-based volumetric modulated arc therapy (VMAT) has been steadily increasing. Helical tomotherapy has been applied in TBI and total marrow irradiation to reduce the dose to critical organs, especially the lungs. However, the methodology of TBI with Halcyon™ linac remains unclear. This study aimed to evaluate whether VMAT with Halcyon™ linac can be clinically used for TBI. Methods VMAT planning with Halcyon™ linac was conducted using a whole-body computed tomography data set. The planning target volume (PTV) included the body cropped 3 mm from the source. A dose of 12 Gy in six fractions was prescribed for 50% of the PTV. The organs at risk (OARs) included the lens, lungs, kidneys, and testes. Results The PTV D98%, D95%, D50%, and D2% were 8.9 (74.2%), 10.1 (84.2%), 12.6 (105%), and 14.2 Gy (118%), respectively. The homogeneity index was 0.42. For OARs, the Dmean of the lungs, kidneys, lens, and testes were 9.6, 8.5, 8.9, and 4.4 Gy, respectively. The V12Gy of the lungs and kidneys were 4.5% and 0%, respectively. The Dmax of the testes was 5.8 Gy. Contouring took 1–2 h. Dose calculation and optimization was performed for 3–4 h. Quality assurance (QA) took 2–3 h. The treatment duration was 23 min. Conclusions A planning study of TBI with Halcyon™ to set up VMAT-TBI, dosimetric evaluation, and pretreatment QA, was established.
  • Wada Y; Monzen H; Otsuka M; Inada M; Doi H; Nakamatsu K; Nishimura Y
    Medical Dosimetry In press 2021/10 [Refereed]
  • Katsuya Okuhata; Mikoto Tamura; Hajime Monzen; Yasumasa Nishimura
    Physical and engineering sciences in medicine 2021/09 
    In this study, we aim to clarify the dosimetric characteristics of a real time variable shape rubber containing tungsten (STR) as a thin bolus in 6-MV photon radiotherapy. The percentage depth doses (PDDs) and lateral dose profiles (irradiation field = 10 × 10  cm2) in the water-equivalent phantom were measured and compared between no bolus, a commercial 5-mm gel bolus, and 0.5-, 1-, 2-, and 3-mm STR boluses. The characteristics of the PDDs were evaluated according to relative doses at 1 mm depth (D1mm) and depth of maximum dose (dmax). To determine the distance of the shift caused by the STR bolus, the PDD value at a depth of 100 mm without a bolus was obtained. For each STR thickness, the difference between the depth corresponding to this PDD value and 100 mm was calculated. The penumbra size and width of the 50% dose were evaluated using lateral dose profiles. The D1mm with no bolus, 5-mm gel bolus, and 0.5-, 1-, 2-, and 3-mm STR boluses were 47.6%, 91.5%, 78.2%, 86.6%, 89.3%, and 89.4%, respectively, and the respective dmax values were 15, 10, 13, 12, 11, and 10 mm. The shifting distance of the 0.5-, 1-, 2-, and 3-mm STR boluses were 2.7, 4.4, 4.8, and 4.9 mm, respectively. There were no differences for those in lateral dose profiles. The 1-mm-thick STR thin bolus shifted the depth dose profile by 4.4 mm and could be used as a customized bolus for photon radiotherapy.
  • Kazuki Wakabayashi; Hajime Monzen; Mikoto Tamura; Yoshiki Takei; Katsuya Okuhata; Shimpei Anami; Hiroshi Doi; Yasumasa Nishimura
    Physics in medicine and biology 66 (18) 2021/09 
    We have developed soft rubber (SR) bolus that can be shaped in real-time by heating flexibly and repeatedly. This study investigated whether the SR bolus could be used as an ideal bolus, such as not changing of the beam characteristics and homogeneity through the bolus and high plasticity to adhere a patient in addition to real-time shapeable and reusability, in electron radiotherapy. Percentage depth doses (PDDs) and lateral dose profiles (LDPs) were obtained for 4, 6, and 9 MeV electron beams and were compared between the SR and conventional gel boluses. For the LDP at depth of 90% dose, the penumbra as lateral distance between the 80% and 20% isodose lines (P80-20) and the width of 90% dose level (r90) were compared. To evaluate adhesion, the air gap volume between the boluses and nose of a head phantom was evaluated on CT image. The dose profiles along the center axis for the 6 MeV electron beam with SR, gel, and virtual boluses (thickness = 5 mm) on the head phantom were also calculated for the irradiation of 200 monitor unit with a treatment planning system and the depth of the maximum dose (dmax) and maximum dose (Dmax) were compared. The PDDs,P80-20, andr90between the SR and gel boluses corresponded well (within 2%, 0.4 mm, and 0.7 mm, respectively). The air gap volumes of the SR and gel boluses were 3.14 and 50.35 cm3, respectively. Thedmaxwith SR, gel and virtual boluses were 8.0, 6.0, and 7.0 mm (no bolus: 12.0 mm), and theDmaxvalues were 186.4, 170.6, and 186.8 cGy, respectively. The SR bolus had the equivalent electron beam characteristics and homogeneity to the gel bolus and achieved excellent adhesion to a body surface, which can be used in electron radiotherapy as an ideal bolus.
  • Kenji Nakamura; Katsuya Okuhata; Mikoto Tamura; Masakazu Otsuka; Kazuki Kubo; Yoshihiro Ueda; Yasunori Nakamura; Kiyoshi Nakamatsu; Masao Tanooka; Hajime Monzen; Yasumasa Nishimura
    Journal of Applied Clinical Medical Physics Wiley 1526-9914 2021/08
  • Makoto Hosono; Mamoru Takenaka; Hajime Monzen; Mikoto Tamura; Masatoshi Kudo; Yasumasa Nishimura
    The British Journal of Radiology British Institute of Radiology 20210388 - 20210388 0007-1285 2021/07 
    Positron emission tomography (PET)/CT is an essential imaging modality for the management of various diseases. Increasing numbers of PET/CT examinations are carried out across the world and deliver benefits to patients; however, there are concerns about the cumulative radiation doses from these examinations in patients. Compared to the radiation exposure delivered by CT, there have been few reports on the frequency of patients with a cumulative effective radiation dose of ≥100 mSv from repeated PET/CT examinations. The emerging dose tracking system facilitates surveys on patient cumulative doses by PET/CT because it can easily wrap up exposure doses of PET radiopharmaceuticals and CT. Regardless of the use of a dose tracking system, implementation of justification for PET/CT examinations and utilisation of dose reduction measures are key issues in coping with the cumulative dose in patients. Despite all the advantages of PET/MRI such as eliminating radiation exposure from CT and providing good tissue contrast in MRI, it is expensive and cannot be introduced at every facility; thus, it is still necessary to utilise PET/CT with radiation reduction measures in most clinical situations.
  • Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka; Yasumasa Nishimura
    Radiation Measurements Elsevier BV 145 106608 - 106608 1350-4487 2021/07
  • KATSUYA OKUHATA; HAJIME MONZEN; MIKOTO TAMURA; KENJI MATSUMOTO; MASAKAZU OTSUKA; KAZUKI KUBO; YOSHIHIRO UEDA; TAKUYA UEHARA; HIROSHI DOI; KAZUKI ISHIKAWA; YASUMASA NISHIMURA
    Anticancer Research Anticancer Research USA Inc. 41 (6) 2925 - 2931 0250-7005 2021/06
  • Wada Y; Monzen H; Tamura M; Otsuka M; Inada M; Ishikawa K; Doi H; Nakamatsu K; Nishimura Y
    J Med Phys 46 (1) 7 - 15 2021/05 [Refereed]
     
    PURPOSE: We investigated the performance of the simplified knowledge-based plans (KBPs) in stereotactic body radiotherapy (SBRT) with volumetric-modulated arc therapy (VMAT) for lung cancer. MATERIALS AND METHODS: For 50 cases who underwent SBRT, only three structures were registered into knowledge-based model: total lung, spinal cord, and planning target volume. We performed single auto-optimization on VMAT plans in two steps: 19 cases used for the model training (closed-loop validation) and 16 new cases outside of training set (open-loop validation) for TrueBeam (TB) and Halcyon (Hal) linacs. The dosimetric parameters were compared between clinical plans (CLPs) and KBPs: CLPclosed, KBPclosed-TB and KBPclosed-Hal in closed-loop validation, CLPopen, KBPopen-TB and KBPopen-Hal in open-loop validation. RESULTS: All organs at risk were comparable between CLPs and KBPs except for contralateral lung: V5 of KBPs was approximately 3%-7% higher than that of CLPs. V20 of total lung for KBPs showed comparable to CLPs; CLPclosed vs. KBPclosed-TB and CLPclosed vs. KBPclosed-Hal: 4.36% ± 2.87% vs. 3.54% ± 1.95% and 4.36 ± 2.87% vs. 3.54% ± 1.94% (P = 0.54 and 0.54); CLPopen vs. KBPopen-TB and CLPopen vs. KBPopen-Hal: 4.18% ± 1.57% vs. 3.55% ± 1.27% and 4.18% ± 1.57% vs. 3.67% ± 1.26% (P = 0.19 and 0.27). CI95 of KBPs with both linacs was superior to that of the CLP in closed-loop validation: CLPclosed vs. KBPclosed-TB vs. KBPclosed-Hal: 1.32% ± 0.12% vs. 1.18% ± 0.09% vs. 1.17% ± 0.06% (P < 0.01); and open-loop validation: CLPopen vs. KBPopen-TB vs. KBPopen-Hal: 1.22% ± 0.09% vs. 1.14% ± 0.04% vs. 1.16% ± 0.05% (P ≤ 0.01). CONCLUSIONS: The simplified KBPs with limited number of structures and without planner intervention were clinically acceptable in the dosimetric parameters for lung VMAT-SBRT planning.
  • Kazuki Wakabayashi; Hajime Monzen; Mikoto Tamura; Kenji Matsumoto; Yoshiki Takei; Yasumasa Nishimura
    Journal of applied clinical medical physics 22 (4) 63 - 70 2021/04 
    PURPOSE: Skin collimation provides a sharp penumbra for electron beams, while the effect of bremsstrahlung from shielding materials is a concern. This phantom study was conducted to evaluate the safety and efficacy of a real-time variable shape rubber containing-tungsten (STR) that can be placed on a patient's skin. METHODS: Electron beam profiles were acquired with the STR placed on a water-equivalent phantom and low melting-point alloy (LMA) placed at the applicator according to commonly used procedures (field sizes: 20- and 40-mm diameters). Depth and lateral dose profiles for 6- and 12-MeV electron beams were obtained by Monte Carlo (MC) simulations and were benchmarked against film measurements. The width of the off-axis distance between 80% and 20% doses (P80-20 ) and the maximum dose were obtained from the lateral dose profiles. Bremsstrahlung emission was analyzed by MC simulations at the depth of maximum dose (R100 ). RESULTS: The depth dose profiles calculated by the MC simulations were consistently within 2% of the measurements. The P80-20 at R100 for 20- and 40-mm diameters were 4.0 mm vs. 7.6 mm (STR vs. LMA) and 4.5 mm vs. 9.2 mm, respectively, for the 6-MeV electron beam with 7.0-mm-thick STR, and 2.7 mm vs. 5.6 mm and 4.5 mm vs. 7.1 mm, respectively, for the 12-MeV electron beam with 12.0-mm-thick STR. A hotspot was not observed on the lateral dose profiles obtained with the STR at R100 . The bremsstrahlung emission under the region shielded by the STR was comparable to that obtained with the LMA, even though the STR was placed on the surface of the phantom. CONCLUSIONS: Skin collimator with STR provided superior dosimetric characteristics and comparable bremsstrahlung emission to LMA collimator at the applicator. STR could be a new tool for the safe and efficient delivery of electron radiotherapy.
  • Yoshihiro Kawai; Mikoto Tamura; Morikazu Amano; Takashi Kosugi; Hajime Monzen
    Anticancer research 41 (2) 919 - 925 2021/02 
    BACKGROUND/AIM: We investigated the dosimetric characteristics of electron radiotherapy for auricular keloid using real-time variable-shape tungsten rubber (STR). PATIENTS AND METHODS: For the first evaluation, STR was shaped into a rectangular irradiation field (3.0×5.0 cm2). In the next step, the STR was reshaped to fit the target (3.5×6.5 cm2) for the second evaluation. Percentage depth doses (PDDs) and lateral dose profiles were obtained with 6-MeV electron beams and compared with those of low-melting-point lead (LML). RESULTS: Compared to the LML on electron applicator, PDD differences were within 0.4 mm, while the penumbras as width of 20-80% dose levels were smaller (maximum reductions: 75.8% and 82.9% at first and second evaluations, respectively). The treatment process of shaping the STR, decision on output, and irradiation was completed within 45 min. CONCLUSION: Electron radiotherapy using STR for keloid can be performed with excellent dose distribution in a short time. First clinical experience found the STR is suitable for use in individualized and immediate electron radiotherapy.
  • Tatsuya Kamima; Yoshihiro Ueda; Jun-Ichi Fukunaga; Mikoto Tamura; Yumiko Shimizu; Yuta Muraki; Yasuo Yoshioka; Nozomi Kitamura; Yuya Nitta; Masakazu Otsuka; Hajime Monzen
    Reports of practical oncology and radiotherapy : journal of Greatpoland Cancer Center in Poznan and Polish Society of Radiation Oncology 26 (6) 849 - 860 2021 
    Background: The aim of this study was to investigate the performance of the RapidPlan (RP ) using models registered pseudostructures, and to determine how many structures are required for automatic optimization of volumetric modulated arc therapy (VMAT) for postoperative uterine cervical cancer. Materials and methods: Pseudo-structures around the PTV were retrospectively contoured for patients who had completed treatment at five institutions. For 22 common patients, plans were generated with a single optimization for models with two (RP_2), four (RP_4), and five (RP_5) registered structures, and the dosimetric parameters of these models were compared with a clinical plan with several optimizations. Results: Most dosimetric parameters showed no major differences between each RP model. In particular, the rectum Dmax, V50Gy, and V40Gy with RP_2, RP_4, and RP_5 were not significantly different, and were lower than those of the clinical plan. The average proportions of plans achieving acceptable criteria for dosimetric parameters were close to 100% for all models. Using RP_2, the average time for the VMAT planning was reduced by 88 minutes compared with the clinical plan. Conclusion: The RapidPlan model with two registered pseudo-structures could generate clinically acceptable plans while saving time.
  • Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka; Kohei Hanaoka; Yoshiyuki Asai
    Igaku butsuri : Nihon Igaku Butsuri Gakkai kikanshi = Japanese journal of medical physics : an official journal of Japan Society of Medical Physics 41 (1) 44 - 47 2021
  • Takaaki Ito; Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Kiyoshi Nakamatsu; Tomoko Harada; Tatsuya Fukui
    Nihon Hoshasen Gijutsu Gakkai zasshi 77 (1) 23 - 31 2021 
    PURPOSE: Knowledge-based planning (KBP) has disadvantages of high monitor unit (MU) and complex multi-leaf collimator (MLC) motion. We investigated the optimal aperture shape controller (ASC) level for the KBP to reduce these factors in volumetric modulated arc therapy (VMAT) for prostate cancer. METHODS: The KBP model was created based on 51 clinical plans (CPs) of patients who underwent the VMAT for prostate cancer. Another 10 CPs were selected randomly, and the KBPs with/without ASC, changed stepwise from very low (KBP-VL) to very high (KBP-VH), were performed with a single auto-optimization. The parameters of dose-volume histograms (DVHs) and MLC performance metrics were evaluated. We obtained the modulation complexity score for VMAT (MCSv), closed leaf score (CLS), small aperture score (SAS), leaf travel (LT), and total MU. RESULTS: The ASC did not affect the DVH parameters negatively. The following comparisons of MLC performance were obtained (KBP vs. KBP-VL vs. KBP-VH, respectively): 0.25 vs. 0.27 vs. 0.30 (MCSv), 0.19 vs. 0.18 vs. 0.16 (CLS), 0.50 vs. 0.45 vs. 0.40 (SAS10 mm), 0.73 vs. 0.68 vs. 0.63 (SAS20 mm), 768.35 mm vs. 671.50 mm vs. 551.32 mm (LT), and 672.87 vs. 642.36 vs. 607.59 (MU). There were significant differences between KBP and KBP-VH for MCSv and LT (p<0.05). CONCLUSIONS: The KBP using an ASC set to the very high level could reduce the complexity of MLC motion significantly more without deterioration of the DVH parameters compared with the KBP in VMAT for prostate cancer.
  • Yuya Yanagi; Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Yoshiki Takei; Kazuo Noma; Tetsuo Kida
    Nihon Hoshasen Gijutsu Gakkai zasshi 77 (2) 145 - 152 2021 
    PURPOSE: This study investigated whether real-time variable shape tungsten rubber (STR) could be applied for nail radiation protection in total skin electron beam (TSEB) therapy. METHODS: Simulated finger phantoms were made from syringes filled with physiological saline of volumes 5, 10, 20, and 30 ml (inner diameters of 14.1, 17.0, 21.7, and 25.3 mm, respectively). Gafchromic film was applied to the phantom, and lead (thickness 1-3 mm) or STR (thickness 1-4 mm) with an area of 4´1.5 cm was used to cover the film. A 6 MeV electron beam with an 8 mm acrylic board was then used to irradiate the phantom. The source-surface distance (SSD) was 444 cm, the field size was 36´36 cm at SSD of 100 cm without an electron applicator, and the monitor unit was 2000 MU. The shielding rates were obtained from the dose profiles. RESULTS: The mean values of the shielding rate values for all phantoms were 50.1, 97.6, and 98.7% for 1, 2, and 3 mm of lead, respectively, and -13.6, 53.9, 91.2, and 99.4% for 1, 2, 3, and 4 mm of STR, respectively. CONCLUSION: STR with a thickness of 4 mm had the same shielding properties as lead with a thickness of 3 mm, which was an approximately 100% shielding rate. STR could therefore be used in TSEB therapy instead of lead.
  • Min-Geon Choi; Martin Law; Do-Kun Yoon; Mikoto Tamura; Kenji Matsumoto; Masakazu Otsuka; Moo-Sub Kim; Shih-Kien Djeng; Hajime Monzen; Tae Suk Suh
    Radiation oncology (London, England) 15 (1) 273 - 273 2020/12 
    BACKGROUND: An O-ring gantry-type linear accelerator (LINAC) with a 6-MV flattening filter-free (FFF) photon beam, Halcyon, includes a reference beam that contains representative information such as the percent depth dose, profile and output factor for commissioning and quality assurance. However, because it does not provide information about the field size, we proposed a method to determine all field sizes according to all depths for radiation therapy using simplified sigmoidal curve fitting (SCF). METHODS: After mathematical definition of the SCF using four coefficients, the defined curves were fitted to both the reference data (RD) and the measured data (MD). For good agreement between the fitting curve and the profiles in each data set, the field sizes were determined by identifying the maximum point along the third derivative of the fitting curve. The curve fitting included the field sizes for beam profiles of 2 × 2, 4 × 4, 6 × 6, 8 × 8, 10 × 10, 20 × 20 and 28 × 28 cm2 as a function of depth (at 1.3, 5, 10 and 20 cm). The field size results from the RD were compared with the results from the MD using the same condition. RESULTS: All fitting curves show goodness of fit, R2, values that are greater than 0.99. The differences in field size between the RD and the MD were within the range of 0 to 0.2 cm. The smallest difference in the field sizes at a depth of 10 cm, which is a surface-to-axis distance, was reported. CONCLUSION: Application of the SCF method has been proven to accurately capture the field size of the preconfigured RD and the measured FFF photon beam data for the Halcyon system. The current work can be useful for beam commissioning as a countercheck methodology to determine the field size from RD in the treatment planning system of a newly installed Halcyon system and for routine quality assurance to ascertain the correctness of field sizes for clinical use of the Halcyon system.
  • Hajime Monzen; Mikoto Tamura; Yoshihiro Ueda; Jun-Ichi Fukunaga; Tatsuya Kamima; Yuta Muraki; Kazuki Kubo; Kiyoshi Nakamatsu
    Radiological physics and technology 13 (4) 327 - 335 2020/12 
    Dosimetric evaluation and variation assessment were performed with two knowledge-based planning (KBP) models created at different periods for volumetric-modulated arc therapy (VMAT) for prostate cancer at five institutes. The first and second models (F- and S-models) for KBP were created before April 2017 and April 2019, respectively. The S-model was created using feedback plans from the F-model. Dose evaluation was compared between the two models using the same two computed tomography (CT) datasets and structures. The evaluation metrics were the dose received by 95.0% and 2.0% of the planning target volume (PTV); dose-volume parameters to the rectum and bladder as V90, V80, and V50; and monitor unit (MU). Dosimetric variation was compared by exporting estimated dose-volume histograms for each model to the Model Analytics website and assessing the organ at risk volume. There were no dosimetric differences between the two models for PTV. The V50 of the rectum in the S-model had improved compared to that of the F-model (case I: 49.3 ± 15.6 and 43.5 ± 15.2 [p = 0.08]; case II: 42.5 ± 16.9 and 36.0 ± 15.6 [p = 0.138]). The differences in other parameters were within ± 1.8% between the rectum and the bladder. The MU was slightly higher in the S-model than in the F-model, and dosimetric variation was reduced to the rectum and bladder among all the institutes. The polished S-model for KBP could be used for standardization of the plan quality and sharing of KBP models in VMAT for prostate cancer.
  • Yoshihiro Ueda; Hajime Monzen; Jun-ichi Fukunaga; Shingo Ohira; Mikoto Tamura; Osamu Suzuki; Shoki Inui; Masaru Isono; Masayoshi Miyazaki; Iori Sumida; Kazuhiko Ogawa; Teruki Teshima
    Reports of Practical Oncology & Radiotherapy Elsevier BV 25 (6) 1023 - 1028 1507-1367 2020/11
  • Yoshiki Takei; Hajime Monzen; Mikoto Tamura; Hiroshi Doi; Yasumasa Nishimura
    Journal of applied clinical medical physics 21 (10) 151 - 157 2020/10 
    This study aimed to evaluate the possibility of reducing the imaging dose for image-guided radiotherapy by using planar kilovoltage orthogonal imaging and fiducial markers (kV-FM). We tested kilovoltage planar images under clinical imaging conditions for the pelvis (75 kVp, 200 mA, 50 ms) at a decreasing tube current (from 200 to 10 mA). Imaging doses were measured with a semiconductor detector. The visibility of the kV-FM, aspects of image quality (spatial resolution, low contrast resolution), and the resultant image registration reproducibility were evaluated using various shapes (folded, linear, tadpole-like) of fiducial markers containing 0.5% iron [Gold Anchor™ (GA); Naslund Medical AB, Huddinge, Sweden]. The GA phantom was created by placing these variously shaped GAs in an agar phantom. The imaging doses with 200 and 10 mA were approximately 0.74 and 0.04 mGy and they were correlated to the tube current (R2  = 0.999). Regardless of the marker's shape, the GA phantom ensured visibility even when the tube current was reduced to the minimum value (10 mA). The low contrast resolution was gradually decreased at less than 50 mA, but the spatial resolution did not change. Although the auto-registration function could not be used, manual-registration could be achieved with an accuracy of within 1 mm, even when the imaging dose was reduced to 1/20 of the clinical imaging condition for the pelvis. When using the GA as the fiducial marker, the imaging dose could be reduced to 1/20 of that used clinically while maintaining the accuracy of manual-registration using the kV-FM for image-guided radiotherapy of the pelvis.
  • Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka; Yasumasa Nishimura; Masahiko Okumura
    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) 77 121 - 126 2020/09 
    PURPOSE: This study performed the accurate measurements of beam profiles with a new rigid board, which was consistent with the supplied reference beam profiles (RBPs) for clinical Halcyon model. METHODS: Percentage depth doses (PDDs), lateral and diagonal dose profiles were measured and compared with RBPs. A water tank was set on the rigid board bridged Halcyon bore without sagging and source-to-surface distance was 90.0 cm. Field sizes were from 2.0 to 28.0 cm squares and depths of lateral and diagonal dose profiles were 1.3, 5.0, 10.0, and 20.0 cm. For the PDD, the depth of maximum dose (dmax), PDD value at depth of 10.0 cm (PDD10), and absolute dose difference (DD) between RBP and measured beam profiles (MBP) were evaluated. For lateral and diagonal dose profiles, DDs for the whole and divided areas (central, shoulder, and extended areas) defined by third derivative, and distance-to-agreement (DTA) in the penumbra area were evaluated. RESULTS: For PDDs, the differences of dmax and PDD10 and DD beyond the dmax were within 1.0 mm, 0.3%, and 1.0%, respectively. For lateral and diagonal dose profiles, the DDs reached approximately 5.0% in the whole area because of penumbra area, while the DDs in the central, shoulder, and extended areas were within 1.0%, 2.0%, and 1.0%, respectively. The DTAs in the penumbra area were within 0.8 mm. CONCLUSIONS: The supplied RBPs can be used clinically owing to the good agreement with the accurate MBPs with rigid board.
  • Yoshiki Takei; Takeshi Kamomae; Hajime Monzen; Takayoshi Nakaya; Kazuma Sugita; Kentaro Suzuki; Hiroshi Oguchi; Mikoto Tamura; Yasumasa Nishimura
    Physical and engineering sciences in medicine 43 (3) 1101 - 1111 2020/09 [Refereed]
     
    Containing 80% tungsten by weight, tungsten functional paper (TFP) is a radiation-shielding material that is lightweight, flexible, disposable, and easy to cut. Through experimental measurements and Monte Carlo simulations, we investigated the feasibility of using TFP as a bolus in electron beam radiotherapy. Commercial boluses of thickness 5 and 10 mm and from one to nine layers of TFPs (0.3-2.7 mm) were positioned on the surface of water-equivalent phantoms. The percentage depth dose curves and transverse dose profiles were measured using a 9-MeV electron beam from a clinical linear accelerator. Normalized to the value at the depth of maximum dose without bolus, the relative doses at the phantom surface for no bolus, 5-mm bolus, 10-mm bolus, 1 TFP, 3 TFPs, 6 TFPs, and 9 TFPs were 78%, 88%, 92%, 84%, 92%, 102%, and 112%, respectively; the therapeutic depths corresponding to a 90% dose level were 29.1 mm, 22.7 mm, 17.7 mm, 26.6 mm, 23.2 mm, 19.3 mm, and 15.8 mm, respectively. The TFP contributed to increased skin dose and provided dose uniformity within the target volume. However, it also resulted in increased lateral constriction and penumbra width. The results of Monte Carlo simulation produced similar trends as the experimental measurements. Our findings suggest that using TFP as a novel thin and flexible skin bolus for electron beam radiotherapy is feasible.
  • Mikoto Tamura; Kenji Matsumoto; Masakazu Otsuka; Hajime Monzen
    Physical and engineering sciences in medicine 43 (3) 947 - 957 2020/09 [Refereed]
     
