近距离放疗施源器挡块对放疗剂量分布的影响

Impact of Shielding in Applicator on Dose Distribution in Brachytherapy

本文根据在近距离放疗施源器中添加挡块有利于保护正常组织的原则,使用Ir-192放射源和圆柱形施源器制定治疗计划,并在施源器内分别添加90°和180°挡块,得到计划剂量分布结果。随后借助特制的模体,采用二维电离室矩阵,分别从施源器冠状面和矢状面测量剂量分布,采用γ分析法(3%,3 mm)比较计划剂量分布和实测剂量分布差异。结果表明,挡块遮挡区内组织器官的辐射剂量远低于肿瘤的处方剂量,说明使用挡块可以有效降低辐射剂量,保护正常组织器官。

The paper aims to investigate principle of applying shieding application to spare healthy tissues in brachytherapy with the use of Ir-192 in designing the treatment regimen. The 90° and 180° shieldings were added to the applicator to calculate the result of dose distribution. Dose distribution was then measured using a 2D ion chamber array dosimeter in the transverse and coronal planes for these treatment plans. Gama analysis method（3%, 3 mm） was adopted to compare the dose distribution with the TPS calculations. The results indicate that the dose distribution to the organs in the shield shadow were obviously much lower than the prescribed doses for treatment volume and essentially remained within their tolerance limits for clinical dose prescriptions. It is concluded that the shielding application can effectively reduce the radiation dosage and protect normal tissues and organs.