[Sparse angular CT projection onto convex set reconstruction using nonlocal means iterative modification].

Based on the fact that nonlocal means (NL-means) filtered image can likely produce an acceptable priori solution, we propose a sparse angular CT projection onto convex set (POCS) reconstruction using NL-means iterative modification. The new reconstruction scheme consists of two components, POCS and NL-means filter. In each phase of the sparse angular CT iterative reconstruction, we first used POCS algorithm to meet the identity and non-negativity of projection data, and then performed NL-means filter to the image obtained by POCS method for image quality improvement. Simulation experiments showed that the proposed POCS scheme can significantly improve the quality of sparse angular CT image by suppressing the noise and removing the streak-artifacts.