| Zhang Yu,Wu Dai,Yuan Jilong,et al.Comparative analysis of leakage and scattered radiation measured using three types of dose rate meters outside X-ray FLASH radiotherapy treatment rooms[J].Chinese Journal of Radiological Medicine and Protection,2026,46(6):605-611 |
| Comparative analysis of leakage and scattered radiation measured using three types of dose rate meters outside X-ray FLASH radiotherapy treatment rooms |
| Received:July 28, 2025 |
| DOI：10.3760/cma.j.cn112271-20250728-00271 |
| KeyWords:High-energy X ray|FLASH radiotherapy|Ambient dose equivalent rate|Radiation protection |
| FundProject:中国疾控中心辐射安全所青年基金人才成长计划项目(2024NA02) |
| Author Name | Affiliation | E-mail | | Zhang Yu | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | | | Wu Dai | Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, ChinaCorrespond | | | Yuan Jilong | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | | | Ma Xiangjie | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | | | Zhao Qiaoqiao | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | | | He Zhijian | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | | | Yang Yiwei | Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, ChinaCorrespond | | | Wang Jianxin | Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, ChinaCorrespond | | | Cheng Jinsheng | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | | | Liu Hui | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | liuhui@nirp.chinacdc.cn | | Chen Jiahe | China CDC Key Laboratory of Radiological Protection and Nuclear Emergency, National Institute for Radiological Protection, Chinese Center for Disease Control and Prevention, Beijing 100088, China | |
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| Abstract:: |
| Objective To compare and analyze the ambient dose equivalent rates measured using three types of commonly used meters (451P, AT1123, and 6150AD b/H) outside the treatment room of an X-ray FLASH radiotherapy device against theoretical calculations, thereby providing a basis for selecting instruments conditions for such measurements. Methods A solid water phantom was used to simulate a patient. Reference dose rates were set at 6, 100, and 150 Gy/s, respectively, also with the corresponding irradiation time. Based on the radiation source term parameters and the shielding structure of the treatment room, the ambient dose equivalent rate at a point of interest outside the west shielding wall (closest to the accelerator head) was calculated using the formula specified in GBZ/T 201.2-2011. Measurements at the same point were performed using the three types of dose rate meters, and the measured values were compared with the calculated values to analyze the deviation characteristics. Results The measured values on the 451P and 6150AD b/H meters were significantly lower than the calculated values under all reference dose rate conditions. The relative deviations were greater than -82.87% and -74.74% at 6 Gy/s, greater than -79.72% and -61.87% at 100 Gy/s, and greater than -84.90% and -76.37% at 150 Gy/s, respectively. The AT1123 failed to provide valid measurements at 6 Gy/s. At 100 Gy/s, its measured value increases with increasing beam-on time, reaching rough consistency at 240 ms. At 150 Gy/s, its measured value increases with increasing beam-on time, with a relative deviation of -17.51% at 160 ms. Interpolation analysis shows that the beam-on time required for using the AT1123 to reach 90% of the calculated value are 170 and 202 ms, respectively. Conclusions Due to their relatively long response time, the rate meters 451P and 6150AD b/H are not recommended for measuring ambient dose equivalent rates under the conditions of this study. Under certain conditions, the AT1123 detector can provide a reasonably accurate measurement of the ambient dose equivalent rate outside the radiotherapy room in the certain conditions. However, continued analysis should be conducted on the basis of taking into account specific pulse time structures and dose rate levels. At the same time, it is necessary to develop radiation protection monitoring instruments specifically designed for the ultra-high dose rate based on the characteristics of X-ray (FLASH radiotherapy). |
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