    This study characterized the plan complexity of the dual-layer multi-leaf collimator (MLC) performance for volumetric modulated arc therapy (VMAT) in Halcyon. Plan complexity metrics were computed independently for each MLC layer (proximal and distal): modulation complexity score (MCS), plan averaged beam area, irregularity, and modulation (PA, PI, and PM) were obtained. These were investigated when weighted by proportions of the effective proximal MLC and distal MLC (MCSw, PAw, PIw, and PMw). Conventional plan complexity metrics for the effective 5.0 mm resolution MLC (MCS5, PA5, PI5, PM5), small aperture score (SAS), effective distal MLC score (EDS), and MU were also evaluated. Forty-five consecutive VMAT plans were analyzed retrospectively for treatment sites of the prostate, head and neck (HN), and other parts. The mean values of the metrics for proximal MLC and distal MLC were 0.310 and 0.245 (MCS), 71.09 cm2 and 55.92 cm2 (PA), 6.24 and 10.19 (PI), and 0.593 and 0.645 (PM), respectively. The degree of plan complexity in the distal MLC was larger than in the proximal MLC. The percentage of the effective distal MLC was higher than that of the proximal MLC (mean EDS = 0.555). The MCSw, PAw, PIw, and PMw showed significant differences between the prostate and HN groups like the PA5, PI5, and PM5; however, the MCS5 did not. Additionally, the MCS5 correlated with MU and PM5, while the MCSw correlated with SAS and PA5. The plan complexity for each MLC layer and subsequently combining these complexities might be useful to better understand the dual-layer MLC performance.
  • 咽頭癌に対する知識ベース強度変調回転放射線治療計画
    植原 拓也; 門前 一; 田村 命; 石川 一樹; 土井 啓至; 西村 恭昌
    頭頸部癌 (一社)日本頭頸部癌学会 46 (2) 162 - 162 1349-5747 2020/07
  • Kenta Kijima; Anchali Krisanachinda; Panya Pasawang; Kohei Hanaoka; Hajime Monzen; Yasumasa Nishimura
    RADIATION PHYSICS AND CHEMISTRY PERGAMON-ELSEVIER SCIENCE LTD 172 0969-806X 2020/07 
    Background/Aim: A newly introduced tungsten-containing rubber is a potentially useful shielding material against radiation from radionuclides because it is lead-free, containing as much as 90% fine tungsten powder by weight. This study aimed to investigate the shielding efficiency and usefulness of tungsten-containing rubber against radiation from radionuclides. Materials and Methods: Shielding efficiency due to different thickness of tungsten-containing rubber was measured for the following radionuclides mostly used in nuclear medicine such as Tc-99m, I-131, F-18 and Ga-68 then the linear attenuation coefficient (mu) and half value layer (HVL) were calculated. The assessment of energy spectrum with and without tungsten-containing rubber of half value layer were evaluated for Tc-99m, I-131, F-18 and Ga-68 . Results: The mu of Tc-99m, I-131, F-18 and Ga-68 were 1.357 mm(-1), 0.096 mm(-1), 0.076 mm(-1), and 0.063 mm(-1), respectively. The HVL for Tc-99m, I-131, F-18 and Ga-68 were 0.51 mm, 7.22 mm, 9.12 mm, and 11.00 mm, respectively. By energy spectrum analysis, decrease in the detection counts were confirmed regardless of the radionuclides and the energy peaks. Conclusion: Tungsten-containing rubber has adequate radiation shielding efficiency for radionuclides. The protection with tungsten-containing rubber of radionuclides in consideration of HVL, the half-life, energy and activity are safe and efficient, and could, therefore, be employed as shield in clinical site.
  • Takuya Uehara; Hajime Monzen; Mikoto Tamura; Kazuki Ishikawa; Hiroshi Doi; Yasumasa Nishimura
    Journal of radiation research 61 (3) 499 - 505 2020/05 [Refereed]
     
    The present study aimed to evaluate whether knowledge-based plans (KBP) from a single optimization could be used clinically, and to compare dose-volume histogram (DVH) parameters and plan quality between KBP with (KBPCONST) and without (KBPORIG) manual objective constraints and clinical manual optimized (CMO) plans for pharyngeal cancer. KBPs were produced from a system trained on clinical plans from 55 patients with pharyngeal cancer who had undergone intensity-modulated radiation therapy or volumetric-modulated arc therapy (VMAT). For another 15 patients, DVH parameters of KBPCONST and KBPORIG from a single optimization were compared with CMO plans with respect to the planning target volume (D98%, D50%, D2%), brainstem maximum dose (Dmax), spinal cord Dmax, parotid gland median and mean dose (Dmed and Dmean), monitor units and modulation complexity score for VMAT. The Dmax of spinal cord and brainstem and the Dmed and Dmean of ipsilateral parotid glands were unacceptably high for KBPORIG, although the KBPCONST DVH parameters met our goal for most patients. KBPCONST and CMO plans produced comparable DVH parameters. The monitor units of KBPCONST were significantly lower than those of the CMO plans (P < 0.001). Dose distribution of the KBPCONST was better than or comparable to that of the CMO plans for 13 (87%) of the 15 patients. In conclusion, KBPORIG was found to be clinically unacceptable, while KBPCONST from a single optimization was comparable or superior to CMO plans for most patients with head and neck cancer.
  • Hiroshi Doi; Mikoto Tamura; Kiyoshi Nakamatsu; Hajime Monzen; Yasumasa Nishimura
    Anticancer research 40 (4) 1981 - 1988 2020/04 [Refereed]
     
    BACKGROUND/AIM: We aimed to elucidate the pathological findings following acute and late re-irradiation in a preclinical model. MATERIALS AND METHODS: Mice were divided into five treatment groups: sham-irradiation (Sham-IR), 10-12 Gy (Single IR Acute), 15 Gy (Single IR Late), 15 Gy followed by 10-12 Gy re-irradiation 7 days later (Re-IR Acute), or 15 Gy followed by 10-12 Gy re-irradiation 12 weeks later (Re-IR Late). Mice were sacrificed after either single irradiation or re-irradiation for pathological assessment. RESULTS: The Re-IR Late group had significantly lower numbers of crypts with apoptotic cells than those observed in mice in the Single IR Acute group. There were no significant differences between the Single IR Acute and re-IR Acute groups in cell proliferation or in a crypt survival assay. CONCLUSION: Re-irradiation with a long interval after the first irradiation may cause similar acute biological effects in normal intestine as observed following irradiation without re-irradiation.
  • Hiroyuki Kosaka; Hajime Monzen; Morikazu Amano; Mikoto Tamura; Shota Hattori; Yuki Kono; Yasumasa Nishimura
    European journal of radiology 124 108814 - 108814 2020/03 [Refereed]
     
    PURPOSE: We investigated whether a tungsten functional paper (TFP) shield and/or organ-based tube current modulation (TCM) can reduce the dose to the eye lens. MATERIALS AND METHODS: All scans were performed using our routine head examination protocol (spiral acquisition, 120 kVp, noise Index 3.5) with an anthropomorphic head phantom. The dose reduction rate was measured by the following methods with a scintillation fiber optic dosimeter: (a) without any dose reduction techniques (Original scan), (b) TFP shield, (c) TCM, and (d) TFP shield plus TCM. Image noise and CT number were obtained and compared between the three groups. In addition, image noise in method (d) was measured with varying distances between the TFP shield and eye lens. RESULTS: The reduction rates using TFP shield, TCM, and TFP shield plus TCM compared with those for the Original scan were 17.8 %, 13.6 %, and 27.7 %, respectively. Image noise (mean ± standard deviation) in the anterior region for the Original scan, TFP shield, TCM, and TFP shield plus TCM were 4.1 ± 0.2, 4.6 ± 0.2, 4.4 ± 0.3, and 5.0 ± 0.2, while the CT numbers were 19.3 ± 0.8, 23.8 ± 0.8, 19.6 ± 0.8, and 24.1 ± 0.8, respectively. Increasing the distance between the TFP and the eye significantly decreased the CT number when using TFP shield plus TCM (p < .05). CONCLUSION: TFP shield plus TCM reduced the dose to the eye lens in head CT while maintaining image quality with an air gap between the TFP and skin surface.
  • Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Kazuki Kubo; Yoshihiro Ueda; Tatsuya Kamima; Masahiro Inada; Hiroshi Doi; Kiyoshi Nakamatsu; Yasumasa Nishimura
    Journal of Medical Physics Medknow 45 (2) 71 - 71 0971-6203 2020 
    PURPOSE: This study aimed to investigate the influence of cleaned-up knowledge-based treatment planning (KBP) models on the plan quality for volumetric-modulated arc therapy (VMAT) of prostate cancer. MATERIALS AND METHODS: Thirty prostate cancer VMAT plans were enrolled and evaluated according to four KBP modeling methods as follows: (1) model not cleaned - trained by fifty other clinical plans (KBPORIG); (2) cases cleaned by removing plans that did not meet all clinical goals of the dosimetric parameters, derived from dose-volume histogram (DVH) (KBPC-DVH); (3) cases cleaned outside the range of ±1 standard deviation through the principal component analysis regression plots (KBPC-REG); and (4) cases cleaned using both methods (2) and (3) (KBPC-ALL). Rectal and bladder structures in the training models numbered 34 and 48 for KBPC-DVH, 37 and 33 for KBPC-REG, and 26 and 33 for KBPC-ALL, respectively. The dosimetric parameters for each model with one-time auto-optimization were compared. RESULTS: All KBP models improved target dose coverage and conformity and provided comparable sparing of organs at risks (rectal and bladder walls). There were no significant differences in plan quality among the KBP models. Nevertheless, only the KBPC-ALL model generated no cases of >1% V78 Gy (prescribed dose) to the rectal wall, whereas the KBPORIG, KBPC-DVH, and KBPC-REG models included two, four, and three cases, respectively, which were difficult to overcome with KBP because the planning target volume (PTV) and rectum regions overlapped. CONCLUSIONS: The cleaned-up KBP model based on DVH and regression plots improved plan quality in the PTV-rectum overlap region.
  • Kenji Matsumoto; Mikoto Tamura; Masakazu Otsuka; Kazuki Wakabayashi; Kenta Kijima; Hajime Monzen
    Nihon Hoshasen Gijutsu Gakkai zasshi 76 (12) 1248 - 1255 2020 
    PURPOSE: This study investigated the dosimetric characteristics of electron beams shaped with a real-time shapeable tungsten-containing rubber (STR) collimator. METHODS: Circular irradiation fields of 40 mm diameter were shaped using STR or low melting-point alloy (LMA) placed on the electron applicator. The STR heated with approximately 70-degree warm water was molded into the template bottom of the applicator. Percent depth doses (PDDs) and lateral dose profiles of 6 and 12 MeV electron beams were measured and compared between STR and LMA. For the PDDs, the depths of maximum dose (dmax), 90% dose (d90), and 80% dose (d80) were evaluated. For the lateral dose profiles, penumbra as the width of the off-axis distance from 80% to 20% doses and treatment diameter covering over 90% dose were evaluated at the surface, dmax, d90, and d80. The transmission of the STR was also investigated at thicknesses fit to electron applicator for 6 and 12 MeV electron beams. RESULTS: The STR was softened with 70-degree warm water. Therefore, it was easy to mold it and attach the applicator. The PDDs and penumbras at the surface, dmax, d90, and d80 for the STR were almost equal to those for the LMA with 6 and 12 MeV electron beams. The treatment diameters covering over 90% dose for the irradiation fields with 40 mm diameter at dmax (LMA vs. STR) were 20.9 vs. 21.1 mm and 19.2 vs. 18.4 mm for 6 and 12 MeV electron beams, respectively. The transmission of the STR was almost same as that of LMA. CONCLUSIONS: The dosimetric characteristics of the STR on the electron applicator were almost same as those of the LMA. The heated STR was shaped easily, flexibly, and immediately. The STR can be used as a substitute for LMA in electron radiotherapy.
  • Inoue, E; Doi, H; Monzen, H; Tamura, M; Inada, M; Ishikawa, K; Nakamatsu, K; Nishimura, Y
    In vivo Anticancer Research USA Inc. 34 (3) 1095 - 1101 0258-851X 2020 [Refereed]
  • Kenji Matsumoto; Masakazu Otsuka; Mikoto Tamura; Hajime Monzen; Masahiko Okumura
    Nihon Hoshasen Gijutsu Gakkai zasshi 76 (4) 339 - 345 2020 [Refereed]
     
    PURPOSE: Novel linac improvements in speed of gantry, collimator, leaf and dose rate may increase the time-efficiency of volumetric modulated arc therapy (VMAT) delivery, however remains to be investigated. In this study, a fast-rotating O-ring linac (Halcyon) with fast moving leaves is compared with a general linac (TrueBeam: TB) in terms of plan quality for VMAT of C-shape, prostate, multi target and, head and neck (H&N) cases from AAPM TG-119. MATERIALS AND METHODS: For the four test cases, VMAT planning was performed using single to four-arc VMAT on a Halcyon and using single to three-arc VMAT on a TrueBeam. Same conditions for optimization were used in each test case. Target coverage metrics and organ at risks (OAR) dose were compared. Monitor unit (MU) and irradiation time in each plan were also compared. RESULTS: In all cases, single-arc plans of Halcyon were inferior to TB plans on dose objectives. Conformity index (CI) to outer target of C-shape case was better for Halcyon (1-arc: 1.242, 2-arc: 1.202, 3-arc: 1.198, 4-arc: 1.181) than for TB (1-arc: 1.247, 2-arc: 1.211, 3-arc: 1.211) except to single arc. D5 (Gy) of core for C-shape case was better for halcyon (1-arc: 23.29, 2-arc: 21.01, 3-arc: 20.64, 4-arc: 20.47) than for TB (1-arc: 24.04, 2-arc: 22.94, 3-arc: 23.04). Calculated MU was smaller for Halcyon than for TB. In addition, Halcyon is more faster than TB because mechanical movements were improved. CONCLUSION: For VMAT plan in each case, Halcyon as well or better at the plan quality of two or three arcs on TB while reducing the delivery time.
  • Kenta Kijima; Anchali Krisanachinda; Mikoto Tamura; Hajime Monzen; Yasumasa Nishimura
    Health physics 2019/12 [Refereed]
     
    This study investigates whether a novel tungsten-containing rubber shield could be used as substitute shielding material in interventional radiology to reduce the occupational exposure of operators to scattered radiation from a patient. The tungsten-containing rubber is a lead-free radiation-shielding material that contains as much as 90% tungsten powder by weight. Air kerma rates of scattered radiation from solid-plate phantoms, simulating a patient, were measured with a semiconductor dosimeter at the height of the operator's eye (1,600 mm from the floor), chest (1,300 mm), waist (1,000 mm), and knee (600 mm) with and without tungsten-containing rubber shielding (1-5 mm thickness). The tungsten-containing rubber and a commercial shielding material (RADPAD) were affixed onto the phantom on the operator's side, and reductions in air kerma rates were compared. Reduction rates for tungsten-containing rubber shielding with thicknesses of 1, 2, 3, 4, and 5 mm at each height level were as follows: 70.37 ± 0.40%, 72.17 ± 0.29%, 72.95 ± 0.31%, 72.58 ± 0.35%, and 73.63 ± 0.63% at eye level; 76.36 ± 0.19%, 77.13 ± 0.10%, 77.36 ± 0.14%, 77.62 ± 0.25%, and 77.66 ± 0.14% at chest level; 67.78 ± 0.31%, 68.12 ± 0.19%, 68.88 ± 0.28%, 68.97 ± 0.14%, and 68.85 ± 0.45% at waist level; and 0.14 ± 0.94%, 0.72 ± 0.56%, 1.08 ± 0.74%, 1.77 ± 0.80%, and 1.79 ± 1.82% at knee level, respectively. Reduction rates with RADPAD were 61.80 ± 0.67%, 60.33 ± 0.61%, 64.70 ± 0.25%, and 0.14 ± 0.66% at eye, chest, waist, and knee levels, respectively. The shielding ability of the 1 mm tungsten-containing rubber was superior to that of RADPAD. The tungsten-containing rubber could be employed to minimize an operator's radiation exposure instead of the commercial shielding material in interventional radiology.
  • Dose distribution comparison in volumetric-modulated arc therapy plans for head and neck cancers with and without an external body contour extended technique.
    Tanaka Y; Monzen H; Matsumoto K; Inomata S; Fuse T
    Rep Pract Oncol Radiother. 24 (6) 576 - 584 2019/11 [Refereed]
  • Ueda Y; Miyazaki M; Sumida I; Ohira S; Tamura M; Monzen H; Tsuru H; Inui S; Isono M; Ogawa K; Teshima T
    Acta oncologica (Stockholm, Sweden) 1 - 10 0284-186X 2019/11 [Refereed]
  • Kubo K; Monzen H; Shimomura K; Matsumoto K; Sato T; Tamura M; Nakamatsu K; Ishii K; Kawamorita R
    Reports of practical oncology and radiotherapy : journal of Greatpoland Cancer Center in Poznan and Polish Society of Radiation Oncology 24 (6) 600 - 605 1507-1367 2019/11 [Refereed]
     
    AIM: To evaluate the success of a patient-specific intensity modulated radiation therapy (IMRT) quality assurance (QA) practice for prostate cancer patients across multiple institutions using a questionnaire survey. BACKGROUND: The IMRT QA practice involves different methods of dose distribution verification and analysis at different institutions. MATERIALS AND METHODS: Two full-arc volumetric modulated arc therapy (VMAT) plan and 7 fixed-gantry IMRT plan with DMLC were used for patient specific QA across 22 institutions. The same computed tomography image and structure set were used for all plans. Each institution recalculated the dose distribution with fixed monitor units and without any modification. Single-point dose measurement with a cylindrical ionization chamber and dose distribution verification with a multi-detector or radiochromic film were performed, according to the QA process at each institution. RESULTS: Twenty-two institutions performed the patient-specific IMRT QA verifications. With a single-point dose measurement at the isocenter, the average difference between the calculated and measured doses was 0.5 ± 1.9%. For the comparison of dose distributions, 18 institutions used a two or three-dimensional array detector, while the others used Gafchromic film. In the γ test with dose difference/distance-to-agreement criteria of 3%-3 mm and 2%-2 mm with a 30% dose threshold, the median gamma pass rates were 99.3% (range: 41.7%-100.0%) and 96.4% (range: 29.4%-100.0%), respectively. CONCLUSION: This survey was an informative trial to understand the verification status of patient-specific IMRT QA measurements for prostate cancer. In most institutions, the point dose measurement and dose distribution differences met the desired criteria.
  • Kubo K; Monzen H; Ishii K; Tamura M; Nakasaka Y; Kusawake M; Kishimoto S; Nakahara R; Matsuda S; Nakajima T; Kawamorita R
    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) 67 132 - 140 1120-1797 2019/11 [Refereed]
     
    PURPOSE: This study aimed to clarify the inter-planner variation of plan quality in knowledge-based plans created by nine planners. METHODS: Five hypofractionated prostate-only (HPO) volumetric modulated arc therapy (VMAT) plans and five whole-pelvis (WP) VMAT plans were created by each planner using a knowledge-based planning (KBP) system. Nine planners were divided into three groups of three planners each: Senior, Junior, and Beginner. Single optimization with only priority modification for all objectives was performed to stay within the dose constraints. The coefficients of variation (CVs) for dosimetric parameters were evaluated, and a plan quality metric (PQM) was used to evaluate comprehensive plan quality. RESULTS: Lower CVs (<0.05) were observed at dosimetric parameters in the planning target volume for both HPO and WP plans, while the CVs in the rectum and bladder for WP plans (<0.91) were greater than those for HPO plans (<0.17). The PQM values of HPO plans for Cases1-5 (average ± standard deviation) were 41.2 ± 7.1, 40.9 ± 5.6, and 39.9 ± 4.6 in the Senior, Junior, and Beginner groups, respectively. For the WP plans, the PQM values were 51.9 ± 6.3, 47.5 ± 4.3, and 40.0 ± 6.6, respectively. The number of clinically acceptable HPO and WP plans were 13/15 and 11/15 in the Senior group, 13/15 and 10/15 plans in the Junior group, and 8/15 and 2/15 plans in the Beginner group, respectively. CONCLUSION: Inter-planner variation in the plan quality with RapidPlan remains, especially for the complicated VMAT plans, due to planners' heuristics.
  • Monzen H; Tamura M; Kijima K; Otsuka M; Matsumoto K; Wakabayashi K; Choi MG; Yoon DK; Doi H; Akiyama H; Nishimura Y
    Physica Medica: European Journal of Medical Physics Elsevier BV 66 29 - 35 1120-1797 2019/10 [Refereed]
  • Tatsuya Kamima; Yoshihiro Ueda; Jun-Ichi Fukunaga; Yumiko Shimizu; Mikoto Tamura; Kazuki Ishikawa; Hajime Monzen
    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) 64 174 - 181 1120-1797 2019/08 
    PURPOSE: The aim of this study was to investigate whether additional manual objectives are necessary for the RapidPlan (RP) with a single optimization. We conducted multi-institutional comparisons of plan quality for head and neck cancer (HNC) using the models created at each institute. METHODS: The ability of RP to produce acceptable plans for dose requirements was evaluated in two types of oropharynx cancers at five institutes in Japan. Volumetric modulated arc therapy plans created without (RP plan) and with additional manual objectives (M-RP plan) were compared in terms of planning target volume (PTV), brainstem, spinal cord and parotid glands in dosimetric parameters. RESULTS: There were no major dosimetric PTV differences between RP and M-RP plans. For the brainstem and spinal cord in the RP plans, only 40% and 30% of the plans achieved the dose requirements, while the M-RP plans with upper objective added to volume 0% at all institutes achieved them for 90% of the plans. For the L-parotid gland, there was no difference in the RP and M-RP plans (both were 40%) in achieving the acceptable criteria. For the R-parotid gland, 60% and 80% of the RP and M-RP plans achieved the constraint criteria, and in terms of the achievement rate, the RP plans were relatively high. CONCLUSIONS: M-RP plans did not require reoptimization; only an upper objective was needed for the brainstem and spinal cord, while the parotid gland dose was reduced in both RP plans with the auto generated line objectives alone.
  • Yoshiki Takei; Hajime Monzen; Kenji Matsumoto; Kohei Hanaoka; Mikoto Tamura; Yasumasa Nishimura
    BJR|Open British Institute of Radiology 1 (1) 20190028 - 20190028 2019/07 
    Objective: The aim of this study was to investigate low-dose kilovoltage cone-beam CT (kV-CBCT) for image-guided radiotherapy, with a particular focus on the accuracy of image registration with low-dose protocols. Methods: Imaging doses were measured with a NOMEX semiconductor detector positioned at the front of head, thorax, and pelvis human body phantoms while kV-CBCT scans were acquired at different tube currents. Aspects of image quality (spatial resolution, noise, uniformity, contrast, geometric distortion, and Hounsfield unit sensitivity) and image registration accuracy using bone and soft tissue were evaluated. Results: With preset and the lowest tube currents, the imaging doses were 0.16 and 0.08 mGy, 5.29 and 2.80 mGy, and 18.23 and 2.69 mGy for head, thorax, and pelvis, respectively. Noise was the only quality aspect directly dependent on tube current, being increased by 1.5 times with a tube current half that of the preset in head and thorax, and by 2.2 times with a tube current 1/8 of the preset in the pelvis. Accurate auto-bone matching was performed within 1 mm at the lowest tube current. The auto-soft tissue matching could not be performed with the lowest tube current; however, manual-soft tissue matching could still be performed within 2 mm or less. Conclusion: Noise was the only image quality aspect dependent on the imaging dose. Auto-bone and manual-soft tissue matching could still be performed at the lowest imaging dose. Advances in knowledge: When optimizing kV-CBCT imaging dose, the impact on bone and soft tissue image registration accuracy should be evaluated.
  • Hirata M; Hanaoka K; Matsumoto K; Tamura M; Okumura M; Monzen H
    Physica medica 63 19 - 24 1120-1797 2019/07 [Refereed]
     
    PURPOSE: The influence of the offset distance from treatment target to gantry isocenter (GIC) on the dosimetric parameter and irradiation time was investigated using TomoTherapy METHODS: The reference position was defined as the centers of both the I'mRT phantom and planning target volume (PTV) with a spherical of 4 cm diameter aligned with the GIC. The dose calculations were performed in two offset methods with 2 and 12 Gy/fr, Method 1. The PTV was moved from 0.0 to 12.5 cm along the RL direction and -5.0 to 5.0 cm along the AP direction (PTV offset), Method 2. The phantom was moved from 0.0 to -7.5 cm along the RL direction and -5.0 to 5.0 cm along the AP direction (Phantom offset). The maximum, minimum and mean doses, homogeneity index, conformity index, irradiation time, and monitor unit were compared. RESULTS: The irradiation times increased with increasing PTV offset. The increases in the irradiation time were 54.4% and 40.8% at PTV offsets of 12.5 cm along the RL direction for 2 and 12 Gy/fr, while the increases were 20.1% and 15.0% at a PTV offset of 5.0 cm along the AP direction. An increased irradiation time was not observed for the phantom offset. The offset didn't affect the other parameters. CONCLUSIONS: The PTV location offset of ≥5 cm from the GIC along the RL and AP axes increased the irradiation time; therefore, the PTV should be aligned with the GIC as much as possible to reduce the irradiation time on TomoTherapy.
  • Otsuka M; Monzen H; Ishikawa K; Doi H; Matsumoto K; Tamura M; Nishimura Y
    In vivo INT INST ANTICANCER RESEARCH 33 (4) 1271 - 1277 0258-851X 2019/07 [Refereed]
     
