统计过程控制方法在加速器质量保证中的应用

The application of statistical process control in linac quality assurance

目的应用统计过程控制（SPC）方法改进加速器质量保证（QA）工作。方法应用SPC方法对QA数据设置控制界限，绘制均值-极差控制图，区分随机误差和系统误差。为了方便应用，用Visual Basic编程开发了SPC的质量控制软件QA—MANAGER。针对6MVX射线的输出剂量检测项目，应用SPC方法分析了两个案例。结果在案例中，SPC方法成功检测到发生的系统误差。结论在加速器QA中使用SPC方法，有助于发现系统偏差，对异常趋势提出预警，以便及时采取措施，消除异常，恢复过程的稳定，从而达到控制质量的目的。

Objective To improving linac quality assurance （QA） program with statistical process control （SPC） method. Methods SPC is applied to set the control limit of QA data, draw charts and differentiate the random and systematic errors. A SPC quality assurance software named QA_MANAGER has been developed by VB programming for clinical use. Two clinical cases are analyzed with SPC to study daily output QA of a 6MV photon beam. Results In the clinical case, the SPC is able to identify the systematic errors. Conclusion The SPC application may be assistant to detect systematic errors in linac quality assurance thus it alarms the abnormal trend to eliminate the systematic errors and improves quality control.