一种可控制驻留时间变化幅度的后装放射治疗逆向优化算法的研究  

A study on a method for restricting dwell time variation in brachytherapy plan optimization

作　　者：毕斌 黎杰 王培 康盛伟 唐斌 汤婷 王先良 Bi Bin;Li Jie;Wang Pei;Kang Shengwei;Tang Bin;Tang Ting;Wang Xianliang(Sichuan Cancer Hospital&Institute,Sichuan Cancer Center,School of Medicine,University of Electronic Science and Technology of China,Radiation Oncology Key Laboratory of Sichuan Province,Chengdu 610041,China)

机构地区：[1]四川省肿瘤医院·研究所,四川省癌症防治中心,电子科技大学医学院,放射肿瘤学四川省重点实验室,成都610041

出　　处：《中华放射医学与防护杂志》2020年第11期873-876,共4页Chinese Journal of Radiological Medicine and Protection

摘　　要：目的报道三维后装放射治疗中一种可控制驻留时间变化幅度的算法的实现方法和结果。方法逆向优化算法(GBPO)使用标准的二次目标函数,在目标函数中增加一个可控制驻留时间变化幅度的项,用驻留时间调制因子(DTMF)调节驻留时间的变化幅度。回顾性研究15例使用了三管施源器(Nucletron part#189.730)治疗的宫颈癌患者,分析DTMF与驻留时间标准差的关系,统计剂量体积直方图(DVH)参数(HR-CTV D100%、V150%,危及器官D0.1 cm3、D1 cm3、D2 cm3),评估GBPO计划和商用计划系统(采用IPSA算法)计划之间的差异。结果当DTMF<20时,驻留时间标准差迅速减小,在DTMF增加到100之后,驻留时间标准差无明显变化。GBPO计划的D100%(3.63±0.36)高于IPSA计划(3.53±0.34),两者比较,差异有统计学意义(t=2.45,P<0.05),两种计划之间其他DVH参数比较的差异无统计学意义(P>0.05)。结论三维后装放射治疗中控制驻留时间变化幅度的方法是可行的,采用GBPO制定的计划在靶区覆盖和危及器官保护方面与IPSA计划相似,GBPO可集成在三维后装放射治疗计划系统中。Objective To report an implementation method and result of an inverse dose optimization algorithm(GBPO)that can control the dwell time variation in three-dimensional brachytherapy.Methods The GBPO used a quadratic objective function.A dwell time modulation item was added to the objective function to restrict the dwell time variation,and a DTMF(dwell time modulation factor)was used to adjust the dwell time variation.A retrospective study was made of 15 cervical cancer patients treated using the Fletcher applicator.The relationship between the DTMF and dwell time deviation was analyzed.Dose-volume histogram(DVH)parameters of HR-CTV(D100%,V150%)and organs at risk(OARs)(D0.1 cm3,D1 cm3,D2 cm3)were used to evaluate the difference between the GBPO plans and the commercial treatment plan system(using the IPSA algorithm)plans.Results When the DTMF was less than 20,the dwell time deviation decreased quickly.However,after the DTMF increased to 100,and the dwell time deviation had no remarkable change.The D100%of GBPO plan was higher than that of IPSA plan(3.63±0.36 vs.3.53±0.34,t=2.45,P<0.05),and the difference in other dosimetric parameters between the GBPO plans and the IPSA plans was not statistically significant(P>0.05).Conclusions The method reported in this study to control the dwell time variation was feasible.The GBPO plans have a comparable quality as the IPSA plans for the studied cervical cancer cases.The GBPO algorithm could be integrated into a three-dimensional brachytherapy treatment planning system.

关 键 词：后装放射治疗 逆向计划 治疗计划系统 宫颈癌 

分 类 号：R730.55[医药卫生—肿瘤]