    Background/Aim: The parotid glands in the head and neck are organs at risks (OARs) adjacent to high dose region and dose of OARs might be increased during the course of radiotherapy. The influence factors of the dose distribution for the parotid glands were investigated in terms of weight loss and mandibular rotation for head and neck cancers treated with volumetric modulated arc therapy (VMAT). Patients and Methods: Ten oropharyngeal cancer patients (OPC) who underwent VMAT were enrolled. The dose volume histogram (DVH) parameters of the parotid glands and planning target volume (PTV) were compared between the planning computed tomography (CT) and the on board imager (OBI) at 1, 5, 10, 15, and 20 fractions. Results: The variation of dose distribution in PTV was not observed in both factors. The relationship between the mandibular rotation and dose difference for the right and left parotid glands (linear regression, r(2)=0.1577 and -0.689) showed a slighty stronger correlation with dose difference than the weight loss (linear regression, r(2)=-0.079 and -0.547). Conclusion: The mandibular rotation tends to have a large influence on dose distribution of the parotid glands for head and neck cancers treated with VMAT.
  • Kijima K; Krisanachinda A; Tamura M; Nishimura Y; Monzen H
    Anticancer research 39 (6) 2799 - 2804 0250-7005 2019/06 [Refereed]
  • Kawai Y; Tamura M; Amano M; Kamomae T; Monzen H
    Anticancer research 39 (6) 2839 - 2843 0250-7005 2019/06 [Refereed]
  • 舌癌画像誘導高線量率組織内照射における下顎骨遮蔽材の腫瘍や顎骨線量への影響
    秋山 広徳; 吉田 謙; 山崎 秀哉; 武中 正; 隅田 伊織; 門前 一; 宮尾 守; 増井 浩二; 辻本 豊; 奥村 大樹; 吾妻 宏紀; 新保 大樹; 吉岡 裕人; 古妻 理之; 田中 英一; 小滝 真也; 清水谷 公成
    頭頸部癌 (一社)日本頭頸部癌学会 45 (2) 245 - 245 1349-5747 2019/05
  • Kosaka H; Monzen H; Matsumoto K; Tamura M; Nishimura Y
    Health physics Ovid Technologies (Wolters Kluwer Health) 116 (5) 625 - 630 0017-9078 2019/05 [Refereed]
  • Otsuka M; Monzen H; Matsumoto K; Tamura M; Inada M; Kadoya N; Nishimura Y
    PloS one 14 (11) e0225965  2019 [Refereed]
  • Moo-Sub Kim; Han-Back Shin; Min-Geon Choi; Hajime Monzen; Jae Goo Shim; Tae Suk Suh; Do-Kun Yoon
    Nuclear Engineering and Technology 2019 [Refereed]
  • Doi, Hiroshi; Nakamatsu, Kiyoshi; Anami, Shimpei; Fukuda, Kohei; Inada, Masahiro; Tatebe, Hitoshi; Ishikawa, Kazuki; Kanamori, Shuichi; Monzen, Hajime; Nishimura, Yasumasa
    IN VIVO INT INST ANTICANCER RESEARCH 33 (1) 195 - 201 0258-851X 2019/01 [Refereed]
     
    Aim: This study aimed to identify prognostic factors for response to whole-brain radiotherapy (WBRT) in patients with brain metastases (BMs) from non-small cell lung cancer (NSCLC). Patients and Methods: This study retrospectively evaluated 100 patients who underwent WBRT for BMs from NSCLC between December 2012 and October 2017. Clinical factors were tested for associations with overall survival after WBRT. Results: The median follow-up time was 134 days (range=14-1,395 days), the median survival time was 143 days, and the 1-year survival rate was 30.4%. Univariate and multivariate analyses revealed that better survival was independently associated with expression of programmed death-ligand 1 (PD-L1), no previous treatment for BMs, no extracranial disease, and a neutrophil-to-lymphocyte ratio (NLR) of <5.0. Conclusion: A low NLR and positive PD-L1 expression independently predict better prognosis in patients with BMs from NSCLC after WBRT. These findings suggest that the potential immune response may influence survival among patients with BMs.
  • Matsumoto K; Saika T; Shimomura K; Hanaoka K; Tamura M; Monzen H; Hayakawa M; Okumura M
    Nihon Hoshasen Gijutsu Gakkai zasshi 75 (2) 167 - 173 0369-4305 2019 [Refereed]
  • 花岡 宏平; 奥村 雅彦; 門前 一
    医学物理 (公社)日本医学物理学会 38 (2) 85 - 88 1345-5354 2018/10
  • Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Kazuki Kubo; Masakazu Otsuka; Masahiro Inada; Hiroshi Doi; Kazuki Ishikawa; Kiyoshi Nakamatsu; Iori Sumida; Hirokazu Mizuno; Do-Kun Yoon; Yasumasa Nishimura
    Radiation oncology (London, England) 13 (1) 163 - 163 2018/08 [Refereed]
     
    BACKGROUND: This study clarified the mechanical performance of volumetric modulated arc therapy (VMAT) plans for prostate cancer generated with a commercial knowledge-based treatment planning (KBP) and whether KBP system could be applied clinically without any major problems with mechanical performance. METHODS: Thirty consecutive prostate cancer patients who underwent VMAT using extant clinical plans were evaluated. The mechanical performance and dosimetric accuracy of the single optimized KBPs, which were trained with other 51 clinical plans, were compared with the clinical plans. The mechanical performance metrics were mean field area (MFA), mean asymmetry distance (MAD), cross-axis score (CAS), closed leaf score (CLS), small aperture score (SAS), leaf travel (LT), modulation complexity score (MCSv), and monitor unit (MU). The γ passing rates were evaluated with ArcCheck and EBT3 film. RESULTS: The mean mechanical performance metrics (clinical plan vs. KBP) were as follows: 18.28 cm2 vs. 17.25 cm2 (MFA), 21.08 mm vs. 20.47 mm (MAD), 0.54 vs. 0.55 (CAS), 0.040 vs. 0.051 (CLS), 0.20 vs. 0.23 (SAS5mm), 458.5 mm vs. 418.8 mm (LT), 0.27 vs. 0.27 (MCSv), and 618.2 vs. 622.1 (MU), respectively. Significant differences were observed for CLS and LT. The average γ passing rates (clinical plan vs. KBP) were as follows: 99.0% vs. 99.1% (3%/3 mm) and 92.4% vs. 92.5% (2%/2 mm) with ArcCHeck, and 99.5% vs. 99.4% (3%/3 mm) and 95.2% vs. 95.4% (2%/2 mm) with EBT3 film, respectively. CONCLUSIONS: The KBP used lower multileaf collimator (MLC) travel and more closed or small MLC apertures than the clinical plan. The KBP system of VMAT for the prostate cancer was acceptable for clinical use without any major problems.
  • Kijima K; Monzen H; Matsumoto K; Tamura M; Nishimura Y
    Anticancer research 38 (7) 3919 - 3927 0250-7005 2018/07 [Refereed]
     
    BACKGROUND/AIM: A newly-introduced tungsten containing rubber (TCR) is a potentially useful shielding material in electron radiotherapy because it is lead-free, containing as much as 90% fine tungsten powder by weight. This study aimed to investigate the shielding ability of TCR against electron beams. MATERIALS AND METHODS: Transmission of TCR was measured for energies of 4, 6, 9 and 12 MeV. Dose profiles were measured to compare the TCR and lead. The electron backscatter factor (EBF) was also compared. RESULTS: The transmission of equivalent thickness for 4, 6, 9 and 12 MeV with TCR (0.78%, 1.34%, 2.16% and 3.08%, respectively) were lower than that with lead (0.81%, 1.44%, 2.19% and 3.16%, respectively) (p<0.05). The dose profiles were not significantly different for TCR and lead. The EBF with TCR was up to 17% lower than that with lead. CONCLUSION: TCR has adequate radiation shielding ability for electron beams and could be employed instead of lead.
  • Shinichi Nakayama; Hajime Monzen; Yuichi Onishi; Soichiro Kaneshige; Ikuo Kanno
    Physica Medica Associazione Italiana di Fisica Medica 50 52 - 58 1724-191X 2018/06 [Refereed]
     
    The purpose of this study was a dosimetric validation of the Vero4DRT for brain stereotactic radiotherapy (SRT) with extremely small fields calculated by the treatment planning system (TPS) iPlan (Ver.4.5.1 algorithm XVMC). Measured and calculated data (e.g. percentage depth dose [PDD], dose profile, and point dose) were compared for small square fields of 30 × 30, 20 × 20, 10 × 10 and 5 × 5 mm2 using ionization chambers of 0.01 or 0.04 cm3 and a diamond detector. Dose verifications were performed using an ionization chamber and radiochromic film (EBT3 the equivalent field sizes used were 8.2, 8.7, 8.9, 9.5, and 12.9 mm2) for five brain SRT cases irradiated with dynamic conformal arcs. The PDDs and dose profiles for the measured and calculated data were in good agreement for fields larger than or equal to 10 × 10 mm2 when an appropriate detector was chosen. The dose differences for point doses in fields of 30 × 30, 20 × 20, 10 × 10 and 5 × 5 mm2 were +0.48%, +0.56%, −0.52%, and +11.2% respectively. In the dose verifications for the brain SRT plans, the mean dose difference between the calculated and measured doses were −0.35% (range, −0.94% to +0.47%), with the average pass rates for the gamma index under the 3%/2 mm criterion being 96.71%, 93.37%, and 97.58% for coronal, sagittal, and axial planes respectively. The Vero4DRT system provides accurate delivery of radiation dose for small fields larger than or equal to 10 × 10 mm2.
  • Masahiro Inada; Hajime Monzen; Kenji Matsumoto; Mikoto Tamura; Takafumi Minami; Kiyoshi Nakamatsu; Yasumasa Nishimura
    Journal of radiation research 59 (3) 333 - 337 0449-3060 2018/05 [Refereed]
     
    Tungsten functional paper (TFP) is a paper-based radiation-shielding material, which is lead-free and easy to cut. We developed a radiation protection undergarment using TFP for prostate cancer patients treated with permanent 125I seed implantation (PSI). The aim of this study was to evaluate the shielding ability of the undergarment with respect to household contacts and members of the public. Between October 2016 and April 2017, a total of 10 prostate cancer patients treated with PSI were enrolled in this prospective study. The external radiation exposure from each patient 1 day after PSI was measured with and without the undergarment. Measurements were performed using a survey meter at 100 cm from the surface of the patient's body. The exposure rates were measured from five directions: anterior, anteriorly oblique, lateral, posteriorly oblique, and posterior. The measured radiation exposure rates without the undergarment, expressed as mean ± standard deviation, from the anterior, anteriorly oblique, lateral, posteriorly oblique, and posterior directions were 1.28 ± 0.43 μSv/h, 0.70 ± 0.34 μSv/h, 0.21 ± 0.062 μSv/h, 0.65 ± 0.33 μSv/h and 1.24 ± 0.41 μSv/h, respectively. The undergarment was found to have (mean ± standard deviation) shielding abilities of 88.7 ± 5.8%, 44.0 ± 42.1%, 50.6 ± 15.9%, 72.9 ± 27.0% and 90.4 ± 10.7% from the anterior, anteriorly oblique, lateral, posteriorly oblique, and posterior directions, respectively. In conclusion, this shielding undergarment is a useful device that has the potential to reduce radiation exposure for the general public and the patient's family.
  • Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masahiko Okumura; Hiroshi Doi; Yasumasa Nishimura
    In Vivo International Institute of Anticancer Research 32 (3) 531 - 536 1791-7549 2018/05 [Refereed]
     
    Aim: In this study, we clarified changes of the surface dose to a low-density material on a carbon couch and verified whether a novel rigid couch (HM couch) could reduce the surface dose. Materials and Methods: We measured the surface dose using only a carbon couch (iBeam Couchtop STANDARD BrainLab), a low-density material (Styrofoam board) on the carbon couch, and an HM couch for 6 and 10 MV photon beams. Results: A 5-cm styrofoam board placed on the carbon couch reduced the surface dose by approximately 7-9%, while it had no impact on the depth dose profile however, in use, such a thickness may cause collision of the patient with the gantry head. The HM couch reduced the surface dose by approximately 7-9% and shifted the depth dose profile by approximately 0.4 cm in the depth direction compared to the carbon couch. Conclusion: The HM couch has the potential to reduce skin toxicity and is expected to be useful in clinical practice instead of carbon couches.
  • Makoto Hirata; Hajime Monzen; Mikoto Tamura; Kazuki Kubo; Kenji Matsumoto; Kohei Hanaoka; Masahiko Okumura; Yasumasa Nishimura
    Anticancer Research International Institute of Anticancer Research 38 (5) 2733 - 2738 1791-7530 2018/05 [Refereed]
     
    Background/Aim: Patient immobilization systems are used to establish a reproducible patient position relative to the couch. In this study, the impact of conventional lok-bars for CT-simulation (CIVCO-bar) and treatment (iBEAM-bar) were compared with a novel lok-bar (mHM-bar) in tomotherapy. Materials and Methods: Verification was obtained as follows: i. artifacts in CT images ii. dose attenuation rate of lok-bar, compared to without lok-bar and iii. dose differences between the calculated and measured absorbed doses. Results: With the CIVCO-bar, there were obvious metal artifacts, while there were nearly no artifacts with the mHM-bar. The mean dose attenuation rates with the mHM-bar and iBEAM-bar were 1.31% and 2.28%, and the mean dose difference was 1.55% and 1.66% for mHM-bar and iBEAM-bar. Conclusion: Using the mHM-bar reduced artifacts on the CT image and improved dose attenuation are obtained. The lok-bar needs to be inserted as a structure set in treatment planning with tomotherapy.
  • Yoshihiro Ueda; Jun-ichi Fukunaga; Tatsuya Kamima; Yumiko Adachi; Kiyoshi Nakamatsu; Hajime Monzen
    Radiation Oncology BioMed Central Ltd. 13 (1) 46  1748-717X 2018/03 [Refereed]
     
    Background: The aim of this study was to evaluate the performance of a commercial knowledge-based planning system, in volumetric modulated arc therapy for prostate cancer at multiple radiation therapy departments. Methods: In each institute, > 20 cases were assessed. For the knowledge-based planning, the estimated dose (ED) based on geometric and dosimetric information of plans was generated in the model. Lower and upper limits of estimated dose were saved as dose volume histograms for each organ at risk. To verify whether the models performed correctly, KBP was compared with manual optimization planning in two cases. The relationships between the EDs in the models and the ratio of the OAR volumes overlapping volume with PTV to the whole organ volume (Voverlap/Vwhole) were investigated. Results: There were no significant dosimetric differences in OARs and PTV between manual optimization planning and knowledge-based planning. In knowledge-based planning, the difference in the volume ratio of receiving 90% and 50% of the prescribed dose (V90 and V50) between institutes were more than 5.0% and 10.0%, respectively. The calculated doses with knowledge-based planning were between the upper and lower limits of ED or slightly under the lower limit of ED. The relationships between the lower limit of ED and Voverlap/Vwhole were different among the models. In the V90 and V50 for the rectum, the maximum differences between the lower limit of ED among institutes were 8.2% and 53.5% when Voverlap/Vwhole for the rectum was 10%. In the V90 and V50 for the bladder, the maximum differences of the lower limit of ED among institutes were 15.1% and 33.1% when Voverlap/Vwhole for the bladder was 10%. Conclusion: Organs' upper and lower limits of ED in the models correlated closely with the Voverlap/Vwhole. It is important to determine whether the models in KBP match a different institute's plan design before the models can be shared.
  • Kazuki Kubo; Hajime Monzen; Mikoto Tamura; Makoto Hirata; Kentaro Ishii; Wataru Okada; Ryuta Nakahara; Shun Kishimoto; Ryu Kawamorita; Yasumasa Nishimura
    Journal of Applied Clinical Medical Physics John Wiley and Sons Ltd 19 (2) 121 - 127 1526-9914 2018/03 [Refereed]
     
    It is important to improve the magnitude of dose variation that is caused by the interplay effect. The aim of this study was to investigate the impact of the number of breaths (NBs) to the dose variation for VMAT-SBRT to lung cancer. Data on respiratory motion and multileaf collimator (MLC) sequence were collected from the cases of 30 patients who underwent radiotherapy with VMAT-SBRT for lung cancer. The NBs in the total irradiation time with VMAT and the maximum craniocaudal amplitude of the target were calculated. The MLC sequence complexity was evaluated using the modulation complexity score for VMAT (MCSv). Static and dynamic measurements were performed using a cylindrical respiratory motion phantom and a micro ionization chamber. The 1 standard deviation which were obtained from 10 dynamic measurements for each patient were defined as dose variation caused by the interplay effect. The dose distributions were also verified with radiochromic film to detect undesired hot and cold dose spot. Dose measurements were also performed with different NBs in the same plan for 16 patients in 30 patients. The correlations between dose variations and parameters assessed for each treatment plan including NBs, MCSv, the MCSv/amplitude quotient (TMMCSv), and the MCSv/amplitude quotient × NBs product (IVS) were evaluated. Dose variation was decreased with increasing NBs, and NBs of > 40 times maintained the dose variation within 3% in 15 cases. The correlation between dose variation and IVS which were considered NBs was shown stronger (R2 = 0.43, P < 0.05) than TMMCSv (R2 = 0.32, P < 0.05). The NBs is an important factor to reduce the dose variation. The patient who breathes > 40 times during irradiation of two partial arcs VMAT (i.e., NBs = 16 breaths per minute) may be suitable for VMAT-SBRT for lung cancer.
  • Masakazu Otsuka; Hajime Monzen; Kenji Matsumoto; Mikoto Tamura; Masahiro Inada; Noriyuki Kadoya; Yasumasa Nishimura
    PloS one 13 (10) e0204721  2018 [Refereed]
     
    BACKGROUND: Four-dimensional computed tomography (4D-CT) ventilation is an emerging imaging modality. Functional avoidance of regions according to 4D-CT ventilation may reduce lung toxicity after radiation therapy. This study evaluated associations between 4D-CT ventilation-based dosimetric parameters and clinical outcomes. METHODS: Pre-treatment 4D-CT data were used to retrospectively construct ventilation images for 40 thoracic cancer patients retrospectively. Fifteen patients were treated with conventional radiation therapy, 6 patients with hyperfractionated radiation therapy and 19 patients with stereotactic body radiation therapy (SBRT). Ventilation images were calculated from 4D-CT data using a deformable image registration and Jacobian-based algorithm. Each ventilation map was normalized by converting it to percentile images. Ventilation-based dosimetric parameters (Mean Dose, V5 [percent lung volume receiving ≥5 Gy], and V20 [percent lung volume receiving ≥20 Gy]) were calculated for highly and poorly ventilated regions. To test whether the ventilation-based dosimetric parameters could be used predict radiation pneumonitis of ≥Grade 2, the area under the curve (AUC) was determined from the receiver operating characteristic analysis. RESULTS: For Mean Dose, poorly ventilated lung regions in the 0-30% range showed the highest AUC value (0.809; 95% confidence interval [CI], 0.663-0.955). For V20, poorly ventilated lung regions in the 0-20% range had the highest AUC value (0.774; 95% [CI], 0.598-0.915), and for V5, poorly ventilated lung regions in the 0-30% range had the highest AUC value (0.843; 95% [CI], 0.732-0.954). The highest AUC values for Mean Dose, V20, and V5 were obtained in poorly ventilated regions. There were significant differences in all dosimetric parameters between radiation pneumonitis of Grade 1 and Grade ≥2. CONCLUSIONS: Poorly ventilated lung regions identified on 4D-CT had higher AUC values than highly ventilated regions, suggesting that functional planning based on poorly ventilated regions may reduce the risk of lung toxicity in radiation therapy.
  • Hanaoka K; Okumura M; Monzen H
    Igaku butsuri : Nihon Igaku Butsuri Gakkai kikanshi = Japanese journal of medical physics : an official journal of Japan Society of Medical Physics 38 (2) 85 - 88 1345-5354 2018 [Refereed]
  • Takeshi Kamomae; Hajime Monzen; Mariko Kawamura; Kuniyasu Okudaira; Takayoshi Nakaya; Takashi Mukoyama; Yoshikazu Miyake; Yoshitomo Ishihara; Yoshiyuki Itoh; Shinji Naganawa
    Physics in medicine and biology 63 (1) 015006 - 015006 0031-9155 2017/12 [Refereed]
     
    Intraoperative electron radiotherapy (IOERT), which is an accelerated partial breast irradiation method, has been used for early-stage breast cancer treatment. In IOERT, a protective disk is inserted behind the target volume to minimize the dose received by normal tissues. However, to use such a disk, the surgical incision must be larger than the field size because the disk is manufactured from stiff and unyielding materials. In this study, the applicability of newly developed tungsten-based functional paper (TFP) was assessed as an alternative to the existing protective disk. The radiation-shielding performance of the TFP was verified through experimental measurements and Monte Carlo simulations. Percentage depth dose curves and lateral dose profiles with and without TFPs were measured and simulated on a dedicated IOERT accelerator. The number of piled-up TFPs was changed from 1 to 40. In the experimental measurements, the relative doses at the exit plane of the TFPs for 9 MeV were 42.7%, 9.2%, 0.2%, and 0.1% with 10, 20, 30, and 40 TFPs, respectively, whereas those for 12 MeV were 63.6%, 27.1%, 8.6%, and 0.2% with 10, 20, 30, and 40 TFPs, respectively. Slight dose enhancements caused by backscatter radiation from the TFPs were observed at the entrance plane of the TFPs at both beam energies. The results of the Monte Carlo simulation indicated the same tendency as the experimental measurements. Based on the experimental and simulated results, the radiation-shielding performances of 30 TFPs for 9 MeV and 40 TFPs for 12 MeV were confirmed to be acceptable and close to those of the existing protective disk. The findings of this study suggest the feasibility of using TFPs as flexible chest wall protectors in IOERT for breast cancer treatment.
  • Takeshi Kamomae; Hidetoshi Shimizu; Takayoshi Nakaya; Kuniyasu Okudaira; Takahiro Aoyama; Hiroshi Oguchi; Masataka Komori; Mariko Kawamura; Kazuhiro Ohtakara; Hajime Monzen; Yoshiyuki Itoh; Shinji Naganawa
    Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB) 44 205 - 211 1120-1797 2017/12 [Refereed]
     
    Pretreatment intensity-modulated radiotherapy quality assurance is performed using simple rectangular or cylindrical phantoms; thus, the dosimetric errors caused by complex patient-specific anatomy are absent in the evaluation objects. In this study, we construct a system for generating patient-specific three-dimensional (3D)-printed phantoms for radiotherapy dosimetry. An anthropomorphic head phantom containing the bone and hollow of the paranasal sinus is scanned by computed tomography (CT). Based on surface rendering data, a patient-specific phantom is formed using a fused-deposition-modeling-based 3D printer, with a polylactic acid filament as the printing material. Radiophotoluminescence glass dosimeters can be inserted in the 3D-printed phantom. The phantom shape, CT value, and absorbed doses are compared between the actual and 3D-printed phantoms. The shape difference between the actual and printed phantoms is less than 1 mm except in the bottom surface region. The average CT value of the infill region in the 3D-printed phantom is -6 ± 18 Hounsfield units (HU) and that of the vertical shell region is 126 ± 18 HU. When the same plans were irradiated, the dose differences were generally less than 2%. These results demonstrate the feasibility of the 3D-printed phantom for artificial in vivo dosimetry in radiotherapy quality assurance.
  • Kazuki Kubo; Hajime Monzen; Kentaro Ishii; Mikoto Tamura; Ryu Kawamorita; Iori Sumida; Hirokazu Mizuno; Yasumasa Nishimura
    PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS ELSEVIER SCI LTD 44 199 - 204 1120-1797 2017/12 [Refereed]
     
    Purpose: This study evaluated whether RapidPlan based plans (RP plans) created by a single optimization, are usable in volumetric modulated arc therapy (VMAT) for patients with prostate cancer. Methods: We used 51 previously administered VMAT plans to train a RP model. Thirty RP plans were created by a single optimization without planner intervention during optimization. Differences between RP plans and clinical manual optimization (CMO) plans created by an experienced planner for the same patients were analyzed (Wilcoxon tests) in terms of homogeneity index (HI), conformation number (CN), D-95%, and D-2% to planning target volume (PTV), mean dose, V-50Gy, V-70Gy, V-75Gy, and V-78Gy to rectum and bladder, monitor unit (MU), and multi-leaf collimator (MLC) sequence complexity. Results: RP and CMO values for PTV D-95%, PTV D-2%, HI, and CN were significantly similar (p < 0.05 for all). RP mean dose, V-50Gy, and V-70Gy to rectum were superior or comparable to CMO values; RP V-75Gy and V-78Gy were higher than in CMO plans (p < 0.05). RP bladder dose-volume parameter values (except V-78Gy) were lower than in CMO plans (p < 0.05). MU values were RP: 730 +/- 55 MU and CMO: 580 +/- 37 MU (p < 0.05); and MLC sequence complexity scores were RP: 0.25 +/- 0.02 and CMO: 0.35 +/- 0.03 (p < 0.05). Conclusions: RP plans created by a single optimization were clinically acceptable in VMAT for patient with prostate cancer. Our simple model could reduce optimization time, independently of planner's skill and knowledge. (C) 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
  • Makoto Hirata; Hajime Monzen; Kohei Hanaoka; Yasumasa Nishimura
    RADIATION PROTECTION DOSIMETRY OXFORD UNIV PRESS 176 (4) 425 - 433 0144-8420 2017/11 [Refereed]
     
    The absorption dose outside the irradiation field for prostate intensity-modulated radiation therapy was measured and evaluated by comparison with calculated values of radiation treatment planning system (TPS). The values of TPS calculated were using Varian CLINAC21EX/Eclipse and TomoTherapy Planning System for constant irradiation time. The absorption dose was measured by placing a glass-element dosemeter in a human-bone enclosure phantom with a planning target volume inside the irradiation field. The organs at risk were the rectum, spinal cord, thyroid, eyeball and the left lung. The calculated values of TPS, Varian CLINAC21EX/Eclipse and TomoTherapy Planning System were calculated, up to 17 and 55 cm from the isocenter, respectively. The absorbed dose outside the irradiation field diverged with increased distance from the isocenter (Varian/Eclipse: p = 0.03, TomoTherapy Planning System: p = 0.25). The calculated values for the absorbed dose outside the irradiation field were underestimated.
  • Hajime Monzen; Ikuo Kanno; Takahiro Fujimoto; Masahiro Hiraoka
    JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS WILEY 18 (5) 325 - 329 1526-9914 2017/09 [Refereed]
     
