基于日志文件的三维独立剂量验证系统在IMRT质控中的可行性研究

目的 评估一种基于日志文件的三维独立剂量验证系统用于临床放疗质控的可行性。方法 以三维水箱测量数据为基准,比较分析Mobius三维独立剂量验证系统计算的百分深度剂量、离轴曲线和输出因子与测量数据的一致性;并对17例鼻咽癌患者进行临床放疗计划的三维独立剂量验证和治疗过程中基于加速器日志文件的三维剂量验证,检测Mobius的剂量计算精度和剂量重建精度,同时也对每个病人分次间治疗的γ通过率(3%/3 mm)进行了统计分析,用以检测分次间治疗的稳定性。结果 Mobius重新计算的百分深度剂量、离轴曲线、输出因子与三维水箱测量的数据具有较好的一致性;17例鼻咽癌患者临床放疗计划的靶区以及危及器官的DVH参数对比结果如下:治疗计划的三维独立剂量验证结果中最大偏差为-2.16%,治疗过程中基于加速器日志文件的三维剂量验证结果中最大偏差为0.18 Gy。17例鼻咽癌整体平均通过率为99.26%,分次间治疗的最大偏差为0.5%。结论 Mobius的独立计算功能和剂量重建功能具有类似计划系统的精度,可快速进行临床放疗计划的三维独立剂量验证和治疗过程中基于加速器日志文件的三维剂量验证。从而为临床治疗提供安全、可靠的技术保障。

Evaluation of the feasibility of log file-based three-dimensional independent dose verification system in quality assurance of intensity-modulated radiation therapy

Objective To assess the feasibility of the log file-based three-dimensional independent dose verification system for the quality assurance of clinical radiotherapy. Methods The statistical values of the percentage depth dose,off-axis curves and output factor calculated by the Mobius system were statistically compared with the measured data by three-dimensional water tank. The three-dimensional independent dose verification in clinical radiotherapy plan and the acceleratr log file-based three-dimensional dose verification during the treatment were performed in 17 patients with nasopharyngeal cancer. The accuracy of dose calculation and reconstruction of Mobius system was assessed. A statistical analysis was performed on the intra-fractionalγpass rate (3%/3 mm) for each patient to evaluate the stability of intra-fractional radiotherapy. Results The percentage depth dose,off-axis curve and output factor statistically calculated by the Mobius system matched well with the data measured by three-dimensional water tank. The dose-volume histogram (DVH) parameters between the target area and organ at risk during clinical radiotherapy plan were statistically compared in 17 patients with nasopharyngeal cancer. The maximum deviation was-2.16% for the three-dimensional independent dose verification in the clinical radiotherapy plan,and 0.18 Gy for the accelerator log file-based three-dimensional dose verification. The averageγpass rate for 17 nasopharyngeal cancer patients was 99.26%,and the maximum deviation of intra-fractional radiotherapy was below 0.5%. Conclusions The function of dose reconstruction and independent calculation of the Mobius system yeilds the same accuracy with the treatment planning system,which can quickly perform three-dimensional independent dose verification in the clinical radiotherapy plan and accelerator log file-based three-dimensional dose verification throughout the treatment,thereby guarantting and providing the safe and reliable technical support for clinical treatment.