医用直线加速器机房屏蔽防护改建研究

摘要

Objective To provide a solution to improve the radiation shielding for medical accelerator room with clay bricks.Methods According to the basic shielding equations provided by the relevant national standards and international reports,equations for shielding reconstruction calculation were derived to calculate the required thickness of clay bricks wall,which reached the reference dose rate control level.The dose rates at reference points after reconstruction were also estimated based on the measured dose rates at reference points before reconstruction of accelerator room,calculated distance correction factors and transmission factors of added clay bricks wall.Results The measured dose rates satisfied the requirement of reference dose rate control level.The estimated dose rates were slightly higher than the measured values.Conclusion The radiation shielding requirement of medical accelerator room is fulfilled with the presented shielding reconstruction method by building clay bricks wall,measured dose rates could be conservatively predicted with the dose rates calculated by derived equations.%目的:针对医用直线加速器机房建造中出现的防护不足提出黏土砖改建方案.方法:参考相关国家标准和国际报告提供的方法推导屏蔽改建计算公式,计算满足剂量率参考控制水平要求的黏土砖墙厚度.根据机房改建前参考点的测量剂量率、距离修正因子和增建黏土砖墙的透射因子估算改建后的参考点剂量率.结果:改建后的参考点剂量率符合剂量率参考控制水平的要求,估算剂量率大于测量值.结论:提出的增建黏土砖墙的改建方法能够满足机房的屏蔽防护要求,推导的剂量率估算公式可以保守预测改建后的测量剂量率.