    Tungsten functional paper (TFP) is a novel paper-based radiation-shielding material. We measured the shielding ability of TFP against x-rays and gamma rays. The TFP was supplied in 0.3-mm-thick sheets that contained 80% tungsten powder and 20% cellulose (C6H10O5) by mass. In dose measurements for x-rays (60, 80, 100, and 120 kVp), we measured doses after through 1, 2, 3, 5, 10, and 12 TFP sheets, as well as 0.3 and 0.5 mm of lead. In lead equivalence measurements, we measured doses after through 2 and 10 TFP sheets for x-rays (100 and 150 kVp), and 0, 7, 10, 20, and 30 TFP sheets for gamma rays from cesium-137 source (662 keV). And then, the lead equivalent thicknesses of TFP were determined by comparison with doses after through standard lead plates (purity >99.9%). Additionally, we evaluated uniformity of the transmitted dose by TFP with a computed radiography image plate for 50 kVp x-rays. A single TFP sheet was found to have a shielding ability of 65%, 53%, 48%, and 46% for x-rays (60, 80, 100, and 120 kVp), respectively. The lead equivalent thicknesses of two TFP sheets were 0.10 +/- 0.02, 0.09 +/- 0.02 mmPb, and of ten TFP sheets were 0.48 +/- 0.02 and 0.51 +/- 0.02 mmPb for 100 and 150 kVp x-rays, respectively. The lead equivalent thicknesses of 7, 10, 20, and 30 sheets of TFP for gamma rays from cesium-137 source were estimated as 0.28, 0.43, 0.91, and 1.50 mmPb with an error of +/- 0.01 mm. One TFP sheet had nonuniformity, however, seven TFP sheets provided complete shielding for 50 kVp x-rays. TFP has adequate radiation shielding ability for x-rays and gamma rays within the energy range used in diagnostic imaging field.
  • Noriyuki Kadoya; Kumiko Karasawa; Iori Sumida; Hidetaka Arimura; Yasumasa Kakinohana; Shigeto Kabuki; Hajime Monzen; Teiji Nishio; Hiroki Shirato; Syogo Yamada
    JOURNAL OF RADIATION RESEARCH OXFORD UNIV PRESS 58 (5) 669 - 674 0449-3060 2017/09 [Refereed]
     
    The promotion plan for the Platform of Human Resource Development for Cancer (Ganpro) was initiated by the Ministry of Education, Culture, Sports, Science and Technology of Japan in 2007, establishing a curriculum for medical physicists. In this study, we surveyed the educational outcomes of the medical physicist program over the past 10 years since the initiation of Ganpro. The Japan Society of Medical Physics mailing list was used to announce this survey. The questionnaire was created by members of the Japanese Board for Medical Physicist Qualification, and was intended for the collection of information regarding the characteristics and career paths of medical physics students. Students who participated in the medical physics program from 2007 to 2016 were enrolled. Thirty-one universities (17 accredited and 14 non-accredited) were represented in the survey. In total, 491, 105 and 6 students were enrolled in the Master's, Doctorate and Residency programs, respectively. Most students held a Bachelor's degree in radiological technology (Master's program, 87%; Doctorate program, 72%). A large number of students with a Master's degree worked as radiological technologists (67%), whereas only 9% (n = 32) worked as medical physicists. In contrast, 53% (n = 28) of the students with a Doctorate degree worked as medical physicists. In total, 602 students (from 31 universities) completed the survey. Overall, although the number of the graduates who worked as medical physicists was small, this number increased annually. It thus seems that medical institutions in Japan are recognizing the necessity of licensed medical physicists in the radiotherapy community.
  • Shimomura, Kohei; Araki, Fujio; Kono, Yuki; Asai, Yoshiyuki; Murakami, Takamichi; Hyodo, Tomoko; Okumura, Masahiko; Matsumoto, Kenji; Monzen, Hajime; Nishimura, Yasumasa
    PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS ELSEVIER SCI LTD 39 59 - 66 1120-1797 2017/07 [Refereed]
     
    The purpose of this study was to obtain the fraction by weight of the elemental composition and mass density of a humanoid tissue phantom that includes lung tissue, soft tissue, and bone tissue, by using dual energy computed tomography (DECT). The fraction by weight and the mass density for tissue-equivalent materials were calculated by means of a least-squares method with a linear attenuation coefficient, using monochromatic photon energies of 10-140 keV, as obtained from DECT. The accuracy of calculated values for the fractions by weight of H (hydrogen), C (carbon), N (nitrogen), and O (oxygen) as verified by comparing the values with those that were analyzed using the combustion technique. The fraction by weight for other elements was confirmed by comparing with the analyzed values by means of energy dispersive photon spectroscopy. The calculated mass densities for each tissue were compared with those that were obtained by dividing the weight by volume. The calculated values of the fraction by weight that were obtained by means of DECT had differences of 1.9%, 9.2%, 6.6%, 7.8%, 0.8%, and 0.2% at a maximum for H, C, N, O, P (phosphorus), and Ca (calcium), respectively, from the reference values analyzed by the combustion technique and energy dispersive photon spectroscopy. The difference in the mass density for tissue was 0.011 g/cm(3) at a maximum. This study demonstrated the fraction by weight and the mass density of the humanoid tissue-equivalent materials that were calculated by means of DECT were expected high accuracy. (C) 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
  • Hajime Monzen; Kazuki Kubo; Mikoto Tamura; Masaru Hayakawa; Yasumasa Nishimura
    JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS WILEY 18 (3) 44 - 51 1526-9914 2017/05 [Refereed]
     
    We developed a novel low-radiation-absorbent lok-bar (HM-bar) that is used to secure the immobilizers to the couch. The aim of this study was to investigate the X-ray scattering and absorption properties of the HM-bar in computed tomography (CT) simulation and radiotherapy dose delivery using the Varian ExactTM lok-bar (VL-bar) as a benchmark. CT images were obtained with or without lok-bar, and then each image was visually evaluated for artifacts. The attenuation rates for each lok-bar were measured using a farmertype ionization chamber (PTW30013) and the I'mRT phantom (IBA Dosimetry GmbH). Measurement points were between gantry angles of 110 and 180 degrees. The treatment apparatus was a NovalisTx (Brainlab AG); X-ray energies were set at 6 MV and 10 MV. In the presence of each lok-bar, the radiation dose was measured in accordance with 10 volumetric modulated arc therapy-stereotactic body radiation therapy (VMAT-SBRT) plans for lung cancer. Artifacts were seldom observed in the CT scans of the HM-bar. The attenuation rate of each lok-bar was higher when the X-ray energy was set at 6 MV than at 10 MV. The highest attenuation rate in the VL-bar was observed at a gantry angle of 112 degrees; the rates were 22.4% at 6 MV and 19.3% at 10 MV. Similarly, the highest attenuation rate for the HM-bar was also observed at a gantry angle of 112 degrees; the rates were 12.2% and 10.1% at 6 MV and 10 MV, respectively. When the VL-bar was evaluated, the isocenter dose of the VMAT-SBRT plans was attenuated by 2.6% as a maximum case. In the case of the HM-bar, the maximum attenuation was 1.4%. In the measurements of each VMAT-SBRT plan, the difference of the dose attenuation rate between the VL-bar and HM-bar was approximately 1%. The HM-bar could be used to minimize the occurrence of artifacts and provide good images in CT scans regarding radiotherapy planning and dose calculation. It can be used for patient therapy at hospitals to provide accurate dose delivery because of its low X-ray scattering and absorption characteristics.
  • Hajime Monzen; Mikoto Tamura; Kohei Shimomura; Yuichi Onishi; Shinichi Nakayama; Takahiro Fujimoto; Kenji Matsumoto; Kohei Hanaoka; Takeshi Kamomae
    JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS WILEY 18 (3) 215 - 220 1526-9914 2017/05 [Refereed]
     
    Tungsten functional paper (TFP), which contains 80% tungsten by weight, has radiation-shielding properties. We investigated the use of TFP for the protection of operators during interventional or therapeutic angiography. The air kerma rate of scattered radiation from a simulated patient was measured, with and without TFP, using a water-equivalent phantom and fixed C-arm fluoroscopy. Measurements were taken at the level of the operator's eye, chest, waist, and knee, with a variable number of TFP sheets used for shielding. A Monte Carlo simulation was also utilized to analyze the dose rate delivered with and without the TFP shielding. In cine mode, when the number of TFP sheets was varied through 1, 2, 3, 5, and 10, the respective reduction in the air kerma rate relative to no TFP shielding was as follows: at eye level, 24.9%, 29.9%, 41.6%, 50.4%, and 56.2%; at chest level, 25.3%, 33.1%, 34.9%, 46.1%, and 44.3%; at waist level, 45.1%, 57.0%, 64.4%, 70.7%, and 75.2%; and at knee level, 2.1%, 2.2%, 2.1%, 2.1%, and 2.1%. In fluoroscopy mode, the respective reduction in the air kerma rate relative to no TFP shielding was as follows: at eye level, 24.8%, 30.3%, 34.8%, 51.1%, and 58.5%; at chest level, 25.8%, 33.4%, 35.5%, 45.2%, and 44.4%; at waist level, 44.6%, 56.8%, 64.7%, 71.7%, and 77.2%; and at knee level, 2.2%, 0.0%, 2.2%, 2.8%, and 2.5%. The TFP paper exhibited good radiation-shielding properties against the scattered radiation encountered in clinical settings, and was shown to have potential application in decreasing the radiation exposure to the operator during interventional radiology.
  • Mikoto Tamura; Hajime Monzen; Kazuki Kubo; Makoto Hirata; Yasumasa Nishimura
    PHYSICS IN MEDICINE AND BIOLOGY IOP PUBLISHING LTD 62 (3) 878 - 889 0031-9155 2017/02 [Refereed]
     
    Electron grid therapy is expected to be a valid treatment for bulky superficial tumors. It is difficult, however, to fit irradiation fields to bulky superficial tumor shapes for conventional electron grid therapy with a cerrobend grid collimator. In this study, we investigated whether a grid collimator using tungsten functional paper (TFP), with its radiation shielding ability, could be used for electron grid therapy. Dose distributions were measured using 9 MeV electron grid beams from a cerrobend grid collimator. For the simulation study, the same grid irradiation fields were shaped using a TFP grid collimator (thicknesses of 0.15, 0.3, 0.6, 0.9, and 1.2 cm) by laying them on a phantom. We then determined the dose distributions using Monte Carlo calculations and compared the cerrobend and TFP electron grid beams regarding dose distributions, including the depths of the maximum dose (d(max)), 90% dose (d(90)), and 80% dose (d(80)), and the ratios of the doses in the areas with and without shielding (valley to peak ratios). The equivalent dosimetric thickness was obtained with the TFP grid collimator that was equivalent to the dose distribution of the cerrobend grid collimator. For the cerrobend electron grid beams, the d(max), d(90), and d(80) were 1.0, 2.1, and 2.5 cm, respectively, and the valley to peak ratios at those depths were 0.48, 0.66, and 0.73, respectively. The equivalent dosimetric thickness of TFP was 0.52 cm. The d(max), d(90), and d(80) for the 0.52 cm thick TFP electron grid beams were 1.1, 1.9, and 2.3 cm, respectively, and the valley to peak ratios at those depths were 0.49, 0.63, and 0.71, respectively. The TFP grid collimator flexibly delivered excellent dose distributions by simply attaching it to the patient's skin. It could thus be used for electron grid therapy instead of the cerrobend grid collimator.
  • Takeshi Kamomae; Masataka Oita; Naoki Hayashi; Motoharu Sasaki; Hideki Aoyama; Hiroshi Oguchi; Mariko Kawamura; Hajime Monzen; Yoshiyuki Itoh; Shinji Naganawa
    PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS ELSEVIER SCI LTD 32 (10) 1314 - 1320 1120-1797 2016/10 [Refereed]
     
    The aim of this study is to investigate the dosimetric uncertainty of stochastic noise and the postirradiation density growth for reflective-type radiochromic film to obtain the appropriate dose from the exactly controlled film density. Film pieces were irradiated with 6-MV photon beams ranging from 0 to 400 cGy. The pixel values (PVs) of these films were obtained using a flatbed scanner at elapsed times of 1 min to 120 h between the end of irradiation and the film scan. The means and standard deviations (SDs) of the PVs were calculated. The SDs of the converted dose scale, u(sd), and the dose increases resulting from the PV increases per +/- 29 min at each elapsed time, u(time), were computed. The combined dose uncertainties from these two factors, u(c), were then calculated. A sharp increase in the PV occurred within the first 3 h after irradiation, and a slight increase continued from 3 h to 120 h. usd was independent of post-irradiation elapsed time. Sharp decreases in utime were obtained within 1 h after irradiation, and slight decreases in utime were observed from 1 to 24 h after irradiation. uc first decreased 1 h after irradiation and remained constant afterward. Assuming that the post-irradiation elapsed times of all of the related measurements are synchronized within +/- 29 min, the elapsed time should be at least 1 h in our system. It is important to optimize the scanning protocol for each institution with consideration of the required measurement uncertainty and acceptable latency time. (C) 2016 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
  • Hanaoka Kohei; Hosono Makoto; Tatebe Hitoshi; Ishikawa Kazuki; Monzen Hajime; Ishii Kazunari; Nishimura Yasumasa
    JOURNAL OF NUCLEAR MEDICINE 57 0161-5505 2016/05 [Refereed]
  • Moo-Sub Kim; Kazuki Kubo; Hajime Monzen; Do-Kun Yoon; Han-Back Shin; Sunmi Kim; Tae Suk Suh
    Progress in Medical Physics 27 (4) 232 - 235 2016 [Refereed]
  • Shintani N; Monzen H; Tamura M; Asai Y; Shimomura K; Matsumoto K; Okumura M; Nishimura Y
    Igaku butsuri : Nihon Igaku Butsuri Gakkai kikanshi = Japanese journal of medical physics : an official journal of Japan Society of Medical Physics 35 (4) 282 - 291 1345-5354 2016 [Refereed]
  • Ota S; Monzen H; Sumida I; Yoshioka Y; Kado R; Inoue S; Ogawa K; Nishimura Y
    J Nucl Med Radiat Ther 6 (243) 2015/09 [Refereed]
  • Kawamorita, R; Monzen, H; Okada, W; Nakahara, R; Kishimoto, S; Ishii; Nishimura, Y
    OMICS J Radiol. 4 (4) 2015/08 [Refereed]
  • Yuichi Onishi; Shinichi Nakayama; Shinsaku Watanabe; Souichirou Kaneshige; Hajime Monzen; Kenji Matsumoto; Naoya Shintani; Takeshi Kamomae
    Journal of the Korean Physical Society Korean Physical Society 67 (1) 89 - 95 1976-8524 2015/07 [Refereed]
     
    We constructed seven intensity-modulated radiation therapy (IMRT) treatment plans for prostate cancer (49 irradiation fields which contained seven randomly-sampled patients and seven fields) and evaluated the dose distributions by using a radiochromic film (EBT3 film) and a 2D detector. We superposed the calculated dose distribution of the IMRT treatment plan on EBT3 film and the 2D detector results and then compared those with the γ-analysis pass rate. The relative positions of the beam and the detector were varied the results of the analysis of the superior-inferior (SI) direction potentially differed, depending on the detector position, under an irradiation beam with the same fluence map. The detector was moved over a range of’ 8 mm in the SI direction in 1-mm step increments, measurement were made at each position, and the results were analyzed. The γ-analysis compared the dose distributions from EBT3 film and the radiation treatment planning system (RTPS) for each patient and field the pass rate with the γ-analysis from 98 to 100% was 2.04%. When we compared the dose distributions of the 2D detector and the RTPS, the pass rate from 98 to 100% was 63.2%. The mean values for the ?-analysis pass rates for EBT3 film and the 2D detector were 94.2 and 97.6%, respectively. Volume averaging of the data indicated a mean pass rate and standard deviation of 98.6 and 0.91%, respectively, and a pass rate of more than 96% for all positions. A 2D detector can, therefore, be used as an alternative apparatus for IMRT dose verification.
  • Yuichi Onishi; Shinichi Nakayama; Shinsaku Watanabe; Souichirou Kaneshige; Hajime Monzen; Kenji Matsumoto; Naoya Shintani; Takeshi Kamomae
    JOURNAL OF THE KOREAN PHYSICAL SOCIETY KOREAN PHYSICAL SOC 67 (1) 89 - 95 0374-4884 2015/07 
    We constructed seven intensity-modulated radiation therapy (IMRT) treatment plans for prostate cancer (49 irradiation fields which contained seven randomly-sampled patients and seven fields) and evaluated the dose distributions by using a radiochromic film (EBT3 film) and a 2D detector. We superposed the calculated dose distribution of the IMRT treatment plan on EBT3 film and the 2D detector results and then compared those with the.-analysis pass rate. The relative positions of the beam and the detector were varied; the results of the analysis of the superior-inferior (SI) direction potentially differed, depending on the detector position, under an irradiation beam with the same fluence map. The detector was moved over a range of +/-8 mm in the SI direction in 1-mm step increments, measurement were made at each position, and the results were analyzed. The.-analysis compared the dose distributions from EBT3 film and the radiation treatment planning system (RTPS) for each patient and field; the pass rate with the.-analysis from 98 to 100% was 2.04%. When we compared the dose distributions of the 2D detector and the RTPS, the pass rate from 98 to 100% was 63.2%. The mean values for the.-analysis pass rates for EBT3 film and the 2D detector were 94.2 and 97.6%, respectively. Volume averaging of the data indicated a mean pass rate and standard deviation of 98.6 and 0.91%, respectively, and a pass rate of more than 96% for all positions. A 2D detector can, therefore, be used as an alternative apparatus for IMRT dose verification.
  • Evaluation of Tungsten-Based Functional Paper for Attenuation Device in Intraoperative Radiotherapy for Breast Cancer
    Takeshi Kamomae; Hajime Monzen; Kuniyasu Okudaira; Yoshikazu Miyake; Hiroshi Oguchi; Masataka Komori; Mariko Kawamura; Yoshiyuki Itoh; Toyone Kikumori; Shinji Naganawa
    Medical Physics 42 (6) 3428  2015/06
  • Shinichi Nakayama; Hajime Monzen; Yuuichi Oonishi; Rika Mizote; Hiraku Iramina; Souichirou Kaneshige; Takashi Mizowaki
    PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS ELSEVIER SCI LTD 31 (4) 414 - 419 1120-1797 2015/06 [Refereed]
     
    Purpose: Photographic film is widely used for the dose distribution verification of intensity-modulated radiation therapy (IMRT). However, analysis for verification of the results is subjective. We present a novel method for marking the isocenter using irradiation from a megavoltage (MV) beam transmitted through slits in a multi-leaf collimator (MLC). Methods: We evaluated the effect of the marking irradiation at 500 monitor units (MU) on the total transmission through the MLC using an ionization chamber and Radiochromic Film. Film dosimetry was performed for quality assurance (QA) of IMRT plans. Three methods of registration were used for each film: marking by irradiating with an MV beam through slits in the MLC (MLC-IC); marking with a fabricated phantom (Phantom-IC); and a subjective method based on isodose lines (Manual). Each method was subjected to local gamma-analysis. Results: The effect of the marking irradiation on the total transmission was 0.16%, as measured by a ionization chamber at a 10-cm depth in a solid phantom, while the inter-leaf transmission was 0.3%, determined from the film. The mean pass rates for each registration method agreed within +/- 1% when the criteria used were a distance-to-agreement (DTA) of 3 mm and a dose difference (DD) of 3%. For DTA/DD criteria of 2 mm/3%, the pass rates in the sagittal plane were 96.09 +/- 0.631% (MLC-IC), 96.27 +/- 0.399% (Phantom-IC), and 95.62 +/- 0.988% (Manual). Conclusion: The present method is a versatile and useful method of improving the objectivity of film dosimetry for IMRT QA. (C) 2015 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
  • 門前 一; 西村 恭昌
    臨床腫瘍プラクティス (株)ヴァンメディカル 11 (2) 157 - 159 1880-3083 2015/05
  • Takeshi Kamomae; Hajime Monzen; Shinichi Nakayama; Rika Mizote; Yuuichi Oonishi; Soichiro Kaneshige; Takashi Sakamoto
    PLOS ONE PUBLIC LIBRARY SCIENCE 10 (5) e0126152  1932-6203 2015/05 [Refereed]
     
    Movement of the target object during cone-beam computed tomography (CBCT) leads to motion blurring artifacts. The accuracy of manual image matching in image-guided radiotherapy depends on the image quality. We aimed to assess the accuracy of target position localization using free-breathing CBCT during stereotactic lung radiotherapy. The Vero4DRT linear accelerator device was used for the examinations. Reference point discrepancies between the MV X-ray beam and the CBCT system were calculated using a phantom device with a centrally mounted steel ball. The precision of manual image matching between the CBCT and the averaged intensity (AI) images restructured from four-dimensional CT (4DCT) was estimated with a respiratory motion phantom, as determined in evaluations by five independent operators. Reference point discrepancies between the MV X-ray beam and the CBCT image-guidance systems, categorized as left-right (LR), anterior-posterior (AP), and superior-inferior (SI), were 0.33 +/- 0.09, 0.16 +/- 0.07, and 0.05 +/- 0.04 mm, respectively. The LR, AP, and SI values for residual errors from manual image matching were -0.03 +/- 0.22, 0.07 +/- 0.25, and -0.79 +/- 0.68 mm, respectively. The accuracy of target position localization using the Vero4DRT system in our center was 1.07 +/- 1.23 mm (2 SD). This study experimentally demonstrated the sufficient level of geometric accuracy using the free-breathing CBCT and the image-guidance system mounted on the Vero4DRT. However, the inter-observer variation and systematic localization error of image matching substantially affected the overall geometric accuracy. Therefore, when using the free-breathing CBCT images, careful consideration of image matching is especially important.
  • Monzen H; Mizowaki T; Yano S; Fujimoto T; Kamomae T; Utsunomiya S; Nakamura M; Hiraoka M
    J Nucl Med Radiat Ther 6 (238) 2015 [Refereed]
  • Itaru Ikeda; Takashi Mizowaki; Tomohiro Ono; Masahiro Yamada; Mitsuhiro Nakamura; Hajime Monzen; Shinsuke Yano; Masahiro Hiraoka
    Medical Dosimetry Elsevier Inc. 40 (4) 325 - 332 1873-4022 2015 [Refereed]
     
    Although the prostate displacement of patients in the prone position is affected by respiration-induced motion, the effect of intrafractional prostate motion in the prone position during "simultaneous integrated boost intensity-modulated radiotherapy" (SIB-IMRT) is unclear. The purpose of this study was to evaluate the dosimetric effects of intrafractional motion on SIB-IMRT to a dominant intraprostatic lesion (IPL) using measured motion data of patients in a prone position, fixed with a thermoplastic shell. We obtained 2 orthogonal x-ray fluoroscopic images at the same moment every 0.2 seconds for 30 seconds before and after treatment, once weekly, from 7 patients with localized prostate cancer with detectable prostatic calcification. Prostate displacements in the left-right (LR), anteroposterior (AP), and superoinferior (SI) directions were calculated using the prostatic calcification as a fiducial marker. We defined the displacement between pretreatment and posttreatment as baseline drift (BD). An SIB-IMRT plan was generated in which each IPL + 3 mm received a dose of 94.5 Gy, whereas the remainder of the prostate + 7 mm received a dose of 75.6 Gy in 9 fields. A simulated plan of dose blurring was generated by the convolution of isocenter-shifted plans using measured motion data in 30 seconds and motion in 30 seconds + distance between pretreatment and posttreatment position (BD) for each of the 7 patients. The motion in 30 seconds mainly reflected respiration-induced motion. The mean displacements of BD were 1.4 mm (- 3.1 to 8.2 mm), - 2.2 mm (- 9.1 to 1.5 mm), and - 0.3 mm (- 5.0 to 1.8 mm) in the AP, SI, and LR directions, respectively. The differences in the target coverage with V90% of the IPL and V100% of the prostate between the simulated plan and original plan were - 3.9% to - 0.3% and - 0.6% to 1.1% for respiration-induced motion and 3.1% to - 67.8% and 3.6% to - 13.3% for BD with respiration-induced motion, respectively. The large motion of BD resulted in an inadequate coverage by the prescribed dose of the SIB-IMRT to the IPL. A 7-mm margin is recommended when real-time tracking techniques are not applied. The effect of respiration-induced motion was small, so long as a 3-mm margin was added.
  • Sayaka Sato; Yuki Miyabe; Kunio Takahashi; Masahiro Yamada; Mitsuhiro Nakamura; Yoshitomo Ishihara; Kenji Yokota; Shuji Kaneko; Takashi Mizowaki; Hajime Monzen; Masahiro Hiraoka
    JOURNAL OF APPLIED CLINICAL MEDICAL PHYSICS MULTIMED INC 16 (2) 73 - 86 1526-9914 2015 [Refereed]
     
    A novel three-dimensional unicursal irradiation technique "Dynamic WaveArc" (DWA), which employs simultaneous and continuous gantry and O-ring rotation during dose delivery, has been implemented in Vero4DRT. The purposes of this study were to develop a commissioning and quality assurance procedure for DWA irradiation, and to assess the accuracy of the mechanical motion and dosimetric control of Vero4DRT. To determine the mechanical accuracy and the dose accuracy with DWA irradiation, 21 verification test patterns with various gantry and ring rotational directions and speeds were generated. These patterns were irradiated while recording the irradiation log data. The differences in gantry position, ring position, and accumulated MU (E-G, E-R, and E-MU, respectively) between the planned and actual values in the log at each time point were evaluated. Furthermore, the doses delivered were measured using an ionization chamber and spherical phantom. The constancy of radiation output during DWA irradiation was examined by comparison with static beam irradiation. The mean absolute error (MAE) of E-G and E-R were within 0.1 degrees and the maximum error was within 0.2 degrees. The MAE of E-MU was within 0.7 MU, and maximum error was 2.7 MU. Errors of accumulated MU were observed only around control points, changing gantry, and ring velocity. The gantry rotational range, in which E-MU was greater than or equal to 2.0 MU, was not greater than 3.2%. It was confirmed that the extent of the large differences in accumulated MU was negligibly small during the entire irradiation range. The variation of relative output value for DWA irradiation was within 0.2%, and this was equivalent to conventional arc irradiation with a rotating gantry. In conclusion, a verification procedure for DWA irradiation was designed and implemented. The results demonstrated that Vero4DRT has adequate mechanical accuracy and beam output constancy during gantry and ring rotation.
  • Takahiro Fujimoto; Hajime Monzen; Manabu Nakata; Takashi Okada; Shinsuke Yano; Toru Takakura; Junichi Kuwahara; Makoto Sasaki; Kyoji Higashimura; Masahiro Hiraoka
    PHYSICA MEDICA-EUROPEAN JOURNAL OF MEDICAL PHYSICS ELSEVIER SCI LTD 30 (7) 838 - 842 1120-1797 2014/11 [Refereed]
     
