目的介绍医用电子加速器机房设计、辐射屏蔽厚度计算和天空反散估算。方法依据相关计算公式,采用顺序替代法计算屏蔽墙体设计厚度,以NCRP151估算原则估算天空反散射剂量。结果顺序替代法计算屏蔽层厚度既简便又省时,所获得数值准确,天空反散射剂量估算结果的影响可以忽略不计。结论采取本方法计算的屏蔽厚度作为机房辐射屏蔽厚度值建造,能达到既确保辐射安全又经济的目的。 Objective To introduce the design of medical electron accelerator room, the calculation of radiation shielding thickness and the inverse estimation of sky. Methods Based on the relevant calculation formulas, the design thickness of the shielding wall was calculated by the sequential substitution method, and the sky backscattering dose was estimated by the NCRP151 estimation principle. Results Sequential substitution method to calculate the thickness of the shield is simple and time-saving, the obtained numerical accuracy, the impact of sky backscatter dose estimation results can be ignored. Conclusion The shielding thickness calculated by this method is used as the radiation shield thickness of the engine room to achieve the goal of ensuring both radiation safety and economy.