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Mathematical Problems in Engineering
Volume 2012 (2012), Article ID 696212, 16 pages
Research Article

Noise Estimation for Single-Slice Sinogram of Low-Dose X-Ray Computed Tomography Using Homogenous Patch

1Visual Computing and Virtual Reality Key Laboratory Of Sichuan Province, Sichuan Normal University, Chengdu 610101, China
2School of Automation Engineering, University of Electronic Science and Technology of China, Chengdu 610054, China
3School of Information Science & Technology, East China Normal University, no. 500, Dong-Chuan Road, Shanghai 200241, China

Received 29 June 2011; Accepted 21 July 2011

Academic Editor: Shengyong Chen

Copyright © 2012 Zhiwu Liao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


We present a new method to estimate noise for a single-slice sinogram of low-dose CT based on the homogenous patches centered at a special pixel, called center point, which has the smallest variance among all sinogram pixels. The homogenous patch, composed by homogenous points, is formed by the points similar to the center point using similarity sorting, similarity decreasing searching, and variance analysis in a very large neighborhood (VLN) to avoid manual selection of parameter for similarity measures.Homogenous pixels in the VLN allow us find the largest number of samples, who have the highest similarities to the center point, for noise estimation, and the noise level can be estimated according to unbiased estimation.Experimental results show that for the simulated noisy sinograms, the method proposed in this paper can obtain satisfied noise estimation results, especially for sinograms with relatively serious noises.