    In electron radiotherapy, shielding material is required to attenuate beam and scatter. A newly introduced shielding material, tungsten functional paper (TFP), has been anticipated to become a very useful device that is lead-free, light, flexible, and easily processed, containing very fine tungsten powder at as much as 80% by weight. The purpose of this study was to investigate the dosimetric changes due to TFP shielding for electron beams. TFP (thickness 0-15 mm) was placed on water or a water-equivalent phantom. Percentage depth ionization and transmission were measured for 4, 6, and 9 MeV electron beams. Off-center ratio was also measured using film dosimetry at depth of dose maximum under similar conditions. Then, beam profiles and transmission with two shielding materials, TFP and lead, were evaluated. Reductions of 95% by using TFP at 0.5 cm depth occurred at 4, 9, and 15 mm with 4, 6, and 9 MeV electron beams, respectively. It is found that the dose tend to increase at the field edge shaped with TFP, which might be influenced by the thickness. TFP has several unique features and is very promising as a useful tool for radiation protection for electron beams, among others. (C) 2014 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.
  • Tomohiro Ono; Yuki Miyabe; Masahiro Yamada; Kenji Yokota; Shuji Kaneko; Akira Sawada; Hajime Monzen; Takashi Mizowaki; Masaki Kokubo; Masahiro Hiraoka
    MEDICAL PHYSICS AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS 41 (10) 101706  0094-2405 2014/10 [Refereed]
     
    Purpose: The Vero4DRT has a maximum field size of 150.0 x 150.0 mm. The purpose of the present study was to develop expanded-field irradiation techniques using the unique gimbaled x-ray head of the Vero4DRT and to evaluate the dosimetric characteristics thereof. Methods: Two techniques were developed. One features gimbal swing irradiation and multiple static segments consisting of four separate fields exhibiting 2.39 degrees gimbal rotation around two orthogonal axes. The central beam axis for each piecewise-field is shifted 40 mm from the isocenters of the left-right (LR) and superior-inferior (SI) directions, and, thus, the irradiation field size is expanded to 230.8 x 230.8 mm. Adjacent regions were created at the isocenter (a center-adjacent expanded-field) and 20 mm from the isocenter (an off-adjacent expandedfield). The field gaps or overlaps of combined piecewise-fields were established by adjustment of gimbal rotation and movement of the multileaf collimator (MLC). Another technique features dynamic segment irradiation in which the beam is delivered while rotating the gimbal. The dose profile is controlled by a combination of gimbal swing motion and opening and closing of the MLC. This enabled the authors to expand the irradiation field on the LR axis because the direction of MLC motion is parallel to that axis. A field 220.6 x 150.0 mm in dimensions was configured and examined. To evaluate the dosimetric characteristics of the expandedfields, films inserted into water-equivalent phantoms at depths of 50, 100, and 150 mm were irradiated and field sizes, penumbrae, flatness, and symmetry analyzed. In addition, the expanded-field irradiation techniques were applied to intensity-modulated radiation therapy (IMRT). A head-and-neck IMRT field, created using a conventional Linac (the Varian Clinac iX), was reproduced employing an expanded-field of the Vero4DRT. The simulated dose distribution for the expanded-IMRT field was compared to the measured dose distribution. Results: The field sizes, penumbrae, flatness, and symmetry of the center- and off-adjacent expandedfields were 230.2-232.1 mm, 6.8-10.7 mm, 2.3%-5.1%, and -0.5% to -0.4%, respectively, at a depth of 100 mm. Similarly, the field sizes, penumbrae, flatness, and symmetry of dynamic segment irradiation on the LR axis were 219.2 mm, 6.0-6.2 mm, 3.4%, and -0.1%, respectively, at a depth of 100 mm. In the area of expanded-IMRT dose distribution, the passing rate of 5% dose difference was 85.8% between measurements and simulation, and the 3%/3 mm gamma passing rate was 96.4%. Conclusions: Expanded-field irradiation techniques were developed using a gimbaled x-ray head. The techniques effectively extend target areas, as required when whole-breast irradiation or head-and-neck IMRT is contemplated. (C) 2014 American Association of Physicists in Medicine.
  • Nagahata T; Yamaguchi H; Monzen H; Nishimura Y
    Nihon Hoshasen Gijutsu Gakkai zasshi 70 (10) 1160 - 1165 0369-4305 2014/10 [Refereed]
  • Yukinori Matsuo; Nami Ueki; Kenji Takayama; Mitsuhiro Nakamura; Yuki Miyabe; Yoshitomo Ishihara; Nobutaka Mukumoto; Shinsuke Yano; Hiroaki Tanabe; Shuji Kaneko; Takashi Mizowaki; Hajime Monzen; Akira Sawada; Masaki Kokubo; Masahiro Hiraoka
    RADIOTHERAPY AND ONCOLOGY ELSEVIER IRELAND LTD 112 (3) 360 - 364 0167-8140 2014/09 [Refereed]
     
    Purpose: To evaluate feasibility and acute toxicities after dynamic tumour tracking (DTT) irradiation with real-time monitoring for lung tumours using a gimbal mounted linac. Materials and methods: Spherical gold markers were placed around the tumour using a bronchoscope prior to treatment planning. Prescription dose at the isocentre was 56 Gy in 4 fractions for T2a lung cancer and metastatic tumour, and 48 Gy in 4 fractions for the others. Dose-volume metrics were compared between DTT and conventional static irradiation using in-house developed software. Results: Of twenty-two patients enrolled, DTT radiotherapy was successfully performed for 16 patients, except 4 patients who coughed out the gold markers, one who showed spontaneous tumour regression, and one where the abdominal wall motion did not correlate with the tumour motion. Dose covering 95% volume of GTV was not different between the two techniques, while normal lung volume receiving 20 Gy or more was reduced by 20%. A mean treatment time per fraction was 36 min using DTT. With a median follow-up period of 13.2 months, no severe toxicity grade 3 or worse was observed. Conclusions: DTT radiotherapy using a gimbal mounted linac was clinically feasible for lung treatment without any severe acute toxicity. (C) 2014 Elsevier Ireland Ltd. All rights reserved.
  • Yusuke Tsuruta; Manabu Nakata; Mitsuhiro Nakamura; Yukinori Matsuo; Kyoji Higashimura; Hajime Monzen; Takashi Mizowaki; Masahiro Hiraoka
    MEDICAL PHYSICS AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS 41 (8) 189 - 197 0094-2405 2014/08 [Refereed]
     
    Purpose: To compare the dosimetric performance of Acuros XB (AXB), anisotropic analytical algorithm (AAA), and x-ray voxel Monte Carlo (XVMC) in heterogeneous phantoms and lung stereotactic body radiotherapy (SBRT) plans. Methods: Water- and lung-equivalent phantoms were combined to evaluate the percentage depth dose and dose profile. The radiation treatment machine Novalis (BrainLab AG, Feldlcirchen, Germany) with an x-ray beam energy of 6 MV was used to calculate the doses in the composite phantom at a source-to-surface distance of 100 cm with a gantry angle of 0 degrees. Subsequently, the clinical lung SBRT plans for the 26 consecutive patients were transferred from the iPlan (ver. 4.1; BrainLab AG) to the Eclipse treatment planning systems (ver. 11.0.3; Varian Medical Systems, Palo Alto, CA). The doses were then recalculated with AXB and AAA while maintaining the XVMC-calculated monitor units and beam arrangement. Then the dose-volumetric data obtained using the three different radiation dose calculation algorithms were compared. Results: The results from AXB and XVMC agreed with measurements within 3.0% for the lungequivalent phantom with a 6 x 6 cm(2) field size, whereas AAA values were higher than measurements in the heterogeneous zone and near the boundary, with the greatest difference being 4.1%. AXB and XVMC agreed well with measurements in terms of the profile shape at the boundary of the heterogeneous zone. For the lung SBRT plans, AXB yielded lower values than XVMC in terms of the maximum doses of ITV and PTV; however, the differences were within 3.0%. In addition to the dose-volumetric data, the dose distribution analysis showed that AXB yielded dose distribution calculations that were closer to those with XVMC than did AAA. Means +/- standard deviation of the computation time was 221.6 +/- 53.1 s (range, 124-358s), 66.1 +/- 16.0 s (range, 42-94 s), and 6.7 +/- 1.1 s (range, 5-9 s) for XVMC, AXB, and AAA, respectively. Conclusions: In the phantom evaluations, AXB and XVMC agreed better with measurements than did AAA. Calculations differed in the density-changing zones (substance boundaries) between AXB/XVMC and AAA. In the lung SBRT cases, a comparative analysis of dose-volumetric data and dose distributions with XVMC demonstrated that the AXB provided better agreement with XVMC than AAA. The computation time of AXB was faster than that of XVMC; therefore, AXB has better balance in terms of the dosimetric performance and computation speed for clinical use than XVMC. 2014 American Association of Physicists in Medicine.
  • Tomohiro Ono; Yuki Miyabe; Masahiro Yamada; Takehiro Shiinoki; Akira Sawada; Shuji Kaneko; Hajime Monzen; Takashi Mizowaki; Masaki Kokubo; Masahiro Hiraoka
    MEDICAL PHYSICS AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS 41 (3) 031705  0094-2405 2014/03 [Refereed]
     
    Purpose: The Vero4DRT system has the capability for dynamic tumor-tracking (DTT) stereotactic irradiation using a unique gimbaled x-ray head. The purposes of this study were to develop DTT conformal arc irradiation and to estimate its geometric and dosimetric accuracy. Methods: The gimbaled x-ray head, supported on an O-ring gantry, was moved in the pan and tilt directions during O-ring gantry rotation. To evaluate the mechanical accuracy, the gimbaled x-ray head was moved during the gantry rotating according to input command signals without a target tracking, and a machine log analysis was performed. The difference between a command and a measured position was calculated as mechanical error. To evaluate beam-positioning accuracy, a moving phantom, which had a steel ball fixed at the center, was driven based on a sinusoidal wave (amplitude [A]: 20 mm, time period [T]: 4 s), a patient breathing motion with a regular pattern (A: 16 mm, average T: 4.5 s), and an irregular pattern (A: 7.2-23.0 mm, T: 2.3-10.0 s), and irradiated with DTT during gantry rotation. The beam-positioning error was evaluated as the difference between the centroid position of the irradiated field and the steel ball on images from an electronic portal imaging device. For dosimetric accuracy, dose distributions in static and moving targets were evaluated with DTT conformal arc irradiation. Results: The root mean squares (RMSs) of the mechanical error were up to 0.11 mm for pan motion and up to 0.14 mm for tilt motion. The RMSs of the beam-positioning error were within 0.23 mm for each pattern. The dose distribution in a moving phantom with tracking arc irradiation was in good agreement with that in static conditions. Conclusions: The gimbal positional accuracy was not degraded by gantry motion. As in the case of a fixed port, the Vero4DRT system showed adequate accuracy of DTT conformal arc irradiation. (C) 2014 American Association of Physicists in Medicine.
  • Yabuta K; Monzen H; Tamura M; Tsuruta T; Itou T; Nohtomi A; Nishimura Y
    Igaku butsuri 34 (3) 139 - 148 1345-5354 2014 [Refereed]
  • Nakamura M; Iramina H; Takamiya M; Ono T; Akimoto M; Mukumoto N; Ishihara Y; Utsunomiya S; Shiinoki T; Miyabe Y; Sato S; Monzen H
    Igaku butsuri 34 (4) 208 - 218 1345-5354 2014 [Refereed]
     
    PURPOSE: The purpose of this study was to investigate the status of the implementation of quality assurance (QA) for intensity-modulated radiation therapy (IMRT) in Japan using a questionnaire survey. METHODS: The questionnaire consisted of seven sections: (1) clinical uses of IMRT, (2) treatment planning systems, treatment machines, phantoms for verification and CT scanning, (3) absorbed dose verification, (4) dose distribution verification, (5) fluence map verification, (6) acceptance criteria for each verification, and (7) comments. RESULTS: The questionnaire was completed by 129 institutions (response rate: 76.8%). IMRT was performed for prostate cancer in 125 institutions (96.9%), followed by head and neck cancer in 83 (64.3%), and brain tumors in 69 (53.5%). Although at least three individuals were engaged in IMRT QA in 77.5% of the institutions, the number of full-time persons involved in IMRT QA was one or less in 94 institutions (72.9%). This indicated that most institutions in Japan have a staff shortage. More than 90% of the institutions verified both the absorbed dose and dose distribution. The acceptance criterion for the absorbed dose verification was set to ±3% in at least 80% of the institutions. Gafchromic film was used for the majority of dose distribution verifications. The acceptance criteria for dose distribution verification mainly involved gamma analysis and a comparison of dose profiles; however, the judgment of acceptance did not depend on the results of the gamma analysis. CONCLUSION: This survey increases our understanding of how institutions currently perform IMRT QA analysis. This understanding will help to move institutions toward more standardization of IMRT QA in Japan.
  • Wambaka Ange Mampuya; Mitsuhiro Nakamura; Yukinori Matsuo; Nami Ueki; Yusuke Iizuka; Takahiro Fujimoto; Shinsuke Yano; Hajime Monzen; Takashi Mizowaki; Masahiro Hiraoka
    MEDICAL PHYSICS AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS 40 (9) 091718  0094-2405 2013/09 [Refereed]
     
    Purpose: To assess the effect of abdominal compression on the interfraction variation in tumor position in lung stereotactic body radiotherapy (SBRT) using cone-beam computed tomography (CBCT) in a larger series of patients with large tumor motion amplitude. Methods: Thirty patients with lung tumor motion exceeding 8 mm who underwent SBRT were included in this study. After translational and rotational initial setup error was corrected based on bone anatomy, CBCT images were acquired for each fraction. The residual interfraction variation was defined as the difference between the centroid position of the visualized target in three dimensions derived from CBCT scans and those derived from averaged intensity projection images. The authors compared the magnitude of the interfraction variation in tumor position between patients treated with [n = 16 (76 fractions)] and without [ n = 14 (76 fractions)] abdominal compression. Results: The mean +/- standard deviation (SD) of the motion amplitude in the longitudinal direction before abdominal compression was 19.9 +/- 7.3 (range, 10-40) mm and was significantly (p < 0.01) reduced to 12.4 +/- 5.8 (range, 5-30) mm with compression. The greatest variance of the interfraction variation with abdominal compression was observed in the longitudinal direction, with a mean +/- SD of 0.79 +/- 3.05 mm, compared to -0.60 +/- 2.10 mm without abdominal compression. The absolute values of the 95th percentile of the interfraction variation for one side in each direction were 3.97/6.21 mm (posterior/anterior), 4.16/3.76 mm (caudal/cranial), and 2.90/2.32 mm (right/left) without abdominal compression, and 2.14/5.03 mm (posterior/anterior), 3.93/9.23 mm (caudal/cranial), and 2.37/5.45 mm (right/left) with abdominal compression. An absolute interfraction variation greater than 5 mm was observed in six (9.2%) fractions without and 13 (17.1%) fractions with abdominal compression. Conclusions: Abdominal compression was effective for reducing the amplitude of tumor motion. However, in most of the authors' patients, the use of abdominal compression seemed to increase the interfraction variation in tumor position, despite reducing lung tumor motion. The daily tumor position deviated more systematically from the tumor position in the planning CT scan in the lateral and longitudinal directions in patients treated with abdominal compression compared to those treated without compression. Therefore, target matching is required to correct or minimize the interfraction variation. (C) 2013 American Association of Physicists in Medicine.
  • Tsubasa Watanabe; Hajime Monzen; Masatake Hara; Takashi Mizowaki; Masahiro Hiraoka
    ANNALS OF NUCLEAR MEDICINE SPRINGER 27 (3) 279 - 284 0914-7187 2013/04 [Refereed]
     
    Technetium-99m sestamibi (Tc-99m-MIBI) scintigraphy has been reported to be a functional imaging tool for in vivo detection of mitochondrial dysfunction in myocardium and multidrug resistance-associated protein expression in tumors. The purpose of this study was to propose a clinically applicable pharmacokinetic model with metabolic equilibrium of Tc-99m-MIBI and to evaluate the accuracy of the model. For this study, eight healthy men received Tc-99m-MIBI scintigraphy. The planar images were obtained at 0.25, 0.5, 1, 2, 3, 4, 5, and 6 h after Tc-99m-MIBI injection. The measured time series Tc-99m-MIBI counts were fitted to our model by nonlinear regression analysis. The predictive performance of the model was determined by comparing the residuals between measured and predicted values. We obtained a good regression by fitting data from 0.25 to 6 h after Tc-99m-MIBI injection, with excellent correlation between measured and predicted Tc-99m-MIBI counts (R (2) = 0.9792) and a slope near unity. The 95 % confidence interval of the mean prediction error included 0, which means that the prediction was not significantly biased. The precision of the prediction was also excellent. Our model shows good predictive capacity, with favorable bias and accuracy. By comparing the predictive values of this model with measured values, mitochondrial Tc-99m-MIBI washout can be quantified. Tc-99m-MIBI washout rates are reported to be a promising method for evaluating cardiac function in patients with cardiac diseases and P-glycoprotein expression in tumor cells. Therefore, this quantification could be useful for mitochondrial functional imaging, especially in patients with cardiac diseases or tumors.
  • M. Nakamura; T. Ono; M. Akimoto; N. Mukumoto; Y. Ishihara; S. Utsunomiya; T. Shiinoki; Y. Miyabe; S. Sato; H. Monzen; M. Hiraoka
    Medical Physics 40 (6) 243  0094-2405 2013 
    Purpose: To investigate the status of the implementation of quality assurance (QA) for intensity‐modulated radiation therapy (IMRT) in Japan using a questionnaire survey. Methods: The questionnaire consisted of six sections: (1) clinical uses of IMRT (2) IMRT‐related equipment verification of the (3) absorbed dose (4) dose distribution and (5) fluence map and (6) acceptance criteria for each verification. There were 55 questions in total. Results: The questionnaire was completed for 124 institutions. IMRT was performed for prostate cancer in 120 institutions (96.8%), followed by head and neck cancer in 81 (65.3%), and brain tumors in 67 (54.0%). Although at least four individuals were engaged in IMRT QA in 54.0% of the institutions, the number of full‐time persons involved in IMRT QA was two or less in 110 institutions (88.7%). This indicated that most institutions in Japan have a staff shortage. Dynamic IMRT was the most common beam delivery technique (52.5%) for prostate cancer, followed by segmental IMRT (25.0%) and volumetric modulated arc radiotherapy (15.0%). Similar tendencies were seen for head and neck cancer and brain tumors. More than 90% of the institutions verified both the absorbed dose and dose distribution. In more than 50% of the institutions, these were verified in each and every beam. The acceptance criterion for the absorbed dose verification was set to +/−3% in at least 80% of the institutions. Gafchromic film was used for the majority of dose distribution verification. The acceptance criteria for dose distribution verification mainly involved gamma analysis and a comparison of dose profiles however, the judgment of acceptance did not depend on the results of the gamma analysis. Conclusion: This survey increases our understanding of how institutions currently perform IMRT QA analysis. This understanding will help to move institutions toward more standardization of IMRT QA in Japan. This research was funded by the Japan Society of Medical Physics. © 2013, American Association of Physicists in Medicine. All rights reserved.
  • Satoru Utsunomiya; Hajime Monzen; Mami Akimoto; Nobutaka Mukumoto; Yoshitomo Ishihara; Takehiko Shiinoki; Mitsuhiro Nakamura; Yuki Miyabe; Sayaka Sato; Satoru Matsuo; Masahiro Hiraoka
    Radiological Physics and Technology 6 (1) 157 - 161 1865-0333 2013/01 [Refereed]
     
    We investigated the neonatal entrance-surface dose (ESD) and doses of scattered radiation emitted by a digital mobile X-ray system. The system is equipped with a novel flat-panel detector and is used in the neonatal intensive care unit. In the present study, the following three experiments were performed on frequently used X-ray-imaging condition: (1) the digital characteristics of the FPD were evaluated (2) the ESD to a water-equivalent phantom was measured with a patient skin dosimeter (PSD) and (3) the scattered radiation around the incubator was measured with an ionization chamber survey meter. The digital characteristic curve showed that the system had excellent linearity and that the contrast characteristics were not affected by the tube voltage in the range of 50-110 kV. The ESD was 51-52 μGy with an 8-cm-thick phantom and 33-34 μGy with a 4.5-cm phantom, for one exposure. The doses measured around the incubator were 0.1-0.6 μSv or below measurable limits. Use of the new device demonstrates the potential of reducing the ESD to the patient and operator. © 2012 Japanese Society of Radiological Technology and Japan Society of Medical Physics.
  • Mami Akimoto; Mitsuhiro Nakamura; Nobutaka Mukumoto; Hiroaki Tanabe; Masahiro Yamada; Yukinori Matsuo; Hajime Monzen; Takashi Mizowaki; Masaki Kokubo; Masahiro Hiraoka
    Medical Physics John Wiley and Sons Ltd 40 (9) 091705  0094-2405 2013 [Refereed]
     
    Purpose: To quantify the predictive uncertainty in infrared (IR)-marker-based dynamic tumor tracking irradiation (IR Tracking) with Vero4DRT (MHI-TM2000) for lung cancer using logfiles. Methods: A total of 110 logfiles for 10 patients with lung cancer who underwent IR Tracking were analyzed. Before beam delivery, external IR markers and implanted gold markers were monitored for 40 s with the IR camera every 16.7 ms and with an orthogonal kV x-ray imaging subsystem every 80 or 160 ms. A predictive model [four-dimensional (4D) model] was then created to correlate the positions of the IR markers (P IR) with the three-dimensional (3D) positions of the tumor indicated by the implanted gold markers (Pdetect). The sequence of these processes was defined as 4D modeling. During beam delivery, the 4D model predicted the future 3D target positions (Ppredict) from the P IR in real-time, and the gimbaled x-ray head then tracked the target continuously. In clinical practice, the authors updated the 4D model at least once during each treatment session to improve its predictive accuracy. This study evaluated the predictive errors in 4D modeling (E4DM) and those resulting from the baseline drift of PIR and Pdetect during a treatment session (EBD). E4DM was defined as the difference between Ppredict and Pdetect in 4D modeling, and EBD was defined as the mean difference between P predict calculated from PIR in updated 4D modeling using (a) a 4D model created from training data before the model update and (b) an updated 4D model created from new training data. Results: The mean E 4DM was 0.0 mm with the exception of one logfile. Standard deviations of E4DM ranged from 0.1 to 1.0, 0.1 to 1.6, and 0.2 to 1.3 mm in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions, respectively. The median elapsed time before updating the 4D model was 13 (range, 2-33) min, and the median frequency of 4D modeling was twice (range, 2-3 times) per treatment session. EBD ranged from -1.0 to 1.0, -2.1 to 3.3, and -2.0 to 3.5 mm in the LR, AP, and SI directions, respectively. EBD was highly correlated with BDdetect in the LR (R = -0.83) and AP directions (R = -0.88), but not in the SI direction (R = -0.40). Meanwhile, EBD was highly correlated with BDIR in the SI direction (R = -0.67), but not in the LR (R = 0.15) or AP (R = -0.11) direction. If the 4D model was not updated in the presence of intrafractional baseline drift, the predicted target position deviated from the detected target position systematically. Conclusions: Application of IR Tracking substantially reduced the geometric error caused by respiratory motion however, an intrafractional error due to baseline drift of > 3 mm was occasionally observed. To compensate for EBD, the authors recommend checking the target and IR marker positions constantly and updating the 4D model several times during a treatment session. © 2013 American Association of Physicists in Medicine.
  • S. Utsunomiya; Y. Miyabe; A. Sawada; T. Shiinoki; Y. Ishihara; N. Mukumoto; M. Nakamura; M. Yamada; H. Monzen; T. Mizowaki; M. Kokubo; M. Hiraoka
    MEDICAL PHYSICS AMER ASSOC PHYSICISTS MEDICINE AMER INST PHYSICS 39 (6) 3782 - 3782 0094-2405 2012/06 
    Purpose: To evaluate the accuracy of intensity modulated radiation therapy (IMRT) delivery during real‐time tumor tracking using a gimbaled X‐ray head of Vero4DRT (MHI‐Tm2000) (Mitsubishi Heavy Industries, Ltd., Japan). Methods: We have utilized a QUASAR platform phantom (Modus Medical Devices Inc.) where a Kodak EDR2 X‐ray film was placed at 5 cm depth in a solid water phantom. A simple step‐and‐shoot test field with five segmental fields and a clinical field for a prostate IMRT were used. Films were irradiated in following three setups: (1) stationary phantom and gimbal, (2) moving phantom and stationary gimbal and (3) moving phantom and real‐time tracking irradiation. The moving phantom was driven by sine waves at a frequency of 0.25, 0.33 and 0.5 Hz with amplitude of 20 mm along tilt direction. 2D dose distributions and profiles were obtained for each case and analyzed using dose analysis software, DD‐IMRT (R‐TECH.INC, Japan). Results: We observed a large dose blurring effect and as large as 40% dose discrepancies between (1) and (2) for the test field at the high dose gradient. In contrast, the comparison of (1) with (3) shows the differences less than 3% in the most area except the high dose gradient. We also found the good agreement between (1) and (3) for a clinical field. The percentage of values of discrepancy less than 5% and 3% were 97.5% and 82.0%, respectively. Conclusions: We demonstrated the significant dose blurring effect with a moving target in step‐and‐shoot IMRT dose delivery and it was greatly improved by real‐time tumor tracking with Vero4DRT. The system showed an excellent accuracy of IMRT dose delivery during tumor tracking as Result of the first evaluation. This research was supported by the Japan Society for the Promotion of Science (JSPS) through its Funding Program for World‐Leading Innovation R&D on Science and Technology (FIRST Program). Research sponsored in part by Mitsubishi Heavy Industries, Ltd. © 2012, American Association of Physicists in Medicine. All rights reserved.
  • Hajime Monzen; Masatake Hara; Makoto Hirata; Takatoshi Suzuki; Makoto Ogasawara; Hirokazu Higuchi; Tomohiro Matsuoka; Hisato Kobayashi; Rumio Yuki; Kunihiko Hirose
    ANNALS OF NUCLEAR MEDICINE SPRINGER 25 (5) 381 - 386 0914-7187 2011/06 [Refereed]
     
