摘要目的 研究铁屏蔽体在主防护墙中不同深度对防护墙外周围剂量当量率的影响.方法 采用FLUKA蒙特卡罗模拟程序构建了质子治疗室的模型,治疗室的屏蔽体由混凝土和钢构成.分别模拟220和250 MeV的质子照射水模体,以获得不同情况下的周围剂量当量率分布.结果 随着嵌入防护墙的铁屏蔽体深度的变化,两种模拟条件下质子治疗机房主防护墙外30 cm处的周围剂量当量率发生显著变化,最大周围剂量当量率(220 MeV:3.42μSv/h,250 MeV:6.39μSv/h)比最小周围剂量当量率(220 MeV:1.75μSv/h,250 MeV:3.32μSv/h)高2倍.结论 在质子治疗加速器的设计中,应仔细评估铁屏蔽体在主防护墙中的位置.

abstractsObjective To investigate the effect of iron shield at different depths within main protection wall on the dose rate outside the protection wall. Methods By adopting the FLUKA code, a therapeutic room model was constructed with its primary protective barrier consisting of concrete and iron. In order to obtain its ambient dose equivalent rate distribution, the 250 MeV protons and 220 MeV protons impinging on water phantom were simulated separately. Results With varying depth of iron plate embedded in barrier, the ambient dose equivalent rates in the two simulated conditions differed sinificantly at 30 cm outside the protection wall. The maximum ambient dose equivalent rate(220 MeV:3.42 μSv/h, 250 MeV:6. 39 μSv/h) was more than 2 times higher than the minimum ambient dose equivalent rate ( 220 MeV:1. 75 μSv/h, 250 MeV: 3. 32 μSv/h ) . Conclusions In the design of therapeutic proton accelerator, it is essential to evaluate carefully the location where the iron shield is in main protection wall.