某15MV医用电子加速器M区内、外泄露辐射测量与分析

Measurement and Analysis of Leakage Radiation of A 15 MV Medical Electron Accelerator inside the M Area and outside the M Area

目的通过对医用电子加速器M区内、外X射线及中子泄漏辐射水平的测量与分析,评价医用电子加速器的自身防护性能。方法按照GBZ 126-2011规定的M区内、外泄漏辐射测量方法,采用热释光元件（塑料管分装的LiF（Mg,Cu,P）、玻璃管分装的6LiF、7LiF对管）测量瓦里安公司生产的23Ex型加速器的患者平面X射线及中子泄露辐射率。结果 M区内X射线泄露辐射率范围是（0.023-0.028）%,平均值为0.025%;M区外X射线泄露辐射率范围是（0.005-0.023）%,平均值为0.014%;M区外中子泄露辐射率范围是（0.023-0.034）%,平均值为0.031%。结论M区内、M区外X射线泄露辐射率平均值、最大值及M区外中子泄露辐射率最大值均符合GBZ 126-2011的要求,但M区外中子泄露辐射率平均值不符合要求。

Objective To evaluate the protective performance of medical electron accelerator through measuring and analyzing the X-ray or neutron leakage radiation levels inside the M area and outside the M area of medical electron accelerators.Methods The ratio of X-ray and neutron leakage radiation on patients＇ radiotherapy plane was tested through thermoluminescent dosemeter（6Li F、7Li F glass tube and Li F（Mg,Cu,P） plastic tube） in a 23 Ex accelerator of Varian according to the measure method of leakage radiation inside the M area and outside the M area of GBZ 126-2011.Results The range of leakage radiation ratios of X-ray is between 0.023% to 0.028% with the average being 0.025% in M area.The range of leakage radiation ratios of X-ray is between 0.005% to 0.023% with the average being 0.014% outside the M area.The range of leakage radiation ratios of neutron is between 0.023% to 0.034% with the average being 0.031% outside the M area.Conclusion The maximum and the average ratio of leakage radiation of X-ray and neutron inside the M area and outside the M area meet the require of GBZ126-2011,but the average ratio of the neutron leakage radiation does not meet the require of GBZ126-2011.