Tokushima University / Educator and Researcher Directory --- Sasaki, Motoharu

Field of Study

○	Radiation Therapy

Subject of Study

○	Optimization of treatment plan, Patient -specific QA, Imaging guided radiation therapy

Book / Paper

Book:

1.	Motoharu Sasaki and Masahide Tominaga : 外部光子線の線量計算 ---放射線治療技術学 ---, KYORITSU SHUPPAN.CO.,LTD, Tokyo, Dec. 2024.
2.	中島大, 小野薫, Motoharu Sasaki, 根本幹央, 伊藤憲一, 大吉一, 岡善隆, 越智悠介, 清水秀年, 杉本渉 and Ryosei Nakada : 第3章IGRT画像照合の部位別実践ポイント ---放射線医療技術学叢書(40)「実践IGRT」---, 公益社団法人日本放射線技術学会出版委員会, Tokyo, Dec. 2023.
3.	池田恢, 石倉聡, 太田誠一, Katsusuke Kyotani, 奥村雅彦, 小口宏, 川村愼二, 木藤哲史, 黒岡将彦, 小泉雅彦, 小林加奈, Motoharu Sasaki, 佐々木良平, 澁谷景子, 新保宗史, 辰己大作, 田辺悦章, 玉本哲郎, 中村光宏, 冨士原将之, 水野秀之 and 椋本宜学 : 放射線治療における第三者機関による出力線量測定および評価に関するガイドライン 2023, 日本放射線腫瘍学会QA委員会, Nov. 2023.
4.	角谷倫之, 木藤哲史, 武川英樹, 藤田幸男, 宮部結城, 新井一弘, 伊藤謙吾, 今江禄一, 金井貴幸, 小玉卓史, 齋藤正英, Motoharu Sasaki, 武村哲浩, 曺翔永, 中島祐二朗, 宮坂有侑也 and 八木雅史 : 詳説非剛体レジストレーション―放射線治療領域―, 中外医薬品, Dec. 2020.
5.	Masahide Tominaga and Motoharu Sasaki : 脳・体幹部定位照射 --- 図解診療放射線技術実践ガイド第4版 ---, 文光堂, Tokyo, Feb. 2020.
6.	今江禄一, 角谷倫之, 木藤哲司, Katsusuke Kyotani, 黒岡将彦, 小玉卓史, Motoharu Sasaki, 武川英樹, 武村哲浩, 藤田幸男, 宮部結城 and 八木雅司 : 放射線治療における非剛体画像レジストレーション利用のためのガイドライン2018年版, 日本放射線腫瘍学会QA委員会DIRワーキンググループ, Apr. 2018. (Keyword) DIR

Academic Paper (Judged Full Paper):

