应用Octavius体模配合PTW Seven29二维矩阵进行HT计划剂量验证

摘要

Objective To investigate the feasibility of dose verification of helical tomotherapy (HT) using the PTW Seven29 2D-ARRAY with Octavius phantom.Methods The 12 patients HT plan were verified with the PTW Seven29 2D-ARRAY combining Octavius phantom.The detector array was guided and registered by MVCT imaging,and measured dose distributions on the corresponding planes were compared with those calculated by the treatment planning system (TPS).Based on several different Gamma criteria,the Gamma analysis method was utilized to evaluate the dose verification.Results According to the different acceptance criteria combination of dose difference/distance to agreement at different threshold level including 3％/2 mm,3％/3 mm,3％/4 mm,3％/5 mm at TH5,TH10,TH20,TH30,the mean passing rates with γparameter ≤ 1 were all above 91.7％ and 93.9％ when PTW Seven29 2D-ARRAY was horizontal and vertical.The dose distribution measured by the 2D-ARRAY combining Octavius phantom was well consistent with that calculated by the TPS.Conclusions 2D-ARRAY with Octavius phantom can get satisfying results when used in HT plan dose verification and is a viable tool to replace traditional film dosimetry system in clinical quality assurance work.%目的 研究采用Octavius体模配合PTW Seven29二维探测器阵列对HT系统的调强计划实施剂量验证的可行性.方法 分别对二维矩阵行冠状位和矢状位测量,获取模体中冠状面和矢状面剂量分布.通过HT系统MVCT成像和配准消除床面沉降的影响,确保实现体模和探测器阵列的精确摆位.实施治疗质量保证计划照射后将二维探测器阵列测量获得的平面剂量分布与HT计划系统模体计划计算获得的平面剂量分布进行比较.对12例恶性肿瘤患者采用γ分析法进行HT计划剂量验证.结果 PTW Seven29二维探测器水平、垂直放置,阈值分别为TH5、TH10、TH20、TH30时,采用3％/2 mm、3％/3 mm、3％/4 mm、3％/5 mm标准的γ参数≤1的平均通过率均＞91.7％和93.9％.测量所得剂量分布与计算结果在相应平面的几何分布均呈现出良好的一致性.结论 Octavius体模配合PTW Seven29二维探测器阵列用于HT计划验证能获得令人满意结果.