260例肿瘤患者VMAT计划验证结果的误差分析  

Deviation analysis of plan verification results of 260 volumetric modulated arc therapy plans

作　　者：王彬[1] 陈立新[1] 张丹丹[1] 胡江[1] 刘伯基[1] 陈阿龙[1] 

机构地区：[1]华南肿瘤学国家重点实验室肿瘤医学协同创新中心中山大学肿瘤防治中心放疗科,广州510060

出　　处：《中华放射肿瘤学杂志》2014年第3期252-255,共4页Chinese Journal of Radiation Oncology

基　　金：国家自然科学基金（81272486）;广东省教育部产学研重点项目（2012B091000144）

摘　　要：目的 总结260例肿瘤患者VMAT计划剂量验证结果,分析VMAT计划验证的γ通过率及其影响因素.方法 回顾2010-2012年期间260例肿瘤患者采用2种探测器矩阵（美国MapCheck2和瑞典Delta4）对2台直线加速器进行VMAT前的剂量验证结果.采用γ通过率（2％/2mm、3％/3 mm、5％/3 mm标准,阈值10％）比较验证结果与TPS计算结果之间差异,并行独立样本t检验.分析3％/3 mm标准下MLC走位精度对γ通过率的影响.结果 2％/2 mm、3％/3 mm和5％/3 mm标准下总验证结果的γ通过率平均值分别为91.7％、98.5％和99.7％,其中3例重新进行了计划设计和优化以达到临床治疗的通过率标准.2％/2 mm标准下2种测量工具测量结果的y通过率平均值稍有不同（90.0％∶93.5％,P =0.000）,而3％/3 mm标准下2种测量工具和2台加速器之间的γ通过率均相近（98.5％：98.5％,P=0.926和98.5％∶98.6％,P=0.670）.3％/3 mm标准下MLC校准前计划的γ通过率为61.1％,校准后的为94.9％.结论 除少数治疗计划需要重新进行设计和优化,绝大多数治疗计划的测量结果均能达到临床治疗的验证标准.在较严格的通过率标准（2％/2 mm）下臂架旋转对VMAT计划的γ通过率有一定影响.MLC校准对VMAT计划的实施非常必要.Objective To investigate the γ pass rate and contributing factors by summarizing the plan verification results of 260 volumetric modulated arc therapy （VMAT） plans.Methods From 2010 to 2012,two different detector arrays （MapCheck2,Sun,Nuclear,USA ; Delta4 ScandiDos,Swenden） were used for plan verification in 260 patients.The measured dose distributions were compared with the calculation results of treatment planning system using γ pass rate （Pγ ≤ 1 for 2%/2 mm,3%/3 mm and 5%/3 mm,threshold 10%）.And the results were put under independent-samples t test.The impact of multi-leaf collimator （MLC） on the γ pass rate （3%/3 mm） was analyzed.Results The average γ pass rates of 2%/2 mm,3%/3 mm and 5%/3 mm of 260 VMAT plans were 91.7%,98.5% and 99.7%,respectively.Among 260 VMAT plans,3 VMAT plans （1.2% of the total） failed to meet the clinical acceptable pass rate and needed to be redesigned or re-optimized.The γ pass rate of 2%/2 mm was slightly different between two measurement devices （90.0% vs 93.5%,P =0.000）,while the γ pass rate of 3%/3 mm showed no significant difference between two measurement devices and two accelerators （98.5% vs 98.5%,P =0.926 and 98.5% vs 98.6%,P =0.670）.The γ pass rate （3%/3 mm） of the treatment plan before MLC calibration was 61.1%,compared to 94.1% after calibration.Conclusions Most dose verification results of treatment plans can meet the clinical requirement.Gantry rotation may influence the γ pass rate of VMAT dose verification under stricter pass rate standard （2%/2 mm）.MLC calibration is essential for VMAT.

关 键 词：容积调强弧形治疗 半导体矩阵 剂量验证 γ通过率 

分 类 号：R730[医药卫生—肿瘤]