CT系统的参数标定及成像

CT System Parameter Calibration and Imaging

摘要: 针对CT系统的参数标定和成像问题，本文通过几何分析、图形重建算法实现了CT系统的参数标定和未知介质相关信息的确定，并利用参数标定的精度和稳定性确定更优的CT标定模板。我们首先分析了数据的关系，求得探测器单元之间的距离。然后建立合理的直角坐标系，利用椭圆的几何知识标定CT系统的参数。为了对未知图形进行重建，我们选择了滤波反投影算法(FBP)和代数重建算法(ART)。得到未知介质的相关信息以及10个点的吸收率。我们利用标定模板的原图形和重建图形，计算某两点间距离的相对误差和CT值的标准误差，从而分析标定模板的精度和稳定性。为了对其进行改进，在Caphan体模的基础上，确定了一个新的标定模板。经验证，新模板参数标定的精度和稳定性都有所提高。

Abstract: Aiming at the parameter calibration and imaging problem of CT system, this paper realizes the ca-libration of CT system parameters and the information of unknown medium through geometric analysis and graph reconstruction algorithm, and uses the accuracy and stability of parameter ca-libration to determine the better CT calibration template. We first analyze the relationship of the data and find the distance between the detector units, then establish a reasonable Cartesian coor-dinate system and use the geometric knowledge of the ellipse to calibrate the parameters of the CT system. In order to reconstruct the unknown image, we chose the filtered back projection algorithm (FBP) and the algebraic reconstruction algorithm (ART) to get information about the unknown medium and the absorption rate of 10 points. We use the original pattern and the reconstructed image of the calibration template to calculate the relative error of the distance between two points and the standard error of the CT value, so as to analyze the accuracy and stability of the calibration template. In order to improve it, based on the Caphan phantom, a new calibration template was established. After verification, the accuracy and stability of the calibration of the new template parameters have been improved.