    The combination of adenosine infusion with low-level exercise has become a common approach for inducing stress during stress myocardial perfusion imaging (MPI). We investigated stress MPI performed by combined low-level exercise and adenosine infusion. This combined protocol can decrease adverse reactions and reduce the effect of scattered rays from the liver. Subjects were clinically referred for a 53-min rest-stress Tc-99m Sestamibi MPI procedure using BIWAKO PROTOCOL. Ninety-eight patients (44.5%) underwent adenosine infusion with ergometer exercise testing and 122 patients (55.5%) underwent adenosine infusion without exercise testing. We evaluated the liver/heart (L/H) uptake ratio, background activity in the upper mediastinum, and adverse reactions. The L/H ratio and background activity were lower in the adenosine-exercise group than in the adenosine-non-exercise group (1.8 +/- A 0.54 vs. 2.1 +/- A 0.62, P < 0.0056; 43.1 +/- A 12.2 vs. 61.5 +/- A 15.4, P < 0.0001). The adenosine-exercise group had fewer adverse reactions than the adenosine-non-exercise group (11.2 vs. 19.7%). All of the adverse reactions were minor, with the exception of severe back pain in one case. The incidence of adverse reactions in our study was lower than that in previous studies for unknown reason. Adenosine infusion in combination with low-level exercise seems to result in higher-quality images and fewer adverse reactions than adenosine infusion without exercise. The combined protocol decreases adverse reactions and improves the quality of myocardial perfusion images by decreasing background activity.
  • Hajime Monzen; Yuko Ban; Makoto Hirata; Akira Nakanishi; Takatoshi Suzuki; Tsutomu Inoue; Taku Yamamoto; Makoto Ogasawara; Chika Tanaka; Toru Iwasa; Rumio Yuki
    Radiological Physics and Technology 4 (1) 19 - 23 1865-0333 2011/01 [Refereed]
     
    For children, cardiac nuclear medicine imaging has not been widely used because of problems of physical motion, even in schoolchildren who require no sedation. In this study, rest-stress myocardial perfusion imaging (MPI) with technetium-99m-tetrofosmin (Tc-99m TF) was performed with the use of a Vac-Loc cushion, a patient immobilizer commonly used for radiotherapy, for immobilizing school-age patients. The immobilizer attenuated the gamma radiation by 6%. By visual assessment, physical motion-related artifacts were markedly improved in images acquired with the immobilizer, compared to those without. In the assessment of image reproducibility with the immobilizer, taking the reproducibility as 2.5∑ + 0.7σ, there were deviations of 4.45, 5.28, and 3.28 mm along the X-, Y-, and Z-axes, respectively, demonstrating a high reproducibility and a negligible rest-stress position error. It is suggested that for radiotherapy, the immobilizer could expand the versatility of MPI while allowing only minimal physical motion in children. © 2010 Japanese Society of Radiological Technology and Japan Society of Medical Physics.
  • Hajime Monzen; Hisashi Shimoyama; Makoto Hirata; Tsutomu Inoue; Takatoshi Suzuki; Muneo Ohba
    Radiological Physics and Technology 3 (1) 78 - 83 1865-0333 2010/01 [Refereed]
     
    We evaluated patients with atrial fibrillation (Af) to define the optimal phase for ECG-gated image reconstruction for multi-slice CT (MSCT) of the left atrial appendage (LAA). We performed MSCT scans in 37 patients with Af, and we reconstructed multi-planar reformation images of the LAA, defined by the absolute delay (ms) immediately after the T wave, and by the relative delay (%). For visual analysis of the image quality for each image, a four-grade scoring system (poor to excellent) was used by two blinded, independent reviewers. Images obtained by absolute delay and by relative delay were classified as being of poor, fair, good, or excellent quality in 2, 2, 8, and 25 cases, and in 18, 11, 8, and 0 cases, respectively. This phase-definition strategy in Af patients is more effective by absolute delay than by relative delay, and MSCT could provide an alternative diagnostic assessment of LAA thrombi. © 2009 Japanese Society of Radiological Technology and Japan Society of Medical Physics.
  • Hajime Monzen; Masatake Hara; Akira Nakanishi; Makoto Hirata; Takatoshi Suzuki; Makoto Ogasawara; Hirokazu Higuchi; Hisato Kobayashi; Rumio Yuki; Kunihiko Hirose
    Radiological Physics and Technology 2 (1) 70 - 76 1865-0333 2009/01 [Refereed]
     
    We have developed a new protocol of myocardial perfusion-gated single-photon emission computed tomography (SPECT), by use of technetium-99m sestamibi (MIBI), in which SPECT imaging at rest followed by SPECT imaging after adenosine with low level ergometer stress can be conducted by use of the Monzen position within a shortened total testing time of 1 h or less. The study group consisted of 137 patients who underwent this new imaging protocol. The diagnostic quality of the images was as good as that of images obtained with the conventional method (30-60 min after the injection of MIBI). The SPECT image quality for the 137 patients was evaluated, and the percentages of images rated as excellent, good, fair, and poor were 65.3, 27.4, 5.8, and 1.5% for the rest image, and 68.2, 21.9, 8.4, and 1.5% for the stress image, respectively. The shortened total testing time reduced the physical and mental burden on the patient compared with that of conventional myocardial perfusion imaging. Because this technique allows us to perform rest and stress myocardial imaging within a short period, it is expected to be very useful in the clinical setting. © 2008 Japanese Society of Radiological Technology and Japan Society of Medical Physics.
  • Hirata M; Monzen H; Suzuki T; Ogasawara M; Nakanishi A; Sumi N; Inoue T; Yamamoto T; Hara M; Kobayashi H; Yuki R
    Igaku butsuri : Nihon Igaku Butsuri Gakkai kikanshi = Japanese journal of medical physics : an official journal of Japan Society of Medical Physics Japan Society of Medical Physics 29 (1) 3 - 11 1345-5354 2009 [Refereed]
     
    Objective
    The present study aimed at establishing a new protocol using both 99mTc-Tetrofosmin (TF) and 123I-BMIPP SPECT to detect myocardial damage within one hour.
    Methods
    Initial 123I-BMIPP SPECT was immediately followed by 99mTc-TF SPECT. The influence of 123I scattered rays on 99mTc energy windows set at 15% and 10% were measured using an RH-2 phantom. Participants in the study were patients with heart diseases who had provided written informed consent to undergo the new protocol. The patients maintained the MONZEN position throughout the procedure and an injection syringe was attached to the left arm for 99mTc-TF injection during123I-BMIPP SPECT.
    Results & Discussion
    The phantom study showed only slight 123I contamination of 99mTc at the 10% window setting. The new method separated the 123I and 99mTc energy windows well and neither crosstalk nor scatter correction were needed. Images obtained from dual (simultaneous) acquisition were contaminated, whereas contamination and influence of scattered rays were absent in images obtained by use of the new protocol. These images were thus useful for clinical diagnosis.
    Conclusion
    The new protocol is more convenient for patients and might improve the efficiency of detecting myocardial damage.
  • Masatake Hara; Hajime Monzen; Rie Futai; Koichi Inagaki; Hisashi Shimoyama; Masaru Morikawa; Nobuyoshi Tomioka; Takashi Konishi; Yutaka Watanabe; Rumio Yuki; Hisato Kobayashi; Kunihiko Hirose
    JOURNAL OF NUCLEAR CARDIOLOGY MOSBY-ELSEVIER 15 (2) 241 - 245 1071-3581 2008/03 [Refereed]
     
    Background In technetium (Tc)-99m myocardial perfusion imaging (MPI), intestinal activity often interferes with the assessment of myocardial perfusion of the inferior wall. We examined whether a small amount of soda water prevents intestinal activity and improves image quality of the inferior wall in Tc-99m tetrofosmin MPI. Methods and Results. Ninety-five patients referred for 1-day rest/stress Tc-99m tetrofosmin MPI were assigned to one of two groups automatically, according to the date when they underwent MPI: the soda water group (n = 63) ingested 100 mL soda water just before image acquisition after adenosine stress, and the control group (n = 32) underwent no intervention. The frequency of intestinal activity was assessed visually on planar images. The inferior myocardial wall and the abdominal activity adjacent to the myocardium were assessed quantitatively on three different planar images during stress, and the mean inferior wall-to-abdomen (I/A) count ratio was calculated. The frequency of intestinal activity was 69.8 % in the soda water group, and 90.6% in the control group (P =.038). The I/A count ratio was significantly higher in the soda water group than in the control group (1.98 +/- 0.51 vs 1.50 +/- 0.35, respectively, P <.0001, +/- SD). Conclusions. The intake of 100 mL of soda water improves intestinal activity and improves the image quality of the inferior wall.
  • Morikazu Amano; Minoru Suzuki; Satoshi Andoh; Hajime Monzen; Kaoru Terai; Brent Williams; Chang W. Song; Kevin H. Mayo; Takeo Hasegawa; Ruud P. M. Dings; Robert J. Griffin
    INTERNATIONAL JOURNAL OF CLINICAL ONCOLOGY SPRINGER TOKYO 12 (1) 42 - 47 1341-9625 2007/02 [Refereed]
     
    Background. The present study investigated whether treatment with anginex, a novel antiangiogenic peptide, could block re-vascularization after radiation treatment. Methods. A squamous cell (SCCVII) xenograft tumor mouse model was employed to assess the effects of anginex given post-radiation on tumor growth, microvessel density (MVD), and oxygen levels. The oxygen status was determined by the partial pressure of O-2. Results. Tumors in untreated mice increased threefold in 7.0 days, anginex-treated tumors (10mg/kg intraperitoneal, twice) required 7.3 +/- 0.9 days, and tumors exposed to 8-Gy radiation increased threefold over 11 days. Combination treatment of anginex and radiation caused the tumors to grow threefold in 16.1 +/- 1.6 days, a delay which was significant and deemed supra-additive. Oxygen levels in tumors treated by stand-alone or combination therapies were significantly reduced; for example from 19.5 +/- 4.9 mmHg in controls to 9.7 +/- 1.9mmHg in combination-treated, size-matched tumors. In addition, immunohistochemistry showed a decrease in MVD in the tumors treated with anginex, radiation, or the combination. These results suggest that a combination of anginex and radiation can greatly affect the amount of functional vasculature in tumors and prolong radiation-induced tumor regression. Conclusion. Antiangiogenesis therapy with anginex, in addition to radiotherapy, will be useful by blocking angiogenesis-dependent regrowth of vessels.
  • Hajime Monzen; Masatake Hara; Makoto Hirata; Akira Nakanishi; Makoto Ogasawara; Takatoshi Suzuki; Tamie Sato; Hisashi Shimoyama; Futoshi Tadehara; Kunihiko Hirose; Rumio Yuki
    ANNALS OF NUCLEAR MEDICINE JAPANESE SOCIETY NUCLEAR MEDICINE 20 (10) 705 - 710 0914-7187 2006/12 [Refereed]
     
    We have devised a new position (Monzen position) which can suppress the influence of scattered rays from surrounding organs (liver, etc.) when conducting myocardial imaging. Unlike the conventional techniques, which require a waiting period of 30-60 minutes before imaging can be started after the infusion of technetium-99m sestamibi or technetium-99m tetrofosmin, this position allows single-photon emission tomography to be started about 5-10 minutes after the infusion of the tracer. Therefore, with this technique the total time required for imaging is reduced and consequently the physical and mental burden of the patient is also reduced. Furthermore, the number of patients who can receive this test at any facility can be increased. This position may also be applicable in myocardial scintigraphy using some other tracers.
  • Seiko Nunoura; H. Kobayashi; A. Furuta; T. Takahashi; K. Akuta; H. Monzen; T. Tano
    Japanese Journal of Clinical Radiology 51 71 - 77 0009-9252 2006/02 
    We prospectively assessed the feasibility of multidetector row CT (MDCT) in imaging the supplied vessels in thirteen patients of hemoptysis and/or lung tumors before interventional radiology. In our samples, treatment was successful in a total of nineteen arteries, of which seventeen were bronchial arteries and two were non-bronchial systemic arteries. The MDCT captured all seventeen bronchial arteries and one of the two non-bronchial arteries, while the conventional angiography only captured five bronchial arteries and none of the bronchial systemic arteries. Therefore, it is concluded that the MDCT offers higher accuracy in imaging the supplied vessels in patients of hemoptysis and/or lung tumors. The adoption of the MDCT would provide us with another option in thoracic interventional radiology.
  • M Amano; H Monzen; M Suzuki; K Terai; S Andoh; A Tsumuraya; T Hasegawa
    JOURNAL OF RADIATION RESEARCH JAPAN RADIATION RESEARCH SOC 46 (4) 373 - 378 0449-3060 2005/12 [Refereed]
     
    The purpose of the present study was to investigate the effects of Pentoxifylline (PTX), Vinpocetine (VPT) and Ticlopidine Hydrochloride (TCD), used commonly for vascular disorders in humans, on the pO(2) in SCCVII tumors of C3H/HeJ mice and on the radioresponse of SCCVII tumors. The pO(2) in the SCCVII tumors, which were measured 30 min after intraperioneal (i.p.) injection of PTX (5 mg/kg), VPT (5 mg/kg), or TCD (10 mg/kg) using polarography, was compared to that in saline-treated control tumors. All the three drugs, PTX, VPT and TCD, yielded significant increase of the pO(2) in the SCCVII tumors from 25.6 to 26.9 mmHg, from 18.6 to 22.9 mmHg, and from 22.6 to 25.9 mmHg, respectively. Frequency histogram of the pO(2) distribution in the saline-treated SCCVII tumors did not show hypoxic fraction of less than 10 mmHg. The radioresponses of the drugs were investigated by tumor growth delay assay. In the drug-treated groups, the SCCVII tumors were irradiated with a single dose of 15 Gy 30 min after injection of the drugs at the same doses as those used in the experiments for intratumoral pO(2) measurement. Compared with the irradiation alone group, significant tumor growth delays were observed in all the drug-treated groups. The time required to reach a four-fold increase in the initial tumor volume were 4 days in the saline-treated control group, 22 days in the irradiation (IR) alone group, 28 days in the PTX + IR group, 29 days in the VPT + IR group, and 32 days in TCD + IR group. In conclusion, VPT and TCD are potentially promising drugs for increasing the intraturnoral pO(2) although the mechanism for radiopotentiation observed in the present study is unknown due to small hypoxic fraction in the SCCVII tumors. Further studies on other mechanisms for radiopotentiation of PTX, VPT or TCD, besides of increasing the pO(2) in the tumor, are needed.
  • Hajime Monzen
    Thermal Medicine (Japanese Journal of Hyperthermic Oncology) Japanese Society for Thermal Medicine 21 (1) 43 - 45 0911-2529 2005 [Refereed]
     
    It is believed that hyperthermia will show anti-tumor effects at the temperature over 42.5 degrees. But we found that the mild hyperthermia as under 42.5 degrees still shows anti-tumor effects due to the immunological activity. We used C3H mice bearing SCC-VII tumor. These mice were heated at the temperature of 39-41 degrees by 1 hour in controlled water bath. After giving mild hyperthermia, white blood cells (WBC), lymphocyte cells (LyC), NK cell activity were increased compared with pre-heat condition. The delays of the SCC-VII tumor growth in C3H mice was observed after mild-hyperthermia. It shows that the immunological activity were increased as activated WBC, LyC and NK cells. Also anti-tumor effects were produced by mild hyperthermia. It is supposed that quantitative stimulation of femoral region by mild hyperthermia has induced the activation of hemopoietic organs in bone marrow of femoral region and this has activated immunological potency, mild hyperthermia seems to be a useful and effective auxiliary therapy which is not only effective for the treatment of malignant tumors but also for the treatment of diseases related to immunological activity (e. g. viral hepatitis type C, collagen diseases, AIDS, postoperative physical restraint, auxiliary therapy during thermotherapy, elimination of immunodeficiency, etc.).
  • T Suzuki; H; MONZEN; J KADOTA
    Thermal Medicine (Japanese Journal of Hyperthermic Oncology) Japanese Society for Thermal Medicine 21 (2) 103 - 255 0911-2529 2005 [Refereed]
     
    Arsenic trioxide (ATO), which is known to be an effective carcinostatic against acute promyelocytic leukemia (APL), has drawn attention throughout the world. Studies on the effectiveness of ATO against solid tumors have started, and progress is expected. In this study, we evaluate the differences in the suppressive effects on tumor growth between different combinations of ATO administration and hyperthermia.
    Mice in which a squamous cell carcinoma (SCC-VII) had grown to 5-7 mm in the right femoral region were subjected to experiments in 5 groups. The groups consisted of the control group, hyperthermia alone group, ATO alone group, A-H group (ATO administration followed by 1-hour hyperthermia at an interval of 2 hours), and H-A group (1-hour hyperthermia followed by ATO administration at an interval of 2 hours). In each group, 10 mice were used for the measurement of the tumor volume, and 1 mouse for the pathological examination. The suppressive effects on tumor growth were examined in the A-H and H-A groups using changes in the tumor volume and pathological findings of the tumor.
    The changes in the tumor volume demonstrated synergistic effects of combined hyperthermia and ATO administration, but there was no significant difference in the suppressive effects between the A-H and H-A groups. The histopathological examination demonstrated more histological changes in the A-H and H-A groups than in the control, hyperthermia alone, and ATO alone groups, but there was no significant difference between the A-H and H-A groups. Our results indicate that there was no difference in the suppressive effects on tumor growth between the treatment sequences of ATO administration and hyperthermia at an interval of 2 hours.
  • Hajime Monzen; Robert J. Griffin; Brent W. Williams; Morikazu Amano; Satoshi Ando; Takeo Hasegawa
    Radiation Medicine - Medical Imaging and Radiation Oncology 22 (4) 205 - 211 0288-2043 2004/07 [Refereed]
     
    Purpose: Arsenic trioxide (ATO) has been reported to be an effective chemotherapeutic agent for acute promyelocytic leukemia (APL), and, recently, anti-tumor effect has been demonstrated in solid tumors. However, little is known about the mechanism of action of the ATO effect on solid tumor. We investigated the anti-vascular effect of ATO and the potential of combining ATO with radiation therapy. Materials and Methods: We studied the anti-vascular effect of ATO and radiosensitization of squamous cell carcinoma (SCC) VII murine tumors of C3H mice. The anti-vascular effect was examined using magnetic resonance imaging(MRI), and radiosensitivity was studied by clonogenic assay and tumor growth delay. Histopathological changes of the tumors after various treatments were also observed with hematoxylin and eosin (H& E) staining. Results: Necrosis and blood flow changes in the central region of tumors in the hind limbs of the animals were observed on T2-weighted imaging after an i.p. injection of 8 mg/kg of ATO alone. ATO exposure followed by radiation decreased the clonogenic survival of SCC VII cells compared with either treatment alone. Tumor growth delay after 10-20 Gy of radiation alone was increased slightly compared with control tumors, but the combination of ATO injection 2 hours before exposure to 20 Gy of radiation significantly prolonged tumor growth delay by almost 20 days. Conclusion: The results suggest that ATO and radiation can enhance the radiosensitivity of solid tumor.
  • S Ando; H Monzen; M Amano; H Ono; T Suzuki; T Hasegawa
    Thermal Medicine (Japanese Journal of Hyperthermic Oncology) Japanese Society for Thermal Medicine 20 (4) 249 - 255 0911-2529 2004 [Refereed]
     
    The temperature measurement of tumor is very important for hyperthermia. A temperature is measured by inserting a thermocouple thermometer into a living body. The fault of this method is that it can get only partial temperature and it has large invasive to the patient. Therefore, it method can't know even if a part of temperature rises. We researched the matter whether temperature measurement could be done without stabbing a thermometer by using the small coils. A magnetic field is generated when the radio-frequency is charged with electricity of the high frequency to the objects. Magnetic field is caught with the coil which put this magnetic field on making it stand opposite to each other. The electric fields decrease by 1/ (2πr). Then, we can calculate the profile of the electric fields using this equation. There are strong correlation between the radio frequency current and temperature in this object. Therefore, we can estimate the temperature distribution in the heating object non-invasive. The results of this study confirmed, there was strong correlation between temperature distribution using thermography and distribution of RF currents from our methods.
  • 川辺 睦; 門前 一
    保健物理 (一社)日本保健物理学会 38 (4) 291 - 293 0367-6110 2003/12
  • 吉村 明伸; 長谷川 武夫; 門前 一; 俵屋 仁司; 高橋 徹
    Radioisotopes (公社)日本アイソトープ協会 52 (12) 687 - 691 0033-8303 2003/12
  • RJ Griffin; H Monzen; BW Williams; H Park; SH Lee; CW Song
    INTERNATIONAL JOURNAL OF HYPERTHERMIA TAYLOR & FRANCIS LTD 19 (6) 575 - 589 0265-6736 2003/11 [Refereed]
     
    It has previously been found that the anti-leukaemia agent Arsenic Trioxide (ATO) causes vascular shutdown in solid tumours and markedly sensitizes tumours to hyperthermia. The present study was designed to evaluate the mechanism of action and dose-dependence of ATO-induced thermosensitization in FSaII and SCK murine tumours. The role of oxidative stress was studied by observing ATO-induced vascular shutdown in vivo and ATO-induced endothelial cell adhesion molecule expression in vitro in the presence or absence of an antioxidant. It was found that a dose as low as 2 mg/kg ATO impaired vascular function, as estimated by Rb-86 uptake, in the tumour. The degree of tumour growth delay induced by I h of hyperthermia at 42.5degreesC, applied 2 h after ATO injection, was proportional to the dose of ATO administered. In addition, it was found that ATO can directly thermosensitize tumour cells in vitro. The development of massive tissue necrosis in the tumour was observed in the days after treatment, especially with the combination of ATO and heating. ATO-induced adhesion molecule expression in vitro was abolished when the anti-oxidant n-acetyl-cysteine (NAC) was introduced prior to exposure, while the addition of NAC in vivo partially blocked ATO-induced vascular shutdown. These results suggest that the expression of adhesion molecules by the vasculature due to oxidative stress contribute to the ATO-induced selective tumour vascular effects observed and that the clinical use of ATO to increase tumour thermosensitivity via direct cellular and vascular effects appears feasible.
  • 診断領域の簡易被ばく線量測定装置に関する研究 患者被ばく線量還元システムの構築を目指して
    門前 一
    MEDICAL NOW (株)島津製作所 (49) 25 - 28 0916-8745 2002/07
  • 森部龍祐; 門前一; 銭谷潔; 結城留実夫; 佐野幹夫; 長谷川武夫
    日本放射線技師会雑誌 48 (11) 1521 - 1526 0287-9395 2001/11

