放射性^(125)I粒子源在肝组织中的照射剂量分布

Dose distribution of ^(125)I source in the liver tissues

目的探讨放射性^(125)I粒子源在肝组织中的剂量分布特征,为其临床近距离放射治疗提供参考。方法采用热释光剂量学方法,通过"米"字形空间布放Li F(Mg,Cu,P)型热释光剂量元件,分析热释光剂量元件受照射后的吸收剂量(X)与热释光剂量仪读数(Y)的关系,观察放射性^(125)I粒子源在肝组织中轴向、径向及4个中分线方向上的辐照吸收剂量变化及剂量场分布。结果热释光剂量仪读数与热释光剂量元件受照射后的吸收剂量呈线性关系,线性回归方程为Y=0.134 2X-0.014 7(R2=0.999,P<0.01)。放射性^(125)I粒子源在轴向、径向、中分线方向上的剂量均随离源距离的增加呈快速衰减,中心剂量热区的场分布呈"苹果"状影像,有逐渐向椭圆形趋变的趋势。受照射角度的不同,等距离位点上吸收剂量大小各异,径向剂量>中分线方向剂量>轴向剂量。结论放射性^(125)I粒子源在肝组织中的剂量分布具有不均匀性,其剂量场呈类似"苹果"形分布,呈剂量凹陷区和剂量凸起分布特征。

Objective To investigate the dose distribution characteristics of radioactive 125 I particle source in liver tis-sues and provide a reference for the brachytherapy dose calculations.Methods We applied the method of thermolumines-cence dosimetry and used＂M＂glyph space to implant LiF （ Mg, Cu, P） .The relationships between the exposure dose （ X） of the thermoluminescence dose element and the measured data （ Y） were analyzed.Then, we measured and calculat-ed the radiation absorbed dose changes and field distribution of 125 I radioactive particle sources in the liver tissues of the ax-ial, radial and the four-point directions of the line.Results The reading of thermoluminescent dosimeter （ Y） had linear relationship with the exposure dose （X）.The linear regression equation was Y=0.134 2X-0.014 7 （R2 =0.999, P〈0.01）.With the increase of the distance from the source, the dose of 125I particle source in axial, radial and middle line showed a rapid decreasing tendency.According to different angles, the absorbed dose of equidistance locus were different, the radial dose 〉dose in middle line direction 〉the axial dose.Conclusion The dose distribution of 125 I particle source in liver tissues was uneven, and the dose distribution is similar to the＂apple＂shape with dose sag area and dose bump area distribution characteristics.