独立三维剂量验证在鼻咽癌容积调强放射治疗计划中的应用

Application of independent three-dimensional dose verification for volumetric modulated arc therapy of nasopharyngeal carcinoma

目的:探讨独立三维剂量验证在鼻咽癌容积调强放射治疗(VMAT)计划中应用的可行性。方法:选取31例鼻咽癌患者的VMAT计划,采用Bland-Altman统计方法对基于独立三维剂量分布和实测重建三维剂量分布的一致性进行分析,从而论证独立三维剂量验证应用于鼻咽癌VMAT计划中的可行性。根据独立三维剂量验证的DVH图和γ通过率分类绘制出受试者工作特征(ROC)曲线,得到鼻咽癌VMAT计划中独立三维剂量验证的最佳γ通过率阈值。结果:鼻咽癌患者的VMAT计划中,两种验证方法有95.34%的测试点落在一致性界限内,因此两种验证方法之间具有较好的一致性。根据ROC曲线和AUC值,选取结构PTV2参数用于γ通过率评价时效果最好,其最佳阈值为95.41%。结论:独立三维剂量验证可以检验计划系统计算的准确性,快速地对计划进行治疗前的验证。最佳阈值有助于对放疗计划进行筛查,为放疗计划的准确实施提供安全、有效的技术保障。

Objective To explore the feasibility of independent three-dimensional dose verification for volumetric modulated arc therapy(VMAT)of nasopharyngeal carcinoma(NPC).Methods The VMAT plans of 31 NPC patients were selected.Bland-Altman method was used to analyze the consistency between independent three-dimensional dose distribution and measured reconstructed three-dimensional dose distribution,so as to demonstrate the feasibility of independent threedimensional dose verification for VMAT of NPC.Based on the dose-volume histogram of independent three-dimensional dose verification and the classification of gamma passing rate,receiver operating characteristic(ROC)curve was drawn,and the optimal gamma passing rate threshold of independent three-dimensional dose verification for VMAT of NPC was obtained.Results For two verification methods for VMAT of NPC,95.34%of the test points were within the consistency range,indicating there was a good consistency between the two verification methods.According to ROC curve and AUC value,PTV2 was selected as the best evaluation of gamma passing rate in the independent three-dimensional dose verification for VMAT of NPC,and its optimal threshold was 95.41%.Conclusion Independent three-dimensional dose verification can be used as a test of the calculation accuracy of the planning system,and the pretreatment planning can be verified quickly.The optimal threshold is helpful to screen the radiotherapy plan and provides a safe and effective technical guarantee for the accurate implementation of radiotherapy plan.