瓦里安Portal Dosimetry和PTW 1500矩阵在Halcyon^TM治疗计划剂量验证的对比研究

A comparative study of dosimetric verification of Halcyon^TM treatment plans using Varian Portal Dosimetry and PTW array 1500

目的比较Portal Dosimetry(PD)和PTW OCTAVIUS 1500矩阵结合Octagonal模体(Oct1500)两种剂量验证方式在Halcyon^TM加速器治疗计划剂量验证中的表现。方法选取在Halcyon^TM做临床试验的20例入组患者,包括22个IMRT/VMAT治疗计划和74个辐射野,分别采用两种验证方式和多种γ2D评估策略进行剂量验证,对比验证方式及评估策略之间的验证结果,为Halcyon^TM治疗计划验证方式和评价策略的选择提供数据支持。结果Oct1500方式74个辐射野和22个治疗计划γ2D通过率分别为95.26±3.59、95.01±3.62(局部剂量)、99.05±1.35、98.57±1.96(最大剂量),两种评估策略之间差异有统计学意义(Z=-7.220、-4.108,P<0.05);PD方式为84.11±1.35(1mm/1%)、99.07±1.35(2mm/2%)、99.86±1.35(3mm/3%),3种评估策略之间差异有统计学意义(Z=-7.475、-7.475、-6.906,P<0.05);74个辐射野全局剂量、3mm/3%的评价策略两种验证方式之间差异有统计学意义(Z=-5.072,P<0.05)。结论两种剂量验证方式均可用于Halcyon^TM治疗计划剂量验证;PD方式在验证效率和由空间分辨率所致的剂量验证精度方面优于Oct1500。推荐使用2mm/2%(PD)和全局剂量、3mm/3%(Oct1500)评估策略。

Objective To compare two pretreatment plan QA methods for Halcyon^TM accelerator using Portal Dosimetry(PD),and PTW OCTAVIUS 1500 detector array+Octagonal phantom(Oct 1500)respectively.Methods Parallel measurement-based pretreatment QA using two methods was performed for 22 IMRT/VMAT plans(74 fields)that have been used to treat 20 patients recruited in the Halcyon clinical trial.Severalγ2D comparisons were also applied to provide guidelines for Halcyon planning QA.Results Using Oct1500 method,theγ2D passing rates for 74 fields in 22 Plans were 95.26±3.59,95.01±3.62(Local Dose),99.05±1.35,98.57±1.96(Max Dose)respectively.Two-related samples non-parametric tests suggested that the differences between the evaluation criteria were of statistical significance(Z=-7.220,-4.108,P<0.05).For PD method,theγ2D passing rates were 84.11%±1.35%(1 mm/1%),99.07%±1.35%(2 mm/2%),and 99.86%±1.35%(3 mm/3%).Two-related samples non-parametric tests suggested that the differences between evaluation criteria of PD method were statistically significant(Z=-7.475,-7.475,-6.906,P<0.05).For 74 fields and max dose,3 mm/3%evaluation criteria,two-related samples non-parametric tests suggested that the differences between PD and Oct1500 method were statistically significant(Z=-5.072,P<0.05).Conclusions Both methods can be used for Halcyon pretreatment plan QA.PD is superior to Oct1500 with respect to efficiency and spatial resolution-induced verification accuracy.The criteria of 2 mm/2%for PD,and Max Dose/3 mm/3%for Oct1500 was suggested.