【摘要】 为了研究不同卷积核和内插方式对重组图象质量的影响,我们编写了供传输型CT 用的程序。程序中除考虑卷积核和内插方式可更换外,还考虑了初始摄象角,摄象覆盖范围和图象重组区域不同的情况。采用了具有不同长短轴的椭园作为产生模拟数据的模型。这些不同尺寸的椭园可具有不同的密度,中心位置和方位。给出了它们的近似 Radon变换。以及使用 Lakshminarayanan.Shepp-Logan 等卷积核的结果。比较了用这个方法和用两单反投影法所得重组图象的质量。文中对重组图象的质量与模型原数据也进行了比较。除了用单行数值比较法外,还计算了重组和数学模型之间的归一化均方根偏差、归一化平均偏差和最大偏差。更多还原

【Abstract】 In order to study the quality of CT image reconstruction using different filtering functions and interpolation algorithms in the convolution-backprojection methods,a practical computer program for the transmission CT system is Prese- nted in this paper.In this program not only the filtering and interpolation functions can be changed,but the initial irradiation angle,the ray beam cove- rage,and the reconstruction region can also be arbitrarily selected. A set of ellipses of different major and minor axis lengths is used as the phantom for generating the simulated projection data.The density,size,center and direction of axis of these ellipses can be individually assigned.As an exam- ple,the,simulated Radon transformation of the phantom and the results of reconstruction using R-L or S-L filtering function are given,and the quality of the reconstructed images is examined and compared with that obtained with simple back projection algorithm. The reconstructed image values are also compared with the original data of the phantom.Besides a comparison of the characteristic line,the normalized mean square root error,the normalized mean error,and the maximum deviation are calculated and discussed.更多还原