蒙特卡罗方法计算后装铱源的不锈钢外壳对吸收剂量的影响

目的基于高剂量率（HDR）后装治疗用的微型铱源（^192Ir）结构，研究不锈钢外壳对其吸收剂量的影响。方法将微型铱源置于高10．5cm、直径11．1cm的圆柱形水模体中心，采用蒙特卡罗计算方法比较有无不锈钢外壳2种情况下铱源周围模体的剂量分布。结果在不锈钢外壳和水模的附近区域，2种情况下的剂量分布存在一定的差别。随着离源距离增加，剂量分布非常接近。结论近距离治疗中，不锈钢外壳在铱源剂量分布计算中的影响可以忽略。

Impact of the steel shell on dose distribution around 192Ir source for branchytherapy

Objective Based on the structure of the 192 Ir source used for high-dose-branchytherapy (HDR), the impact of the steel shell on the dose distribution was studied. Methods The 192 Ir source was placed at the center of a cylindric water phantom which height was 10.5 cm and diameter was 11.1 cm. With Monte Carlo calculation the dose distribution in the phantom was compared between adding and not adding a steel shell. Results In the two situations,the relative dose difference was noted at the interface between the steel shell and the water phantom. Following the increase of the distance away from the source, the dose distribution rapidly became proximate. Conclusion The impact of the steel shell on the dose of the ~(192)Ir source can be ignored. ;