MatriXX测量近距离放疗放射源驻留时间精度的方法研究  

Investigating the accuracy of dwell time of radioactive source in brachytherapy using MatriXX measurement

作　　者：江芬芬[1] 胡本辉 JIANG Fenfen;HU Benhui(Department of Radiation Oncology,Jiangxi Maternal and Child Health Hospital,Nanchang 330006,China)

机构地区：[1]江西省妇幼保健院肿瘤放疗室,江西南昌330006

出　　处：《中国医学物理学杂志》2021年第5期551-555,共5页Chinese Journal of Medical Physics

基　　金：江西省卫生健康委科技计划(20195530)。

摘　　要：目的:应用二维电离室矩阵(MatriXX)测量近距离放疗后装机中192Ir在不同间距驻留点的驻留时间,并与治疗计划系统(TPS)计算的驻留时间作比较,验证放射源驻留时间的精准度。方法:采用不同角度的宫腔管(15°、30°、45°)分别粘贴在MatriXX表面,通过后装治疗计划系统设计不同计划,计划的治疗长度设为10 cm,各个驻留点权重和时间相等,重复执行5次计划,通过MatriXX记录数据。根据临床后装治疗的要求,用MatriXX测量不同驻留点间距(2.5、5.0、10.0 mm)的时间,开展后装源驻留时间重复性和准确性实验。结果:用MatriXX测量近距离后装源不同驻留间距对应的驻留时间相对于TPS计划系统计算时间的偏差均小于±1%。另外,当驻留点间距为2.5 mm时,其驻留时间偏差最大,为0.9%;驻留点间距为10 mm时,其时间偏差最小为0.3%。结论:在合适的驻留间距范围内用MatriXX验证近距离放疗放射源驻留时间和重复性方法准确可靠,经济适用,同时选择较大的驻留间距可提高测量驻留时间的精度。Objective To verify the accuracy of the dwell time of 192Ir radioactive source in brachytherapy by comparing the dwell time of 192Ir at different dwell point distances measured using two-dimension ion chamber matrix(MatriXX)with that calculated by treatment planning system.Methods The uterine tandems with different angles(15°,30°,45°)were pasted on the surface of MatriXX,respectively.Different plans with the treatment length of 10 cm were designed through treatment planning system(TPS).The weight and time of each dwell point were set to be equal.The plan was repeated 5 times,and meanwhile the data was recorded by MatriXX.Based on the requirements of brachytherapy,the dwell time at different dwell point distances(2.5,5.0,10.0 mm)was measured by MatriXX,and the experiments on the repeatability and accuracy of dwell time were also carried out.Results The relative deviation of the dwell time at different dwell point distances measured by MatriXX and that calculated by TPS was less than±1%.Furthermore,when the dwell point distances were 2.5 mm and 10.0 mm,the maximum deviations of dwell time were 0.9%and 0.3%,respectively.Conclusion Within an appropriate dwell point distance range,using MatriXX to validate the repeatability and accuracy of dwell time of radioactive source in brachytherapy is feasible,reliable,economical and applicable.Moreover,the accuracy of dwell time measurement can be improved by selecting a larger dwell point distance.

关 键 词：二维电离室矩阵 近距离放疗 驻留时间 驻留间距 

分 类 号：R811.1[医药卫生—放射医学] R318[医药卫生—临床医学]