1.	NAKANO Shoma, Motoharu Sasaki, Nakaguchi Yuji, Takeshi Kamomae, Kanako Sakuragawa, YAMAJI Yuto and Hitoshi Ikushima : Comparative evaluation of two dose-volume histogram prediction tools for treatment planning: treatment planning quality and dose verification accuracy, Technical Innovations & Patient Support in Radiation Oncology, 2025. (Keyword) verification / RapidPlan / PlanIQ / Volumetric-modulated arc therapy
2.	Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Akira Tsuzuki, Sohma Sawada, Kohki Shibuya, Masataka Oita, Masahide Tominaga, Yuki Tominaga and Hitoshi Ikushima : Comparative analysis of two dose-volume histogram prediction tools for treatment planning in volumetric-modulated arc therapy: A multi-planner study, Medical Dosimetry, Vol.49, No.3, 271-275, 2024. (Summary) The increase in high-precision radiation therapy, particularly volumetric-modulated arc therapy (VMAT), has increased patient numbers and expanded treatment sites. However, a significant challenge in VMAT treatment planning is the inconsistent plan quality among different planners and facilities. This study explored the use of dose-volume histogram (DVH) prediction tools to address these disparities, specifically focusing on RapidPlan (Varian Medical Systems) and PlanIQ (Sun Nuclear). RapidPlan predicts achievable DVHs and automatically generates optimization objectives. While it has demonstrated organ-at-risk (OAR) dose reduction benefits, the quality of the plan used to build its model significantly affects its predictions. On the other hand, PlanIQ offers ease of use and does not require prior model-building. Five planners participated in this study, each creating two treatment plans: one referencing RapidPlan and the other using PlanIQ. The planners had the freedom to adjust parameters while referencing the DVH predictions. The plans were evaluated using "Plan Quality Metric" (PQM) scores to assess the planning target volume excluding the rectum and OARs. The results revealed that RapidPlan-referenced plans often outperformed PlanIQ-based plans, with less interplanner variability. PlanIQ played a pivotal role in the construction of the RapidPlan model. This study is the first to compare plans generated by multiple planners using both tools. This study provides insights into optimizing treatment planning by considering the characteristics of both RapidPlan and PlanIQ. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.meddos.2024.02.002 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 38556402 ● Search Scopus @ Elsevier (PMID): 38556402 ● Search Scopus @ Elsevier (DOI): 10.1016/j.meddos.2024.02.002 (DOI: 10.1016/j.meddos.2024.02.002, PubMed: 38556402)
3.	Nagi Masumoto, Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Yuki Kanazawa and Hitoshi Ikushima : Knowledge-based model building for treatment planning for prostate cancer using commercial treatment planning quality assurance software tools, Radiological Physics and Technology, Vol.17, No.1, 337-345, 2024. (Summary) This study devised a method to efficiently launch the RapidPlan model for volumetric-modulated arc therapy for prostate cancer in small- and medium-sized facilities using high-quality treatment plans with the PlanIQ software as a reference. Treatment plans were generated for 30 patients with prostate cancer to construct the RapidPlan model using PlanIQ as a reference. In the context of PlanIQ-referenced treatment planning, treatment plans were developed, such that the feasibility dose-volume histogram of each organ-at-risk fell within F ≤ 0.1. For validation of the RapidPlan model, treatment plans were formulated for 20 patients using both RapidPlan and PlanIQ, and the differences were evaluated. The results of RapidPlan model validity assessment revealed that the RapidPlan-produced treatment plans exhibited higher quality in 11 of 20 patients. No significant differences were found between the treatment plans. In conclusion, high-quality treatment plans formulated using PlanIQ as reference facilitated efficient implementation of RapidPlan modeling. (Keyword) RapidPlan / PlanIQ / treatment planning quality (Link to Publication Site) ● Publication site (DOI): 10.1007/s12194-023-00759-6 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 37938420 ● Search Scopus @ Elsevier (PMID): 37938420 ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-023-00759-6 (DOI: 10.1007/s12194-023-00759-6, PubMed: 37938420)
4.	Daiki Nakanishi, Masataka Oita, Jun-Ichi Fukunaga, Taka-Aki Hirose, Tadamasa Yoshitake and Motoharu Sasaki : Investigation of uncertainty in internal target volume definition for lung stereotactic body radiotherapy, Radiological Physics and Technology, Vol.16, No.4, 497-505, 2023. (Summary) This study evaluated the validity of internal target volumes (ITVs) defined by three- (3DCT) and four-dimensional computed tomography (4DCT), and subsequently compared them with actual movements during treatment. Five patients with upper lobe lung tumors were treated with stereotactic body radiotherapy (SBRT) at 48 Gy in four fractions. Planning 3DCT images were acquired with peak-exhale and peak-inhale breath-holds, and 4DCT images were acquired in the cine mode under free breathing. Cine images were acquired using an electronic portal imaging device during irradiation. Tumor coverage was evaluated based on the manner in which the peak-to-peak breathing amplitude on the planning CT covered the range of tumor motion (± 3 SD) during irradiation in the left-right, anteroposterior, and cranio-caudal (CC) directions. The mean tumor coverage of the 4DCT-based ITV was better than that of the 3DCT-based ITV in the CC direction. The internal margin should be considered when setting the irradiation field for 4DCT. The proposed 4DCT-based ITV can be used as an efficient approach in free-breathing SBRT for upper-lobe tumors of the lung because its coverage is superior to that of 3DCT. (Link to Publication Site) ● Publication site (DOI): 10.1007/s12194-023-00737-y (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 37713060 ● Search Scopus @ Elsevier (PMID): 37713060 ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-023-00737-y (DOI: 10.1007/s12194-023-00737-y, PubMed: 37713060)
5.	Daisuke Satoh, Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Takashi Kawanaka, Akiko Kubo, Chisato Tonoiso, Yuki Kanazawa, Masataka Oita, Akimi Kajino, Akira Tsuzuki and Hitoshi Ikushima : Differences between professionals in planning treatment for patients with stage III lung cancer using treatment-planning QA software, Reports of Practical Oncology and Radiotherapy, Vol.28, No.5, 671-680, 2023. (Summary) The quality of treatment planning for stage III non-small cell lung cancer varies within and between facilities due to the different professions involved in planning. Dose estimation parameters were calculated using a feasibility dose-volume histogram (FDVH) implemented in the treatment planning quality assurance software PlanIQ. This study aimed to evaluate differences in treatment planning between occupations using manual FDVH-referenced treatment planning to identify their characteristics. The study included ten patients with stage III non-small cell lung cancer, and volumetric-modulated arc therapy was used as the treatment planning technique. Fifteen planners, comprising five radiation oncologists, five medical physicists, and five radiological technologists, developed treatment strategies after referring to the FDVH. Medical physicists had a higher mean dose at D98% of the planning target volume (PTV) and a lower mean dose at D2% of the PTV than those in other occupations. Medical physicists had the lowest irradiation lung volumes (V5 Gy and V13 Gy) compared to other professions, and radiation oncologists had the lowest V20 Gy and mean lung dose. Radiological technologists had the highest irradiation volumes for dose constraints at all indexes on the normal lung volume. The quality of the treatment plans developed in this study differed between occupations due to their background expertise, even when an FDVH was used as a reference. Therefore, discussing and sharing knowledge and treatment planning techniques among professionals is essential to determine the optimal treatment plan for each facility and patient. (Keyword) Non-small-cell lung cancer / PlanIQ / Treatment planning quality / Volumetric-modulated arc therapy (Link to Publication Site) ● Publication site (DOI): 10.5603/rpor.97511 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 38179286 ● Search Scopus @ Elsevier (PMID): 38179286 ● Search Scopus @ Elsevier (DOI): 10.5603/rpor.97511 (DOI: 10.5603/rpor.97511, PubMed: 38179286)
6.	Kenji Yamada, Yoshiki Kawata, Masafumi Amano, Hidenobu Suzuki, Masahide Tominaga, Motoharu Sasaki, Hikaru Nishiyama, Masafumi Harada and Noboru Niki : Influence of Pitch on Surface Dose Distribution and Image Noise of Computed Tomography Scans, Sensors, Vol.23, No.7, 3472, 2023. (Summary) This study evaluated the effect of pitch on 256-slice helical computed tomography (CT) scans. Cylindrical water phantoms (CWP) were measured using axial and helical scans with various pitch values. The surface dose distributions of CWP were measured, and reconstructed images were obtained using filtered back-projection (FBP) and iterative model reconstruction (IMR). The image noise in each reconstructed image was decomposed into a baseline component and another component that varied along the z-axis. The baseline component of the image noise was highest at the center of the reconstructed image and decreased toward the edges. The normalized 2D power spectra for each pitch were almost identically distributed. Furthermore, the ratios of the 2D power spectra for IMR and FBP at different pitch values were obtained. The magnitudes of the components varying along the z-axis were smallest at the center of the reconstructed image and increased toward the edge. The ratios of the 3D power spectra on the fx axis for IMR and FBP at different pitch values were obtained. The results showed that the effect of the pitch was related to the component that varied along the z-axis. Furthermore, the pitch had a smaller effect on IMR than on FBP. (Keyword) Helical computed tomography / Pitch / Surface dose distribution / FBP / IMR / Image noise / Power spectrum (Tokushima University Institutional Repository) ● Metadata: 119404 (Link to Publication Site) ● Publication site (DOI): 10.3390/s23073472 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.3390/s23073472 (Tokushima University Institutional Repository: 119404, DOI: 10.3390/s23073472)
7.	Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Shoji Ueda, Yuto Endo, Daisuke Satoh and Hitoshi Ikushima : Predicting the complexity of head-and-neck volumetric-modulated arc therapy planning using a radiation therapy planning quality assurance software, Reports of Practical Oncology and Radiotherapy, Vol.27, No.6, 963-972, 2022. (Summary) The more complex the treatment plan, the higher the possibility of errors in dose verification. Recently, a treatment planning quality assurance (QA) software (PlanIQ) with a function to objectively evaluate the quality of volumetric-modulated arc therapy (VMAT) treatment plans by scoring and calculating the ideal dose-volume histogram has been marketed. This study aimed to assess the association between the scores of ideal treatment plans identified using PlanIQ and the results of dose verification and to investigate whether the results of dose verification can be predicted based on the complexity of treatment plans. Dose verification was performed using an ionization chamber dosimeter, a radiochromic film, and a three-dimensional dose verification system, Delta4 PT. Correlations between the ideal treatment plan scores obtained by PlanIQ and the results of the absolute dose verification and dose distribution verification were obtained, and it was examined whether dose verifications could be predicted from the complexity of the treatment plans. Even when the score from the ideal treatment plan was high, the results of absolute dose verification and dose distribution verification were sometimes poor. However, even when the score from the ideal treatment plan was low, the absolute volume verification and dose distribution verification sometimes yielded good results. Treatment plan complexity can be determined in advance from the ideal treatment plan score calculated by PlanIQ. However, it is difficult to predict the results of dose verification using an ideal treatment plan. (Keyword) volumetric-modulated arc therapy / dose verification / PlanIQ (Link to Publication Site) ● Publication site (DOI): 10.5603/RPOR.a2022.0122 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 36632304 ● Search Scopus @ Elsevier (PMID): 36632304 ● Search Scopus @ Elsevier (DOI): 10.5603/RPOR.a2022.0122 (DOI: 10.5603/RPOR.a2022.0122, PubMed: 36632304)
8.	Fumitaka Kawabata, Takeshi Kamomae, Kuniyasu Okudaira, Masataka Komori, Hiroshi Oguchi, Motoharu Sasaki, Masaki Mori, Mariko Kawamura, Shinji Abe, Shunichi Ishihara and Shinji Naganawa : Development of a high-resolution two-dimensional detector-based dose verification system for tumor-tracking irradiation in the CyberKnife system, Journal of Applied Clinical Medical Physics, Vol.23, No.8, e13645, 2022. (Summary) We aim to evaluate the basic characteristics of SRS MapCHECK (SRSMC) for CyberKnife (CK) and establish a dose verification system using SRSMC for the tumor-tracking irradiation for CK. The field size and angular dependence of SRSMC were evaluated for basic characterization. The output factors (OPFs) and absolute doses measured by SRSMC were compared with those measured using microDiamond and microchamber detectors and those calculated by the treatment planning system (TPS). The angular dependence was evaluated by comparing the SRSMC with a microchamber. The tumor-tracking dose verification system consists of SRSMC and a moving platform. The doses measured using SRSMC were compared with the doses measured using a microchamber and radiochromic film. The OPFs and absolute doses of SRSMC were within ±3.0% error for almost all field sizes, and the angular dependence was within ±2.0% for all incidence angles. The absolute dose errors between SRSMC and TPS tended to increase when the field size was smaller than 10 mm. The absolute doses of the tumor-tracking irradiation measured using SRSMC and those measured using a microchamber agreed within 1.0%, and the gamma pass rates of SRSMC in comparison with those of the radiochromic film were greater than 95%. The basic characteristics of SRSMC for CK presented acceptable results for clinical use. The results of the tumor-tracking dose verification system realized using SRSMC were equivalent to those of conventional methods, and this system is expected to contribute toward improving the efficiency of quality control in many facilities. (Keyword) Humans / Neoplasms / Radiometry / Radiosurgery / Radiotherapy Dosage / Radiotherapy Planning, Computer-Assisted (Tokushima University Institutional Repository) ● Metadata: 117820 (Link to Publication Site) ● Publication site (DOI): 10.1002/acm2.13645 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 35789532 ● Search Scopus @ Elsevier (PMID): 35789532 ● Search Scopus @ Elsevier (DOI): 10.1002/acm2.13645 (Tokushima University Institutional Repository: 117820, DOI: 10.1002/acm2.13645, PubMed: 35789532)
9.	Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga : Development of a B1 correction method without additional scanning VFA T1 map., European Congress of Radiology (EPOS), 10, 2022.
10.	Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga : Development of self-calibrating B1 correction for three-dimensional variable flip angle T1 mapping, Proceedings of ISMRM, Vol.31, No.3218, 2022.
11.	Takaharu Kudoh, Akihiro Haga, Keiko Kudoh, Akira Takahashi, Motoharu Sasaki, Yasusei Kudo, Hitoshi Ikushima and Youji Miyamoto : Radiomics analysis of [18F]-fluoro-2-deoxyglucose positron emission tomography for the prediction of cervical lymph node metastasis in tongue squamous cell carcinoma, Oral Radiology, 2022. (Summary) This study aimed to create a predictive model for cervical lymph node metastasis (CLNM) in patients with tongue squamous cell carcinoma (SCC) based on radiomics features detected by [F]-fluoro-2-deoxyglucose (F-FDG) positron emission tomography (PET). A total of 40 patients with tongue SCC who underwent F-FDG PET imaging during their first medical examination were enrolled. During the follow-up period (mean 28 months), 20 patients had CLNM, including six with late CLNM, whereas the remaining 20 patients did not have CLNM. Radiomics features were extracted from F-FDG PET images of all patients irrespective of metal artifact, and clinicopathological factors were obtained from the medical records. Late CLNM was defined as the CLNM that occurred after major treatment. The least absolute shrinkage and selection operator (LASSO) model was used for radiomics feature selection and sequential data fitting. The receiver operating characteristic curve analysis was used to assess the predictive performance of the F-FDG PET-based model and clinicopathological factors model (CFM) for CLNM. Six radiomics features were selected from LASSO analysis. The average values of the area under the curve (AUC), accuracy, sensitivity, and specificity of radiomics analysis for predicting CLNM from F-FDG PET images were 0.79, 0.68, 0.65, and 0.70, respectively. In contrast, those of the CFM were 0.54, 0.60, 0.60, and 0.60, respectively. The F-FDG PET-based model showed significantly higher AUC than that of the CFM. The F-FDG PET-based model has better potential for diagnosing CLNM and predicting late CLNM in patients with tongue SCC than the CFM. (Tokushima University Institutional Repository) ● Metadata: 116770 (Link to Publication Site) ● Publication site (DOI): 10.1007/s11282-022-00600-7 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 35254609 ● Summary page in Scopus @ Elsevier: 2-s2.0-85125757133 (Tokushima University Institutional Repository: 116770, DOI: 10.1007/s11282-022-00600-7, PubMed: 35254609, Elsevier: Scopus)
12.	Kanako Sakuragawa, Motoharu Sasaki, Takeshi Kamomae, Yokoishi Michihiro, Ryosuke Kasai, KAJINO Akimi and Hitoshi Ikushima : Differences in image density adjustment parameters on the image matching accuracy of a floor-mounted kV X-ray image-guided radiation therapy system, Journal of Applied Clinical Medical Physics, Vol.23, No.2, e13505, 2022. (Summary) This study aimed to investigate the effect of two different image density adjustment parameters on the results of image matching at six degrees of freedom using radiographic images generated by the ExacTrac X-ray system in brain stereotactic radiosurgery (SRS). This study comprised 32 patients who underwent brain SRS at our hospital from January 2020 to December 2020. In this study, (1) the default parameter (an image density parameter between "tissue" and "bone") was an image density parameter for digitally reconstructed radiograph (DRR) generation used at many facilities, and (2) the bone parameter was the steepest contrast parameter used at our hospital. Of the 32 patients, 24 (75%) had a couch angle of 0.5 mm or more in the translational direction or 0.5° or more in the rotational direction, and 10 (31%) had a couch angle of 1.0 mm or more in the translational direction or 1.0° or more in the rotational direction. Among the 131 cases of all couch angles, 46 (35%) cases had a translational direction of 0.5 mm or more or a rotational direction of 0.5° or more, and 15 (11%) had a translational direction of 1.0 mm or more or a rotational direction of 1.0° or more. The results of this study indicate the usefulness of using appropriate DRR parameters for each case, rather than using the default settings. The use of appropriate DRR parameters can lead to accurate position matching results, leading to fewer image-guided radiation therapy shots and a lower imaging dose. (Keyword) Stereotactic radiosurgery / digitally reconstructed radiograph / ExacTrac / brain metastasis (Tokushima University Institutional Repository) ● Metadata: 117228 (Link to Publication Site) ● Publication site (DOI): 10.1002/acm2.13505 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 34931431 ● Summary page in Scopus @ Elsevier: 2-s2.0-85121471034 (Tokushima University Institutional Repository: 117228, DOI: 10.1002/acm2.13505, PubMed: 34931431, Elsevier: Scopus)
13.	Hiroki Inata, Masahide Tominaga, Motoharu Sasaki, Yuta Kuribayashi, Noritaka Sodeoka, Azusa Katakami and Osamu Nishizaki : Estimation of imaging intervals and intra-fraction displacement in CyberKnife image-guided radiotherapy for intracranial lesions, Medical Physics, Vol.48, No.12, 7580-7589, 2021. (Keyword) imaging interval / intra-fraction / internal margin / IGRT / CyberKnife (Link to Publication Site) ● Publication site (DOI): 10.1002/mp.15169 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1002/mp.15169 (DOI: 10.1002/mp.15169)
14.	Masahide Tominaga, Yukari Nagayasu, Motoharu Sasaki, Furuta Takuya, Hiroaki Hayashi, Masataka Oita, Yuichi Nishiyama and Akihiro Haga : Influence of distant scatterer on air kerma measurement in the evaluation of diagnostic X-rays using Monte Carlo simulation, Radiological Physics and Technology, Vol.14, No.4, 381-389, 2021. (Summary) The evaluation of the entrance surface dose (ESD) ensures safe radiation doses for X-ray imaging patients. The air kerma free-in-air value used to estimate ESD may be affected by those X-rays that scatter from the scatterer placed behind the chamber at the time of measurement, thereby leading to assessment errors. Therefore, the influence of scattered radiation on air kerma measurements was investigated. Monte Carlo simulations were performed for various detector-to-scatterer distances and scatterer materials. The simulation results were compared with actual measurements to confirm the simulation accuracy. The source-chamber distance was set to 50 and 100 cm for the experimental measurements and simulation, respectively, and the chamber-scatterer distance was varied. The Monte Carlo simulation results reproduced the actual measurements with an accuracy of 3.5%. The effect of backscattering varied with the tube voltage and irradiation field size. The effect was observed in the order of prominence for the following scatterer materials: water-equivalent phantom, acrylic, concrete, lead, and iron. Furthermore, this effect decreased exponentially with increasing chamber-scatterer distance. For a field size of 10 × 10 cm, the finite-distance backscatter factor decreased with an increasing chamber-scatterer distance for all materials. The cause of backscattering in diagnostic X-ray energy regions differs depending on the scatterer material, as well as the photon energy and field size. Backscattering decreases exponentially as the distance between the detector and scatterer increases. (Keyword) Air kerma / Backscattering / Dosimetry / Monte Carlo simulation (Link to Publication Site) ● Publication site (DOI): 10.1007/s12194-021-00641-3 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 34716568 ● Search Scopus @ Elsevier (PMID): 34716568 ● Search Scopus @ Elsevier (DOI): 10.1007/s12194-021-00641-3 (DOI: 10.1007/s12194-021-00641-3, PubMed: 34716568)
15.	Motoharu Sasaki, Yuji Nakaguchi, Takeshi Kamomae, Akimi Kajino and Hitoshi Ikushima : Impact of treatment planning quality assurance software on volumetric-modulated arc therapy plans for prostate cancer patients, Medical Dosimetry, Vol.46, No.4, e1-e6, 2021. (Summary) Software that evaluates the quality of treatment plans (PlanIQ) has become commercially available in recent years. It includes a feasibility assessment tool that provides the ideal dose volume histogram (DVH) for each organ at risk, based on the ideal dose falloff from the prescribed dose at the target boundary. It is important to investigate whether the PlanIQ assessment tool (Feasibility DVH) can assist treatment planners who have limited to no experience in treatment planning. Therefore, the present study aimed to evaluate this tool's usefulness for improving the quality of treatment plans. This study included 5 patients with prostate cancer. The treatment planners were 2 graduate students, 2 undergraduate students, and one clinical planner. All students were radiological technology and medical physics students with no clinical experience. Two different volumetric-modulated arc therapy (VMAT) plans were developed before and after Feasibility DVH. The quality of each treatment plan was evaluated based on a scoring system implemented in PlanIQ. Of 5 patients included, 4 received improved treatment plans when Feasibility DVH was used. Moreover, 4 of 5 treatment planners showed improvement in treatment planning using Feasibility DVH. The findings suggest that using the Feasibility DVH tool may improve treatment plans for different planners and patients. However, planners at any level of experience should be trained to check the dose distribution in addition to checking the DVH, which depends on the adequacy of the contours. (Link to Publication Site) ● Publication site (DOI): 10.1016/j.meddos.2021.03.013 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33972163 ● Search Scopus @ Elsevier (PMID): 33972163 ● Search Scopus @ Elsevier (DOI): 10.1016/j.meddos.2021.03.013 (DOI: 10.1016/j.meddos.2021.03.013, PubMed: 33972163)
