CAJ | 학술논문

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.
목적 총결260례종류환자VMAT계화제량험증결과,분석VMAT계화험증적γ통과솔급기영향인소.방법 회고2010-2012년기간260례종류환자채용2충탐측기구진(미국MapCheck2화서전Delta4)대2태직선가속기진행VMAT전적제량험증결과.채용γ통과솔(2％/2mm、3％/3 mm、5％/3 mm표준,역치10％)비교험증결과여TPS계산결과지간차이,병행독립양본t검험.분석3％/3 mm표준하MLC주위정도대γ통과솔적영향.결과 2％/2 mm、3％/3 mm화5％/3 mm표준하총험증결과적γ통과솔평균치분별위91.7％、98.5％화99.7％,기중3례중신진행료계화설계화우화이체도림상치료적통과솔표준.2％/2 mm표준하2충측량공구측량결과적y통과솔평균치초유불동(90.0％∶93.5％,P =0.000),이3％/3 mm표준하2충측량공구화2태가속기지간적γ통과솔균상근(98.5％:98.5％,P=0.926화98.5％∶98.6％,P=0.670).3％/3 mm표준하MLC교준전계화적γ통과솔위61.1％,교준후적위94.9％.결론 제소수치료계화수요중신진행설계화우화,절대다수치료계화적측량결과균능체도림상치료적험증표준.재교엄격적통과솔표준(2％/2 mm)하비가선전대VMAT계화적γ통과솔유일정영향.MLC교준대VMAT계화적실시비상필요.
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.