^125I粒子平面插植剂量学研究

A dosimetric research on radioactive ^125I seed plane implantation

目的 观察同活度、同数量^125I粒子单平面布源的剂量分布.方法 利用计算机三维治疗计划系统（TPS）模拟9颗2.96×10^7Bq（贝克）^125I粒子9种分布模式,求出60、80、130、145、200Gy剂量分布曲线及曲线包含的面积、长径、短径.结果 粒子不同分布时相同等剂量曲线包含的面积、长径、短径存在差异.60、80、130、145、200Gy等剂量曲线内面积最大的粒子排列分别为：X1.5Y1.5、X1Y1.5、X1Y1（2）1.5、X1Y1、X1Y1（2）0.5,对应的面积分别为：1641.91、1166.42、791.09、718.27、474.63 mm^2.结论 同活度、同数量^125I粒子的不同布源方式直接影响剂量分布.同一剂量曲线内面积最大时的粒子排列剂量分布较均匀,靶区内无剂量学冷点,可能会有较好疗效.

Objective To study the dosimetrie effect of different ^125I seeds arrangements when implanted at the same number and activity （2.96×10^7 Bq） in a plane. Methods Nine different arrangements of ^125I seed plane implantation were established with the three-dimensional treatment planning system （TPS） and the isodose curves of 60, 80, 130, 145 and 200 Gy were figured out. The areas and radius in these isodose curves were calculated with the professional image analysis software. Results The areas and radius in the same isedose curves were dissimilar when the arrangement was different. The arrangements which had the maxima area in the 60, 80, 130, 145 and 200 Gy isodose curves were X1.5Y1.5, X1Y1.5, X1Y1（2）1.5, X1Y1, X1Y1（2） 0.5 with the area of 1641.91, 1166.42,791.09,718.27,474.63 mm^2 respectively. The seeds arrangement with the maximum area in the same isodose curve had a better dose distribution and there were no cold spots in the target. Conclusion The dose and therapeutic effect was influenced significantly by the arrangemeut of the seeds even the number and activity were equal.