Evaluating the stray radiation around medical electron accelerators is a mandatory issue. Surveying the radiation leakage dose is important for patients, technicians, and health physicists, due to radiation protection aspects. Consequently, radiation leakage dose around the head of a mobile-dedicated intraoperative radiotherapy accelerator (LIAC), at different electron energies and field sizes have been evaluated in this study. More specifically, the MCNPX Monte Carlo code was used to model the LIAC head, connected applicator, and employed water phantom. Radiation leakage dose around the LIAC head was calculated for different energy and field sizes through tuning the Monte Carlo results to the practically measured doses. These measurements were performed using an Advance Markus ionization chamber inside an automated MP3-XS water phantom. The good agreement between the calculated dose distributions within the water tank and corresponding dose measurements show that the simulation model of the LIAC head is appropriate for radiation leakage assessment. The obtained radiation leakage dose distribution highly depends on the electron energy and applicator diameter. With increasing the electron energy, the leakage dose decreased, while increasing the field size increased the leakage dose. It is concluded that the rate of stray radiation and leakage dose around the LIAC head in both vertical and horizontal planes were acceptable according to the recommended radiation protection criteria. To meet the recommended dose limit (100 µSv/week for controlled areas), the maximum number of patients should be kept to four patients per week inside a standard and unshielded operating room.

中文翻译：

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基于蒙特卡洛的专用IOERT加速器周围辐射泄漏剂量的确定。

评估医用电子加速器周围的杂散辐射是必须解决的问题。由于辐射防护方面的原因，对辐射泄漏剂量进行调查对于患者，技术人员和健康物理学家而言非常重要。因此，本研究评估了移动专用术中放疗加速器（LIAC）头部周围在不同电子能量和场大小下的辐射泄漏剂量。更具体地说，MCNPX蒙特卡罗代码用于建模LIAC喷头，连接的喷头并使用水模。通过将蒙特卡洛结果调整为实际测量的剂量，可以计算出针对不同能量和场大小的LIAC头周围的辐射泄漏剂量。这些测量是使用自动MP3-XS水体模内的Advance Markus电离室进行的。计算得出的水箱内的剂量分布与相应的剂量测量值之间的良好一致性表明，LIAC扬程的模拟模型适合进行辐射泄漏评估。所获得的辐射泄漏剂量分布高度取决于电子能量和施加器直径。随着电子能量的增加，泄漏剂量减小，而场尺寸的增加增加了泄漏剂量。结论是，根据推荐的辐射防护标准，在垂直和水平平面上LIAC头周围的杂散辐射率和泄漏剂量都是可以接受的。为了达到建议的剂量限制（控制区域为每周100 µSv），每周应在标准无屏蔽手术室内将最多患者数保持为四名患者。