16.	Yohsuke Kanoh, Hitoshi Ikushima, Motoharu Sasaki and Akihiro Haga : Automatic Contour Segmentation of Cervical Cancer using Artificial Intelligence, Journal of Radiation Research, Vol.62, No.5, 934-944, 2021. (Summary) In cervical cancer treatment, radiation therapy is selected based on the degree of tumor progression, and radiation oncologists are required to delineate tumor contours. To reduce the burden on radiation oncologists, an automatic segmentation of the tumor contours would prove useful. To the best of our knowledge, automatic tumor contour segmentation has rarely been applied to cervical cancer treatment. In this study, diffusion-weighted images (DWI) of 98 patients with cervical cancer were acquired. We trained an automatic tumor contour segmentation model using 2D U-Net and 3D U-Net to investigate the possibility of applying such a model to clinical practice. A total of 98 cases were employed for the training, and they were then predicted by swapping the training and test images. To predict tumor contours, six prediction images were obtained after six training sessions for one case. The six images were then summed and binarized to output a final image through automatic contour segmentation. For the evaluation, the Dice similarity coefficient (DSC) and Hausdorff distance (HD) was applied to analyze the difference between tumor contour delineation by radiation oncologists and the output image. The DSC ranged from 0.13 to 0.93 (median 0.83, mean 0.77). The cases with DSC <0.65 included tumors with a maximum diameter < 40 mm and heterogeneous intracavitary concentration due to necrosis. The HD ranged from 2.7 to 9.6 mm (median 4.7 mm). Thus, the study confirmed that the tumor contours of cervical cancer can be automatically segmented with high accuracy. (Keyword) cervical cancer / automatic tumor contour segmentation / radiation therapy / diffusion-weighted imaging / Dice similarity coefficient (Tokushima University Institutional Repository) ● Metadata: 116749 (Link to Publication Site) ● Publication site (DOI): 10.1093/jrr/rrab070 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 34401914 ● Search Scopus @ Elsevier (PMID): 34401914 ● Search Scopus @ Elsevier (DOI): 10.1093/jrr/rrab070 (Tokushima University Institutional Repository: 116749, DOI: 10.1093/jrr/rrab070, PubMed: 34401914)
17.	Hirofumi Honda, Masahide Tominaga, Motoharu Sasaki, Masataka Oita, Kanzaki Hiromitsu, Hamamoto Yasushi, Ishii Yoshiaki, Yamamoto Ryuji, Mochizuki Teruhito, Kido Teruhito and Yoshihiro Uto : Usability of detecting delivery errors during treatment of prostate VMAT with a gantry-mounted transmission detector, Journal of Applied Clinical Medical Physics, Vol.22, No.7, 66-76, 2021. (Summary) Volumetric-modulated arc therapy (VMAT) requires highly accurate control of multileaf collimator (MLC) movement, rotation speed of linear accelerator gantry, and monitor units during irradiation. Pretreatment validation and monitoring of these factors during irradiation are necessary for appropriate VMAT treatment. Recently, a gantry mounted transmission detector "Delta Discover® (D4D)" was developed to detect errors in delivering doses and dose distribution immediately after treatment. In this study, the performance of D4D was evaluated. Simulation plans, in which the MLC position was displaced by 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm from the clinically used original plans, were created for ten patients who received VMAT treatment for prostate cancer. Dose deviation (DD), distance-to-agreement (DTA), and gamma index analysis (GA) for each plan were evaluated by D4D. These results were compared to the results (DD, DTA and GA) measured by Delta Phantom + (D4P). We compared the deviations between the planned and measured values of the MLC stop positions A-side and B-side in five clinical cases of prostate VMAT during treatment and measured the GA values. For D4D, when the acceptable errors for DD, DTA, and GA were determined to be ≤3%, ≤2 mm, and ≤3%/2 mm, respectively, the minimum detectable errors in the MLC position were 2.0, 1.5, and 1.5 mm based on DD, DTA, and GA respectively. The corresponding minimum detectable MLC position errors were 2.0, 1.0, and 1.5 mm, respectively, for D4P. The deviation between the planned and measured position of MLC stopping point of prostate VMAT during treatment was stable at an average of -0.09 ± 0.05 mm, and all GA values were above 99.86%. In terms of delivering doses and dose distribution of VMAT, error detectability of D4D was comparable to that of D4P. The transmission-type detector "D4D" is thus suitable for detecting delivery errors during irradiation. (Keyword) in vivo dosimetry / transmission detector / three-dimensional dose verification system / volume-modulated arc therapy (Tokushima University Institutional Repository) ● Metadata: 116183 (Link to Publication Site) ● Publication site (DOI): 10.1002/acm2.13260 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33955161 ● Search Scopus @ Elsevier (PMID): 33955161 ● Search Scopus @ Elsevier (DOI): 10.1002/acm2.13260 (Tokushima University Institutional Repository: 116183, DOI: 10.1002/acm2.13260, PubMed: 33955161)
18.	Hasegawa Yu, Akihiro Haga, Sakata Dousatsu, Yuki Kanazawa, Masahide Tominaga, Motoharu Sasaki, Imae Toshikazu and Nakagawa Keiichi : Estimation of X-ray Energy Spectrum of Cone-Beam Computed Tomography Scanner Using Percentage Depth Dose Measurements and Machine Learning Approach, Journal of the Physical Society of Japan, Vol.90, 074801-1-074801-7, 2021. (Link to Publication Site) ● Publication site (DOI): 10.7566/JPSJ.90.074801 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.7566/JPSJ.90.074801 (DOI: 10.7566/JPSJ.90.074801)
19.	Takeshi Kamomae, Takuma Matsunaga, Junji Suzuki, Kuniyasu Okudaira, Fumitaka Kawabata, Yutaka Kato, Hiroshi Oguchi, Morihito Shimizu, Motoharu Sasaki, Yuki Takase, Mariko Kawamura, Kazuhiro Ohtakara, Yoshiyuki Itoh and Shinji Naganawa : Dosimetric impacts of beam-hardening filter removal for the CyberKnife system, Physica Medica, Vol.86, 98-105, 2021. (Summary) Equipment refurbishment was performed to remove the beam-hardening filter (BHF) from the CyberKnife system (CK). This study aimed to confirm the change in the beam characteristics between the conventional CK (present-BHF CK) and CK after the BHF was removed (absent-BHF CK) and evaluate the impact of BHF removal on the beam quality correction factors k. The experimental measurements of the beam characteristics of the present- and absent-BHF CKs were compared. The CKs were modeled using Monte Carlo simulations (MCs). The energy fluence spectra were calculated using MCs. Finally, k were estimated by combining the MC results and analytic calculations based on the TRS-398 and TRS-483 approaches. All gamma values for percent depth doses and beam profiles between each CK were less than 0.5 following the 3%/1 mm criteria. The percentage differences for tissue-phantom ratios at depths of 20 and 10 cm and percentage depth doses at 10 cm between each CK were -1.20% and -0.97%, respectively. The MC results demonstrated that the photon energy fluence spectrum of the absent-BHF CK was softer than that of the present-BHF CK. The k values for the absent-BHF CK were in agreement within 0.02% with those for the present-BHF CK. The photon energy fluence spectrum was softened by the removal of BHF. However, no remarkable impact was observed for the measured beam characteristics and k. Therefore, the previous findings of the k values for the present-BHF CK can be directly used for the absent-BHF CK. (Keyword) Algorithms / Monte Carlo Method / Photons / Radiometry / Radiotherapy Planning, Computer-Assisted (Link to Publication Site) ● Publication site (DOI): 10.1016/j.ejmp.2021.05.011 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 34082183 ● Search Scopus @ Elsevier (PMID): 34082183 ● Search Scopus @ Elsevier (DOI): 10.1016/j.ejmp.2021.05.011 (DOI: 10.1016/j.ejmp.2021.05.011, PubMed: 34082183)
20.	Motoharu Sasaki, Nakaguchi Yuji, Takeshi Kamomae, Tsuzuki Akira, Kobuchi Satoshi, Kuwahara Kenmei, Shoji Ueda, Yuto Endoh and Hitoshi Ikushima : Analysis of prostate intensity- and volumetric-modulated arc radiation therapy planning quality with PlanIQTM, Journal of Applied Clinical Medical Physics, Vol.22, No.4, 132-142, 2021. (Summary) The purpose of this study was to assess the quality of treatment planning using the PlanIQ software and to investigate whether it is possible to improve the quality of treatment planning using the "Feasibility dose-volume histogram (DVH) " implemented in the PlanIQ software. Using the PlanIQ software, we retrospectively analyzed the learning curve regarding the quality of the treatment plans for 148 patients of prostate intensity-modulated radiation therapy and volumetric-modulated radiation therapy performed at our institution over the past eight years. We also sought to examine the possibility of improving treatment planning quality by re-planning in 47 patients where the quality of the target dose and the dose limits for organs at risk (OARs) were inadequate. The re-planning treatment plans referred to the Feasibility DVH implemented in the PlanIQ software and modified the treatment planning system based on the target dose and OAR constraints. Analysis of the learning curve of the treatment plans quality using PlanIQ software retrospectively showed a trend of improvement in the treatment plan quality from year to year. The improvement in the treatment plans quality was more influenced by dose reduction in the OARs than by target coverage. In all cases where re-planning was performed, the improvement in the treatment plan's quality resulted in a better treatment plan than the one adopted for delivery to patients in the clinical plan. The PlanIQ provided insights into the quality of the treatment plans at our institution and identified problems and areas for improvement in the treatment plans, allowing for the development of appropriate treatment plans for specific patients. (Keyword) Humans / Male / Organs at Risk / Prostate / Radiotherapy Dosage / Radiotherapy Planning, Computer-Assisted / Radiotherapy, Intensity-Modulated / Retrospective Studies (Tokushima University Institutional Repository) ● Metadata: 116342 (Link to Publication Site) ● Publication site (DOI): 10.1002/acm2.13233 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33768648 ● Search Scopus @ Elsevier (PMID): 33768648 ● Search Scopus @ Elsevier (DOI): 10.1002/acm2.13233 (Tokushima University Institutional Repository: 116342, DOI: 10.1002/acm2.13233, PubMed: 33768648)
21.	Kenta Kitagawa, Hitoshi Ikushima, Motoharu Sasaki, Shunsuke Furutani, Takashi Kawanaka, Akiko Kubo, Chisato Tonoiso, Takaharu Kudoh, Yohsuke Kanoh and Tsuzuki Akira : Effect of dental metal artifact conversion volume on dose distribution in head-and-neck volumetric-modulated arc therapy, Journal of Applied Clinical Medical Physics, Vol.21, No.12, 253-262, 2020. (Summary) Purpose: During treatment planning for head-and-neck volumetric-modulated arc therapy (VMAT), manual contouring of the metal artifact area of artificial teeth is done, and the area is replaced with water computed tomography (CT) values for dose calculation. This contouring of the metal artifact areas, which is performed manually, is subject to human variability. The purpose of this study is to evaluate and analyze the effect of inter-observer variation on dose distribution.Methods: The subjects were 25 cases of cancer of the oropharynx for which VMAT was performed. Six radiation oncologists (ROs) performed metal artifact contouring for all of the cases. Gross tumor volume, clinical target volume, planning target volume (PTV), and oral cavity were evaluated. The contouring of the six ROs was divided into two groups, small and large groups. A reference RO was determined for each group and the dose distribution was compared with those of the other radiation oncologists by gamma analysis (GA).As an additional experiment, we changed the contouring of each dental metal artifact area, creating enlarged contours (L), reduced contours (S), and undrawn contours (N) based on the contouring by the six ROs and compared these structure-sets.Results: The evaluation of inter-observer variation showed no significant difference between the large and small groups, and the GA pass rate was 100%. Similar results were obtained comparing structure-sets L and S, but in the comparison of structure-sets L and N, there were cases with pass rates below 70%.Conclusions: The results show that the artificial variability of manual artificial tooth metal artifact contouring has little effect on the dose distribution of VMAT. However, it should be noted that the dose distribution may change depending on the contouring method in cases where the overlap between PTV and metal artifact areas is large. (Keyword) dental metal artifact / head-and-neck / volumetric-modulated arc therapy (Tokushima University Institutional Repository) ● Metadata: 115924 (Link to Publication Site) ● Publication site (DOI): 10.1002/acm2.13101 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33226172 ● Summary page in Scopus @ Elsevier: 2-s2.0-85097008301 (Tokushima University Institutional Repository: 115924, DOI: 10.1002/acm2.13101, PubMed: 33226172, Elsevier: Scopus)
22.	Motoharu Sasaki, Hitoshi Ikushima, Kanako Sakuragawa, Michihiro Yokoishi, Akira Tsuzuki and Wataru Sugimoto : Determination of reproducibility of end-exhaled breath-holding in stereotactic body radiation therapy, Journal of Radiation Research, Vol.61, No.6, 977-984, 2020. (Keyword) dice similarity coefficient / Hausdorff distance / breath-hold irradiation / lung cancer (Tokushima University Institutional Repository) ● Metadata: 116210 (Link to Publication Site) ● Publication site (DOI): 10.1093/jrr/rraa079 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 32930802 ● Search Scopus @ Elsevier (PMID): 32930802 ● Search Scopus @ Elsevier (DOI): 10.1093/jrr/rraa079 (Tokushima University Institutional Repository: 116210, DOI: 10.1093/jrr/rraa079, PubMed: 32930802)
23.	Motoharu Sasaki, Hitoshi Ikushima, Akira Tsuzuki and Wataru Sugimoto : The effect of rectal gas on dose distribution during prostate cancer treatment using full arc and partial arc Volumetric Modulated Arc Therapy (VMAT) treatment plans, Reports of Practical Oncology and Radiotherapy, Vol.25, No.6, 974-980, 2020. (Summary) In this study, we investigated the effect of rectal gas on the dose distribution of prostate cancer using a volumetric modulated arc therapy (VMAT) treatment planning. The first is the original structure set, clinical target volume (CTV), the rectum, and the bladder used clinically. The second is a structure set (simulated gas structure set) in which the overlapping part of the rectum and PTV is overwritten with Hounsfield Unit -950 as gas. Full arc and limited gantry rotation angle with VMAT were the two arcs. The VMAT of the full arc was 181°-179° in the clockwise (CW) direction and 179°-181° in the counterclockwise (CCW) direction. Three partial arcs with a limited gantry rotation angle were created: 200°-160 °CW and 160°-200 °CCW; 220°-140 °CW and 140°-220 °CCW; and finally, 240°-120 °CW and 120°-240 °CCW. The evaluation items were dose difference, distance to agreement, and gamma analysis. In the CTV, the full arc was the treatment planning technique with the least effect of rectal gas. In the rectum, when the gantry rotation angle range was short, the pass rate tended to reduce for all evaluation indices. The bladder showed no characteristic change between the treatment planning techniques in any of the evaluation indices. The VMAT treatment planning with the least effect on dose distribution caused by rectal gas was shown to be a full arc. (Keyword) Volumetric modulated arc therapy / Gas / Dose distribution / Prostate cancer (Link to Publication Site) ● Publication site (DOI): 10.1016/j.rpor.2020.09.013 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 33100914 ● Search Scopus @ Elsevier (PMID): 33100914 ● Search Scopus @ Elsevier (DOI): 10.1016/j.rpor.2020.09.013 (DOI: 10.1016/j.rpor.2020.09.013, PubMed: 33100914)
24.	Motoharu Sasaki and Hitoshi Ikushima : Impact of Changes in Body Contours on Radiation Therapy Dose Distribution After Uterine Cervical Cancer Surgery, Japanese Journal of Radiology, Vol.38, No.11, 1099-1107, 2020. (Summary) Patients receiving postoperative irradiation for uterine cervical cancer might not be able to eat during radiation therapy because of the effects of concurrent chemo-radiotherapy; this may lead to changes in the patient's body shape during treatment. When performing image-guided radiotherapy, it is necessary to determine immediately whether treatment can be performed on the day or whether re-planning is required. The purpose of this study was to determine indicators for re-planning by examining the effects of changing body contours on radiation therapy dose. The original body contour was reduced by 1 cm in the front portion (structure-set 1). Based on the original dose distribution, the dose recalculation was performed with a structure set created using the body contour of structure-set 1. The difference between the original and recalculated dose distributions of structure-set 1 was evaluated through gamma analysis (GA). In the GA results for dose distribution obtained via recalculation with structure-set 1, a pass rate of 90% or more was obtained for a criterion of 2 mm/2% in all cases. The results suggest that dose re-planning is rarely required when the body shape is reduced by only 1 cm in the front. (Keyword) body shape change / after uterine cervical cancer surgery / VMAT (Link to Publication Site) ● Publication site (DOI): 10.1007/s11604-020-01011-6 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 32617837 ● Summary page in Scopus @ Elsevier: 2-s2.0-85087392393 (DOI: 10.1007/s11604-020-01011-6, PubMed: 32617837, Elsevier: Scopus)
25.	Motoharu Sasaki, Wataru Sugimoto and Hitoshi Ikushima : Simplification of Head and Neck Volumetric Modulated Arc Therapy Patient-specific Quality Assurance, Using a Delta4 PT, Reports of Practical Oncology and Radiotherapy, Vol.25, No.5, 793-800, 2020. (Summary) In many facilities, intensity-modulated radiation therapy (IMRT), and volumetric modulated arc therapy (VMAT) use intensity-modulated beams, formed by a multi-leaf collimator (MLC). In IMRT and VMAT, MLC and linear accelerator errors (both geometric and dose), can significantly affect the doses administered to patients. Therefore, IMRT and VMAT treatment plans must include the use of patient-specific quality assurance (QA) before treatment to confirm dose accuracy. In this study, we compared and analyzed the results of dose verification using a multi-dimensional dose verification system Delta4 PT, an ionization chamber dosimeter, and gafchromic film, using data from 52 patients undergoing head and neck VMAT as the test material. Based on the results of the absolute dose verification for the ionization chamber dosimeter and Delta4 PT, taking an axial view, the upper limit of the 95% confidence interval was 3.13%, and the lower limit was -3.67%, indicating good agreement. These results mean that as long as absolute dose verification for the axial view does not deviate from this range, Delta4 PT can be used as an alternative to an ionization chamber dosimeter for absolute dose verification. When we then reviewed dose distribution verification, the pass rate for Delta4 PT was acceptable, and was less varied than that of gafchromic film. This results in that provided the pass rate result for Delta4 PT does not fall below 96%, it can be used as a substitute for gafchromic film in dose distribution verification. These results indicate that patient-specific QA could be simplified. (Keyword) Delta4 PT / volumetric modulated radiation therapy / head and neck / patient-specific quality assurance (Link to Publication Site) ● Publication site (DOI): 10.1016/j.rpor.2020.07.004 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 32879621 ● Search Scopus @ Elsevier (PMID): 32879621 ● Search Scopus @ Elsevier (DOI): 10.1016/j.rpor.2020.07.004 (DOI: 10.1016/j.rpor.2020.07.004, PubMed: 32879621)
26.	Motoharu Sasaki, Hitoshi Ikushima, Wataru Sugimoto and Kenta Kitagawa : Long-term stability of a three-dimensional dose verification system., Radiological Physics and Technology, Vol.13, No.1, 83-91, 2020. (Summary) Recently, the number of patients undergoing intensity-modulated radiation therapy and volumetric modulated arc therapy has increased with the expansion of the adaptation site. However, it is necessary to improve the efficiency of time-consuming dose verification. Therefore, patient-specific quality assurance is expected to shift from dose verification using a conventional ionization chamber dosimeter and film to a three-dimensional dose verification system. However, caution is required when using a three-dimensional dose verification system, especially when it comes to the calibration of the detector. Calibration is performed regularly, but not all necessary verifications are done routinely. There are many uncertainties on how the sensitivity of the three-dimensional dose verification system changes over time. In this study, on the same day, when dose verification using a three-dimensional system for one head and neck case was performed, dose verification using a conventional ionization chamber dosimeter and film was also performed once every two months, for 2 years. From the results of the absolute dose and dose distribution verification using the ionization chamber dosimeter and Gafchromic film, the output of the linear accelerator, mechanical accuracy and precision were secured. From the results of the three-dimensional dose verification system, when the distance to agreement was evaluated at 2 mm and 3 mm, and gamma analysis was performed at 2 mm/2% and 3 mm/3%, the passing rate was almost 100%, and a sensitivity change in 2 years was not observed. (Keyword) Long-term stability / Patient-specific QA / Three-dimensional dose verification system / VMAT (Link to Publication Site) ● Publication site (DOI): 10.1007/s12194-020-00554-7 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 32006217 ● Summary page in Scopus @ Elsevier: 2-s2.0-85078907756 (DOI: 10.1007/s12194-020-00554-7, PubMed: 32006217, Elsevier: Scopus)
27.	Hirokazu Miyoshi, Fumio Kida, Yoshiyasu Kawase, Kenji Yamada, Motoharu Sasaki, Hidenori Shoji and Hitoshi Hase : Emission image of X-ray-irradiated CR-39 stick doped with methylviologen-encapsulated silica nanocapsules using LED light, Progress in Nuclear Science and Technology, Vol.6, 91-94, 2019. (Tokushima University Institutional Repository) ● Metadata: 118669 (Link to Publication Site) ● Publication site (DOI): 10.15669/pnst.6.91 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.15669/pnst.6.91 (Tokushima University Institutional Repository: 118669, DOI: 10.15669/pnst.6.91)
28.	Shunsuke Furutani, Hitoshi Ikushima, Motoharu Sasaki, Chisato Tonoiso, Ayaka Takahashi, Akiko Kubo, Takashi Kawanaka and Masafumi Harada : Clinical outcomes of hypofractionated image-guided multifocal irradiation using volumetric-modulated arc therapy for brain metastases., Journal of Radiation Research, Vol.60, No.1, 134-141, 2019. (Summary) Volumetric-modulated arc therapy (VMAT) can be used to design hypofractionated radiotherapy treatment plans for multiple brain metastases. The purpose of this study was to evaluate treatment outcomes of hypofractionated image-guided multifocal irradiation using VMAT (HFIGMI-VMAT) for brain metastases. From July 2012 to December 2016, 67 consecutive patients with 601 brain metastases were treated with HFIGMI-VMAT at our institution. The prescribed dose was 50 Gy to a 95% volume of the planning target volume in 10 fractions. Fifty-five of the 67 patients had non-small-cell lung cancer, and the remaining 12 had other types of cancer. The median number of brain metastases was five, and the median maximum diameter was 1.2 cm. The median duration of follow-up was 12.0 months (range, 1.9-44.8 months), and the median survival time 18.7 months. Four patients with six lesions had local recurrences. The local control rate in the 64 assessed patients was 98.4% and 95.3% at 6 and 12 months, respectively (three died before assessment). The local control rate for the 572 assessed lesions was 99.8% and 99.3% at 6 and 12 months, respectively. Thirty-nine patients developed distant brain metastases, the distant brain control rate being 59.7% and 40.5% at 6 and 12 months, respectively. Acute toxicities were generally mild (Grade 1-2). Three patients (4.5%) developed radiation necrosis requiring corticosteroid therapy. The HFIGMI-VMAT technique with flat dose delivery was well tolerated and achieved excellent local control. This technique is a promising treatment option for patients with multiple and large brain metastases. (Tokushima University Institutional Repository) ● Metadata: 115535 (Link to Publication Site) ● Publication site (DOI): 10.1093/jrr/rry091 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 30445426 ● Search Scopus @ Elsevier (PMID): 30445426 ● Search Scopus @ Elsevier (DOI): 10.1093/jrr/rry091 (Tokushima University Institutional Repository: 115535, DOI: 10.1093/jrr/rry091, PubMed: 30445426)
