Evaluation of dosimetry effect of lack of side-scatter volume on large field measurements with a MapCheck detector array

作     者：MA Pan DAI Jianrong CUI Weijie 

作者机构：Department of Radiation Oncology/Cancer Institute Chinese Academy of Medical Sciences Beijing 100021 China 

出 版 物：《Nuclear Science and Techniques》 (核技术（英文）)

年 卷 期：2009年第20卷第5期

页      面：292-296页

核心收录：

学科分类：08[工学] 082701[工学-核能科学与工程] 0827[工学-核科学与技术] 

主　　题：放射量 测定 LSSV 核技术 

摘      要：In this paper, we describe a quantitative evaluation of the dosimetry effect of lack of side-scatter volume (LSSV). MapCheck, an integration diode array, was used to measure dose maps for three large non-IMRT fields (30cm ×30 cm and 40 cm×40 cm open fields, and 30 cm×30 cm wedge field with wedge angle of 60°) and 19 large IMRT fields. For each field, measurement was performed twice, under the conditions of (1) full scatter volume and (2) LSSV. Condition 1 was satisfied by adding PMMA slabs against the side of the MapCheck, and Condition 2, without PMMA slabs. The measured dose maps were compared with pass rate and their difference was scored when the acceptance criterion was set to 0.5%, 1%, 2%, 3%, etc. For very large open fields, the effect of LSSV may be clinically significant, while for large wedge fields and IMRT fields, the effect is negligible.