国产加速器IMRT和VMAT的剂量学测试

Dosimetry test of domestically-made accelerator intensity-modulated radiation therapy and volumetric-modulated arc therapy

目的应用TG119报告中的测试例对联影公司URT-Linac 506C加速器和URT计划系统FF模型进行全面的评估。方法主要研究调强放疗(IMRT)和容积调强弧形治疗(VMAT)计划剂量目标、点剂量和剂量分布计算准确性。测试模体采用AAPM TG119号报告测试例模体,主要包括模拟多靶区、模拟前列腺肿瘤、模拟头颈肿瘤和模拟C形靶区(简单)等。使用指形电离室和胶片,在URT计划系统(临床实验版本)和URT-Linac 506C加速器上分别优化计算和测量剂量,并分析计划剂量和测量值之间的偏差。结果URT计划系统中的4个测试案例的计划剂量目标均满足TG119标准要求。对于不同案例点剂量验证,IMRT计划最大误差为2.62%,VMAT计划最大误差为3.90%,均满足TG119报告中点剂量误差小于4.5%的要求。复合剂量分布胶片测量结果的γ通过率IMRT计划均>97.50%,VMAT计划均>93.27%。结论URT-Linac 506C加速器和URTT放疗计划系统FF计算模型性能试验结果均达到TG119报告验证标准。

Objective To create AAPM TG 119 test plans for intensity-modulated radiation therapy(IMRT)and volumetric-modulated arc therapy(VMAT)in order to evaluate the accuracy of the United Imaging Healthcare's URT treatment planning system(URT-TPS).The plans were delivered to the phantom using the United Imaging Healthcare's URT-Linac 506C.Methods The overall accuracy of IMRT and VMAT planning,measurement,and analysis were evaluated for four test geometries provided by American Association of Physicists in Medicine(AAPM)Task Group Report 119(TG-119)on multi-target,prostate,head and neck and C-shape(easy).The dose distributions were measured in the coronal plane.The point measurements were measured by a Farmer type ion chamber and fluence measurements were completed with film and Delta4 phantom,respectively.Measured planar dose distributions were analyzed using gamma index with criteria 3%/3 mm.Results For IMRT and VMAT plans,the planning results matched the TG-119 planning results.Measured point doses of IMRT and VMAT were within 2.62%and 3.90%of the planned doses,respectively.Measured film dosimetry gamma values of IMRT and VMAT were>97.50%and>93.27%,respectively.Conclusion Based on these analyses which were performed in line with the TG119 recommendations,it is evident that the URT treatment planning system and URT-Linac 506C have commissioned IMRT and VMAT techniques with adequate accuracy.