29.	Motoharu Sasaki, Masahide Tominaga, Kamomae Takeshi, Hitoshi Ikushima, Kitaoka Motonori, Bando Ryota, Kanako Sakuragawa and Masataka Oita : Influence of multi-leaf collimator leaf transmission on head and neck intensity-modulated radiation therapy and volumetric-modulated arc therapy planning., Japanese Journal of Radiology, Vol.35, No.9, 511-525, 2017. (Summary) The aim of this study was to quantify the effect of multi-leaf collimators (MLCs) with different leaf widths on the planning of intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT). Toward this objective, dose transmission through a high-definition 120-leaf MLC (HD120MLC) and 120-leaf Millennium MLC (M120MLC) was investigated, using it with a test case and clinical case studies. In test case, studies with IMRT and VMAT plans, the difference in MLC leaf width had a limited effect on planning target volumes (PTVs). Organs at risk (OARs) were more affected by a reduction in dose transmission through the MLC than by a reduction in MLC leaf width. The results of the test case studies and clinical case studies were mostly similar. In the latter, the different MLCs had no effect on the PTV regardless of the treatment method; however, the HD120MLC plans achieved dose reductions to OARs similar to or larger than the dose reduction of the M120MLC plans. The similar results of the test case and clinical case studies showed that despite a limitation of the irradiation field size, the HD120MLC plans were superior. (Link to Publication Site) ● Publication site (DOI): 10.1007/s11604-017-0661-8 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 28647834 ● Summary page in Scopus @ Elsevier: 2-s2.0-85021229873 (DOI: 10.1007/s11604-017-0661-8, PubMed: 28647834, Elsevier: Scopus)
30.	Noriyuki Kadoya, Yujiro Nakajima, Msahide Saito, Yuki Miyabe, Masahiko Kurooka, Satoshi Kito, Yukio Fujita, Motoharu Sasaki, Kazuhiro Arai, Kensuke Tani, Masashi Yagi, Akihisa Wakita, Naoki Tohyama and Keiichi Jingu : Multi-institutional Validation Study of Commercially Available Deformable Image Registration Software for Thoracic Images., International Journal of Radiation OncologyBiologyPhysics, Vol.96, No.2, 422-431, 2016. (Summary) To assess the accuracy of the commercially available deformable image registration (DIR) software for thoracic images at multiple institutions. Thoracic 4-dimensional (4D) CT images of 10 patients with esophageal or lung cancer were used. Datasets for these patients were provided by DIR-lab (dir-lab.com) and included a coordinate list of anatomic landmarks (300 bronchial bifurcations) that had been manually identified. Deformable image registration was performed between the peak-inhale and -exhale images. Deformable image registration error was determined by calculating the difference at each landmark point between the displacement calculated by DIR software and that calculated by the landmark. Eleven institutions participated in this study: 4 used RayStation (RaySearch Laboratories, Stockholm, Sweden), 5 used MIM Software (Cleveland, OH), and 3 used Velocity (Varian Medical Systems, Palo Alto, CA). The ranges of the average absolute registration errors over all cases were as follows: 0.48 to 1.51 mm (right-left), 0.53 to 2.86 mm (anterior-posterior), 0.85 to 4.46 mm (superior-inferior), and 1.26 to 6.20 mm (3-dimensional). For each DIR software package, the average 3-dimensional registration error (range) was as follows: RayStation, 3.28 mm (1.26-3.91 mm); MIM Software, 3.29 mm (2.17-3.61 mm); and Velocity, 5.01 mm (4.02-6.20 mm). These results demonstrate that there was moderate variation among institutions, although the DIR software was the same. We evaluated the commercially available DIR software using thoracic 4D-CT images from multiple centers. Our results demonstrated that DIR accuracy differed among institutions because it was dependent on both the DIR software and procedure. Our results could be helpful for establishing prospective clinical trials and for the widespread use of DIR software. In addition, for clinical care, we should try to find the optimal DIR procedure using thoracic 4D-CT data. (Keyword) Female / Humans / Japan / Male / Radiography, Thoracic / Reproducibility of Results / Sensitivity and Specificity / Software / Software Validation / Subtraction Technique / Thoracic Neoplasms / Tomography, X-Ray Computed (Link to Publication Site) ● Publication site (DOI): 10.1016/j.ijrobp.2016.05.012 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 27475673 ● Search Scopus @ Elsevier (PMID): 27475673 ● Search Scopus @ Elsevier (DOI): 10.1016/j.ijrobp.2016.05.012 (DOI: 10.1016/j.ijrobp.2016.05.012, PubMed: 27475673)
31.	Takeshi Kamomae, Masataka Oita, Naoki Hayashi, Motoharu Sasaki, Hideki Aoyama, Hiroshi Oguchi, Mariko Kawamura, Hajime Monzen, Yoshiyuki Itoh and Shinji Naganawa : Characterization of stochastic noise and post-irradiation density growth for reflective-type radiochromic film in therapeutic photon beam dosimetry., Physica Medica, Vol.32, No.10, 1314-1320, 2016. (Summary) The aim of this study is to investigate the dosimetric uncertainty of stochastic noise and the post-irradiation 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 400cGy. The pixel values (PVs) of these films were obtained using a flatbed scanner at elapsed times of 1min to 120h 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, and the dose increases resulting from the PV increases per ±29min at each elapsed time, u, were computed. The combined dose uncertainties from these two factors, u, were then calculated. A sharp increase in the PV occurred within the first 3h after irradiation, and a slight increase continued from 3h to 120h. u was independent of post-irradiation elapsed time. Sharp decreases in u were obtained within 1h after irradiation, and slight decreases in u were observed from 1 to 24h after irradiation. u first decreased 1h after irradiation and remained constant afterward. Assuming that the post-irradiation elapsed times of all of the related measurements are synchronized within ±29min, the elapsed time should be at least 1h 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. (Keyword) Radiochromic film / Stochastic noise / Post-irradiation density growth / Dosimetric uncertainty (Link to Publication Site) ● Publication site (DOI): 10.1016/j.ejmp.2016.07.091 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 27473441 ● Search Scopus @ Elsevier (PMID): 27473441 ● Search Scopus @ Elsevier (DOI): 10.1016/j.ejmp.2016.07.091 (DOI: 10.1016/j.ejmp.2016.07.091, PubMed: 27473441)
32.	Motoharu Sasaki, Hitoshi Ikushima, Masahide Tominaga, T Kamomae, T Kishi, Masataka Oita and Masafumi Harada : Dose impact of rectal gas on prostatic IMRT and VMAT, Japanese Journal of Radiology, Vol.33, No.12, 723-733, 2015. (Summary) In this study, we compared the dose impact of the heterogeneity caused by rectal gas using two methods of treatment planning for intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (VMAT). In addition to the structure set used for the standard treatment plan, we created a structure set for evaluation for each patient. These sets were transferred to the same isocenter as the respective treatment plans for IMRT and VMAT that were to become the standard. Values were then recalculated. During the standard prostatic IMRT and VMAT treatment planning, all study participants met dose restrictions in place at our hospital. Dose restrictions were fulfilled in treatment plans for evaluation, excluding those with a clinical target volume (CTV) of V(100%) and planning target volume (PTV) of D95 when the rectum was excluded. However, in treatment plans for evaluation, IMRT was shown to have a higher concordance rate with standard treatment plans than VMAT. If rectal gas is present during either IMRT or VMAT, a dose decrease will occur in relation to CTV and PTV, suggesting that a plan does not eliminate adverse effects on organs at risk. (Tokushima University Institutional Repository) ● Metadata: 109667 (Link to Publication Site) ● Publication site (DOI): 10.1007/s11604-015-0481-7 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 26573828 ● Search Scopus @ Elsevier (PMID): 26573828 ● Search Scopus @ Elsevier (DOI): 10.1007/s11604-015-0481-7 (Tokushima University Institutional Repository: 109667, DOI: 10.1007/s11604-015-0481-7, PubMed: 26573828)
33.	Masataka Oita, Yoshihiro Uto, Masahide Tominaga, Motoharu Sasaki, Yasuo Hara, Taro Kishi and Hitoshi Hori : Radiosensitivity Uncertainty Evaluation for the In Vitro Biophysical Modeling of EMT6 Cells, Anticancer Research, Vol.34, No.8, 4621-4626, 2014. (Summary) The aims of this study were to evaluate the cell survival uncertainty distribution of radiation and to assess the accuracy of predictions of tumor response by using three different in vitro experimental cell cultures with radiosensitizers (including etanidazole). Using EMT6 cells and X-rays, the cell survival fraction was obtained from 15, 34, and 21 different experiments under normoxic, hypoxic, and hypoxic-plus-radiosensitizer culture, respectively. The α coefficients were 0.257 ± 0.188, 0.078 ± 0.080, and 0.182 ± 0.116 Gy(-1), respectively. The β coefficients were 0.0159 ± 0.0208, 0.0076 ± 0.0113, and 0.0062 ± 0.0077 Gy(-2), respectively. The α coefficient and the dose that killed half of the clonogens population (D50) were significantly different between normoxic cell and hypoxic cell cultures (p<0.01), respectively. The use of radiosensitizers under hypoxic conditions improved radiosensitivity. Our results suggest that parameter value distributions are required for biophysical modeling of applications for radiotherapy. (Keyword) Radiotherapy / biophysical modelling / in vitro / radiosensitivity uncertainty (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 25075109 ● Search Scopus @ Elsevier (PMID): 25075109 (PubMed: 25075109)
34.	Motoharu Sasaki, Masahide Tominaga, t Kamomae, Hitoshi Ikushima, T Kishi, T Kawashita, A Tada, M Shigemitsu and Masataka Oita : Clinical evaluation of automatic contours for head and neck region using deformable image registration software, Japanese Journal of Radiological Technology, Vol.69, No.11, 1250-1260, 2013. (Summary) The purpose of this study was to clinically evaluate the automatic outline extraction properties using general-purpose deformable image registration (DIR) software for the head and neck region. To this end, we evaluated the following: (1) the difference between manual outline extraction carried out by a radiation therapy specialist and automatic outline extraction using the DIR software, and (2) the precision of the automatic outline extraction for the diachronic figure change and change in the organ shape. The manually-extracted outline and that extracted using the DIR software closely resembled each other at 0.70. Further, in the same case, the automatic outline extraction precision of the DIR software was greater at about 0.80. Our findings suggest DIR software to be useful for lessening the work involved in outline extraction. (Keyword) deformable image registration (DIR) / auto-segmentation / head and neck (Link to Publication Site) ● Publication site (DOI): 10.6009/jjrt.2013_JSRT_69.11.1250 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 24256648 ● CiNii @ National Institute of Informatics (CRID): 1390001206363278720 ● Summary page in Scopus @ Elsevier: 2-s2.0-84896689742 (DOI: 10.6009/jjrt.2013_JSRT_69.11.1250, PubMed: 24256648, CiNii: 1390001206363278720, Elsevier: Scopus)
35.	Motoharu Sasaki, Hitoshi Ikushima, Y Nakaguchi, T Kishi, M Kimura, R Bandou and M Oita : A comparison of four commercial radiation treatment planning systems for prostate intensity modulated radiation therapy, Japanese Journal of Radiological Technology, Vol.69, No.7, 761-772, 2013. (Summary) At present, every manufacturer of intensity modulated radiation therapy (IMRT) equipment uses multi-leaf collimators (MLCs); however, each company's intensity modulation methods and dose calculation algorithms differ. This study used four typical radiation treatment planning systems (RTPSs) employed domestically for prostate IMRT plans to carry out 15 case studies by one planner based on the dose limits at this clinic. The results were used to compare the differences, if any, in RTPS treatment plans. With prostate IMRT plans, an overlap area exists between the PTV and the rectum. For this reason, while observing dose limits of 60-75 Gy (within the dose tolerated by the rectum), securing uniformity and concentration of dose is essential to create the most appropriate treatment plan for the PTV and other targets. Although each RTPS uses different planning methods, it was generally possible to observe this clinic's dose limits by adjusting the parameter values. When identical beam data is used, it is possible to create similar treatment plans. (Keyword) Algorithms / Humans / Male / Prostatic Neoplasms / Radiotherapy Planning, Computer-Assisted / Radiotherapy, Intensity-Modulated (Link to Publication Site) ● Publication site (DOI): 10.6009/jjrt.2013_JSRT_69.7.761 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 23877154 ● Search Scopus @ Elsevier (PMID): 23877154 ● Search Scopus @ Elsevier (DOI): 10.6009/jjrt.2013_JSRT_69.7.761 (DOI: 10.6009/jjrt.2013_JSRT_69.7.761, PubMed: 23877154)
36.	Bado Ryota, Hitoshi Ikushima, Takashi Kawanaka, Takaharu Kudoh, Motoharu Sasaki, Masahide Tominaga, Taro Kishi, Shunsuke Furutani, Akiko Kubo and Koichi Tamura : Changes of tumor and normal structures of the neck during radiation therapy for head and neck cancer requires adaptive strategy., The Journal of Medical Investigation : JMI, Vol.60, No.1,2, 46-51, 2013. (Summary) The treatment period over which radiation therapy is administered extends over several weeks. Since tumor shrinkage in response to radiation therapy and weight loss due to radiation-induced mucositis may impact on the dose distribution in both target and organ at risk in patients with head and neck cancer, the anatomical changes of tumor and neck volumes during this period should be taken into consideration. We investigated the anatomical changes that occurred in the target and normal structure of the neck during radiation therapy for pharyngeal cancer, and evaluated the necessity of an adaptive strategy. Ten patients with pharyngeal cancer who underwent radical chemoradiation therapy using 3-dimensional conformal radiation therapy RT (66-70 Gy in 33-35 fractions) between April 2009 and September 2010 were enrolled in the study. Patients underwent CT scans every week during their course of treatment. We analyzed the CT data in the radiation treatment planning system and measured changes of tumor, organ at risk, and neck volume. Gross tumor volume (GTV) was rapidly reduced by 28% of the original volume on average in the first 3 weeks. The right and left submandibular glands volume decreased to 70% and 63% of their initial volumes on average, respectively. The volume of the neck in the radiation fields decreased to 89% of its initial volume on average by the sixth week mainly caused by body weight loss due to acute radiation morbidity. Considerable anatomical change in the radiation filed that will affect dose distribution of the target and organ at risk was observed during radiation therapy for head and neck cancer. (Keyword) adaptive strategy / chemoradiotherapy / head and neck cancer (Tokushima University Institutional Repository) ● Metadata: 106041 (Link to Publication Site) ● Publication site (DOI): 10.2152/jmi.60.46 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 23614911 ● Search Scopus @ Elsevier (PMID): 23614911 ● Search Scopus @ Elsevier (DOI): 10.2152/jmi.60.46 (Tokushima University Institutional Repository: 106041, DOI: 10.2152/jmi.60.46, PubMed: 23614911)
37.	竹永枝里子, 中口裕二, 丸山雅人, 末永望, 筧清孝, 甲斐祐大, 河野友宏, Motoharu Sasaki and 橋田昌宏 : Comparison of Various Image Guided Radiation Therapy Systems; Image-guided Localization Accuracy and Patient Throughput, Japanese Journal of Radiological Technology, Vol.68, No.10, 1327-1332, 2012. (Summary) In this study, we evaluated various image guided radiation therapy (IGRT) systems regarding accuracy and patient throughput for conventional radiation therapy. We compared between 2D-2D match (the collation by 2 X-rays directions), cone beam computed tomography (CBCT), and ExacTrac X-Ray system using phantom for CLINAC iX and Synergy. All systems were able to correct within almost 1 mm. ExacTrac X-Ray system showed in particular a high accuracy. As for patient throughput, ExacTrac X-Ray system was the fastest system and 2D-2D match for Synergy was the slowest. All systems have enough ability with regard to accuracy and patient throughput on clinical use. ExacTrac X-Ray system showed superiority with accuracy and throughput, but it is important to note that we have to choose the IGRT technique depending on the treatment site, the purpose, and the patient's state. (Keyword) image guided radiation therapy (IGRT) / accuracy / throughput / cone beam computed tomography(CBCT) / precision (Link to Publication Site) ● Publication site (DOI): 10.6009/jjrt.2012_JSRT_68.10.1327 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 23089834 ● Summary page in Scopus @ Elsevier: 2-s2.0-84880396201 (DOI: 10.6009/jjrt.2012_JSRT_68.10.1327, PubMed: 23089834, Elsevier: Scopus)
38.	Motoharu Sasaki, Masahide Tominaga, Hitoshi Ikushima, 岸太郎, 川下徹也, Yasuo Hara, 福永有希子, Masashi Kimura, Yasufumi Shitakubo, Satoru Takashi and Masataka Oita : Impact of multileaf collimator leaf positioning accuracy on intensity modulated radiation therapy., Japanese Journal of Radiological Technology, Vol.67, No.5, 497-506, 2011. (Summary) In multileaf collimator (MLC)-based intensity modulated radiation therapy (IMRT), the dose is influenced by the uncertainty of MLC driving control. In this study, we examined the influence of MLC driving control accuracy on dose evaluation (gamma analysis) by evaluating 60-day MLC driving control accuracy (stationary positioning accuracy and positioning reproducibility) once a week as well as measuring IMRT dose distribution. The MLC positioning accuracy accompanied variation over time and tended to expand by 0.1 to 0.15 mm in one week and about 1 mm in 60 days. In terms of reproducibility, errors were within 0.2 mm for more than 95%. For prostate IMRT, when MLC stationary positioning accuracy was around 1 mm, no significant difference was observed in the pass rate in gamma analysis. Therefore, the results suggest that regular maintenance by setting a permissible value determined by the MLC positioning accuracy test can be an effective indicator in the future for maintaining the safety of IMRT. (Keyword) multileaf collimator / positioning error / intensity modulated radiation therapy / dose distribution (Link to Publication Site) ● Publication site (DOI): 10.6009/jjrt.67.497 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 21666373 ● CiNii @ National Institute of Informatics (CRID): 1390282681337851008 ● Summary page in Scopus @ Elsevier: 2-s2.0-84863934579 (DOI: 10.6009/jjrt.67.497, PubMed: 21666373, CiNii: 1390282681337851008, Elsevier: Scopus)
39.	Motoharu Sasaki, Masahide Tominaga, Hitoshi Ikushima, 岸太郎, 川下徹也, 原康男, 福永有希子, Kenji Yamada, Masataka Oita and Hiromu Nishitani : 強度変調放射線治療におけるradiographic filmと radiochromic filmの比較評価, Japanese Journal of Radiological Technology, Vol.66, No.5, 525-534, 2010. (Summary) Purpose: Radiographic film is generally used for inspection of dose distribution in intensity modulated radiation therapy (IMRT) at many institutions. However, the distribution of filmless systems can be expected to be used increasingly in the future. Therefore, we confirmed the utility of radiochromic film by comparing it with radiographic film that does not need an automatic processor. Result: Difference in does measured by radiographic film and radiochromic film tended to increase in the low does area, but it was limited in a range of 1.5%. Conclusion: When the dose distribution was verified in a highly accurate radiation therapy such as IMRT, the results suggested that radiochromic film can be useful in addition to radiographic film. (Keyword) radiochromic film / radiochromic film / dose distribution / dose distribution / intensity-modulated radiation therapy / intensity-modulated radiation therapy / radiographic film / radiographic film (Link to Publication Site) ● Publication site (DOI): 10.6009/jjrt.66.525 (Link to Search Site for Scientific Articles) ● CiNii @ National Institute of Informatics (CRID): 1390001206361620480 ● Summary page in Scopus @ Elsevier: 2-s2.0-77955931427 (DOI: 10.6009/jjrt.66.525, CiNii: 1390001206361620480, Elsevier: Scopus)
40.	Y Kishida, Hitoshi Ikushima, Motoharu Sasaki, Y Hara, M Oita and Hiromu Nishitani : Use of a diagnostic positron emission tomography-computed tomography system for planning radiotherapy positioning: distortion of the tabletop., Japanese Journal of Radiology, Vol.28, No.2, 143-148, 2010. (Summary) The aim of this study was to evaluate distortion of the tabletop in a diagnostic positron emission tomography-computed tomography (PET-CT) system to determine its suitability for planning radiotherapy positioning. Distortion of the tabletop was compared among PET-CT, lineac CT, and CT simulator systems. A phantom or angiography catheter was fixed to the tabletop and imaged after iron plate weight loading. The acquired images were analyzed using radiotherapy planning software. Distortion of the tabletop was measured based on the displayed coordinates. Sinking represented the greatest distortion of the tabletop in all systems. Using the same baseline, the maximum sinking were -0.4, -0.2, and +0.4 cm, respectively. The distortion of the tabletop in the PET-CT system was more similar to that in the lineac CT than in the CT simulator system. Distortion of the tabletop in a diagnostic PET-CT system may be within the acceptable range to allow its use for planning radiotherapy positioning. (Keyword) Image Processing, Computer-Assisted / Perceptual Distortion / Phantoms, Imaging / Positron-Emission Tomography / Radiotherapy Planning, Computer-Assisted / Tomography, X-Ray Computed (Link to Publication Site) ● Publication site (DOI): 10.1007/s11604-009-0398-0 (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 20182849 ● Search Scopus @ Elsevier (PMID): 20182849 ● Search Scopus @ Elsevier (DOI): 10.1007/s11604-009-0398-0 (DOI: 10.1007/s11604-009-0398-0, PubMed: 20182849)
41.	Shunsuke Furutani, Hitoshi Ikushima, Kyosuke Osaki, Masataka Oita, Motoharu Sasaki, Yoshihiro Takegawa and Hiromu Nishitani : Quality Assurance of I-125 Seed Permanent Implant Therapy Using a Self-color Developing Reflection-type Dosimetry Sheet Film, Radiation Medicine, Vol.23, No.7, 474-477, 2005. (Summary) We evaluated a self-color developing sheet-type film for the detection of dead seeds in I-125 permanent implant therapy for prostate cancer. As a preliminary study, we irradiated X-rays to a self-developing reflection-type sheet film and created a relational curve between absorbed dose and film density. I-125 seeds were placed on a film and the approximate absorbed dose of I-125 was calculated from the relational curve of X-rays. A cartridge in which a dead seed was loaded among 10 I-125 seeds was placed on the film and the detectability of the dead seed was evaluated. Using the relational curve of X-rays, it was possible to measure the approximate absorbed dose of I-125 seeds and to easily detect a dead seed at a glance. Using sterilized film, it was possible to detect a dead seed. The self-developing film method is feasible for the detection of a dead seed in a cartridge without re-sterilization of seeds. (Keyword) I-125 seed / dead seed / quality assurance (Link to Search Site for Scientific Articles) ● PubMed @ National Institutes of Health, US National Library of Medicine (PMID): 16485537 ● Search Scopus @ Elsevier (PMID): 16485537 (PubMed: 16485537)

