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...