Journal of applied clinical medical physics · 2026
Credentialing of small-field dosimetry for the lung SBRT in Japan Clinical Oncology Group clinical trial.
СтатьяНазвание и аннотация: Перевод пока не подготовлен
Обработка статьи · этапы, ошибки и управление
Загрузка состояния…
Ошибки и ограничения
История · было → стало
Состояние обновляется каждые 5 секунд, пока блок открыт. Процент показывается только там, где известен объём работы. Пауза останавливает продолжение этапа; текущий запрос к источнику может завершиться.
Kawahara Daisuke, Ozawa Shuichi, Minemura Toshiyuki, Kumazaki Yu, Hirashima Hideaki, Kito Satoshi, Okamoto Hiroyuki, Nakamura Mitsuhiro, Nishio Teiji, Nishibuchi Ikuno, Matsuo Yukinori, Kimura Tomoki, Ishikura Satoshi, Shikama Naoto, Nagata Yasushi, Mizowaki Takashi
Аннотация
BACKGROUND: Small-field dosimetry plays a pivotal role in stereotactic body radiation therapy (SBRT), where high-precision dose delivery is essential. In multi-institutional clinical trials, quality assurance (QA) becomes increasingly critical due to the variability in linear accelerator (linac) output calibration and treatment planning system (RTPS) configurations. Conventional relative dose factor, which assess relative dose outputs, lack absolute dose information and thus cannot verify the consistency of linac calibration or monitor unit (MU)-to-dose conversion across institutions. These limitations may compromise treatment quality and undermine the integrity of clinical trials. Therefore, an enhanced QA method that incorporates absolute dosimetry is required.
PURPOSE: This study introduces and implements a novel credentialing procedure for small-field dosimetry in SBRT clinical trials using the absorbed dose per MU, expressed in cGy/MU. By integrating absolute dose information into the verification process, this method aims to evaluate both linac output calibration and small-field modeling accuracy across institutions.
METHODS: A nationwide dosimetric survey was conducted involving 545 beams from 120 institutions participating in Japan Clinical Oncology Group (JCOG) trials. Treatment plans were created in each institution's RTPS by prescribing 10 Gy to the isocenter for square field sizes of 2 × 2 to 10 × 10 cm2. Doses were calculated at depths of 5 and 10 cm in a virtual water phantom under a fixed source-to-surface distance of 90 cm. The absorbed dose per MU values were calculated and compared against multicenter averages stratified by linac type and beam energy. A ±3% tolerance criterion was applied for credentialing. Institutions with deviations were contacted and corrective actions were taken as needed.
RESULTS: Of the 545 beams analyzed, 97.8% met the ±3% tolerance criteria. Discrepancies in the ten beams were attributed to small-field beam modeling errors or incorrect RTPS MU-to-dose settings, which were subsequently corrected through feedback. Although variations were observed between the dose calculation algorithms and RTPSs, the differences were within 0.6%, 0.4%, and 1.6%, respectively. The credentialing process proved robust in standardizing dose calculations for clinical trial participation.
CONCLUSION: The proposed absorbed dose per MU-based method enables comprehensive small-field dosimetry evaluation by incorporating absolute dose verification into the credentialing process. This approach effectively identifies calibration inconsistencies that are not detectable using traditional relative dose factor methods. Its application across a large cohort of institutions demonstrated high accuracy and inter-institutional consistency, reinforcing its utility as a practical QA tool in SBRT clinical trials. By enhancing standardization in RTPS performance and linac output verification, this method strengthens the foundation of safe and reliable SBRT implementation in multi-center clinical research.
PURPOSE: This study introduces and implements a novel credentialing procedure for small-field dosimetry in SBRT clinical trials using the absorbed dose per MU, expressed in cGy/MU. By integrating absolute dose information into the verification process, this method aims to evaluate both linac output calibration and small-field modeling accuracy across institutions.
METHODS: A nationwide dosimetric survey was conducted involving 545 beams from 120 institutions participating in Japan Clinical Oncology Group (JCOG) trials. Treatment plans were created in each institution's RTPS by prescribing 10 Gy to the isocenter for square field sizes of 2 × 2 to 10 × 10 cm2. Doses were calculated at depths of 5 and 10 cm in a virtual water phantom under a fixed source-to-surface distance of 90 cm. The absorbed dose per MU values were calculated and compared against multicenter averages stratified by linac type and beam energy. A ±3% tolerance criterion was applied for credentialing. Institutions with deviations were contacted and corrective actions were taken as needed.
RESULTS: Of the 545 beams analyzed, 97.8% met the ±3% tolerance criteria. Discrepancies in the ten beams were attributed to small-field beam modeling errors or incorrect RTPS MU-to-dose settings, which were subsequently corrected through feedback. Although variations were observed between the dose calculation algorithms and RTPSs, the differences were within 0.6%, 0.4%, and 1.6%, respectively. The credentialing process proved robust in standardizing dose calculations for clinical trial participation.
CONCLUSION: The proposed absorbed dose per MU-based method enables comprehensive small-field dosimetry evaluation by incorporating absolute dose verification into the credentialing process. This approach effectively identifies calibration inconsistencies that are not detectable using traditional relative dose factor methods. Its application across a large cohort of institutions demonstrated high accuracy and inter-institutional consistency, reinforcing its utility as a practical QA tool in SBRT clinical trials. By enhancing standardization in RTPS performance and linac output verification, this method strengthens the foundation of safe and reliable SBRT implementation in multi-center clinical research.