Academic Paper (Unrefereed Paper):

1.	Motoharu Sasaki : 透過型積算線量計(In vivo Dosimetry)はどこまでわかるのか, 放射線治療部会雑誌, Vol.37, No.2, 39-41, 2023.
2.	Motoharu Sasaki : 放射線治療計画QAソフトウェア利活用, 放射線治療部会雑誌, Vol.34, No.2, 47-48, 2020.
3.	Motoharu Sasaki : DIRの受入試験，コミッショニング，QA, 放射線治療部会雑誌, Vol.32, No.2, 30-32, 2018. (Keyword) Deformable Image Registration (Tokushima University Institutional Repository) ● Metadata: 114006 (Link to Search Site for Scientific Articles) ● CiNii @ National Institute of Informatics (CRID): 1050865122806263680 (Tokushima University Institutional Repository: 114006, CiNii: 1050865122806263680)
4.	Motoharu Sasaki : 市販Deformable Image Registration ソフトウェアの臨床における問題点, 放射線治療部会雑誌, Vol.28, No.2, 27-33, 2014. (Keyword) Deformable Image Registration (Link to Publication Site) ● Publication site (DOI): 10.18973/curejsrt.28.2_27 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.18973/curejsrt.28.2_27 (DOI: 10.18973/curejsrt.28.2_27)

