X射线体元蒙特卡罗算法计划统计不确定度对直肠癌容积旋转调强放射治疗计划的影响  

Effect of the SUpC of XVMC algorithm on VMAT for rectal cancer

作　　者：叶为镪 李博[1] 张伟[1] 韦珍珍[1] 于超俊 张大伟[1] 苏世达[1] 覃文[1] Ye Weiqiang;Li Bo;Zhang Wei;WeiZhenzhen;Yu Chaojun;Zhang Dawei;Su Shida;Qin Wen(Department of Radiotherapy,The First Affiliated Hospital of Guangxi Medical University,Nanning 530021,China)

机构地区：[1]广西医科大学第一附属医院放疗科,南宁530021

出　　处：《中国医学装备》2024年第4期18-22,45,共6页China Medical Equipment

基　　金：广西壮族自治区卫生健康委员会自筹经费科研课题(Z20200178);广西高校中青年教师科研基础能力提升项目(2020KY03027)。

摘　　要：目的:研究Monaco放射治疗计划系统X射线体元蒙特卡罗(XVMC)算法中计划统计不确定度(SUpC)对直肠癌容积旋转调强放射治疗(VMAT)计划优化与剂量计算的影响。方法:回顾性选取2018年1-12月广西医科大学第一附属医院收治的10例直肠癌患者放射治疗资料,在Monaco放射治疗计划系统中采用XVMC算法,分别设置SUpC为0.25、0.50、0.75、1.00、1.25和1.50,设计6种VMAT计划(SUpC_(0.25)、SUpC_(0.50)、SUpC_(0.75)、SUpC_(1.00)、SUpC_(1.25)和SUpC_(1.50))进行优化和计算,比较6种不同VMAT计划中靶区最大剂量(D_(max))、平均剂量(D_(mean))、均匀性(HI)和适形度(CI)的差异,以及危及器官(OAR)的膀胱、小肠、股骨头和正常组织剂量差异,分析SUpC值对VMAT计划的控制点SUpC(SUpCP)、损失值loss、历史密度(HD)、优化计算时间(Time)、子野数(Segment)、机器跳数(MU)、出束时间(DT)等参数的影响。结果:随着SUpC增大,与SUpCP_(0.25)相比,其余5种计划靶区D_(max)、D_(mean)及HI分别增大,CI分别降低,差异有统计学意义(F=45.62、13.83、24.94、15.79,P<0.05),OAR膀胱的D_(max)、D_(mean)和正常组织的D_(max)、50 Gy剂量体积百分比(V_(50))分别增大,差异具有统计学意义(F=26.54、0.87、45.52、7.05,P<0.05)。与SUpCP_(0.25)相比,其余5种计划优化计算时间Time随SUpC增大分别减少,差异具有统计学意义(F=329.69,P<0.05)。SUpC≤1时,靶区D_(max)相比于SUpC_(0.25)时剂量偏差≤3%;SUpC≥1时,优化计算时间<10 min。结论:随着SUpC值增大,高剂量区域的D_(max)增多,靶区剂量被高估,靶区HI和CI变差,加速优化计算效率。针对Monaco计划系统进行直肠癌VMAT计划设计时推荐使用SUpC值为1,可以在保证计划质量最好的情况下有效提高直肠癌VMAT计划的优化效率,为直肠癌VMAT临床计划设计提供理论依据。Objective:To study the effect of statistical uncertainty per calculation(SUpC)of X-ray voxel Monte Carlo(XVMC)algorithm of Monaco radiotherapy plan system on the optimization and dose calculation of volumetric modulated arc therapy(VMAT)for rectal cancer.Methods:This study selected the radiotherapy data of 10 patients with rectal cancer at the First Affiliated Hospital of Guangxi Medical University retrospectively.In Monaco radiotherapy plan system,the XVMC algorithm was adopted,and the SUpC was respectively set as 0.25,0.50,0.75,1.00,1.25 and 1.50 to design 6 kinds of VMAT plans(SUpC_(0.25),SUpC_(0.50),SUpC_(0.75),SUpC_(1.00),SUpC_(1.25),SUpC_(1.50))for optimization and calculation.The differences of maximum dose(D_(max)),mean dose(D_(mean)),homogeneity index(HI),conformity index(CI)of target regions among 6 kinds of VMAT plans were compared.The differences of the doses of bladder,small intestine and femoral head of organs at risk(OAR)and normal tissue among different VMAT plans also were compared.In addition,the effects of statistical uncertainty per control point(SUpCP),loss value(loss),history density(HD),time of optimization and calculation(Time),sub field(Segment),monitor unit(MU),delivery time(DT)on the optimization of VMAT plan were analyzed.Results:Compared with SUpCP_(0.25),the D_(max),D_(mean) and HI of other 5 kinds of target regions respectively increased,and CI of them respectively decreased with the increasing of SUpC,and the differences were significant(F=45.62,13.83,24.94,15.79,P<0.05),respectively.The D_(max) and D_(mean) of OAR bladder,and the D_(max) and V_(50) of normal tissue respectively increased,and the differences were significant(F=26.54,0.87,45.52,7.05,P<0.05).Compared with SUpCP_(0.25),the time of optimization and calculation(Time)of other 5 kinds of plans respectively decreased with the increasing of SUpC,and the difference was significant(F=329.69,P<0.05).When SUpC≤1,the dose deviation of target region D_(max) was smaller or equal to 3%than SUpC_(0.25),and the time of optimization

关 键 词：X射线体元蒙特卡罗(XVMC)算法 不确定度 直肠癌 容积旋转调强放射治疗(VMAT) 

分 类 号：R811.1[医药卫生—放射医学]