准直器叶片到位精度对宫颈癌容积调强计划验证的影响  

Impact of multi-leaf collimator positioning accuracy on quality control of volumetric modulation arc therapy plan for cervical cancer treated with Elekta linear accelerator

作　　者：梁健 余凤姿[2] 朱金汉 宋婷[1] LIANG Jian;YU Fengzi;ZHU Jinhan;SONG Ting(School of Biomedical Engineering,Southern Medical University,Guangzhou 510515,China;State Key Laboratory of Oncology in South China//Department of Radiotherapy,Sun Yat-sen University Cancer Center,Guangzhou 510060,China)

机构地区：[1]南方医科大学生物医学工程学院,广东广州510515 [2]华南肿瘤学国家重点实验室//中山大学肿瘤防治中心放疗科,广东广州510060

出　　处：《南方医科大学学报》2022年第7期1089-1094,共6页Journal of Southern Medical University

基　　金：广州市科技计划项目(202206010180)。

摘　　要：目的探讨加速器多叶准直器(MLC)叶片到位精度对宫颈癌容积调强放疗计划剂量验证通过率的影响。方法在加速器常规质控基础上,选用Mapcheck和Arccheck两种半导体探测器矩阵在校准MLC叶片到位精度前后,分别测量30例宫颈癌容积调强放疗计划的二维和三维剂量分布。采用3%、3 mm和2%、2 mm标准,计算二维和三维剂量验证的Gamma通过率;并通过3DVH软件进一步将三维剂量分布误差与患者解剖结构建立起相互关系,评估加速器MLC叶片到位精度对宫颈癌容积调强放疗计划通过率的影响。结果MLC校准前后,3%、3 mm标准下Mapcheck测得的Gamma通过率分别为(88.80±1.81)%和(99.25±0.53)%,平均提高10.45%;Arccheck测得的Gamma通过率分别为(87.61±1.98)%和(98.13±0.99)%(P<0.05),平均提高了10.52%。3DVH测得的Gamma通过率分别为(89.87±2.28)%和(98.30±1.15)%(P<0.05),平均提高了8.43%。结论MLC叶片到位精度是影响加速器宫颈癌容积调强放疗计划执行准确性的主要因素之一。通过使用Autocal软件,可以快速、准确的完成多叶准直器的校准工作。Objective To investigate the influence of positioning accuracy of the multi-leaf collimators(MLC)on the passing rate of the plan dose verification for volumetric modulation arc therapy(VMAT)of cervical cancer using an Elekta linear accelerator.Methods The dose distributions were measured using Sun Nuclear's Mapcheck and Arccheck semiconductors matrix before and after MLC calibration in30 cervical cancer patients undergoing VMAT.Dosimetric comparisons were performed with 2D and 3D gamma passing rates of 3%,3 mm and 2%,and 2 mm.The 3D gamma distribution was reconstructed with respect to the patient's anatomy using 3DVH software to evaluate the possible influence of MLC positioning accuracy.Results Before and after MLC calibration,the gamma passing rates of Mapcheck were(88.80±1.81)%and(99.25±0.53)%under 3%and 3 mm standard,respectively,with an average increase of 10.45%.The corresponding gamma passing rates of Arccheck were(87.61±1.98)%and(98.13±0.99)%,respectively,with an average increase of 10.52%.The gamma passing rates of 3DVH were(89.87±2.28)%and(98.3±1.15)%,respectively,with an average increase of 8.43%.Conclusion The MLC positioning accuracy is one of the main factors influencing dosimetric accuracy of VMAT for cervical cancer.The application of Autocal software facilitates MLC calibration and improves the accuracy and safety of VMAT delivery for cervical cancer.

关 键 词：宫颈癌 容积调强 计划验证 Autocal 多叶准直器 

分 类 号：R737.33[医药卫生—肿瘤]