碘-125粒子源径向与轴向剂量分布的实验分析

Radial and axial dose distribution of I-125 seed brachytherapy

研究碘-125粒子源轴向与径向的剂量学特性,为粒子源植入治疗管腔癌症提供实验数据。用LiF(Mg,Cu,P)热释光(Thermoluminescent,TL)方片、颗粒和玻璃管三种探测元件,模拟测量碘-125粒子源的剂量分布。I-125粒子源不同角度的径向剂量各向异性;其轴向剂量分布的分散性接近15%,说明钛管内的渗碘银棒可能偏离了中心轴向。进行碘-125粒子源植入治疗时,研究粒子源的剂量学参数及其排列方式对治疗效果可能产生的影响是非常必要的。

Background： Iodine-125 seeds brachytherapy is a cancer treatment method with seeds implanted in tumor tissue. Before clinic application, experiments should be done to determine the dosimetric parameters of seed due to their influences on treatment effects. In this paper, using thermoluminescent dosimeters （TLD） method, axial and radial dose distribution of Iodine-125 seed are measured and analyzed in the lumen tissue model. Purpose： The aim is to investigate the radial and axial dosimetric properties of 1-125 seed, and provide scientific data for cavity cancers treatments with seeds brachtherapy. Methods： LiF （Mg, Cu, P） TL flake, grain and glass dosimeters were used for analog measurements of dose distribution inside the cavity phantom. Three kinds of TLD were measured by FJ-427A1 spectrometer after irradiation. Results： The radial dose distribution at different directions was anisotropic, and the variance of axial dose distribution was more than 10%. These results indicated that the iodide rod inside the titanium tube might deviate from the center of the axial. Conclusion： It is necessary to study the influences of seeds dosimetric parameters and arrangements on possible brachytherapy effects.