应用EP ID代替胶片法对MLC的质控研究  

The study of electronic portal imaging devices for the position accuracy of multi-leaf collimator instead of the film

作　　者：曹征[1] 李红霞[1] 鲍扬漪[2] 洪德雄 

机构地区：[1]合肥市第一人民医院滨湖医院血液肿瘤科放疗中心,230061 [2]合肥市第一人民医院滨湖医院血液肿瘤科, 230061

出　　处：《中华放射肿瘤学杂志》2015年第5期573-577,共5页Chinese Journal of Radiation Oncology

摘　　要：目的：研究EPID代替胶片对加速器MLC的质控方法并探讨其在任意机架角度下的可行性。方法采用RIT113软件对EPID影像和EBT3胶片影像数据进行分析。以EBT3胶片射野边缘50％等剂量曲线位置定义MLC叶片实际位置，在同一射野条件下EPID影像数据中找到MLC叶片实际位置所对应百分剂量值，从而完成EPID到EBT3胶片的替代过程。结果加速器机架角0°时，以EBT3胶片确定的MLC叶片位置处EPID影像对应的期望百分剂量值为44％，最大MLC位置误差为0.12 mm。任意机架角度时，EPID影像数据通过与0°结果做距离一致性分析比对，半径为0.5 mm时所有像素点均通过。结论采用EPID代替胶片对加速器MLC叶片到位质控方法可行，且其精度满足临床要求并适用于任意机架角的测量，具有广泛推广和借鉴意义。Objective To explore the application of the electronic portal imaging device （ EPID） to test on MLC leaves position accuracy instead of EBT3 film, and the feasibility analysis under any gantry angle. Methods RIT113 software was used to analyze the image data of radiochromic film EBT3 and EPID of Siemens ARTISTE accelerator. The replacement process from EBT3 film to EPID for the test MLC leaves positioning was completed by defining the positions of 50% isodose curve of the field edge of EBT3 after radiation as the actual positions of MLC leaves, therefore finding out the percentage isodose value of the same position in the EPID portal imaging from the corresponding radiation field. Results When the accelerator gantry angle was 0, the mean percentage isodose value was 44% at the MLC leaves positions determined by EBT3, and the maximum position error of MLC leaves is 0.12 mm. When the accelerator gantry was any other angles, the results were compared with the zero angle situation through DTA, all of the points passed when the DTA radium was 0.5 mm. Conclusions Using EPID instead of EBT3 to do the test MLC leaves positioning is feasible, furthermore, it is suitable under any gantry angle with excellent accuracy for the clinical practive, which deserves to be widely spread.

关 键 词：电子射野影像装置 放射自显影胶片 多叶准直器 质量控制 模体 

分 类 号：R730.55[医药卫生—肿瘤]