中文摘要：

为了在稀疏角度扫描条件下更好地去除重建图像中的条状伪影和保留细节信息,将非局部先验引入锥束CT重建.基于有序子集投影划分思想,提出了有序子窗搜索算法,用以解决锥束CT迭代重建算法中非局部先验计算量过大的问题.该算法将每一个体素的搜索窗划分为M个不重复的子窗,每次迭代中选取不同子集元素计算非局部先验约束.实验结果表明,通过非局部先验约束,可以获得质量更好的重建图像.而且无论是在主观视觉效果方面,还是在峰值信噪比和结构相似性指标等客观评价指标方面,有序子窗搜索算法和传统非局部算法的重建结果均无明显差别,但前者可以明显降低先验项的时间复杂度.

英文摘要：

To remove streak artifacts and preserve detail information under the condition of sparse viewscan,the non-local prior is introduced into the cone-beam computed tomography（ CT） reconstruction. Based on the idea of ordered subsets in the partition of projection images,the ordered subwindowsearch method is proposed to solve the problem that the non-local prior calculation is too massive in the iterative reconstruction algorithm of cone-beam CT. The search windowof each voxel is divided into Mnon-repetitive sub-windows in the proposed algorithm. Different sub-windows are selected to calculate the non-local prior in each iteration. The experimental results showthat better reconstruction images can be obtained by the non-local prior. And there is no obvious difference between the proposed algorithm and the conventional non-local algorithm in terms of the subjective visual effect and the objective evaluation indices such as the peak signal-to-noise ratio and the structural similarity index. But the time complexity of the non-local prior is reduced obviously by the former.