Abstract

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Title:: Exploring the effects of positioning methods on the superficial absorbed dose in postmastectomy radiation therapy using thermoluminescent dosimeter based on anthropomorphic phantom

Author(s):: WANG Qin1; DENG Minmin2; YU Yanjun2; NI Wenjie1; ZHANG Fuli2; 1. Department of Radiotherapy, Beijing Shijitan Hospital, Capital Medical University, Beijing 100038, China 2. Department of Radiotherapy, the Seventh Medical Center of Chinese PLA General Hospital, Beijing 100700, China

Keywords:: Keywords: breast cancer superficial absorbed dose thermoluminescent dosimeter dose measurement

Abstract:: Abstract: Objective To investigate the effects of positioning methods on the superficial absorbed dose in volumetric modulated arc therapy (VMAT) following radical mastectomy using LiF (Mg, Cu, P) thermoluminescent dosimeter (TLD) based on anthropomorphic phantom, thereby providing some reference for clinical treatment. Methods Linear accelerator 6 MV X-ray was used for the dose calibration and angular response measurement of TLD. The superficial absorbed dose of the Alderson Rando phantom in VMAT following radical mastectomy was measured under 3 positioning conditions, namely breast bracket in control group, breast bracket covered with Bolus of 5 mm in experimental group 1, and body plate combined with thermoplastic film in experimental group 2. Results The measured superficial absorbed dose in control group and 2 experimental groups were 94.4-99.9, 179.4-184.6 and 150.4-156.8 cGy, accounting for 47.2%-50.0%, 89.7%~92.3% and 75.2%~78.4% of the prescription dose, respectively. Conclusion The superficial absorbed dose differs significantly under 3 positioning conditions. In clinical practice, thermoplastic film is able to improve the superficial dose, but there exists greater uncertainty. Bolus should be rationally used to reduce the respiratory range and improve the superficial absorbed dose, so as to achieve the optimal treatment outcome.