Conference Activities & Talks

  • Establish of dose-parameter analysis model to improve VMAT plan quality for prostate cancer
    Takaaki Ito; Wataru Omas; Kazutaka Yoshida; Hajime Monzen
    22nd Asia-Oceania Congress on Medical Physics, 2022  2022/12
  • Variation of Imaging Dose for Cone-Beam CT and Helical CT among Multi-Institutional Clinical Protocols in Image-Guided Radiotherapy (IGRT)
    Yusuke Sakai; Yoshiki Takei; Hiroyuki Kosaka; Kenji Nakamura; Yuya; Yanagi; Kazuki; Wakabayashi; Takaaki Ito; Kazuki Kubo; Hajime Monzen
    22nd Asia-Oceania Congress on Medical Physics, 2022  2022/12
  • Lung Compensation Filter with Real-time Shapeable Tungsten Rubber (STR)
    Yuya Yanagi; Takaaki Ito; Yusuke Sakai; Masakazu Otsuka; Hajime Monzen
    22nd Asia-Oceania Congress on Medical Physics, 2022  2022/12
  • 前立腺治療概論 IMRT・VMAT治療計画実習(Optimization)  [Invited]
    門前一
    放射線治療専門放射線技師認定機構主催 令和4年度実機講習会(治療計画)プログラム
  • RapidPlanの基礎  [Invited]
    門前一
    第50回北海道放射線治療研究会  2022/11
  • 大学院への進み方、国際交流の醍醐味  [Invited]
    門前一
    大瑠璃祭 特別講演 京都医療科学大学  2022/10
  • Physical characteristics of a novel real-time shapeable soft rubber bolus  [Not invited]
    Hiroyuki Kosaka; Mikoto Tamura; Kenji Matumoto; Masakazu Otsuka; Hidekazu Nanbu; Hajime Monzen
    第124回日本医学物理学会学術集会  2022/09
  • 核 医 学 内 用 療 法 の 基 礎 と 線 量 計 測  [Invited]
    門前一
    第11回JBMP医学物理講習会  2022/09
  • Halcyon™ による全身照射の試み  [Invited]
    門前一
    Varian Oncology Summit 2022  2022/08
  • Rapid Plan 総論  [Invited]
    門前 一
    第2回RapidPlan講習会  2022/06
  • 門前 一
    第81回日本医学放射線学会総会ランチョンセミナー  2022/04
  • Dosimetric evaluation of a real-time variable shape tungsten rubber as a skin collimator in electron radiotherapy.
    Kazuki Wakabayashi; Hajime Monzen; Mikoto Tamura; Kenji Matsumoto; Yoshiki Takei; Yasumasa Nishimura
    The 5th International Cancer Research Symposium.  2022/01
  • Establish of dose-parameter analysis model to improve VMAT plan quality for prostate cancer.
    Takaaki Ito; Wataru Omasa; Kazutaka Yoshida; Mikoto Tamura; Hajime Monzen
    21st Asia-Oceania Congress of Medical Physics.  2021/12
  • Radiation Protection of Nail with Real-time Shapeable Tungsten Rubber in the Total Skin Electron Beam (TSEB) Therapy.
    Yuya Yanagi; Mikoto Tamura; Hajime Monzen
    21st Asia-Oceania Congress of Medical Physics.  2021/12
  • The iteratively improved method with KBP to standardize VMAT plan quality in prostate cancer.
    Kenji Nakamura; Katsuya Okuhata; Masakazu Otsuka; Mikoto Tamura; Hajime Monzen
    21st Asia-Oceania Congress of Medical Physics.  2021/12
  • Development of a Novel Real-Time Shapeable Bolus for Electron Radiotherapy.
    Kazuki Wakabayashi; Hajime Monzen; Mikoto Tamura; Yoshiki Takei; Katsuya Okuhata; Shimpei Anami; Hiroshi Doi; Yasumasa Nishimura
    21st Asia-Oceania Congress of Medical Physics.  2021/12
  • Protection of radiation exposure for physician's brain using a tungsten rubber flap in interventional radiology.
    Shota Hattori; Hiroyuki Kosaka; Hajime Monzen; Mikoto Tamura
    21st Asia-Oceania Congress of Medical Physics.  2021/12
  • Reduction of γ-ray attenuation with a new rigid couch in SPECT.
    Yasunori Nakamura; Hajime Monzen; Mikoto Tamura; Takeshi Nii; Masayoshi Mizuta
    21st Asia-Oceania Congress of Medical Physics.  2021/12
  • Dosimetric characteristics of a thin bolus with real time variable shape tungsten rubber for photon beam.
    Katsuya Okuhata; Mikoto Tamura; Hajime Monzen; Yasumasa Nishimura
    The 9th Korea-Japan Joint Meeting on Medical Physics.  2021/09
  • Artificial Intelligene技術を用いた前立腺がんVMAT治療計画の線量評価:多施設研究  [Invited]
    上田 悦弘; 門前 一; 田村 命; 福永 淳一; 上間 達也; 清水 由美子; 村木 勇太
    第77回日本放射線技術学会総会学術大会
  • Rapid Plan 総論  [Invited]
    門前 一
    第1回Rapid Plan講習会  2020
  • Radiation protection with novel Tungsten material in diagnostic radiology field  [Invited]
    Hiroyuki Kosaka; Hajime Monzen
    The 11th Annual Scientific Meeting of Thai Medical Physicist Society  2019
  • Feasibility Study of Nevel Tungsten Shielding Material for Electron Radiation Therapy
    Kenta Kijima; Anchali Krisanachinda; Mikoto Tamura; Hajime Monzen
    The 11th Annual Scientific Meeting of Thai Medical Physicist Society  2019
  • Our methodology and experience in pre-treatment patient specific IMRT QA and survey of consistency in IMRT QA result between institutions
    Kazuki Kubo; Hajime Monzen; Kohei Shimomura; Kenji Matsumoto; Tomoharu Sato; Mikoto Tamura; Kiyoshi Nakamatsu; Kentro Ishii; Ryu Kawamorita
    The 11th Annual Scientific Meeting of Thai Medical Physicist Society  2019
  • Immunogenic prognostic factors in patients with brain metastases from non-small cell lung cancer.
    Hiroshi Doi; Kiyoshi Nakamatsu; Simpei Anami; Takuya Uehara; Yutaro Wada; Kohei Fukuda; Masahio Inada; Kazuki Ishikawa; Sshuichi Kanamori; Hajime Monzen; Yasumasa Nishimura
    European Society for Therapeutic Radiotherapy & Oncology (ESTRO) 38  2019
  • The impact for the irradiation time by offset distance between PTV and isocenter in Tomotherapy
    Kenji Matsumoto; Makoto Hirata; Kohei Hanaoka; Mikoto Tamura; Hajime Monzen; Masahiko Okumura
    7th Asia Radiation Therapy Symposium  2019
  • Radiation shielding efficiency of tungsten rubber in interventional radiology
    Kenta Kijima; Anchali Krisanachinda; Petchaleya Suwanpradit; Mikoto Tamura; Yasumasa Nishimura; Hajime Monzen
    7th Asia Radiation Therapy Symposium  2019
  • A cleaned-up RapidPlan modeling method for volumetric modulated arc therapy in prostate cancer
    Mikoto Tamura, Hajime Monzen, Kenji Matsumoto, Masakazu Otsuka, Kazuki Kubo, Yasumasa Nishimura
    7th Asia Radiation Therapy Symposium  2019
  • Comparison of measured and standard beam profiles with a novel rigid board for a Halcyon linear accelerator
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka; Masahiko Okumura; Yasumasa Nishimura
    7th Asia Radiation Therapy Symposium  2019
  • Development of a novel couch to reduce potential risk for the skin toxicity in megavoltage radiotherapy
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masahiko Okumura; Hiroshi Doi; Yasumasa Nishimura
    The 7th Japan-Taiwan Radiation Oncology Symposium  2019
  • Usefulness of the principle of selective excitation technique non-electrocardiogram-gated 3D-TOF method in lower-extremity MRA using a whole-body coil
    Yasunori Nakamura; Masayoshi Mizuta; Satoru Matsuo; Hajime Monzen
    The 7th Annual Congress of Vietnam Association Radiation Technologist  2019
  • Verification of representative beam data for a novel linac halcyon with 3D water phantom and measurement board  [Invited]
    Kenji Matsumoto; Kohei Shimomura; Mikoto Tamura; Kohei Hanaoka; Hajime Monzen; Masahiko Okumura
    The 7th Annual Congress of Vietnam Association Radiation Technologist  2019
  • Feistily study of the shielding ability of novel tungsten rubber against the electron beam in radiation therapy  [Invited]
    Hajime Monzen; Kenta Kijima; Mikoto Tamura; Seiichi Ota; Kenji Matsumoto
    The 7th Annual Congress of Vietnam Association Radiation Technologist  2019
  • Feasibility of a new photochromic diarylethene film for clinical dosimetry in diagnostic area  [Invited]
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka
    The 7th Annual Congress of Vietnam Association Radiation Technologist  2019
  • An experimental animal model of reirradiation in terms of radiation induced in normal intestine
    Hiroshi Doi; Mikoto Tamura; Hajime Monzen; Yasumasa Nishimura
    The 61st American Society for Radiation Oncology Annual Meeting 2019  2019
  • Inter-planner variation in treatment plan quality of hypofractionated prostate only and SIB whole pelvis VMAT plans created with a KBP
    Kazuki Kubo; Hajime Monzen; Kentaro Ishii; Mikoto Tamura; Ryu Kawamorita
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Shielding Efficiency of Novel Tungsten Rubber Against Radionuclides at Nuclear Medicine Division
    Kenta Kijima; Anchali Krisanachinda; Panya Pasawang; Kohei Hanaoka; Hajime Monzen; Yasumasa Nishimura
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Mechanical performance and dosimetric accuracy of a commercial knowledge-based VMAT planning for oropharyngeal cancer
    Katsuya Okuhata; Hajime Monzen; Mikoto Tamura; Kenji Matsumoto; Masakazu Otsuka; Kazuki Kubo; Takuya Uehara; Hiroshi Doi; Kazuki Ishikawa; Yasumasa Nishimura
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • To compare the radiation shielding ability of tungsten functional paper and Organ-based tube current modulation for the eye lens in head computed tomography: A phantom study
    Hiroyuki Kosaka; Shota Hattori; Koji Yamada; Mikoto Tamura; Hajime Monzen
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • The effectiveness of offset on the planning target volume away from the gantry isocenter in TomoTherapy: A phantom study
    Makoto Hirata; Kohei Hanaoka; Kenji Matsumoto; Mikoto Tamura; Hajime Monzen
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Qualitative evaluation of metal artifact reduction in follow-up after coiling of intracranial aneurysms: comparison of digital tomo synthesis images with computed tomography images
    Shota Hattori; Hiroyuki Kosaka; Mikoto Tamura; Hajime Monzen; Kojo Yamada
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Evaluation of shielding ability of a novel radiation shielding material, free-form tungsten containing rubber: actual measurement and Monte Carlo simulation
    Kazuki Kubo; Masakazu otsuka; Min-Geon Choi; Mikoto Tamura; Kenji Matsumoto; Hajime Monzen
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Dosimetric shield evaluation with a novel radiation shielding material, tungsten containing rubber in electron beams
    Kazuki Kubo; Kenta Kijima; Kenji Matsumoto; Mikoto Tamura; Hajime Monzen
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Comparison of plan quality with KBP for prostate VMAT plan established in three different terms
    Masakazu Otsuka; Hajime Monzen; Mikoto Tamura; Kazuki Kubo; Kenji Matsumoto; Yassumasa Nishimura
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Feasibility of using tungsten functional paper as a thin bolus for electron beam radiotherapy
    Yoshiki Takei; Takeshi Kamomae; Mikoto Tamura; Hajime Monzen
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Traveling performance of dual-layer multi-leaf collimator in HalcyonTM linac: A clinical experience
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Development of a new photochromic diarylethene film for clinical dosimetry
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Evaluation of knowledge-based model performance of volumetric modulated arc therapy (VMAT) for head and neck cancer: Multi-institutional trial  [Not invited]
    Hajime Monzen; Tatsuya Kamima; Yoshihiro Ueda; Jun-ichi Fukunaga; Yumiko Shimizu; Mikoto Tamura; Kazuki Ishikawa
    The 19th Asia-Oceania Congress of Medical Physics  2019
  • Feasibility of a tungsten rubber grid collimator for electron grid therapy  [Not invited]
    Kenta Kijima; Anchali Krisanachinda; Mikoto Tamura; Yasumasa Nishimura; Hajime Monzen
    European Society Radiotherapy & Oncology meets Asia 2019  2019
  • Comparison of plan quality with KBP for prostate VMAT plan established in three different terms  [Not invited]
    Masakazu Otsuka; Hajime Monzen; Mikoto Tamura; Kazuki Kubo; Kenji Matsumoto; Yasumasa Nishimura
    European Society Radiotherapy & Oncology meets Asia 2019  2019
  • Feasibility study of the shielding ability of novel Tungsten rubber  [Invited]
    Hajime Monzen
    The 7th Annual Conference of Vietnam Association of Radiological Technologists  2019
  • 放射線治療での取り組みとMachine Learning 活用術  [Invited]
    門前 一
    第26回新潟放射線治療研究会・新潟大学医学物理セミナー  2019
  • Visibility evaluation of gold fiducial marker for dose reduction in IGRT by using kV imaging
    Yoshiki Takei; Ryosuke Sakurai; Kentarou Otsubo; Hidekazu Nambu; Hiroshi Doi; Hajime Monzen
    The 10th Annual Scientific Meeting of Thai Medical Physicist Society  2018
  • Comparison of treatment plan between boron neutron capture therapy and volumetric modulated arc therapy for brain tumor patients
    Kazuki Kubo; Hajime Monzen; Do-Kun Yoon; Kentaro Ishii; Ryu Kawamorita; Tae Suk Suh; Yasumasa Nishimura
    The 10th Annual Scientific Meeting of Thai Medical Physicist Society  2018
  • Skin reaction in radiotherapy and low absorption new material for couch top
    Kenji Matsumoto; Mikoto Tamura; Kohei Hanaoka; Hajime Monzen; Masahiko Okumura
    The 10th Annual Scientific Meeting of Thai Medical Physicist Society  2018
  • The shielding ability of the tungsten functional paper against scattered x-rays for operator in interventional radiology
    Mikoto Tamura; Hajime Monzen; Hiroyuki Kosaka; Ryota Kawanami; Shota Hattori; Daisuke Morimoto; Yuki Goto; Koji Yamada; Masahiko Okumura; Yasumasa Nishimura
    The 10th Annual Scientific Meeting of Thai Medical Physicist Society  2018
  • Shielding ability of novel tungsten rubber against electron beam
    Kenta Kijima; Hajime Monzen; Kenji Matsumoto; Mikoto Tamura; Yasumasa Nishimura
    The 10th Annual Scientific Meeting of Thai Medical Physicist Society  2018
  • Developing novel low-attenuation-material for immobilization devices on head and neck radiotherapy  [Invited]
    Seiichi Ota; Takahiro Saiga; Kenji Matsumoto; Kohei Shimomura; Hajime Monzen; Masahiko Okumura
    The 10th Annual Scientific Meeting of Thai Medical Physicist Society  2018
  • Static and moving phantom studies for radiation treatment planning in a 4-dimentional PET/CT  [Invited]
    Kohei Hanaoka; Masahiko Okumura; Yasumasa Nishimura; Hanjime Monzen; Shota Watanabe; Yusuke Shibata; Hayato Kaida; Makoto Hosono; Kazunari Ishii
    The 10th Annual Scientific Meeting of Thai Medical Physicist Society  2018
  • Comparison of multiple institutions' patient-specific IMRT QA measurement
    Kazuki Kubo; Hajime Monzen; Kohei Shimomura; Kenji Matsumoto; Tomoharu Sato; Mikoto Tamura; Kiyoshi Nakamatsu; Kentaro Ishii; Ryu Kawamorita
    The 6th Vietnamese Annual Conference of Radiological Technologist  2018
  • Contouring technique to improve calculated dose accuracy and comparison of calculation algorithm in a commercial treatment planning system
    Kenji Matsumoto; Hiroki Sugimoto; Hajime Monzen; Masahiko Okumura
    The 34th Japan Conference of Radiological Technologists & 6th Asia Radiotherapy Symposium  2018
  • A phantom study:The impact of offset distance in Tomotherapy
    Makoto Hirata; Hajime Monzen; Takatoshi Suzuki; Tsutomu Inoue; Kazuyoshi Oonishi; Hiroyuki Daimon; Kazuki Imanishi; Yumi Adachi; kazunori Fujii; Noriaki Takeda
    The 34th Japan Conference of Radiological Technologists & 6th Asia Radiotherapy Symposium  2018
  • Exposure and image quality in computed tomography using tungsten functional paper
    Hiroyuki Kosaka; Morikazu Amano; Kenji Matsumoto; Mikoto Tamura; Hajime Monzen
    The 34th Japan Conference of Radiological Technologists & 6th Asia Radiotherapy Symposium  2018
  • Comparison of dosimetric parameters and plan complexity between volumetric modulated arc therapy plans with different collimator angles for prostate with whole pelvis irradiation
    Kazuki Kubo; Hajime Monzen; Katsuya Okuhata; Mikoto Tamura; Masakazu Otsuka; Ryu Kawamorita; Kentaro Ishii; Yasumasa Nishimura
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • Development of a novel lok-bar low-radiation-absent in dose delivery and dose monitoring using cone beam computed tomography
    Masakazu Otsuka; Hajime Monzen; Kenji Matsumoto; Mikoto Tamura; Masahiko Okumura; Yasumasa Nishimura
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • Application of a novel lok-bar for high-precision radiotherapy with tomotherapy
    Mikoto Tamura; Hajime Monzen; Makoto Hirata; Kazuki Kubo; Kenji Matsumoto; Kohei Hanaoka; Masahiko Okumura; Yasumasa Nishimura
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • Effect of cleaned-up Rapidplan model to plan quality for volumetric modulated arc therapy in prostate cancer
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • A phantom study: The impact of irradiation time by offset distance with Tomotherapy
    Makoto Hirata; Hajime Monzen; Takatoshi Suzuki; Kazuyoshi Oonishi
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • Simple reduction method of eye lens exposure in routine head computed tomography
    Hiroyuki Kosaka; Daisuke Murata; Koji Yamada; Hajime Monzen
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • The Shielding Ability of Novel Tungsten Rubber Against the Electron Beam for Clinical Use in Radiation Therapy
    Kenta Kijima; Hajime Monzen; Kenji Matsumoto; Mikoto Tamura; Yasumasa Nishimura
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • Feasibility of novel thin bolus using tungsten functional paper for electron beam radiotherapy
    Takeshi Kamomae; Hajime Monzen; Kazuma Sugita; Kuniyasu Okudaira; Morikazu Amano; Yoshihiro Kawai; Hiroshi Oguchi; Motoki Kumagai; Mariko Kawamura; Kazuhiro Ohtakara; Yoshiyuki Ito; Shinji Naganawa
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • In an appropriate and effective way to CT imaging for Deformable Image Registration
    Morikazu Amano; Yoshihiro Kawai; Yasuhiko Matsuoka; Makoto Sakashita; Noriyuki Kadoya; Takeshi Kamomae; Hajime Monzen
    The 18th Asia-Oceania Congress of Medical Physics  2018
  • RapidPlan: Knowledge-based planning systemの概要と実践について  [Invited]
    門前 一
    第34回放射線技師学術総会  2018
  • Current status of Japanese research  [Invited]
    Hajime Monzen
    Catholic university Special Lecture  2018
  • Reduction of the skin surface dose for megavoltage photon beams passing carbon couch
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masahiko Okumura; Yasumasa Nishimura
    American Association of Physicists in Medicine (AAPM) Annual Meeting and Exhibition  2017
  • Characteristics of novel radiation protection device (Tungsten functional paper) and establish recycle model for environment
    Hiroyuki Kosaka; Hajime Monzen
    The 5th Vietnam Association of Radiological Technologists  2017
  • Skin reaction in radiation therapy and low absorption materials for couch top
    Kenji Matsumoto; Hajime Monzen; Kohei Hanaoka; Mikoto Tamura; Masahiko Okumura
    The 5th Vietnam Association of Radiological Technologists  2017
  • Measurement of absorbed dose at off-axis point in IMRT
    Makoto Hirata; Hajime Monzen; Kohei Hanaoka; Yasumasa Nishimura
    The 8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Potential impact of metal artifact caused by loc-bar on PET/CT image
    Kohei Hanaoka; Masahiko Okumura; Kenji Matsumoto; Kohei Shimomura; Hajime Monzen
    The 8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Treatment planning comparison between boron neutron capture therapy and volumetric modulated arc therapy for patients with brain cancer
    Kazuki Kubo; Do-Kun Yoon; Hiroki Tanaka; Hajime Monzen; Yoshinori Sakurai; Kentaro Ishii; Ryu Kawamorita; Tae Suk Suh; Yasumasa Nishimura
    The 8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Shielding ability of tungsten rubber against electron beam
    Kenta Kijima; Hajime Monzen; Kenji Matsumoto; Yasumasa Nishimura
    The 8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Feasibility study of bone removal image generation using single shot x-ray imaging with a four-layer stack of image plates
    Hiroyuki Kosaka; Kohei Shimomura; Hajime Monzen
    The 8th Japan-Korea Joint Meeting on Medical Physics  2017
  • The basic feasibility for radiation protection using metal functional paper in 125I seeds brachytherapy
    Kenji Matsumoto; Hajime Monzen; Masakazu otsuka; Mikoto Tamura; Masahiko Okumura
    The 8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Evaluation and optimization of patient dose from kilovoltage cone beam computed tomography imaging in radiation therapy
    Yoshiki Takei; Kenji Matsumoto; Mikoto Tamura; Ryosuke Sakurai; Kentaro Otsubo; Hidekazu Nambu; Hajime Monzen
    The 8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Influence of variation in dose distribution: Comparison between CT-and CBCT- based plans for oropharyngeal cancer
    Masakazu Otsuka; Hajime Monzen; Kazuki Ishikawa; Kenji Matsumoto; Mikoto Tamura; Tamaki Nishi; Yasumasa Nishimura
    8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Impact of CT dataset on dose calculation for lung stereotactic ablative radiotherapy
    Shinichi Nakayama; Mikoto Tamura; Yuichi Onishi; Yutako Oyama; Hirofumi Enomoto; Miharu Oshima; Hajime Monzen; Soichiro Kaneshige
    8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Reduction of the skin surface dose for megavoltage photon beams
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masahiko Okumura; Yasumasa Nishimura
    8th Japan-Korea Joint Meeting on Medical Physics  2017
  • Evaluation of lung toxicity risk with computed tomography ventilation functional image for lung stereotactic body radiation therapy and three-dimensional conformal radiation therapy
    Masakazu Otsuka; Hajime Monzen; Noriyuki Kadoya; Masahiro Inada; Kenji Matsumoto; Yasumasa Nishimura
    59th American Society of Radiation Oncology Annual Meeting  2017
  • Set-up accuracy in dose distribution: Comparison between CT-and CBCT-based plans for oropharyngeal cancer
    Masakazu Otsuka; Hajime Monzen; Kazuki Ishikawa; Kenji Matsumoto
    The 17th Asia-Oceania Congress of Medical Physics  2017
  • Reduction method of the skin surface dose in megavoltage photon radiotherapy
    Masahiko Okumura; Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Masakazu Otsuka; Kohei Hanaoka; Kohei Shimomura; Yasumasa Nishimura
    The 17th Asia-Oceania Congress of Medical Physics  2017
  • 放射線技師のための臨床研究・国際戦略とは  [Invited]
    門前 一
    第3回近畿放射線技術フォーラム  2017
  • Current Development and Strengths of Nuclear Medicine (NM) in Japan
    Kohei Hanaoka; Hajime Monzen
    The 4th annual conference of Vietnam Association of Radiological Technologists  2016
  • Pretherapeutic FDG heterogeneity in tumors can predict local control in oropharyngeal cancer patients undergoing intensity-modulated radiation therapy
    Kohei Hanaoka; Makoto Hosono; Hitoshi Tatebe; Kazuki Ishikawa; Hajime Monzen; Kazunari Ishii; Yasumasa Nishimura
    SNMMI 2016 Annual Meeting  2016
  • A study of suitable conditions for stereotactic radiation therapy using VMAT for lung cancer
    Kazuki Kubo; Hajime Monzen; Mikoto Tamura; Makoto Hirata; Yasumasa Nishimura
    The 35th European SocieTy for Radiation & Oncology, Annual Conference  2016
  • Tungsten functional paper: Shielding characteristics of a novel paper-based material for clinical use with x-rays and gamma rays
    Hajime Monzen; Mikoto Tamura; Kenji Matsumoto; Kohei Hanaoka; Ikuo Kanno; Yasumasa Nishimura
    19th International Society of Radiographer and Radiation Technologist (ISRRT)  2016
  • Application of the tungsten functional paper as reduction of exposed dose to operators in interventional and therapeutic angiography using Monte Carlo calculation
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Kohei Hanaoka; Yasumasa Nishimura
    19th International Society of Radiographer and Radiation Technologist (ISRRT)  2016
  • Study of reduction of the injured skin reaction in radiotherapy with carbon fiber couch
    Mikoto Tamura; Hajime Monzen; Kenji Matsumoto; Kohei Hanaoka; Yasumasa Nishimura
    19th International Society of Radiographer and Radiation Technologist (ISRRT)  2016
  • A study of the electron GRID therapy with a novel tungsten functional paper
    The 22th International Conference on Medical Physics  2016
  • Development of a novel carbon lok-bar:Challenge regarding reduction of ray scattering and absorption in radiation therapy
    Hajime Monzen; Kazuki Kubo; Mikoto Tamura; Masaru Hayakawa; Yasumasa Nishimura
    The 22th International Conference on Medical Physics  2016
  • Dosimetric comparison of RapidPlan and manually optimized plan in volumetric modulated arc therapy for prostate cancer
    Kazuki Kubo; Hajime Monzen; Mikoto Tamura; Kentaro Ishii; Ryo Ogino; Ryu Kawamorita; Wataru Okada; Ryuta Nakahara; Shun Kishimoto; Kotoko Imai; Toshifumi Nakajima; Yasumasa Nishimura
    The 22th International Conference on Medical Physics  2016
  • 医学物理学会関連研究のトッピクスの紹介  [Invited]
    門前 一
    第55回日本生体医工学会大会  2016
  • Present status of Japan (Medical Physics)  [Invited]
    Hajime Monzen
    IAEA meeting RAS6081 Workshop  2016
  • A comparison of out-of-Target organ Dose From Megavoltage Computed Tomography by TomoTherapy
    Makoto Hirata; Hajime Monzen
    15th Asia Oseania Congress of Medical Physics  2015
  • 医学物理士に求められる臨床、研究、国際支援  [Invited]
    門前 一
    九州大学がんプロ講演会  2015
  • 放射線治療に潜む罠  [Invited]
    門前 一
    第1回長崎県放射線治療セミナー  2015
  • 放射線生物学の基礎  [Invited]
    門前 一
    平成26年度沖縄放射線治療技術研究会セミナー  2015
  • Radiation protection and current status of RT in Japan  [Invited]
    Hajime Monzen
    Hue University Special Lecture  2015
  • Analysis of physical density and weight fraction for human tissue materials using dual energy computed tomography
    Koehi Shimomura; Hajime. Monzen; Fujio Araki
    7th Korea-Japan Joint Meeting on Medical Physics  2014
  • Novel evaluation of a radiation protection for operator in interventional radiology with a tungsten-based functional paper
    Hajime Monzen; MikotoTamura
    14th Asia Oseania Congress of Medical Physics  2014
  • A novel method for dose distribution registration using fiducial marks made by a megavoltage beam in film dosimetry for intensity-modulated radiation therapy quality assurance
    Shinich Nakayama; Hajime Monzen; Yuichi Oonishi; Takashi Mizowaki
    14th Asia Oseania Congress of Medical Physics  2014
  • Evaluation of dosimetric attenuation with new tungsten-based functional paper for intraoperative radiotherapy (IORT) for breast cancer
    Takeshi Kamomae; Hajime Monzen
    14th Asia Oseania Congress of Medical Physics  2014
  • Radiation dose reduction in computed tomography: a new material method with TFP
    Morikazu Amano; Hajime Monzen
    14th Asia Oseania Congress of Medical Physics  2014
  • The basic feasibility study for radiation protection by using metal functional paper in 125I seeds brachytherapy
    Matsumoto Kenji; Hajime Monzen; Yoshiyuki Asai; Kohei Shimomura K; Masahiko Okumura M
    14th Asia Oseania Congress of Medical Physics  2014
  • 0からの放射線生物学のすゝめ  [Invited]
    門前 一
    第20回放射線治療かたろう会  2014
  • 金属遮蔽紙の臨床応用  [Invited]
    門前 一
    第14回近畿放射線医学フォーラム  2014
  • 医学物理士にできること  [Invited]
    門前 一
    第19回東海腫瘍核医学研究会  2014
  • Toward a next generation radiotherapy  [Invited]
    Hajime Monzen
    14th Asia Oseania Congress of Medical Physics  2014
  • Evaluation of a New Irradiation Technique with the Vero4DRT  [Invited]
    Hajime Monzen
    Christian Medical College Special Lecture  2013
  • A Survey of Quality Assurance in Intensity-Modulated Radiation Therapy in Japan
    Mitsuhiro Nakamura; Tomohiro Ono; Mami Akimoto; Nobutaka Mukumoto; Yoshitomo Ishihara; Satoru Utsunomiya; Takehiro Shiinoki; Yuki Miyabe; Sayaka Sato; Hajime Monzen; Masahiro Hiraoka
    AAPM  2013
  • Dosimetric shield evaluation with Tungsten sheet in 4, 6, and 9 MeV electron beams
    Takahiro Fujimoto; Hajime Monzen; Shinsuke Yano; Takashi Okada; Manabu Nakata; Toru Takakura; Makoto Sasaki; Jyunichi Kuwahara; Kyouji Higashimura; Masahiro Hiraoka
    ESTRO33  2013
  • Verification of mechanical accuracy of new irradiation technique with simultaneous gantry and ring rotation
    S. Sato; Y. Miyabe; K. Takahashi; M. Nakamura; Y. Ishihara; M. Yamada; S. Kaneko; T. Mizowaki; H. Monzen; M. Hiraoka
    ESTRO33  2013
  • Realization of intensity-modulated dynamic tumor-tracking radiotherapy with real-time monitoring using the gimbaled x-ray head of Vero4DRT
    Mitsuhiro Nakamura; Yuki Miyabe; Yoshitomo Ishihara; Akira Nakamura; Yukinori Matsuo; Satoshi Itasaka; Hajime Monzen; Takashi Mizowaki; Masaki Kokubo; Masahiro Hiraoka
    4D Treatment Planning Workshop 2013  2013
  • Four-dimensional dose calculation in dynamic tumor tracking irradiation using the gimbaled x-ray head of Vero4DRT
    Yuki Miyabe; Mitsuhiro Nakamura; Yoshitomo Ishihara; Akira Nakamura; Yukinori Matsuo; Satoshi Itasaka; Hajime Monzen; Takashi Mizowaki; Masaki Kokubo; Masahiro Hiraoka
    4D Treatment Planning Workshop 2013  2013
  • 最新の放射線治療  [Invited]
    門前 一
    藤枝市民総合病院  2012
  • 医学物理の役割  [Invited]
    門前 一
    大阪大学  2012
  • 放射線治療概論  [Invited]
    門前 一
    放射線技師基礎技術講習(大阪)  2012
  • SHIELD TEST EXPERIMENT WITH NEW TUNGSTEN PAPER IN CLINICAL X-RAY
    Hajime MONZEN; Masaru HAYAKAWA; Yuji MIKI; Masahiro HIRAOKA
    ICRS-12 & RPSD  2012
  • 医学物理の役割  [Invited]
    門前 一
    近畿医療技術専門学校放射線科学友会  2011
  • 小児における総時間短縮安静時先行アデノシン負荷の心筋血流シンチグラム  [Invited]
    門前 一
    第51回日本核医学会学術総会  2011
  • Can two dimensional ionization chamber systems (Matrixx) overtop the film in the dosimetry for quality assurance of IMRT plans?
    Hajime Monzen; Makoto Hirata; Takatoshi Suzuki; Sayaka Sato; Yuki Miyabe; Mitsuhiro Nakamura; Takehiro Shiinoki; Takashi Mizowaki; Masahiro Hiraoka
    ICRR2011  2011
  • 読影の補助から治療計画への挑戦  [Invited]
    門前 一
    近畿医療技術専門学校滋賀学友会  2010
  • BIWAKO プロトコールの紹介-患者さんに優しい心臓核医学検査を目指して-  [Invited]
    門前 一
    第66回沖縄県核医学懇話会  2010
  • DPC下での心臓核医学の運用  [Invited]
    門前 一
    第9回 心臓核医学ミッドサマーセミナー  2010
  • 医療技術国際交流への関わり  [Invited]
    門前 一
    近畿地域放射線技師会  2010
  • MIBIを使った心筋検査の紹介  [Invited]
    門前 一
    第10回福井県RI画像技術セミナー  2009
  • 信頼される心臓核医学検査を目指して  [Invited]
    門前 一
    第49回日本核医学会学術総会  2009
  • 心筋血流検査短時間法における新しい撮像法  [Invited]
    門前 一
    第1回MAGIC(東京)  2008
  • 放射線技師の役割  [Invited]
    門前 一
    第3回九州放射線医療技術学術大会  2008
  • 医療制度にどう対応するか:核医学  [Invited]
    門前 一
    第46回 三重県核医学談話会  2008
  • 『国際交流、世界と未来への架け橋』  [Invited]
    門前 一
    近畿地域放射線技師会  2008
  • ベトナムへの放射線技術移転の紹介  [Invited]
    門前 一
    第14回 近畿、北陸地区 放射線科フィルムカンファレンス  2007
  • AF患者の心疾患診断に有用なモダリティは?  [Invited]
    門前 一
    第10回 道東循環画像研究会  2007
  • Myocardial perfusion, function and fatty acid imaging for diagnosing CAD  [Invited]
    Hajime Monzen
    8th International Conference of Nuclear Cardiology  2007
  • 時間短縮プロトコールの改良(Modification of Ultra Fast Protocol)  [Invited]
    門前 一
    第27回核医学技術学会総会学術大会
  • 正しい心筋SPECT画像を撮るために 心臓SPECT検査でのアーチファクト軽減法  [Invited]
    門前 一
    第32回ニュータウンカンファレンス
  • Modification of Ultra fast Protocol  [Invited]
    Hajime Monzen
    Annual meeting:Society of Nuclear Medicine and Molecular Imaging  2006
  • BIWAKO PROTOCOL: A new patient positioning for Tc-99m sestamibi MPI to complete a rest-stress protocol in less than one hour
    Hajime Monzen
    The 9th World Congress of Nuclear Medicine and Biology,  2006
  • Advantages of exercise during adenosine infusion in myocardial perfusion stress test.
    Hajime Monzen
    The 9th World Congress of Nuclear Medicine and Biology,  2006
  • MIBIを用いた安静-アデノシン負荷  [Invited]
    門前 一
    第9回 道東循環画像研究会  2006
  • The Anti-tumor effects, Immuno-activity and Radiation Protection of beta-1,3D Glucan from yeast
    Yoshimura A; Monzen H
    The First Asian and Oceanic Congress for Radiation  2002
  • Non-Invasive Measurement of the Temperature Using Scanning Small Coils
    Ando S; Monzen H
    The First Asian and Oceanic Congress for Radiation  2002
  • The Enhacemeny of Anti-tumor Effects, immuno-activity and Radiation Protection after injection of EF2001 (Lactic Bacteria)
    Amano M; Monzen H
    The First Asian and Oceanic Congress for Radiation  2002
  • The study of easy way to confirm the irradiation dose of the patient on the diagnostic procedure.
    Hajime Monzen
    The First Asian and Oceanic Congress for Radiation  2002
  • Enhancement of the imunological activity and anti-tumor by mild hyperthermia
    Yoshimura A. Monzen; H
    The Korean Association for Radiation Protection, Autumn Meeting  2001
  • Enhancement the anti-tumor effects of hyperthermia in pH Value.
    Monzen H; Hasegawa T
    The Korean Association for Radiation Protection, Autumn Meeting  2001
  • 医療を求める人々のために 医療の体質と放射線技師の姿を求めて  [Invited]
    門前 一
    日本放射線技師会学術総会  1999