Review, Commentary:

1.	Motoharu Sasaki : 頭頸部および婦人科領域におけるVelocity の臨床利用, 月刊インナービジョン2022年7月号, Vol.37, No.7, 84-85, Jul. 2022.
2.	Hirofumi Honda, Masahide Tominaga, Motoharu Sasaki, Masataka Oita and Yoshihiro Uto : 放射線治療における透過型検出器の現状と展望, Radiation Biology Research Communications, Vol.56, No.3, 245-259, Sep. 2021. (Keyword) 透過型検出器 / 生体内線量測定 / 強度変調回転放射線治療 (Link to Search Site for Scientific Articles) ● CiNii @ National Institute of Informatics (CRID): 1520853835303095424 (CiNii: 1520853835303095424)
3.	Motoharu Sasaki : 放射線治療分野の自動輪郭抽出技術, Japanese Journal of Radiological Technology, Vol.77, No.6, 591-595, Jun. 2021. (Link to Publication Site) ● Publication site (DOI): 10.6009/jjrt.2021_JSRT_77.6.591 (Link to Search Site for Scientific Articles) ● CiNii @ National Institute of Informatics (CRID): 1390288448342486528 ● Search Scopus @ Elsevier (DOI): 10.6009/jjrt.2021_JSRT_77.6.591 (DOI: 10.6009/jjrt.2021_JSRT_77.6.591, CiNii: 1390288448342486528)
4.	Motoharu Sasaki : VRを用いた実習について, 徳島大学医学部保健学科だより, Vol.20, 3-4, Jun. 2020.
5.	Masahide Tominaga, 下窪康史, Hitoshi Ikushima, 本田道隆 and Motoharu Sasaki : Cone-beam CT 画像を用いた小線源治療計画への応用, 画像通信, Vol.77, No.2, 55-61, Oct. 2016.

Proceeding of International Conference:

1.	Kanon Monda, Hitoshi Ikushima, Yuki Matsumoto, Motoharu Sasaki, Micihito Shimokawa and Akihiro Haga : Proposal of a differential diagnostic index for recurrent brain metastasis or radiation-induced brain necrosis by radiomics analysis using C-11 methionine PET, The 3rd ICRPT, Apr. 2024.
2.	Kanon Monda, Hitoshi Ikushima, Yuki Matsumoto, Motoharu Sasaki, Michihito Shimokawa and Akihiro Haga : The differential diagnosis of recurrent brain metastasis or radiationinduced brain necrosis by radiomics analysis using C-11 methionine positron emission tomography, ECR 2024, Feb. 2024.
3.	Kanon Monda, Hitoshi Ikushima, Yuki Matsumoto, Motoharu Sasaki, Michihito Shimokawa and Masafumi Harada : Proposal of a rigid registration method for contrast-enhanced MRI and C-11 methionine PET using iterative closest point and convolutional Neural Network, ISMRM JPC2023, The 8th Annual Scientific Meeting of the ISMRM Japanese Chapter, Sep. 2023.
4.	Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga : Development of a B1 correction method without additional scanning VFA T1 map., European Congress of Radiology, Wien, Jul. 2022.
5.	Motoharu Sasaki, Nakaguchi Yuji, Shoji Ueda, ENDO Yuto, KAJINO Akimi, SATOH Daisuke and Hitoshi Ikushima : Predicting the complexity of head and neck VMAT planning using a TPS quality assurance software, 2022 AAPM 64th Annual Meeting, Jul. 2022.
6.	Nagomi Fukuda, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga : Development of self-calibrating B1 correction for three-dimensional variable flip angle T1 mapping, Joint Annual Meeting ISMRM-ESMRMB & ISMRT 31st Annual Meeting, London, May 2022.
7.	Fukuda Nagomi, Yuki Kanazawa, Hiroaki Hayashi, Yuki Matsumoto, Masafumi Harada, Motoharu Sasaki and Akihiro Haga : Variable flip angle T1 mapping without acquiring data for B1 correction, Joint International Conference on Radiological Physics and Technology, Yokohama, Apr. 2022.
8.	Motoharu Sasaki, Hitoshi Ikushima, KOHBUCHI Satoshi, KUWAHARA Kenmei, KAJINO Akimi, SATOH Daisuke, Sugimoto Wataru and Masataka Oita : Prediction of Dose Discrepancies Using Differences in Plan Normalization Values of Head-And-Neck VMAT Plans, 2021 AAPM Virtual 63rd Annual Meeting, Jul. 2021.
9.	Motoharu Sasaki, Nakaguchi Yuji, Takeshi Kamomae, KOHBUCHI Satoshi, KUWAHARA Kenmei, KAJINO Akimi, SATOH Daisuke and Hitoshi Ikushima : Effect of VMAT Improvement Before and After Referring to Radiation Therapy Planning QA Software, 2021 AAPM Virtual 63rd Annual Meeting, Jul. 2021.
10.	Hasegawa Yu, Akihiro Haga, Sakata Dousatsu, Yuki Kanazawa, Masahide Tominaga, Motoharu Sasaki, Imae T. and Nakagawa Keiichi : Estimation of X-ray energy spectrum for CT scannerfrom percentage depth dose measurement, 2020 JOINT AAPM COMP meeting, Jul. 2020.
11.	Honda Hirofumi, Masahide Tominaga, Motoharu Sasaki, Yoshihiro Uto, Masataka Oita, Hamamoto Yasushi, Mochizuki Teruhito, Kido Teruhito, Ishii Y, Yamamoto Ryuji and Omoto K : Detectability of MLC Stop Position Error During Treatment by Gantry-Mounted Transmission Detector, AAPM 62th annual meeting (WEB), Jul. 2020.
12.	Motoharu Sasaki, Hitoshi Ikushima, Kenta Kitagawa, Yohsuke Kanoh, Masahide Tominaga, Hirofumi Honda, Wataru Sugimoto and Masataka Oita : Impact of Changes in Body Shapes on Radiation Therapy Dose Distribution After Uterine Cervical Cancer Surgery, AAPM 62th annual meeting (WEB), Jul. 2020.
13.	Masataka Oita, M Udaka, H Aoyama, Motoharu Sasaki, Masahide Tominaga and Yoshihiro Uto : Immunological aspects of Improved Tumor and Normal Tissue Responses Using Biophysical modelling, AAPM 60th Annual Meeting, Jul. 2018.
14.	Hirokazu Miyoshi, Fumio Kida, Yoshiyasu Kawase, Kenji Yamada, Motoharu Sasaki, Hidenori Shoji and Hitoshi Hase : Emission image of X-ray-irradiated CR-39 stick doped with methylviologen-encapsulated silica nanocapsules using LED light, The Ninth International Symposium on Radiation Safety and Detection Technology (ISORD-9), 36, Nagoya, Jul. 2017.
15.	Honda Hirofumi, Kubo Kei, Yamamoto Ryuuji, Ishii Yoshiaki, Kanzaki Hiromitsu, Hmamoto Yasushi, 望月輝一, Masataka Oita, Motoharu Sasaki, Masahide Tominaga and Yoshihiro Uto : Feasibility of dose delivery error detection by a transmission detector for patient-specific QA, Radiotherapy and Oncology, Vol.123, No.1, S787-S788, May 2017. (Link to Publication Site) ● Publication site (DOI): 10.1016/S0167-8140(17)31909-6 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/S0167-8140(17)31909-6 (DOI: 10.1016/S0167-8140(17)31909-6)
16.	Kadoya Noriyuki, Nakajima Yujiro, Saito Masahide, MIyabe Yuki, Kurooka Masahiko, Satoshi Kito, Motoharu Sasaki, Yukio Fujita, Arai Kazuhiro, Tani Kensuke, Yagi Masashi, Wakita Akihisa, Tohyama Naoki and Jingu Keiichi : Multi-Institutional Validation Study of Commercially Available Deformable Image Registration Software for Thoracic Images, AAPM 58th Annual Meeting, Jul. 2016.
17.	Motoharu Sasaki, Hitoshi Ikushima, Masahide Tominaga, 川下徹也, Takeshi Kamomae, Ryota Bandoh, Kanako Sakuragawa and Masataka Oita : Dose impact of rectal gas on prostate VMAT, AAPM 58th Annual Meeting, Jul. 2016.
18.	Masataka Oita, Nakata K., Motoharu Sasaki, Masahide Tominaga, Hideki Aoyama, Hirofumi Honda and Yoshihiro Uto : Does the Biophysical Modeling for Immunological Aspects in Radiotherapy Precisely Predict Tumor and Normal Tissue Responses?, AAPM 58th Annual Meeting, Jun. 2016.
19.	Masataka Oita, Hideki Aoyama, Motoharu Sasaki, Masahide Tominaga, Hirofumi Honda and Yoshihiro Uto : Application of biophysical modelling for normal tissue response with immunological aspects in radiotherapy, Radiotherapy and Oncology, Vol.118, No.S1, S79-S80, Feb. 2016. (Link to Publication Site) ● Publication site (DOI): 10.1016/s0167-8140(16)30162-1 (Link to Search Site for Scientific Articles) ● Search Scopus @ Elsevier (DOI): 10.1016/s0167-8140(16)30162-1 (DOI: 10.1016/s0167-8140(16)30162-1)
20.	Masataka Oita, Yoshihiro Uto, Hitoshi Hori, Masahide Tominaga and Motoharu Sasaki : Effects of Uncertainties of Radiation Sensitivity of Biological Modelling for Treatment Planning, AAPM 56th Annual Meeting, Jun. 2014.
21.	Masataka Oita, Motoharu Sasaki, Yamada Masao, Aoyama Hideki and Tateoka Kunihiko : A Comprehensive QA Method of MLC Accuracies for Dynamic IMRT, AAPM 53th Annual Meeting, Jun. 2011.

Proceeding of Domestic Conference:

