加速器15MV射线引起残留辐射的测量研究  

Measurement of residual radiation induced by 15 MV energy beam in medical linear accelerator

作　　者：陈亚正[1] 祁国海[1] 李厨荣[1] 张声江[1] 廖雄飞[1] 肖明勇[1] 黎杰[1] 王培[1] 

机构地区：[1]四川省肿瘤医院放疗中心,四川成都610041

出　　处：《中国医学装备》2016年第11期16-19,共4页China Medical Equipment

基　　金：四川省科技支撑计划(2015JQ0053)"现代放疗技术中引发第二原发癌风险的辐射剂量因素研究"

摘　　要：目的:研究高能射线出束结束后的电离辐射情况,监测分析其残留辐射数据。方法:使用15 MV高能X射线的医用电子直线加速器对15 cm×15 cm×15 cm的水箱进行照射,开设5cm×5 cm、10 cm×10 cm和15 cm×15 cm的照射野,并对每一照射野均出射跳数为50 MU、100MU和300 MU的射线。每间隔5 s记录一次监测仪所在位置的剂量当量率,记录时间为30 min,分析比较剂量当量率与照射野和跳数MU的关系以及3种照射野的剂量当量率变化趋势。结果:①剂量当量率呈非线性跌落,并且在某时间段内剂量率有上升的反弹现象;②对于同一照射野,跳数为300 MU的射线产生的剂量率最高,其余依次为100 MU和50 MU的射线,即剂量当量率H_(300 MU)>H_(100 MU)>H_(50 MU);3对于相同跳数的射线,不同面积射野产生的剂量当量率无明显的规律,即剂量当量率不决定于射野面积。结论:医用电子直线加速器使用15 MV的射线进行治疗时所引起的残留辐射应引起注意,且必须采取相应的辐射防护措施。Objective： To study the ionizing radiation after the end of high energy beam, detect and analyze the data of residual radiation. Methods： A 15 cm×15 cm×15 cm water phantom was irradiated with a 15 MV high energy X-ray medical linear accelerator. The irradiation field was 5 cm×5 cm, 10 cm×10 cm and 15 cm×15 cm. For each field, 50 MU,100 MU and 300 MU of X-ray were emitted. The dose equivalent rate within 30 mins was recorded every 5 s. The relationship between the dose equivalent rate and the irradiation field and the number of MU was analyzed and the change trend of the dose rate of the three fields was analyzed. Results： ①The dose rate showed a non-linear drop, and the dose rate increased in a certain period of time. ②For the same radiation field, the dose rate of 300 MU was the highest, followed by 100 MU and 50 MU of radiation, the dose equivalent rate of H_（300 MU）H_（100 MU）H_（50 MU）. 3 For the same number MU, different areas of radiation field dose equivalent rate showed no obvious characteristic, so the dose rate is not determined by the field area. Conclusion： Residual radiation caused by radiation therapy of 15 MV in medical electronic linear accelerator should be paid attention to and radiation protection measures must be taken by the department.

关 键 词：高能射线 残留辐射 剂量率 医用直线加速器 

分 类 号：R197.39[医药卫生—卫生事业管理]