基于小波融合多野剂量评估计划整体通过率的可行性

Feasibility of evaluating the plan overall passing rate based on wavelet fused with multi field dose assessment

目的:评价基于小波方法融合电子射野影像装置(EPID)多野剂量分析计划整体通过率的可行性。方法:选取70例不同部位的容积调强(VMAT)双弧计划,用Varian公司的a Si500-ⅡEPID系统进行剂量验证,将TPS计划和验证结果的通量图导出,用Matlab读取通量图,并基于小波的一层分解重构分别对每个计划的单弧通量图进行融合。用Matlab仿真3%/3 mm标准的γ通过率,并记录双弧计划每个弧的结果和融合后的结果,共3组数据。同时利用PTW Detector729矩阵对计划进行剂量验证作为对照组,与融合后的结果行配对t检验分析。结果:双弧计划每个弧的通过率和融合后的通过率均在95%以上,两种方式不同部位双弧VMAT计划的通过率均无统计学差异(t=1.453~2.129,P>0.05)。结论:基于小波融合EPID多野剂量可用于评估VMAT双弧计划整体通过率,其结果有助于更全面保障调强放疗计划验证的准确性。

Objective To discuss on the feasibility of multi field dose assessment of electronic portal imaging device（EPID）based on wavelet method for evaluating the plan overall passing rate.Methods The double-arc volumetric modulated arc therapy（VMAT） plans for different body sites in 70 patients were selected.After the dosimetric verification of Varian a Si500-Ⅱ EPID system,the flux maps of treatment planning system plans and verification results were exported and read by using Matlab.The flux maps of each single arc in plans were fused,respectively,based on the wavelet decomposition.The gamma passing rate of 3%/3 mm in Matllab simulation were used to record three sets of data,including the results of each single arc and the fusion results.In addition,t-test was used to analyze the results of image fusion and the results of control group,in which PTW Detector 729 array was used for dosimetric verification.Results No statistical difference in gamma passing rate between the two methods for different body sites was found（t=1.453-2.129,P〉0.05）,and all the gamma passing rates of each arc in the double-arc plan and the fused images were more than 95%.Conclusion The wavelet fused with EPID multi field dose assessment comprehensively evaluate the overall passing rate of double-arc VMAT plans,and the results provides value for the comprehensive verification of intensity-modulated radiotherapy plans.