医用电子直线加速器感生放射性的测量和分析

目的 通过对医用电子直线加速器感生放射性进行测量，研究感生放射性冷却规律，并为评估患者、医务人员及公众额外受照剂量提供基础数据。方法 采用automess—6150AD6/H+6150AD-b/H型环境监测X-γ辐射周围剂量当量率仪对5台医用电子直线加速器感生放射性进行测量。结果 5台医用电子直线加速器感生放射性水平与测量位置、时间等因素有关：出束停止后10 s，加速器机头外壳表面5 cm周围剂量当量率最大值为5.55 μSv/h，距外壳1 m处固定点的周围剂量当量率最大值为4.07 μSv/h；在出束停止5 min后，加速器机头外壳表面5 cm周围剂量当量率最大值为2.11 μSv/h，距外壳1 m处固定点的周围剂量当量率最大值为1.77 μSv/h。结论 医用电子直线加速器感生放射性测量结果随时间推移逐渐冷却；测量结果维持在一个较为固定的范围，数值的波动范围较窄。

Measurement and analysis of induced radioactivity in medical electronic linear accelerator

Objective By measuring the induced radioactivity of the medical electron linear accelerator, and analyzing the measuring results and the measuring process, the cooling law of the induced radioactivity was studied, to provide basic data for evaluating additional doses to patients, medical staff and the public.Methods Five Medical Electron Linear accelerators were used to measure the induced radioactivity by using automes-6150AD6/H+6150AD-b/H x-γ radiation peripheral dose equivalent rate meter for environmental monitoring.Results The level of induced radioactivity of 5 medical electron linear accelerators is related to the factors such as measuring position and time: 10 second after the end of beam output, the maximum dose equivalent rate is 5.55 μSv/h around 5 cm on the surface of the head housing of the accelerator, and the maximum ambient dose equivalent rate at 1 m from the fixed point of the housing is 4.07 μSv/h, 5 minutes after the end of output, the maximum dose equivalent rate is 2.11 μSv/h around the 5 cm surface and 1.77 μSv/h around the 1 m fixed point.Conclusion The measured radioactivity induced by the medical electron linear accelerator gradually cools over time, the measurement valuesare maintained in a relatively fixed range, and the fluctuation range of the values is narrow.