Abstract

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Title:: Users guide to international calibration protocol TRS-398V7 for absorbed dose to water

Author(s):: WANG Zhipeng1; WANG Kun1; JIN Sunjun1; WU Han1; 2; HAN Jiale1; 2; LU Gang1; 2; YANG Xiaoyuan1; 1. National Institute of Metrology, Beijing 100029, China 2. School of Mechanical and Electrical Engineering, Anhui University of Science and Technology, Huainan 232001, China

Keywords:: Keywords: absorbed dose to water ionization chamber dosimeter calibration coefficient beam quality conversion factor uncertainty TRS-398

Abstract:: Abstract: To fulfill the calibration requirements for absorbed dose to water in external beam radiotherapy, the summary offers a streamlined calibration procedure and recommendations in accordance with TRS-398 (version 7) published by International Atomic Energy Agency in 2024. It addresses various considerations for reference measurement conditions in external beam radiotherapy and defines the appropriate scope for ionization chambers. In terms of ionization chamber measurements, it elaborates on the methods for measuring various correction factors and provides a table of beam quality conversion factors. The calibration uncertainty is examined by comparing the contributions of different factors before and after the update. The results demonstrate that using IBA FC65-G ionization chamber to calibrate high-energy photon beams, high-energy electron beams, proton beams and light ion beams results in relative deviations of -0.4%, 0.5%, -1.7% and -1.3% as compared with the earlier versions, with relative standard uncertainties of 1.0%, 1.1%, 1.7% and 2.6%, respectively. The guideline which is tailored to the national radiotherapy dose calibration standards and practices presents an optimized calibration approach for TRS-398, allowing clinicians to conduct absolute dose calibration more efficiently and accurately.