应用二维电离室矩阵进行虚拟楔形板物理参数检测

摘要

目的 探讨二维电离室矩阵Matrixxenclution在加速器虚拟楔形板测量中的应用.方法 利用二维电离室矩阵及固体水测量西门子加速器的虚拟楔形角度与楔形因子以及不同虚拟楔形野二维面剂量分布,与TPS上生成相同条件下的剂量分布进行3 mm/3％标准γ分析,总结50次测量结果.结果 虚拟楔形野15°和30°方向的γ通过率分别为(91.47±1.76)％、(92.99±1.54)％和(93.27±1.24)％、(92.92±1.68)％.随射野增大及虚拟楔形角度增加,通过率有所增加,然对20cm×20 cm射野,60°剂量分布测量结果稍差.除小野、小楔形角度情况外最大楔形角偏差＜2°,楔形因子≈1,最大偏差≤0.05,计划剂量分布与实测剂量分布除大野、大角度楔形角度薄端剂量差外,具有良好一致性.结论 Matrixxenvlution用于加速器虚拟楔形野物理参数的检测具有一次摆位照射即可获得所有计算参数及剂量分布优点,是目前楔形野剂量验证较为快速、便捷、经济实用的QA工具之一.%Objective To investigate the virtual wedge (VW) dosimetric parameters with the ionization chamber array Matrixxenvlution.Methods Using Matrixxenvlution and solid water to measure and calculate Siemens accelerator's VW angle and VW factors of different fields and compare the wedge field dose distribution to that of treatment planning system (TPS) by gamma analysis,summarized the measurement results of 50 times.Results The γ pass rate (3 mm/ 3％) of 15° and 30° VW in both direction were (91.47 ± 1.76)％,(92.99 ± 1.54)％ and (93.27 ± 1.24)％,(93.27 ± 1.68)％,respectively,with the increase of filed size and the VW angle,but for 20 cm ×20 cm field and VW 60°,the result was not very good.The largest angle deviation ＜ 2° except small field size and wedge angle,VW factors were approximately equal to 1,the maximum deviation was no more than 0.05,plan dose distribution and the measured dose distribution have good consistency except large field with large wedge angle.Conclusions Matrixxenvlution used in the measurement of VW dosimetric parameters which can obtain all parameters for angle calculation and dose plane analysis with only once positioning,and become more rapid,convenient,economical and practical one of quality assurance tools for VW dose verification.