机载影像系统日检质控程序及结果分析

A daily quality assure procedure for the on board imager and analysis of the results

目的建立加速器机载影像（OBI）系统日检程序，测量得到各参数变化规律及误差范围，保证设备满足临床需要。方法每日对OBI系统进行安全检查、机械精度检查、2D／2D配准精度检查、治疗床运动精度检查。结果等中心一致性检测在左右、进出方向最大偏差分别为-0．7、0．8mm，x1、x2、Y2、Y1铅门偏差最大值分别为-2．1、2．2、±1．7、-2．1mm。OBI系统机械臂运动精度31％标准值为85．2cm、偏差为0mm，69％标准值为85．1cin、偏差为1mm。在左右、上下、前后方向2D／2D配准精度分别为0．46、1．35、-0．04mm，治疗床运动精度分别为-0．1、0．3、0．2mm。结论OBI系统日检能发现设备是否运转正常和满足临床要求，而对易变项目针对性提高关注度并及时处理和对较稳定项目适当调整检测频度都可以提高质控效率。

Objective Performing a daily quality assure （QA） program to get variation and error range of on board imager （OBI） system, so that the OBI system can meet the needs of clinical treatment. Methods The daily QA program including： mechanical accuracy, 2D/2D Shift calculations accuracy, couch motion accuracy. Results The max deviation was - 0. 7 mm in left-right （LR） direction and 0. 8 mm in superior-inferior （SI） direction in Linac＆ OBI isocenter accuracy check. The max deviations in 4 blades （x1 ,x2 ,Y2,Yl ） position accuracy check were： -2. 1 mm, 2. 2 mm, ＋ 1.7 mm, -2. 1 ram, In OBI mechanical arms position accuracy check, 31% standard data was 85.2 cm with 0 mm deviation;69% standard data was 85.1 cm with l mm deviation. In LR, SI and anterior-posterior direction, 2D/2D shift calculations accuracy was 0. 46 mm,1.35 mm, -0. 04 mm and couch motion accuracy was -0. 1 mm,0. 3 mm,0. 2 mm,respectively. Conclusions By performing the daily QA program, it could be found whether OBI works properly and satisfies the clinical use. The physicist can pay more attention to the parameters which change frequently, and adjust the frequency of the parameters which arc stable, so that working efficiently.