基于加速器的锥形束CT系统机械精度的精确测量方法及其实现

目的:设计并实现一种锥形束CT（CBCT）机械精度的检测方法，可对CBCT的机械性能参数进行精确测量和分析（重复性在0.5 mm以内，测量误差在0.5 mm内，耗时数分钟）。方法:系统硬件包括双目红外相机、定位小球、注册笔和水平注册仪。双目红外相机可输出定位小球中心的空间坐标，利用定位小球中心位置坐标可计算出加速器机械等中心坐标，利用CBCT拍出的定位小球图像可计算出CBCT影像中心与加速器机械等中心的偏差，利用注册笔可计算出CBCT平板角度偏差。结果:在某医院加速器配备的CBCT上运用本方法进行3次测试和分析，得到加速器机械等中心坐标、CBCT影像等中心坐标、两等中心距离误差和CBCT平板打开垂直度等数据。结论:本研究提出的检测CBCT机械精度的方法操作过程较简单，结果精准，可重复性高，将复杂的质控过程数字化、自动化和简单化，给CBCT的日常质量检测带来非常大的便利，也为相关技术人员以及医护人员在临床上安全应用CBCT提供指导。【关键词】锥形束CT；红外双目相机；定位小球；机械等中心；影像等中心

Method for detecting the mechanical precision of cone-beam computed tomography device based on accelerator and its implementation

Objective To design and implement a mechanical precision detection method for measuring and analyzing the mechanical parameters of cone-beam computed tomography(CBCT)device,with the repeatability within 0.5 mm,measurement error within 0.5 mm and time consumption of a few minutes.Methods The system hardware included infrared binocular camera,positioning ball,registration pen and horizontal registered instrument.The infrared binocular camera output the central spatial coordinates of the positioning ball.According to the coordinates,the mechanical isocenter coordinate of accelerator was calculated.Moreover,the deviation between the mechanical isocenter of accelerator and the imaging isocenter of CBCT device was calculated based on the CBCT image of positioning point;and then registration pen was used to calculate CBCT flat angle errors.Results The proposed method was used to conduct 3 experiments on a CBCT device in a hospital to obtain the mechanical isocenter coordinate of accelerator,CBCT imaging isocenter coordinate,distance deviation between two isocenters,and CBCT flat angle errors,etc.Conclusion This proposed method for detecting the mechanical precision of CBCT device has the advantages of simple operation,accurate results and high repeatability,digitizing,automating and simplifying complicated quality control processes,which bring great convenience to daily quality inspection of CBCT device and provide guidance for relevant technical personnel and medical staff in the safe application of CBCT in clinic.