MISC

  • 植原拓也; 西村恭昌; 石川一樹; 稲田正浩; 土井啓至; 松本賢治; 門前一  日本放射線腫瘍学会高精度放射線外部照射部会学術大会プログラム・抄録集  36th-  2023
  • Halcyonにおける全身照射の試み(序章)
    門前 一  インナービジョン  37-  (12)  86  -86  2022/11  [Invited]
  • ナレッジベース治療計画ソフトウェア Rapid Plan
    門前一  Future of Helthcare  (8)  40  -41  2022/09  [Invited]
  • 門前 一  インナービジョン  2022/03  [Invited]
  • 医療版SDGsを目指して:鉛フリーへの第一歩、STRの開発
    門前 一  RadFan Plus/My Bookmark  2021/11  [Invited]
  • Halcyonの“Flattening Sequence” について
    門前 一  インナービジョン  2021/11  [Invited]
  • 薄型タングステンゴムを用いたCT透視下IVRにおける術者被ばくの低減
    中村 泰典; 門前 一; 田村 命; 木嶋 健太; 水田 正芳  日本放射線技術学会雑誌  77-  (9)  1123  -1123  2021/09
  • 班報告 Artificial Intelligence技術を用いた前立腺がんVMAT治療計画の線量評価:多施設研究
    上田 悦弘; 門前 一; 田村 命; 上間 達也; 福永 淳一; 清水 由美子; 村木 勇太  日本放射線技術学会総会学術大会予稿集  77回-  176  -176  2021/03
  • 松本 賢治; 田村 命; 大塚 正和; 若林 和樹; 木嶋 健太; 門前 一  日本放射線技術学会雑誌  76-  (12)  1248  -1255  2020/12
  • リアルタイム可変型放射線遮蔽材の開発
    門前 一  機能材料  40-  60  -72  2020/03  [Invited]
  • 秋山広徳; 吉田謙; 山崎秀哉; 武中正; 隅田伊織; 門前一; 宮尾守; 増井浩二; 辻本豊; 奥村大樹; 吾妻宏紀; 新保大樹; 吉岡裕人; 古妻理之; 田中英一; 小滝真也; 清水谷公成  頭頸部癌  45-  (2)  245  -245  2019/05
  • 松本 賢治; 雜賀 貴大; 霜村 康平; 花岡 宏平; 田村 命; 門前 一; 早川 典; 奥村 雅彦  日本放射線技術学会雑誌  75-  (2)  167  -173  2019/02
  • UICC第8版による再stagingを行った中咽頭癌に対するIMRTの治療成績
    建部 仁志; 石川 一樹; 横川 正樹; 稲田 正浩; 福田 浩平; 松浦 知弘; 立花 和泉; 中松 清志; 門前 一; 金森 修一; 西村 恭昌  Japanese Journal of Radiology  37-  (Suppl.)  38  -38  2019/02
  • 核医学分野における医学物理-明日からの機能検査- PET/CTを用いた放射線治療計画
    花岡 宏平; 奥村 雅彦; 門前 一  医学物理  38-  (2)  85  -88  2018/10
  • 門前一  日本診療放射線技師会誌  65-  (9)  973  -973  2018/09
  • M. Otsuka; H. Monzen; N. Kadoya; M. Inada; K. Matsumoto; Y. Nishimura  INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS  99-  (2)  E708  -E708  2017/10
  • 呼吸同期FDG PET/CTによる放射線治療計画について
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  • TSAI Tien‐Hsiu; 丸山能央; 西松大祐; 神野郁夫; 門前一; 霜村康平; 小坂浩之  応用物理学会秋季学術講演会講演予稿集(CD-ROM)  77th-  ROMBUNNO.16a‐A37‐8  2016/09
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  • 中咽頭癌に対する強度変調放射線治療(IMRT)の治療成績
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  • 宇都宮悟; 門前一; 溝脇尚志; 平岡真寛  Jpn J Radiol  33-  (Supplement)  4  -4  2015/02
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  • M. Akimoto; M. Nakamura; N. Mukumoto; M. Yamada; K. Yokota; H. Tanabe; N. Ueki; S. Kaneko; Y. Matsuo; H. Monzen; T. Mizowaki; M. Kokubo; M. Hiraoka  INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS  90-  S826  -S827  2014/09
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  • 【胸部の最新画像情報2006】 喀血・肺癌に対する血管内治療術前のmultidetector-row CTによる目的血管検索の有用性
    布浦 誓子; 小林 久人; 古田 昭寛; 高橋 孝博; 芥田 敬三; 門前 一; 田濃 孝司  臨床放射線  51-  (1)  71  -77  2006/01
  • チャーガによる抗がん作用及び放射線防護効果に研究
    門前 一; 長谷川 武夫; 岡本 秀史; 具 然和  日本癌学会総会記事  64回-  481  -481  2005/09
  • 心腔内血栓診断におけるMDCT画像再構成法の検討
    門前 一; 田濃 孝司; 山元 卓; 井上 努; 結城 留実夫; 下山 寿; 佐藤 民恵; 広瀬 邦彦  日赤医学  57-  (1)  174  -174  2005/09
  • CTAによる形成外科疾患四肢動脈造影の撮像法と有用性の検討
    門前 一; 田濃 孝司; 平田 誠; 鷲見 直弘; 井上 努; 山元 卓; 結城 留実夫; 古田 明寛; 布浦 誓子; 石川 浩三  日赤医学  57-  (1)  175  -175  2005/09
  • 四肢におけるCT angiogramの有用性について
    石川 浩三; 大井 克之; 樋上 敦; 長尾 由理; 諸岡 久香; 門前 一  日赤医学  57-  (1)  203  -203  2005/09
  • 16列マルチスライスCTによる心房細動患者の左心耳血栓検出に関する検討
    下山 寿; 富岡 宣良; 佐藤 民恵; 二井 理恵; 原 正剛; 森川 雅; 渡邊 裕; 廣瀬 邦彦; 門前 一; 山元 卓; 田濃 孝司; 結城 留実夫  日赤医学  57-  (1)  295  -295  2005/09
  • 布浦誓子; 小林久人; 古田昭寛; 高橋孝博; 門前一; 田濃孝司; 芥田敬三  日本医学放射線学会学術集会抄録集  64th-  S142  2005/02
  • IVR治療術前のMDCTによる肺癌・喀血の責任血管検索の有用性
    布浦 誓子; 小林 久人; 古田 昭寛; 高橋 孝博; 門前 一; 田濃 孝司; 芥田 敬三  日本医学放射線学会学術集会抄録集  64回-  S142  -S142  2005/02
  • MDCTを用いたCTHAにおけるthin slice section(1mm厚)の有用性の検討
    古田 昭寛; 小林 久人; 布浦 誓子; 高橋 孝博; 門前 一; 田濃 孝司; 芥田 敬三  日本医学放射線学会学術集会抄録集  64回-  S270  -S271  2005/02
  • EF2001(Enterococcus・Faecalis)による抗腫瘍効果と放射線防護効果に関する研究
    門前 一; 中村 敬; 長谷川 武夫; 鈴木 郁功; 岩佐 広行; 具 然和  日本癌学会総会記事  63回-  289  -289  2004/09
  • マウスの甲状腺細胞におけるCytokine誘発自己免疫毒性に対するGanoderma Lucidumの効果(Effect of Ganoderma Lucidum on Cytokine-Induced Antigen Expression in Mouse Thyroid Cells)
    具 然和; 崔 仁淑; 山下 剛範; 大嶋 正己; 門前 一; 鈴木 郁功; 中村 敬  医学と生物学  148-  (9)  38  -44  2004/09
  • 超急性期脳梗塞におけるCTAの有用性
    門前 一; 田濃 孝司; 久嶋 康秀; 結城 留実夫; 福田 俊一; 大塚 信一  日赤医学  56-  (1)  267  -267  2004/09
  • CTAによる気管支動脈描出の有用性
    門前 一; 田濃 孝司; 久嶋 康秀; 結城 留実夫; 古田 昭寛; 小林 久人; 里田 直樹  日赤医学  56-  (1)  267  -267  2004/09
  • 血球作用物質による組織内酸素分圧の上昇に関する研究
    天野 守計; 門前 一; 鈴木 敬俊; 長谷川 武夫  日本放射線技師会雑誌  51-  (1)  38  -44  2004/01
  • マイルド・ハイパーサーミアによる免疫能活性の増強について
    長谷川 武夫; 小野 博史; 高橋 徹; 大野 由紀子; 鈴木 友昭; 村林 甲介; 前田 佳予子; 門前 一; 山本 五郎  日本ハイパーサーミア学会誌  19-  (4)  221  -221  2003/12
  • 放射線治療における組織内酸素分圧測定の有用性
    伊田 和司; 天野 守計; 門前 一; 前田 佳予子; 福山 篤司; 安藤 聡志; 小野 博史; 大野 由紀子; 鈴木 友昭; 村林 甲介; 長谷川 武夫  生体医工学  41-  (4)  517  -517  2003/12
  • 診療放射線技師の意識調査 滋賀県のアンケート調査から
    枚田 敏幸; 本多 恵理子; 久嶋 康秀; 門前 一; 金子 雅一; 草野 邦典; 福田 哲也; 南 一男  日本放射線技師会雑誌  50-  (10)  885  -885  2003/10
  • Mild-HyperthermiaとChemotherapy併用療法による薬剤取り込みの増強と抗腫瘍効果の増強
    小野 博史; 門前 一; 安藤 聡志; 鈴木 友昭; 高橋 徹; 山本 五郎; 長谷川 武夫  日本ハイパーサーミア学会誌  19-  (Suppl.)  155  -155  2003/09
  • 三酸化二砒素とハイパーサーミア併用療法による抗腫瘍効果の増強
    鈴木 友昭; 門前 一; 安藤 聡志; 小野 博史; 高橋 徹; 山本 五郎; 長谷川 武夫  日本ハイパーサーミア学会誌  19-  (Suppl.)  160  -160  2003/09
  • 鈴木友昭; 東智史; 門前一; 福山篤司; 安藤聡志; 小野博史; 長谷川武夫  日本放射線技術学会中部部会誌  5-  (1)  196  -197  2003/03
  • 福山篤司; 安藤聡志; 門前一; 天野守計; 小野博史  日本放射線技術学会中部部会誌  5-  (1)  108  -109  2003/03
  • 安藤聡志; 福山篤司; 門前一; 天野守計; 小野博史; 長谷川武夫  日本放射線技術学会中部部会誌  5-  (1)  110  -111  2003/03
  • 門前 一; 具 然和; 長谷川 武夫; 結城 留実夫  Radioisotopes  52-  (3)  128  -135  2003/03
  • 鈴木 敬俊; 門前 一; 銭谷 潔; 結城 留実夫; 佐々木 理  日本放射線技師会雑誌  50-  (3)  189  -193  2003/03
  • 鈴木 敬俊; 門前 一; 銭谷 潔; 結城 留実夫; 佐々木 理  放射線防護分科会会誌  (15)  74  -74  2002/10
  • マイルド・ハイパーサーミアによる免疫能活性
    長谷川 武夫; 高橋 徹; 具 然和; 野口 憲一; 小野 博史; 安藤 聡志; 天野 守計; 長塚 悟; 門前 一; 前田 佳予子; 福山 篤司; 山本 五郎  日本放射線影響学会大会講演要旨集  45回-  97  -97  2002/09
  • テアニンによる放射線増感効果と生理活性
    小野 博史; 門前 一; 前田 佳予子; 福山 篤司; 天野 守計; 安藤 聡志; 長塚 悟; 野口 憲一; 伊芸 直樹; 小関 誠; Juneja Lekh Raj; 高橋 徹; 具 然和; 長谷川 武夫  日本放射線影響学会大会講演要旨集  45回-  143  -143  2002/09
  • 安藤 聡志; 福山 篤司; 小野 博史; 松浦 香苗; 門前 一; 天野 守計  日本放射線技術学会雑誌  58-  (9)  1157  -1158  2002/09
  • リスクマネージメントに対する取り組み 滋賀県内のアンケート調査から
    枚田 敏幸; 本多 恵理子; 中原 喜彦; 山本 芳弘; 番野 仁司; 門前 一; 鰐部 亜砂子  日本放射線技師会雑誌  49-  (9)  1161  -1161  2002/09
  • 福山 篤司; 安藤 聡志; 増田 竜樹; 小林 幸江; 中北 文歌; 矢邊 真弓; 吉村 明伸; 野口 憲一; 長塚 悟; 小野 博史; 天野 守計; 伊藤 今日一; 門前 一; 前田 佳予子; 宮田 勝行; 長谷川 武夫  鈴鹿医療科学大学紀要  9-  (9)  54  -63  2002/08
  • 長谷川 武夫; 具 然和; 小川 篤; 松井 幸正; 畑中 眞紀; 安藤 聡志; 天野 守計; 長塚 悟; 小野 博史; 野口 憲一; 伊藤 今日一; 福山 篤司; 吉村 明伸; 前田 佳予子; 門前 一; 宮田 勝行  鈴鹿医療科学大学紀要  9-  (9)  64  -77  2002/08
  • 長谷川 武夫; 具 然和; 池畑 恵; 今井 美智子; 松岡 理恵; 野口 憲一; 吉村 明伸; 安藤 聡志; 天野 守計; 伊藤 今日一; 福山 篤司; 長塚 悟; 小野 博史; 門前 一; 宮田 勝行; 鈴木 郁功; 前田 佳予子; 小関 誠  鈴鹿医療科学大学紀要  9-  (9)  78  -86  2002/08
  • 長谷川 武夫; 具 然和; 伊芸 直樹; 下山 紳一; 鈴田 博樹; 野口 憲一; 吉村 明伸; 安藤 聡志; 天野 守計; 伊藤 今日一; 福山 篤司; 長塚 悟; 小野 博史; 前田 佳予子; 門前 一; 宮田 勝行  鈴鹿医療科学大学紀要  9-  (9)  87  -96  2002/08
  • 長谷川 武夫; 具 然和; 伊藤 規充; 河合 寿恵; 鈴木 亜貴子; 野口 憲一; 吉村 明伸; 安藤 聡志; 天野 守計; 伊藤 今日一; 福山 篤司; 長塚 悟; 小野 博史; 門前 一; 前田 佳予子; 宮田 勝行  鈴鹿医療科学大学紀要  9-  (9)  97  -107  2002/08
  • 診療放射線技師の過去・現在・そして…? 大学VS専修学校
    門前 一  大阪府放射線技師会誌  48-  83  -83  2002/03
  • ONO Hirobumi; MONZEN Hajime; MAEDA Kayoko; FUKUYAMA Atsushi; AMANO Morikazu; ANDO Satoshi; NAGATSUKA Satoru; NOGUCHI Kenichi; IGEI Naoki; OZEKI Makoto; Raj Lekh Juneja; TAKAHASHI Toru; GU Yeunhwa; HASEGAWA Takeo  Journal of radiation research  43-  (4)  484  -484  2002
  • HASEGAWA Takeo; TAKAHASHI Toru; GU Yeunhwa; NOGUCHI Kenichi; ONO Hirobumi; ANDO Satoshi; AMANO Morikazu; NAGATSUKA Satoru; MONZEN Hajime; MAEDA Kayoko; FUKUYAMA Atsushi; YAMAMOTO Itsuo  Journal of radiation research  43-  (4)  453  -453  2002
  • 高周波加温治療時の非襲侵的温度モニター装置の開発
    安藤 聡志; 畑中 眞紀; 松井 幸正; 小川 篤; 宮田 勝行; 門前 一; 伊藤 今日一; 福山 篤司; 吉村 明伸; 天野 守計  BME  15-  (12)  319  -319  2001/12
  • マイルド・ハイパーサーミアによる免疫能活性の増強
    長谷川 武夫; 具 然和; 高橋 徹; 宮田 勝行; 門前 一; 鈴木 郁功; 小倉 和恵  日本放射線影響学会大会講演要旨集  44回-  128  -128  2001/10
  • HASEGAWA Takeo; GU YeunHwa; TAKAHASHI Tohru; MIYATA Katsuyuki; MONZEN Hajime; SUZUKI Ikukatsu; OGURA Kazue  Journal of radiation research  42-  (4)  542  -542  2001
  • 医療を求める人々のために 医療の体質と放射線技師の姿を求めて
    久保田 勉; 井上 雅史; 岩本 淳子; 門前 一  日本放射線技師会雑誌  47-  (1)  36  -62  2000/01

Industrial Property Rights

  • 特願2022-066075:MRI用医療器具  2022年/04/13
    門前 一  近畿大学, 凸版印刷株式会社, 早川ゴム株式会社, トキハ産業株式会社
  • 門前 一  201803009393433488
  • 特開2021-28609(P2021-28609A):温度変性放射線遮蔽材  2021/02/25
    門前 一
  • 特願2020-211252:簡易組み立てベッド、多目的テーブルおよび搬送軽量ボード  2020年/12/21
    門前 一
  • 特願2020-43099:吸引式変形マットの固定具  2020年/03/12
    門前 一, 奥村雅彦, 松本賢治, 花岡宏平, 霜村康平  凸版印刷株式会社 学校法人近畿大学
  • 特願2014-134364:低エネルギー放射線防護材  2014年/06/30
    門前一

Research Grants & Projects

  • 日本学術振興会:科学研究費助成事業
    Date (from‐to) : 2023/04 -2026/03 
    Author : 門前 一; 土井 啓至; 久保 和輝
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2021/04 -2024/03 
    Author : 細野 眞; 門前 一; 田村 命
     
    本研究ではRI内用療法において、線量計測や線量シミュレーション手法を用いることにより、腫瘍や臓器のマクロな線量評価の手法と微小な組織の線量評価の手法を開発し、その結果を織り込んで標準的な実施指針を提案し、RI内用療法の臨床研究への導入を推進することを目的とする。第3者の被ばくについてもその手法を織り込んだ標準的な実施指針を目指している。さて新規RI内用療法の臨床応用にあたっては妥当な放射線安全のもとで治療の有効性と安全性を検証するために実施指針が求められる。新規RI内用療法が次々に開発されている現在、本研究は、正常臓器や病巣の吸収線量の評価に基づいて実施指針を作成するために、標準的なテンプレートを作成する。そのような標準的なテンプレートは同時に治療手法の最適化を図ることにも通じる。そこで線量計算ソフトを導入して体内分布データに基づいてRI内用療法患者の線量計算手法を確立した。またラジウム-223治療を実施した去勢抵抗性前立腺癌骨転移のデータを蓄積し、個別化治療の開発に繋がる因子を解析した。またルテチウムオキソドトレオチド(177Lu)を実際に症例において実施し、それによって得られた知見を新規RI内用療法における臨床応用に求められる要件に活用することができた。今後の新しいRI内用療法においては体内分布データの取得手法を開発することと、それに基づいた線量評価を実施するための手法を構築していくことが重要である。本研究の独自性と創造性については、本研究で実施している新規核種の線量評価に基づいた手法の検討は、通常の医療施設やアイソトープ研究施設では実施困難である。アルファ線核種を初めとする新規核種を使用できる設備を持っていること、また臨床医である研究代表者と放射線計測と線量分析を専門とする研究分担者が共同研究することが本研究の特徴である。
  • Japan Society for the Promotion of Science:Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
    Date (from‐to) : 2020/04 -2023/03 
    Author : 土井 啓至; 門前 一
     
    肺癌に対する根治的放射線治療において、Volumetoric Modulated Arc Therapy(VMAT)やHelical Tomotherapy(HT)は強度変調放射線治療(IMRT)の標準的な技術であるが、治療後の放射線肺臓炎(RP)が懸念される。今回、VMATあるいはHTを用いたIMRTを受けた肺癌患者において、RPと関連する要因を検討した。2018年4月~2020年12月までに60Gy/30fr/6週のIMRTを受けた肺癌52例(VMAT:31例、HT:21例)を検討した。年齢の中央値は70歳(53-85歳)、臨床病期はそれぞれⅡ期が5例、Ⅲ期が47例であり、うち11例に肺切除歴を認めた。放射線治療の開始から肺臓炎発生までの累積時間はKaplan-Meier法で算出し、放射線治療後の肺臓炎と関連する臨床的要因についてはCOX比例ハザードモデルを用いて解析を行った。観察期間中央値は14ヵ月(5~33ヵ月)、観察期間中に18例が再発、8例が死亡した。RPはGrade(G)1 : 26例、G2 : 12例、G3: 6例、G4 : 1例、G5 : 1例であった(CTCAE ver5.0)。G2以上のRPの発生は、単変量解析において計画標的体積(PTV)≧365cc、全肺のV20≧18%およびV5≧44%、Dmean≧11Gy、患側肺のV20≧36%およびV5≧61%とそれぞれ有意に関連していた(p<0.05)。しかし、多変量解析ではG2以上のRPに関連する因子は認めなかった。G3以上のRPについては、単変量解析の結果、肺切除の既往歴、全肺容積≧3150cc、全肺のV5≧44%、患側肺のV20≧36%、V5≧61%と有意に関連していた。さらに、多変量解析にて肺切除歴はG3以上のRPと有意に関連していた(p=0.048)。
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Social Contribution

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    Date (from-to) : 2022/10/06
    Role : Lecturer
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    Date (from-to) : 2012/08-2017/02
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    Sponser, Organizer, Publisher  : JICA
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    Date (from-to) : 2005/09-2008/08
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Academic Contribution

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    Date (from-to) :2021/08/01
    Organizer, responsible person: ひらめき☆ときめきサイエンス~ようこそ大学の研究室へ~KAKENHI


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