Iterative image reconstruction for low-dose x-ray CT using a sinogram restoration induced edge-preserving prior

Low-dose x-ray computed tomography (CT) scan is clinically desired. However, the quality of low-dose CT image is severely degraded due to excessive photon quantum noise and electronic noise. To improve the quality of CT image with lower milliampere-seconds (mAs), in this study, we developed an iterative image reconstruction algorithm based on the maximum a posterior (MAP) principle. To preserve the edges of the reconstructed image, an edge-preserving prior was designed using a reference image reconstructed from the restored sinogram via a sinogram restoration induced non-local means image filter. For simplicity, the present approach is named as “MAP-SRNLM”. Experimental results demonstrate that the present algorithm can achieve more significant gains than the existing algorithms in terms of noise reduction, contrast-to-noise ratio and resolution preservation.