算法差异在Compass调强计划验证中的作用

摘要

Objective To carry out IBA Compass-based verification of the radiotherapy plans for lung cancer and rectal cancers calculated with anisotropic analytical algorithm (AAA) in Varian Eclipse treatment planning system and analyze the causes and classification of the dose disparities in the plans.Methods The pre-operative radiotherapy plans in 10 cases of lung cancer and 10 cases of rectal cancer were retrospectively analyzed for Compass-based verification.The dose distributions computed by different algorithms,namely Eclipse AAA (TPS Dose),Compass collapsed cone convolution (CCC) (Compute Dose),and Compass using measured data (Reconstructed Dose),were compared in terms of the Gamma passing rateand dose-volume histogram (DVH) in regions with 10％ of the maximum dose.Results With the3rnm/3％/Global criteria,the pre-operative plans for rectal cancer achieved a Gamma passing rates of (97.37±2.41)％ for AAA/CR,(97.88±2.21)％ for CC/CR,and (99.69±0.15)％ for AAA/CC.No significant difference was found in the Gamma passing rate between AAA/CR and CC/CR (P=0.598).For lung cancer cases,the Gamma passing rates were (92.09±2.79)％,(96.17±2.78)％,and (98.96±1.06)％ for AAA/CR,CC/CR,and AAA/CC,respectively,showing a significant difference between AAA/CR and CC/CR (P=0.005).Conclusion For Compass-based plan verification,the difference between AAA and CCC algorithms is a major contributor to the dose disparities in the plans for lung cancer but only has a minor impact on dose disparities in cases of rectal cancer,where the Gamma passing rate is subjected to greater influences by the accuracies in the position of the multi-leaf collimator,gantry rotation,and dosage.%目的:用IBA Compass系统对Varian Eclipse计划系统各向异性解析算法(AAA)计算的肺癌和直肠癌计划进行验证,研究差异原因并进行分类分析.方法:分别选取肺癌和直肠癌术前放疗患者各10例,用Compass系统在加速器实测验证,将Eclipse AAA计算的TPS Dose、Compass卷积/超分割算法(CCC)再计算的Compute Dose以及Compass通过实测并基于CCC算法重建的Reconstructed Dose进行两两对比(AAA/CR、CC/CR、AAA/CC),比较分析计划最大点剂量的10％生成的区域的Gamma结果和剂量体积直方图(DVH)结果.结果:在3mm/3％/Global标准下,直肠癌术前计划:AAA/CRγ通过率为(97.37±2.41)％,CC/CRγ通过率为(97.88±2.21)％,AAA/CC γ通过率为(99.69±0.15)％,AAA/CRγ通过率与CC/CRγ通过率的差异无统计学意义(P=0.598).肺癌计划:AAA/CRγ通过率为(92.09±2.79)％,CC/CRγ通过率为(96.17±2.78)％,AAA/CC γ通过率为(98.96±1.06)％,AAA/CR γ通过率与CC/CRγ通过率的差异具有显著统计学意义(P=0.005).结论:用Compass验证AAA算法计划,在肺癌病例中AAA与CCC算法的差异是影响计划通过率的主要原因,在直肠癌计划中AAA与CCC算法的差异影响相对较低,通过率更多受到MLC到位精度、机架旋转精度、剂量准确度等执行不确定性影响.