Improving of the SNR of the low-dose CT image is a crucial issue for the low-dose CT application.In this paper

we employed an EM (expectation-maximization) scheme to restore the sinogram by the maximum a conditional expectation of the posteriori estimation

based on the special statistical property of low-dose CT sinogram

i.e.

the extremely low SNR and the non-stationary noise property of the sinogram data.At the same time

parameters of the statistical model were estimated in the EM scheme.In addition

a Gibbs sampler was used to solve the computation problem.The effectiveness of the proposed algorithm was validated by both computer simulations and experimental studies.The gain of the proposed approach over other methods was quantified by noise-resolution tradeoff curves.