1.	岸本悠斗, Motoharu Sasaki, Takashi Kawanaka, Akiko Kubo, Chisato Tonoiso, Takaharu Kudoh and Hitoshi Ikushima : F-18 FDG-PETによる子宮頸癌放射線治療後の予後予測, 日本放射線腫瘍学会第37回学術大会, Nov. 2024.
2.	門田香音, Yuki Matsumoto, Hitoshi Ikushima, Motoharu Sasaki and Akihiro Haga : 11C-Methionine PETラジオミクスによる脳腫瘍の再発と壊死の鑑別, 日本放射線腫瘍学会第37回学術大会, Nov. 2024.
3.	Motoharu Sasaki : IGRT教育における位置照合と提案能力の養成:課題と解決策, 第52回日本放射線技術学会秋季学術大会, Nov. 2024.
4.	YOSHIDA Masahiro, Motoharu Sasaki, 中口裕二, Kanako Sakuragawa and Hitoshi Ikushima : 治療計画QAソフトウェアによる前立腺癌VMAT治療計画の改善効果と線量検証への影響, 第20回中四国放射線医療技術フォーラム, Oct. 2024.
5.	Chisato Tonoiso, Hitoshi Ikushima, Akihiro Haga, Motoharu Sasaki, Takashi Kawanaka, Akiko Kubo, Masato Nishimura and Akiko Abe : 子宮頸癌リンパ節転移の術前予測におけるMRIレディオミクス解析の有用性, 第66回日本婦人科腫瘍学会学術講演会, Jul. 2024.
6.	Kanon Monda, Yuki Matsumoto, Motoharu Sasaki, Michihito Shimokawa, Akihiro Haga and Hitoshi Ikushima : 転移性脳腫瘍に対する放射線治療後の脳壊死と再発を鑑別する11C-Mthionine PET Radiomicsモデルの開発, 37, Mar. 2024.
7.	Chisato Tonoiso, 梶野晃未, Motoharu Sasaki, Akiko Kubo, Takashi Kawanaka, Hitoshi Ikushima and Masafumi Harada : 放射線治療効果を検出するMRI Radiomics特徴量の探索, 第139回日本医学放射線学会中国・四国地方会, Dec. 2023.
8.	下川通仁, Motoharu Sasaki, Akihiro Haga and Hitoshi Ikushima : 脳転移放射線治療後の壊死と再発の鑑別におけるMTI Radiomicsの有用性, 日本放射線腫瘍学会第36回学術大会, Nov. 2023.
9.	SAWADA Sohma, Motoharu Sasaki, SHIBUYA Kohki, 中口裕二 and Hitoshi Ikushima : 前立腺超寡分割照射時代における知識ベース治療計画システム構築の二次利用促進, 第19回中四国放射線医療技術フォーラム, Nov. 2023.
10.	SHIBUYA Kohki, Motoharu Sasaki, SAWADA Sohma, 中口裕二 and Hitoshi Ikushima : 知識ベース治療計画のモデル構築における標準化に向けて, 第19回中四国放射線医療技術フォーラム, Nov. 2023.
11.	ENDO Yuto, Motoharu Sasaki, Hitoshi Ikushima, 中口裕二 and Masafumi Harada : 知識ベース治療計画のモデル構築の効率的な作成に向けた取り組み, 第126回日本医学物理学会学術集会, Sep. 2023.
12.	ENDO Yuto, Motoharu Sasaki, Hitoshi Ikushima, 中口裕二 and Masafumi Harada : 2種類のLINACによる前立腺VMATにおけるOARの線量低減の可能性, 第126回日本医学物理学会学術集会, Sep. 2023.
13.	Kanon Monda, Hitoshi Ikushima, Yuki Matsumoto, Motoharu Sasaki, Michihito Shimokawa and Masafumi Harada : Proposal of a rigid transformation method for contrast-enhanced MRI and C-11 methionine PET using iterative closest point and convolutional Neural Network, ISMRM Japanese Chapter, Sep. 2023.
14.	竹内秀真, Motoharu Sasaki, 山下恭, Takashi Kawanaka, Akiko Kubo, Chisato Tonoiso, 下窪康史, 櫻川加奈子 and Hitoshi Ikushima : Deformable image registrationを用いた子宮頸がん放射線治療の合算線量評価, 日本放射線腫瘍学会小線源治療部会第25回学術大会, May 2023.
15.	Motoharu Sasaki : 透過型積算線量計(In vivo Dosimetry)はどこまでわかるのか, 第79回日本放射線技術学会総会学術大会, Apr. 2023.
16.	Motoharu Sasaki, Nagi Masumoto, 中口裕二, Shota Abe, KAJINO Akimi, SATOH Daisuke, ENDO Yuto, 都築明 and Hitoshi Ikushima : 知識ベース治療計画および治療計画QAソフトウェアを用いた計画者のばらつき, 第36回高精度放射線外部照射部会学術大会, Mar. 2023.
17.	KAJINO Akimi, Hitoshi Ikushima, Motoharu Sasaki, Tamaki Otani, Michiko Yamashita and Akihiro Haga : 放射線治療効果を早期に検出できるRadiomics特徴量の探索, 日本放射線腫瘍学会第35回学術大会, Nov. 2022.
18.	Motoharu Sasaki : PlanIQ Feasibilityの治療計画改善と有効活用, 日本放射線腫瘍学会第35回学術大会, Nov. 2022.
19.	YUTO Sadamasu, Motoharu Sasaki, KAJINO Akimi, Akimi Kajino, Daisuke Satoh, SHUMA Takeuchi, MICHIHITO Shimokawa, ENDO Yuto and Hitoshi Ikushima : 中咽頭IGRTにおけるCBCTの撮影回数の低減の可能性, 第18回中四国放射線医療技術フォーラム, Oct. 2022.
20.	Kanako Sakuragawa, Motoharu Sasaki, 横石道寛, Akiko Kubo, 川下徹也 and Masafumi Amano : 全乳房照射時のセットアップエラーが線量分布に及ぼす影響に関する検討, 第18回中四国放射線医療技術フォーラム, Oct. 2022.
21.	Shota Abe, Motoharu Sasaki, 中口裕二, Nagi Masumoto and Hitoshi Ikushima : 頭頚部VMATにおける金属アーチファクト対策の新規提案, 第18回中四国放射線医療技術フォーラム, Oct. 2022.
22.	Nagi Masumoto, Motoharu Sasaki, 中口裕二, Akimi Kajino, Daisuke Satoh, Yuto Endo, Shota Abe and Hitoshi Ikushima : 知識ベース治療計画および治療計画QAソフトウェアを用いた計画者の変動, 第18回中四国放射線医療技術フォーラム, Oct. 2022.
23.	Motoharu Sasaki, Nagi Masumoto, 中口裕二, Shota Abe and Hitoshi Ikushima : 治療計画QAソフトウェアを利用した知識ベース治療計画データベース作成の有用性, 第50回日本放射線技術学会秋季学術大会, Oct. 2022.
24.	SATOH Daisuke, Motoharu Sasaki, 中口裕二, KUWAHARA Kemmei, KAJINO Akimi and Hitoshi Ikushima : 治療計画品質保証ソフトウェアが非小細胞Ⅲ期肺癌の正常臓器に対する線量低減へ与える影響, 第35回高精度放射線外部照射部会学術大会(WEB開催), Mar. 2022.
25.	Motoharu Sasaki, 中口裕二, ENDO Yuto, KUWAHARA Kemmei, KAJINO Akimi, SATOH Daisuke and Hitoshi Ikushima : 実現可能DVH参照後の汎用加速器とO-ring加速器を用いたリスク臓器への線量低減の可能性, 第35回高精度放射線外部照射部会学術大会(WEB開催), Mar. 2022.
26.	翔平大喜多, 直井上, Yuki Ueno, Kenji Yamada, Kanako Sakuragawa, Ryosuke Kasai, 陸登清水, Motoharu Sasaki and Masafumi Amano : 撮影条件の違いによる経時的差分処理胸部X線画像の評価, 第17回中四国放射線医療技術フォーラム(WEB開催), Dec. 2021.
27.	Yuki Ueno, Kenji Yamada, 直井上, 翔平大喜多, Kanako Sakuragawa, Ryosuke Kasai, 陸登清水, Motoharu Sasaki and Masafumi Amano : 画像処理の違いによる経時差分処理胸部X線画像の評価, 第17回中国四国放射線医療技術フォーラム(WEB開催), Dec. 2021.
28.	直井上, Kenji Yamada, Kanako Sakuragawa, Ryosuke Kasai, 陸登清水, Motoharu Sasaki and Masafumi Amano : ポジショニングの違いによる経時差分処理胸部X線画像の評価, 第17回中国四国放射線医療技術フォーラム(WEB開催), Dec. 2021.
29.	Kanako Sakuragawa, Motoharu Sasaki, 横石道寛, Ryosuke Kasai, 川下徹也 and Masafumi Amano : Exactracシステムにおける画像照合精度に及ぼすDRR画像パラメータの違いに関する検討, 第17回中国四国放射線医療技術フォーラム(WEB開催), Dec. 2021.
30.	Motoharu Sasaki, Kanako Sakuragawa, KAJINO Akimi, SATOH Daisuke and Hitoshi Ikushima : 線量計算アルゴリズムの違いによる前立腺VMATの線量分布への直腸ガスの影響, 第17回中四国放射線医療技術フォーラム(WEB開催), Dec. 2021.
31.	KOHBUCHI Satoshi, 高倉亨, Motoharu Sasaki, 田嶋綾乃, 上原愛樹, 廣瀬知世, 木村仁人 and Hitoshi Ikushima : 電離箱線量計の印加電圧によるイオン再結合補正係数の変化, 第65回日本放射線技術学会近畿支部学術大会, Oct. 2021.
32.	Hitoshi Ikushima, 加納洋介, Motoharu Sasaki and Akihiro Haga : 深層学習を用いた子宮頸がん肉眼的腫瘍体積自動抽出, 第63回日本婦人科腫瘍学会, Jul. 2021.
33.	Hirofumi Honda, Masahide Tominaga, Motoharu Sasaki, Masataka Oita, 石井香明, 山本竜次, 大元謙二, 上津孝太郎, 城戸輝仁 and Yoshihiro Uto : ガントリー搭載型検出器を用いたMLC位置エラーのγ解析の検討, 第34回高精度放射線外部照射部会学術大会(WEB開催), Apr. 2021.
34.	Motoharu Sasaki, 中口裕二, Yuto Endoh, Shoji Ueda, Yohsuke Kanoh, Kenta Kitagawa and Hitoshi Ikushima : 放射線治療計画QAソフトウェアの参照による前立腺VMAT計画の改善効果, 第34回高精度放射線外部照射部会学術大会(WEB開催), Apr. 2021.
35.	Yohsuke Kanoh, Hitoshi Ikushima, Akihiro Haga and Motoharu Sasaki : 人工知能を用いた子宮頸がんの自動輪郭抽出, 第34回高精度放射線外部照射部会学術大会(WEB開催), Apr. 2021.
36.	Takaharu Kudoh, Akihiro Haga, Motoharu Sasaki, Chisato Tonoiso, Akiko Kubo, Takashi Kawanaka, Shunsuke Furutani and Hitoshi Ikushima : Radiomicsの手法を用いたPETによる舌癌頸部リンパ節転移の予測, 日本放射線腫瘍学会第33回学術大会, Oct. 2020.
37.	Motoharu Sasaki : 放射線治療計画QAソフトウェアの利活用, 第76回日本放射線技術学会総会学術大会(WEB開催), May 2020.
38.	Kenta Kitagawa, Motoharu Sasaki, Yohsuke Kanoh and Hitoshi Ikushima : 頭頸部VMATにおける義歯金属アーチファクト領域の物質変換体積の違いが線量分布に及ぼす影響, 第33回高精度放射線外部照射部会学術大会(WEB開催), May 2020.
39.	Motoharu Sasaki, 中口裕二, Kenta Kitagawa and Hitoshi Ikushima : 治療計画QAソフトウェアを用いた前立腺IMRTおよびVMAT計画のレトロスペクティブ解析, 第33回高精度放射線外部照射部会学術大会(WEB開催), May 2020.
40.	Motoharu Sasaki, Kenta Kitagawa, Yohsuke Kanoh, Masahide Tominaga and Hitoshi Ikushima : 体輪郭の変化が子宮頸がん術後照射VMATの線量分布へ及ぼす影響, 第33回高精度放射線外部照射部会学術大会(WEB開催), May 2020.
41.	Yu Hasegawa, Akihiro Haga, Dousatsu Sakata, Yuki Kanazawa, Masahide Tominaga, Motoharu Sasaki, Toshikazu Imae and Keiichi Nakagawa : Estimation of X-ray energy spectrum for CT scanner from percentage depth dose measurement, 第119回⽇本医学物理学会学術⼤会WEB開催, May 2020.
42.	Hirofumi Honda, Masahide Tominaga, Motoharu Sasaki, Masataka Oita, 石井香明, 高田紀子, 鶴岡慎太郎, 石川浩史, 濱本泰, 望月輝一 and Yoshihiro Uto : ガントリー搭載型検出器を用いたMLC解析の検討, 第32回日本放射線腫瘍学会学術大会, Nov. 2019.
43.	今江禄一, 渡邉雄一, 辰己大作, 藤本隆広, 佐々木誠, Motoharu Sasaki, 中口裕二 and 阿部修 : 高精度放射線治療における包括的かつ実用的な投与線量保証法に関する研究班, 第47回日本放射線技術学会秋季学術大会, Oct. 2019.
44.	Motoharu Sasaki, Masahide Tominaga, Kanako Sakuragawa, 横石道寛, Kyohei Ishikawa, Kenta Kitagawa, Yohsuke Kanoh and Hitoshi Ikushima : 3次元線量検証システムを用いた長期安定性の調査, 第47回日本放射線技術学会秋季学術大会, Oct. 2019.
45.	Yukari Nagayasu, Masahide Tominaga, 安友基勝, Takeshi Kojima, Motoharu Sasaki and Kenji Yamada : Edge Spread Functionの最適化によるMTF測定精度向上の試み, 第15回中国四国放射線医療技術フォーラムCSFRT2019, Sep. 2019.
46.	永安結花里, Masahide Tominaga, 古田琢哉 and Motoharu Sasaki : モンテカルロシミュレーションを用いた診断用X線の放射線計測における後方散乱線の影響解析, 第15回中国四国放射線医療技術フォーラムCSFRT2019, Sep. 2019.
47.	Masahide Tominaga, 山内奈緒, Akihiro Haga, Motoharu Sasaki and Takeshi Kojima : 治療計画用CT画像を用いた非小細胞肺癌の病理分類, 第15回中国四国放射線医療技術フォーラムCSFRT2019, Sep. 2019.
48.	Motoharu Sasaki, Masahide Tominaga, 川下徹也, 横石道寛, Kanako Sakuragawa and Hitoshi Ikushima : VMATにおけるplan normalization valueが線量検証へ及ぼす影響, 第32回高精度放射線外部照射部会学術大会, Mar. 2019. (Keyword) VMAT / quality assurance / head and neck / plan normalization value
49.	鹿重俊哉, Motoharu Sasaki, Kenji Yamada, Kanako Sakuragawa and Ryosuke Kasai : 畳み込み自己符号化器を用いた臨床CT画像におけるノイズ低減, 第46回日本放射線技術学会秋季学術大会, Oct. 2018.
50.	Masahide Tominaga, Motoharu Sasaki, Motokatsu Yasutomo, Kenji Yamada, Takeshi Kojima, Akihiro Haga, Hitoshi Ikushima and 角谷倫之 : Digital Phantomを用いたImage Registrationソフトウェアの性能評価, 第31回高精度放射線外部照射部会学術大会, Feb. 2018.
51.	Ryosuke Fukura, 川下徹也, Motoharu Sasaki, Shota Azane and Masahide Tominaga : 2種類の3次元水ファントムを用いたスキャンデータの比較検討, 第13回中四国放射線医療技術フォーラム(CSFRT2017 ), Dec. 2017.
52.	Ryosuke Kasai, Kenji Yamada, Motoharu Sasaki, Kanako Sakuragawa, 清水陸登, Tadashi Inoue, Toshiya Kanoshige and 湯浅将生 : CT画像におけるDeep Learningと局所特徴量による画像分類精度の検討, 第13回中四国放射線医療技術フォーラム CSFRT, Dec. 2017.
53.	Ryosuke Kasai, Kenji Yamada, Motoharu Sasaki, Kanako Sakuragawa, 清水陸登, Tadashi Inoue, Toshiya Kanoshige and 湯浅将生 : Convolutional Neural Networkを用いたディープラーニングによるCT画像認識精度の検討, 第45回日本放射線技術学会秋季学術大会, Nov. 2017.
54.	Kenji Yamada, Motokatsu Yasutomo, Motoharu Sasaki, Kanako Sakuragawa, Masahide Tominaga, Ryosuke Kasai, 井上直 and 鹿重俊哉 : 確率密度関数を用いたエッジ法におけるMTF測定時のLSF取得法, 第45回日本放射線技術学会秋季学術大会, Oct. 2017.
55.	Kanako Sakuragawa, Motokatsu Yasutomo, Kenji Yamada, Motoharu Sasaki, Masahide Tominaga, Ryosuke Kasai, 井上直 and 鹿重俊哉 : ディジタル乳房撮影装置の焦点のボケ関数から導かれる焦点サイズの推定法, 第45回日本放射線技術学会秋季学術大会, Oct. 2017.
56.	Toshiya Kanoshige, Ryosuke Kasai, Kenji Yamada, Motoharu Sasaki, Kanako Sakuragawa, 清水陸登, Tadashi Inoue and 湯浅将生 : ハミルトニアンモンテカルロ法を用いたCT金属アーチファクト定量評価, 第45回日本放射線技術学会秋季学術大会, Oct. 2017.
57.	Masahide Tominaga, Motoharu Sasaki, 安友基勝, Takeshi Kojima, Kenji Yamada, Hitoshi Ikushima and 角谷倫之 : 市販Image registrationソフトウェアの評価用Digital Phantomの開発, 日本放射線腫瘍学会第30回高精度外部放射部会学術大会, Mar. 2017.
58.	細谷未来, Motoharu Sasaki, Shunsuke Furutani, Takashi Kawanaka, Akiko Kubo, Takaharu Kudoh and Hitoshi Ikushima : Dosimetric comparison of VMAT and 3DCRT in patients with cervical cancer, The 29th Annual Meeting of the Japanese Society for Radiation, Nov. 2016.
59.	Kanako Sakuragawa, 川下徹也, Motoharu Sasaki, Shota Azane, 川田直伸 and 杉本渉 : VMAT線量検証におけるpinpoint線量計と3次元線量計の結果の比較, 第12回中四国放射線医療技術フォーラム, Nov. 2016.
60.	Ryosuke Kasai, 清水陸登, Kenji Yamada, Toshiya Kanoshige, Motoharu Sasaki, Tadashi Inoue, Kanako Sakuragawa and 川田直伸 : 再構成FOVとCTストリークアーチファクト低減処理の極値統計学を用いた定量評価, 第12回中四国放射線医療技術フォーラム CSFRT, Nov. 2016.
61.	Tomohiro Sagawa, Masahide Tominaga, 田中翼, Motoharu Sasaki, 本田道隆 and Hitoshi Ikushima : Computed Radiography を用いた Multi-Leaf collimator の精度管理, 医用画像情報学会(MII), Oct. 2016.
62.	下窪康史, Masahide Tominaga, Ryosuke Kasai, Motoharu Sasaki, 田中翼, 佐川友啓, 本田道隆 and Hitoshi Ikushima : 子宮頸癌に対する腔内小線源治療計画時におけるCBCT画像の画質評価, 医用画像情報学会(MII), Oct. 2016.
63.	松本晃範, Masahide Tominaga, Motoharu Sasaki, Hiroaki Hayashi, 岡崎徹, 橋詰拓弥 and 小林育夫 : Accumulated-dose Dependence of Measured Values of Small Type OSL Dosimeter in Radiotherapy, 第72回日本放射線技術学会学術大会, Apr. 2016.
64.	Motoharu Sasaki, Masahide Tominaga, 松本晃範, Hiroaki Hayashi, 岡崎徹, 橋詰拓弥 and 小林育夫 : Evaluation of surface dose using originally-produced bolus toward head and neck radiotherapy, 第72回日本放射線技術学会学術大会, Apr. 2016.
65.	Masahide Tominaga, Motoharu Sasaki, Motoharu Sasaki, Kento Tanaka, 安友基勝, 山田健二 and Hitoshi Ikushima : 市販Image registrationソフトウェアの画像類似度の比較評価, 日本放射線腫瘍学会第29回高精度外部放射部会学術大会, Feb. 2016.
66.	Kento Tanaka, Masahide Tominaga, Motoharu Sasaki, 安友基勝 and 山田健二 : 市販Image registrationソフトウェアの画像類似度の比較評価, 第11回中国四国放射線技術フォーラム, Nov. 2015.
67.	松本晃範, Masahide Tominaga, Motoharu Sasaki, 宇恵希, 森田里佳, Hiroaki Hayashi, 岡崎徹 and 小林育夫 : Evaluation of consecutive read values of small-type OSL dosimeter in radiation therapy region., 第43回日本放射線技術学会秋季学術大会, Oct. 2015.
68.	小畑祐太, 三宅裕司, Motoharu Sasaki, 下窪靖史, Shunsuke Furutani, Takashi Kawanaka, Akiko Kubo, Takaharu Kudoh and Hitoshi Ikushima : 子宮頸癌腔内照射におけるリンパ節領域の線量評価, 日本放射線腫瘍学会小線源治療部会, Jun. 2015.
69.	Takaharu Kudoh, Motoharu Sasaki, Akiko Kubo, Takashi Kawanaka, Shunsuke Furutani and Hitoshi Ikushima : 頭頸部癌放射線治療中の転移リンパ節のサイズ変化と制御との関連, 日本放射線腫瘍学会27回学術大会, Dec. 2014.
70.	Noboru Isobe, Motoharu Sasaki, Shunsuke Furutani, Takashi Kawanaka, Akiko Kubo and Takaharu Kudoh : 子宮頸癌に愛するIMRTの有効性ー骨盤骨線量の検討ー, 日本放射線腫瘍学会27回学術大会, Dec. 2014.
71.	曽我部翔, Masahide Tominaga, 松本晃範, Motoharu Sasaki, 中川滉平, Hiroaki Hayashi and 岡崎徹 : 高エネルギーX線における小型 OSL 線量計の基本特性, 第10回中四国放射線医療技術フォーラム, Oct. 2014.
72.	松本晃範, Masahide Tominaga, 曽我部翔, Hiroaki Hayashi and Motoharu Sasaki : 診断領域のX線における後方散乱線についての一考察, 第10回中四国放射線医療技術フォーラム, Oct. 2014.
73.	Motoharu Sasaki, 岸太郎, 藤田明彦, 川下徹也, Yasuo Hara, 三枝裕司, 下窪康史, Masahide Tominaga and 多田章久 : 頭頸部 VMAT における治療計画装置のバージョンの違いに関する治療計画評価, 中四国放射線医療技術, Oct. 2014.
74.	Masataka Oita, Yoshihiro Uto, Hitoshi Hori, Masahide Tominaga, Motoharu Sasaki and 岸太郎 : 細胞間放射線感受性の違いを考慮した治療計画技術応用に関する基礎的検討, 第16回癌治療増感研究シンポジウム, Feb. 2014.
75.	二宮樹里, 北岡幹教, Motoharu Sasaki and 中村譲 : DMLC-IMRT,VMATにおけるMLCリーフ幅の違いが治療計画に及ぼす影響, 第63回中国・四国放射線治療懇話会, Dec. 2013.
76.	Masataka Oita, Yoshihiro Uto, Hitoshi Hori, Masahide Tominaga, Motoharu Sasaki and 岸太郎 : 細胞間放射線感受性の違いを考慮した最適放射線治療計画法に関する検討, 第17回バイオ治療法研究会学術集会, Dec. 2013.
77.	Ryosuke Fukura, Masahide Tominaga, Hitoshi Ikushima, Keigo Masuda, 岸太郎 and Motoharu Sasaki : 前立腺 IMRT および VMAT 計画評価におけるレトロスペクティブ解析, 中四国放射線医療技術フォーラム2014, Nov. 2013.
78.	Keigo Masuda, Masahide Tominaga, Hitoshi Ikushima, Ryosuke Fukura, 岸太郎 and Motoharu Sasaki : 6 軸治療寝台システムを用いた位置精度に関する基礎的検討, 中四国放射線医療技術フォーラム2014, Nov. 2013.
79.	三宅悠太, Takashi Kawanaka, 三枝裕司, 下窪康史, Motoharu Sasaki, 岸太郎, Shunsuke Furutani, Akiko Kubo, Takaharu Kudoh and Hitoshi Ikushima : Cone beam CTによる3次元画像誘導小線源治療, 日本放射線腫瘍学会第26回学術大会, Oct. 2013.
80.	Hitoshi Ikushima, 三枝裕司, 下窪康史, Takashi Kawanaka, Akiko Kubo, Takaharu Kudoh, 原康男, Motoharu Sasaki, 川下徹也 and 岸太郎 : 第120回日本医学放射線学会中国・四国放射線治療懇話会, Jun. 2013.
81.	木村雅司, Akiko Kubo, Motoharu Sasaki, Yasuo Hara, Takashi Kawanaka, Shunsuke Furutani, Takaharu Kudoh and Hitoshi Ikushima : 放射線治療期間中に生じる標的の変化, 日本放射線腫瘍学会第25回学術大会, Dec. 2012.
82.	廣田充宏, Masahide Tominaga, Motoharu Sasaki, 鎌田真奈, Yoshihiro Tanaka, Yasuo Hara, 坂東良太 and Hitoshi Ikushima : 三次元検出器システムの特性に関する検討, 第8回中四国放射線医療技術フォーラム, Oct. 2012.
83.	鎌田真奈, Masahide Tominaga, Motoharu Sasaki, 廣田充宏, Yoshihiro Tanaka, Yasuo Hara, 坂東良太 and Hitoshi Ikushima : 三次元検出器システムの特性に関する検討, 第8回中四国放射線医療技術フォーラム, Oct. 2012.
84.	Motoharu Sasaki, 岸太郎, 川下徹也, Yasuo Hara, 三枝裕司, 福永有希子, 下窪康史, Masahide Tominaga and 多田章久 : 多発脳転移における VMAT の検討 ∼線量検証∼, 第8回中四国放射線医療技術フォーラム, Oct. 2012.
85.	Motoharu Sasaki, 岸太郎, 川下徹也, Yasuo Hara, 三枝裕司, 福永有希子, 下窪康史, Masahide Tominaga and 多田章久 : 多発脳転移における VMAT の検討 ∼治療計画∼, 第8回中四国放射線医療技術フォーラム, Oct. 2012.
86.	Masahide Tominaga, Motoharu Sasaki, 鎌田真奈, 廣田充宏, Yoshihiro Tanaka, Yasuo Hara, 坂東良太 and Hitoshi Ikushima : 三次元検出器の特性に関する検討, 第25回高精度放射線治療研究会, Jul. 2012.
87.	田辺円花, 湯浅千尋, Masahide Tominaga, Motoharu Sasaki and Hitoshi Ikushima : MUの独立検証, Oct. 2010.
88.	湯浅千尋, 田辺円花, Masahide Tominaga, Motoharu Sasaki and Hitoshi Ikushima : CR装置を用いたMLCのQAについての一考察, Oct. 2010.

