自屏蔽加速器屏蔽防护优化探讨

An exploration of shielding optimization for self-shielded accelerators

目的对3款带有自屏蔽结构的加速器机房布局和屏蔽防护进行分析,为优化自屏蔽加速器机房屏蔽防护设计提供依据。方法采用MC模拟和经验公式计算相结合的方法,对比分析3款自屏蔽加速器机房主屏蔽区透射剂量率和次屏蔽区散射剂量率等辐射防护水平。结果MC模拟和经验公式计算结果均显示Unity MR Linac次屏蔽区散射线剂量率明显高于主屏蔽区主射束透射剂量率,最高可达后者的5倍;Unity MR Linac和TOMO横断面散射剂量率明显高于矢状面。结论自屏蔽结构的外形、材料及厚度差异,增加了机房屏蔽计算及防护设计的复杂性,应改进屏蔽计算方法,实现新型放疗机房辐射防护最优化。

Objective To analyze the room layout and shielding of three types of self-shielded accelerators,and to provide a basis for optimizing the shielding design of rooms for self-shielded accelerators.Methods We compared the radiation shielding levels(transmitted radiation dose rate outside the primary barrier and scattered radiation dose rate outside the secondary barrier)of three self-shielded accelerator rooms by Monte Carlo simulation and empirical formula calculation.Results According to Monte Carlo simulation and empirical formula calculation,for the Unity MR Linac accelerator,the scatter radiation dose rate outside the secondary barrier was significantly higher(up to five times)than the transmitted primary radiation dose rate outside the primary barrier.The scatter radiation dose rate of the cross section was significantly higher than that of the sagittal section for both Unity MR Linac and TOMO accelerators.Conclusion The differences in the shape,material,and thickness of self-shielding structures complicate the shielding calculation and design for accelerator rooms.The shielding calculation method should be improved to optimize the radiation shielding of novel accelerator rooms.