Open AccessReduction in stray radiation dose using a body‐shielding device during external radiation therapy
Author(s) -
Zhang Shuxu,
Jiang Shaohui,
Zhang Quanbin,
Lin Shengqu,
Wang Ruihao,
Zhou Xiang,
Zhang Guoqian,
Lei Huaiyu,
Yu Hui
Publication year - 2017
Publication title -
journal of applied clinical medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.83
H-Index - 48
ISSN - 1526-9914
DOI - 10.1002/acm2.12035
Subject(s) - electromagnetic shielding , radiation , radiation shielding , medical physics , radiation protection , reduction (mathematics) , nuclear medicine , radiation dose , radiation therapy , optics , physics , materials science , nuclear engineering , medicine , radiology , mathematics , engineering , geometry , quantum mechanics
Abstract With the purpose of reducing stray radiation dose ( SRD ) in out‐of‐field region ( OFR ) during radiotherapy with 6 MV intensity‐modulated radiation therapy ( IMRT ), a body‐shielding device ( BSD ) was prepared according to the measurements obtained in experimental testing. In experimental testing, optimal shielding conditions, such as 1 mm lead, 2 mm lead, and 1 mm lead plus 10 mm bolus, were investigated along the medial axis of a phantom using thermoluminescent dosimeters ( TLD s). The SRD s at distances from field edge were then measured and analyzed for a clinical IMRT treatment plan for nasopharyngeal carcinoma before and after shielding using the BSD . In addition, SRD s in anterior, posterior, left and right directions of phantom were investigated with and without shielding, respectively. Also, the SRD at the bottom of treatment couch was measured. SRD decreased exponentially to a constant value with increasing distance from field edge. The shielding rate was 50%–80%; however, there were no significant differences in SRD s when shielded by 1 mm lead, 2 mm lead, or 1 mm lead plus 10 mm bolus ( P >0.05). Importantly, the 10 mm bolus absorbed back‐scattering radiation due to the interaction between photons and lead. As a result, 1 mm lead plus 10 mm bolus was selected to prepare the BSD . After shielding with BSD , total SRD s in the OFR decreased to almost 50% of those without shielding when irradiated with IMRT beams. Due to the effects of treatment couch and gantry angle, SRD s at distances were not identical in anterior, posterior, left and right direction of phantom without BSD . As higher dose in anterior and lower dose in posterior, SRD s were substantial similarities after shielding. There was no significant difference in SRD s for left and right directions with or without shielding. Interestingly, SRD s in the four directions were similar after shielding. From these results, the BSD developed in this study may significantly reduce SRD in the OFR during radiotherapy, thus decreasing the risk of secondary cancers.