不同探测器测量射波刀输出因子比较分析  

Comparison of different detectors in output factor measurement for the CyberKnife system

作　　者：李君[1] 杨瑞杰[1] 张喜乐[1] 刘路[1] 潘羽晞 王俊杰[1] 

机构地区：[1]北京大学第三医院肿瘤放疗科,100191

出　　处：《中华放射肿瘤学杂志》2017年第11期1322-1326,共5页Chinese Journal of Radiation Oncology

基　　金：国家自然科学基金资助项目（81071237）

摘　　要：目的 比较分析5种不同探测器测量射波刀输出因子,以选择适合的探测器。方法分别使用电离室探测器PTW30013、PTW31010,半导体探测器PTW 60017、60018,宝石探测器PTW60019及EBT3胶片测量射波刀12个孔径准直器的输出因子。比较分析不同探测器及探测器放置方向测量的输出因子。结果 准直器孔径〉30 mm时5种探测器测量的输出因子差异〈1%,准直器孔径〈30 mm时不同探测器测量结果差异较大,准直器孔径越小差异越大。与胶片测量结果比较,PTW60019与胶片的一致性最好,偏差〈2%。半导体探测器测量结果稍高,电离室探测器测量结果过小。探测器放置方向不同,输出因子测量结果不同。PTW60019探测器平行射野中心轴放置时,测量的输出因子比垂直射野中心轴放置的结果偏低,PTW31010探测器测量结果相反。结论 准直器孔径〉30 mm时PTW31010、PTW60017、60018及PTW60019可直接用于射波刀输出因子测量,准直器孔径〈30 mm时需要对上述探测器的测量结果进行修正。PTW30013不适合小野输出因子测量。Objective To compare five different detectors in output factor （OF） measurement for the CyberKnife （CK） system,and to select a suitable detector. Methods OFs for 12 different sizes of CK collimators were measured by EBT3 films and 5 different commercially available detectors,consisting of diode detectors PTW 60017 and PTW 60018,ionizing chamber detectors PTW 31010 and PTW 30013,and diamond detector PTW 600019.OF was compared between different detectors and different measurement orientations. Resutls When the size of collimator was larger than 30 mm,the OF deviation among five detectors was less than 1%.When the size of collimator was smaller than 30 mm,however,the OF deviation among five detectors became large and obviously increased with the decrease in the size of collimator. With a OF deviation less than 2%,PTW 60019 achieved the best agreement with films. Compared with films,diode detectors gave slightly higher OFs,while ionizing chamber detectors gave much smaller OFs. The OF measurement was also affected by measurement orientation. PTW 60019 gave a smaller OF in the direction parallel to the central axis than in the direction perpendicular to the central axis of the radiation field,while PTW 31010 had an opposite result. Conclutions When the size of collimator is larger than 30 mm,PTW 31010,PTW 60017,PTW 60018,and PTW 60019 can be directly used for the OF measurement. When the size of collimator is smaller than 30 mm,correction is needed for the OF measurement using the above detectors. PTW 30013 is not suitable for the OF measurement in the small radiation field.

关 键 词：小照射野 输出因子 探测器 射波刀 

分 类 号：R730.55[医药卫生—肿瘤]