不同照射条件下医用加速器机房辐射水平验证检测

Verification Testing of Radiation Levels of Medical Accelerator Rooms Under Different Irradiation Conditions

目的研究不同照射条件下医用加速器机房周围环境X射线辐射水平。方法参考《建设项目职业病危害放射防护评价规范第2部分:放射治疗装置》(GBZ/T 220.2-2009)以Synergy型10 MV加速器为研究对象,使用451B电离室型X、γ剂量率仪,分为等中心处放置模体组和无模体组,分别在四种不同的机架角度(0°、90°、180°、270°)测量机房四周屏蔽墙及防护门处周围剂量当量率,并对检测结果进行分析。结果等中心放置模体组中,机架90°时,西墙外X射线周围剂量当量率大于其他角度;270°时,东墙外X射线周围剂量当量率最大;机架270°时防护门处周围剂量当量率高于其它角度的检测结果,差异有统计学意义;同不放置模体组比较,放置模体组防护门处周围剂量当量率明显增高,且270°时剂量率是不放置模体的1.5倍,但四周屏蔽墙周围剂量当量率却无显著差别。结论医用加速器机房四周屏蔽墙及防护门口X射线辐射水平随机架角度的变化而不同;检测门口辐射水平时,应设置模体。

Objective To study the X - ray radiation levels of medical accelerator room under different irradiation condi- tions. Methods In accordance with the standard》The specification of radiological protection assessment for occupational haz- ard in construction project Part 2： Radiotherapy facility》GBZ / T 220.2 -2009 ,using the 451B ionization chamber X γdose rate meter with the 10MeV accelerator as research object, the research object are divided into two groups, module group and blank group , measuring the radiation dose rate of shield walls and protective doors respectively when the accelerator＇ s rack angle changes in four different gantry angles （0°, 90 °, 180 °, 270 °）, analyzing the results . Results When the angle is 90 °, the X - ray dose rate outside the west wall is higher than the other angle. When 270 °, the X - ray dose rate outside the east wall is higher than others, and the dose rate outside the protective door is highest in the 270 °. The module group＇ s dose rate outside the protective door is 1.5 times higher than blank group. Conclusion The X - ray radiation dose level surround- ing the accelerator room walls and protective door changes while the accelerator＇ s rack angle changes differently. When detec- ting the doors＇ radiation level, the module should be set.