Department of Radiation Oncology, Saitama Prefectural Cancer Center, 780 Komuro, Ina-machi, Saitama 362-0806, Japan.
Department of Radiological Technology, Graduate School of Health Sciences, Teikyo-Univercity, 6-22 Misaki-machi, Omuta, Fukuoka 836-8505, Japan.
J Radiat Res. 2023 Nov 21;64(6):962-966. doi: 10.1093/jrr/rrad063.
In conducting dosimetric assays of seed sources containing iodine-125 (125I), several major guidelines require the medical physicist to verify the source strength before patient treatment. Japanese guidelines do not mandate dosimetric assays at medical facilities, but since 2017, three incidents have occurred in Japan wherein seeds with incorrect strengths were delivered to medical facilities. Therefore, this study aimed to survey the current situation and any barriers to conducting the dosimetric assay of iodine-125 seeds at medical facilities in Japan. We conducted a questionnaire-based survey from December 2020 to April 2021, to examine whether seed assay and verification of the number of seeds delivered were being performed. We found that only 9 facilities (16%) performed seed assay and 28 (52%) verified the number of seeds. None of the facilities used an assay method that ensured traceability. The reasons for not performing an assay were divided into two categories: lack of resources and legal issues. Lack of resources included lack of instruments, lack of knowledge of assay methods, shorthand, or all of the above, whereas legal issues included the inability to resterilize iodine-125 seeds distributed in Japan and/or purchase seeds dedicated to the assay. Dosimetric assays, including simple methods, are effective in detecting calibration date errors and non-radioactive seeds. The study findings suggest that familiarization of medical personnel with these assay methods and investigation of the associated costs of labor and equipment should be recommended, as these measures will lead to medical reimbursement for quality assurance.
在对含有碘-125（125I）的种子源进行剂量测定时，几项主要指南要求医学物理学家在对患者进行治疗前验证源强度。日本指南并未要求在医疗机构进行剂量测定，但自 2017 年以来，日本发生了三起因向医疗机构输送错误强度种子的事件。因此，本研究旨在调查日本医疗机构目前进行碘-125 种子剂量测定的现状和任何障碍。我们于 2020 年 12 月至 2021 年 4 月进行了一项基于问卷调查的调查，以检查是否对种子进行了测定以及是否对输送的种子数量进行了验证。我们发现，只有 9 家（16%）设施进行了种子测定，28 家（52%）验证了种子数量。没有一家机构使用可确保可追溯性的测定方法。不进行测定的原因分为两类：资源不足和法律问题。资源不足包括缺乏仪器、缺乏测定方法知识、简写或全部，而法律问题包括无法对在日本分发的碘-125 种子进行再消毒和/或购买专用于测定的种子。剂量测定，包括简单方法，可有效检测校准日期错误和非放射性种子。研究结果表明，应熟悉这些测定方法并调查相关的劳动力和设备成本，因为这些措施将为质量保证带来医疗报销。
