目的:探讨基于辐射自显影胶片EBT3剂量响应特性中非均匀性及其对螺旋断层放射治疗计划剂量验证的影响.方法:取10张同一批次EBT3胶片,每张胶片分为8个区域,胶片不同剂量曝光后扫描分析其剂量响应的非均匀性.建立剂量响应曲线A和修正的剂量响应曲线B.取10例TomoHD系统调强放疗计划并利用EBT3胶片进行剂量验证,采用不同剂量响应曲线A和B分别分析并比较不同γ值时两组通过率情况.结果:对10张胶片像素值的非均匀性进行分析,每张胶片像素值的变异系数分别为2.32％、1.32％、0.74％、1.20％、0.87％、0.72％、0.88％、0.72％、1.00％、0.70％;而10例放疗计划验证胶片采用A、B两种剂量响应曲线进行分析,γ=1.5、1.0时两组通过率具有显著统计学差异(P=0.007和0.008),而γ＜1时两组通过率虽略有差异但不具统计学意义.结论:辐射自显影胶片剂量响应非均匀性存在一定差异,且与胶片所受剂量有关,其非均匀性随着剂量增加而相对减小;临床验证中考虑EBT3剂量响应曲线的修正是有必要的,特别是低剂量.%Objective To investigate the dose-response non-uniformity of self-developing EBT3 film and its influence on the performance of the film for dose quality assurance of tomotherapy plan.Methods Ten EBT3 films from the same batch were selected for analysis.Each film was divided into 8 areas,and after exposure to irradiation of different doses,the doseresponse non-uniformity of the film was assessed,and the measured and corrected dose-response curves A and B were created.Ten intensity-modulated radiotherapy (IMRT) plans from the TomoHD system were selected for dose verification using EBT3 films,and the gamma passing rates were analyzed with the dose-response curves A and B.Results The nonuniformity of the pixel values in the 10 films was analyzed,and the coefficients of variationof the pixel values in each film were 2.32％,1.32％,0.74％,1.20％,0.87％,0.72％,0.88％,0.72％,1.00％,and 0.70％.Analysis of the 10 IMRT plans with the dose-response curves A and B showed that the passing rates of the films differed significantly between the two groups for gamma values of 1.5 (P=0.007) and 1.0 (P=0.008) but not for a gamma value below 1.0.Conclusion The selfdeveloping films showed differences in the dose-response non-uniformity,which was also related inversely with the exposure dose of the films.Correcting the EBT3 dose-response curves is necessary in clinical dose verification of the tomotherapy plans,especially for the low dose areas.
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