Nuclear Science and Techniques

《核技术》(英文版) ISSN 1001-8042 CN 31-1559/TL     2019 Impact factor 1.556

Nuclear Science and Techniques ›› 2009, Vol. 20 ›› Issue (5): 292-296 doi: 10.13538/j.1001-8042/nst.20.292-296

• RADIOCHEMISTRY, RADIOPHARMACEUTICALS AND NUCLEAR MEDICIN • Previous Articles     Next Articles

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

MA Pan DAI Jianrong* CUI Weijie   

  1. Department of Radiation Oncology/Cancer Institute, Chinese Academy of Medical Sciences, Beijing 100021, China
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MA Pan, DAI Jianrong, CUI Weijie. Evaluation of dosimetry effect of lack of side-scatter volume on large field measurements with a MapCheck detector array.Nuclear Science and Techniques, 2009, 20(5): 292-296     doi: 10.13538/j.1001-8042/nst.20.292-296

Abstract:

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.

Key words: Large field, Lack of side-scatter volume, Diode array