水吸収線量測定サンドイッチファントムを用いた密封小線源¹⁹²Ir 線源強度計測の安定性・信頼性の検討

抄録

Purpose: In this study, we evaluated the stability and reliability of absorbed dose-to-water for an HDR ¹⁹²Ir sandwich setup phantom method by comparing measurements with absorbed dose-to-water determination based on the AAPM TG-43 protocol. Methods: The sandwich setup phantom was designed with a dedicated device for two ion chamber measurements of absorbed dose-to-water for a mHDR-v2r ¹⁹²Ir brachytherapy source is presented. To test the reliability of sandwich setup phantom of measurements with absorbed dose-to-water, we were compared with values based on AAPM TG-43 protocol and evaluated temporal variations of the measurement, intra-rater reliability. Results: The measured doses at sandwich setup phantom agreed within 1.0% with AAPM TG-43 protocol. In all measurement fractions, the temporal variations of measurement value were less than 1.0%, and the intra-rater reliability were 0.94% or more. Conclusions: The measurement value obtained by the absorbed dose-towater had good reliability, and sandwich setup phantom is potentially useful and convenient for daily dose management of ¹⁹²Ir sources in clinics.