六种不同混凝土在质子治疗机房屏蔽性能研究

目的 研究6种不同混凝土为主墙时，230 MeV质子治疗室主屏蔽体外的剂量水平，获取6种不同混凝土的屏蔽性能。方法 采用FLUKA程序构建计算模型，将不同混凝土组成引入FLUKA程序，模拟230 MeV质子束流照射情况下关注点周围剂量当量率随混凝土厚度的变化，拟合6种混凝土透射曲线，得到6种不同混凝土的屏蔽性能参数。结果 230 MeV质子束90°方向照射水靶时，混凝土厚度超过40 cm后，6种不同的混凝土对质子束的衰减均呈指数衰减，拟合的衰减曲线R² > 0.99，普通混凝土、重晶石混凝土、磁铁矿混凝土、褐铁矿混凝土、磷铁矿混凝土和铁硅酸盐混凝土的线衰减系数分别为：0.014 8 cm^?1、0.017 2 cm^?1、0.019 6 cm^?1、0.021 9 cm^?1、0.025 6 cm^?1、0.029 0 cm^?1。结论 混凝土材料中的元素组成和占比在很大程度上直接影响着混凝土对于质子束的屏蔽能力，6种不同的混凝土对质子的屏蔽性能相差较大。因此在质子治疗室屏蔽材料的选取时应该结合混凝土的材料组成和屏蔽性能、施工难易程度及工程成本等诸多因素综合考量。

Shielding performance of six different types of concrete in proton therapy room

Objective To study the dose level of proton beams outside the main shield of the 230 MeV proton therapy room with six different types of concrete as the main wall, and to obtain the shielding performance of six different types of concrete. Methods The FLUKA program was used to build a calculation model, and different concrete compositions were introduced into the FLUKA program to simulate the change in ambient dose equivalent rate of the focus with concrete thickness under 230 MeV proton beam irradiation. The transmission curves of six different types of concrete were fitted to obtain shielding performance parameters. Results On the condition that the 230 MeV proton beam irradiated to the water target in 90° direction and the concrete thickness exceeded 40 cm, the proton beam was exponentially decayed for six different types of concrete, and the fitted decay curves had a R² of > 0.99. The linear attenuation coefficients for normal concrete, barite concrete, magnetite concrete, limonite concrete, phosphorite concrete, and ferrosilicate concrete were 0.0148 cm^-1, 0.0172 cm^?1, 0.0196 cm^?1, 0.0219 cm^?1, 0.0256 cm^?1, and 0.0290 cm^?1, respectively. Conclusion The composition and proportion of elements in concrete materials directly affect the shielding ability of concrete against proton beams to a large extent, and the shielding performance of six different types of concrete against proton beams varies greatly. Therefore, shielding materials for the proton therapy room should be selected by a comprehensive consideration of the material compositions and shielding performance of concrete, the difficulty of construction, and construction cost.