Et cetera, Workshop:

1.	Motoharu Sasaki : 画像登録と画像レジストレーションについての基礎知識, 令和6年度第12回岡山大学医学物理コース(インテンシブ)地域連携セミナー(WEB開催), Feb. 2025.
2.	Motoharu Sasaki : 第三者評価ガイドライン2023の解説および第三者出力線量評価認定制度の概要, 第62回放射線治療セミナー(WEB開催), Oct. 2024.
3.	Motoharu Sasaki : 患者個別線量検証の簡略化に向けての取り組みの一例, 第31回徳島放射線治療研究会(WEB開催), Jul. 2023.
4.	Motoharu Sasaki : 詳説の解説, 第24回夏季学術大会中国四国放射線治療研究会, Jul. 2023.
5.	Motoharu Sasaki : DIRの利活用, 2022医学物理士セミナー③『放射線治療における画像の利用』(オンデマンド配信), Oct. 2022.
6.	Motoharu Sasaki : 商用機を活用した放射線治療業務の標準化，効率化と簡略化によるワークライフバランス推進, 第151回放射線治療かたろう会(WEB開催), Sep. 2022.
7.	Motoharu Sasaki : 厚生労働省科学研究費助成事業「放射線療法の提供体制構築に資する研究」および関連学会の最新動向の情報提供, 第29回徳島放射線治療研究会(WEB開催), Jun. 2022.
8.	Motoharu Sasaki : 極小照射野を取り巻く新たな潮流ー極小照射野の多施設データからの考察-, 令和3年度第23回岡山大学医学物理コース(インテンシブ)地域連携セミナー(WEB開催), Mar. 2022.
9.	Motoharu Sasaki : 極小照射野を取り巻く新たな潮流∼近年の極小照射野測定に関する先行研究の紹介∼, 第28回徳島放射線治療研究会(WEB開催), Feb. 2022.
10.	Motoharu Sasaki : 放射線治療計画QAソフトウェアを用いた定量化と治療計画改善効果の可能性, 令和2年度第13回岡山大学医学物理コース(インテンシブ)地域連携セミナー(WEB開催), Mar. 2021.
11.	Motoharu Sasaki : 透過型検出器を用いたリアルタイム品質管理の可能性, 令和2年度第10回岡山大学医学物理コース(インテンシブ)地域連携セミナー(WEB開催), Feb. 2021. (Keyword) Transmission detector / Quality assurance / safety
12.	Yoshihiro Tanaka, Masahide Tominaga, Motoharu Sasaki, 廣田充宏, 鎌田真奈, Yasuo Hara, 坂東良太 and Hitoshi Ikushima : 三次元線量検出システムを用いたDVHに関する基礎的検討, 第26回高精度放射線治療研究会, Feb. 2013.
13.	Masahide Tominaga, Motoharu Sasaki, 磯部昇, Hitoshi Ikushima and 岸太郎 : 前立腺癌のIG-IMRTにおいてinter-fractional organ motion errorが線量分布に及ぼす影響, 第26回高精度放射線治療研究会, Feb. 2013.
14.	Motoharu Sasaki : MOSAIQ体験記∼MOSAIQと行くマルチベンダー化への旅∼, エレクタオンコロジーミーティング(2012大阪), Jul. 2012.

Report:

1.	Motoharu Sasaki : 平成23年度前期国際研究集会派遣会員報告書, Japanese Journal of Radiological Technology, Vol.67, No.12, 1640-1641, Dec. 2011.

Grants-in-Aid for Scientific Research (KAKEN Grants Database @ NII.ac.jp)

Novel Cancer Treatment Strategies Based on Radiomics Imaging Analysis (Project/Area Number: 23K07158 )
Molecular Imaging Radiomics Model for Prediction of Radiotherapy Effect (Project/Area Number: 20K07698 )
Search by Researcher Number (00885600)

Assistant Professor : Sasaki, Motoharu

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Grants-in-Aid for Scientific Research (KAKEN Grants Database @ NII.ac.jp)