锥束CT的图像分块OSEM重建算法

在计算机断层成像（CT）中,有序子集最大期望值算法（OSEM）能够在较短的时间内重建出高质量的图像。对含有噪声的投影数据,投影旋转分度子集划分的不同会影响到图像的重建质量和收敛速度。针对三维锥束CT情况,研究了一种基于图像分块的变子集OSEM重建方法,该方法将图像空间分割成等大小的图像块,然后在迭代过程中,对于不同的图像块用变化的子集进行图像重建。计算机仿真实验表明：该方法在锥束CT图像重建中,能够在抑制噪声的同时提高重建图像的收敛速度。

OSEM reconstruction algorithm of cone-beam CT based on image block

In computed tomography,OSEM(Ordered Subsets Expectation Maximization) has good reconstructed image quality and costs less computation time.When there are noises in projection data,the image quality and convergence are influenced by the different subsets of projective orientation.To three dimensional cone beam CT,OSEM reconstruction algorithm with varied subsets based on image block is researched,the new means partition the image space into equal parts,then for different block image with varied subsets to reconstruct image after each iteration.Computer simulation experiment results show that,in cone-beam CT image reconstruction,this means can improve the convergence speed of image reconstruction and reduce the effect coming from the noise.