调强放疗计划验证γ通过率的参考范围

Reference Range ofγPass Rate in the Verification of Intensity-Modulated Radiotherapy Plan

目的目前,我国尚无统一的关于调强放疗(IMRT&VMAT)计划验证γ通过率的参考范围,该研究通过回顾性分析,以期建立合理的可实现的γ通过率参考范围。方法回顾性分析2017年6月至2019年7月于医院行调强放疗的2487例患者的计划剂量验证结果,采用SPSS 19.0统计软件按照病种部位(因素A)、计划系统(因素B)和验证工具(因素C)对3%/3 mm、3%/2 mm和2%/2 mm评价标准下的γ通过率进行分类,并进行3×3×2析因分析,检验各因素对γ通过率的影响情况,同时参照AAPM TG-119报告提出的置信限(CL)的定义,探讨2%/2 mm、3%/2 mm和3%/3 mm评价标准对应病种部位、计划系统及验证工具下的调强放疗计划γ通过率的置信度区间。结果不同病种部位、计划系统和验证工具均是γ通过率的独立影响因素,它们之间的差异均有统计学意义(P<0.01);同时,病种部位与计划系统、病种部位与验证工具、计划系统与验证工具对γ通过率的影响均有交互作用(P<0.01)。对于头颈部、胸部和腹部肿瘤,在不考虑计划系统和验证工具的情况下,其3%/3 mm、3%/2 mm、2%/2 mm的γ通过率的平均CL分别为(5.7、9.4、16.2)、(5.1、9.6、19.3)、(5.5、9.9、20.4);对于Pinnacle、Oncentra和Monaco计划系统,在不考虑病种部位和验证工具的情况下,其3%/3 mm、3%/2 mm、2%/2 mm的γ通过率的平均CL分别为(7.2、12.1、23.0)、(4.6、9.4、18.4)、(4.4、7.4、14.5);对于ArcCheck和MapCheck验证工具,在不考虑病种部位和计划系统的情况下,其3%/3 mm、3%/2 mm、2%/2 mm的γ通过率的平均CL分别为(5.0、9.6、18.9)、(5.8、9.6、18.3)。结论病种部位、计划系统及验证工具对调强放疗计划验证的γ通过率既是独立影响的主效应因素,又存在因素之间的交互作用,即不同病种部位、计划系统和验证工具的调强放疗计划验证的γ通过率不同,CL值也不同。

Objective At present,the reference range ofγpass rates related to the verification of intensitymodulated radiation therapy(IMRT)&volumetric modulated arc therapy(VMAT)plans have not been unified in our country.In this study,retrospective analysis was made aiming to establish a reasonable and accessible reference range ofγpassing rate.Methods The dosimetric verification results of plans from 2487 patients who undergone IMRT&VMAT from June 2017 to July 2019 were retrospectively analyzed.Theγpass rates evaluated by 3%/3 mm,3%/2 mm and 2%/2 mm criteria were classified according to the disease sites(factor A),planning systems(factor B)and verification methods(factor C)and then the 3×3×2 factorial analysis was carried out to test the influence of the three factors mentioned above onγpass rate by SPSS software.According to the definition of confidence limit(CL)proposed by AAPM TG-119 report,the CLs ofγpass rates evaluated by 3%/3 mm,3%/2 mm and 2%/2 mm criteria of intensity-modulated radiation therapy plans for different disease sites,planning systems,and verification methods were investigated.Results The disease sites,planning systems and verification methods were all proven to be the independent influencing factors,and the differences were statistically significant(P<0.01);The effects on theγpass rates were interactive between disease sites and planning systems,disease sites and verification methods,and planning systems and verification methods(P<0.01).Without considering the planning systems and verification methods,the average CLs for head&neck,chest and abdomen tumors were(5.7,9.4,16.2),(5.1,9.6,19.3),(5.5,9.9,20.4)with 3%/3 mm,3%/2 mm and 2%/2 mm criteria.Without considering disease sites and verification methods,the average CLs for planning systems of Pinnacle,Oncentra and Monaco were(7.2,12.1,23.0),(4.6,9.4,18.4),(4.4,7.4,14.5)with 3%/3 mm,3%/2 mm and 2%/2 mm criteria.Without considering disease sites and planning systems,the average CLs for ArcCheck and MapCheck were(5.0,9.6,18.9),(5.8,9.6,18.3).Conclusion Theγpass rates in the verification of intensity-modulated radiation therapy plans were affected by the factors of disease sites,planning systems and verification methods independently,and there existed interaction effects between the above three factors,that is,the CL values changed with theγpass rates in the verification of intensity-modulated radiation therapy plans by different disease sites,planning systems and verification methods.