A fast iterative soft-threshold algorithm is proposed to accelerate the convergence of iterative soft-threshold algorithm for image reconstruction from few-view projections.The algorithm bases on total variation minimization. Simultaneous algebraic reconstruction technique(SART)is used to reconstruct image from few-view projections and to meet the constraint of the projection data. Then discrete gradient transform(DGT)of the reconstructed image is calculated and the soft-threshold filtering is performed on the DGT. Finally the reconstructed image is updated using the pseudo-inverse of the DGT. The proposed algorithm takes the images in previous two iterations as the input image for a new iteration
and hence the convergence is accelerated. Experimental results and comparisons with the SART algorithm
the fast iterative soft-thr
eshold algorithm with Harr wavelet constraint
and the iterative soft-threshold filtering algorithm with total variation constraint on the projections of Shepp-Logan phantom under the conditions without noise and corrupted by Poisson noise assuming with 5×10
4
and 2×10
5
photons per detector element show that the proposed algorithm can not only speed up the convergence
but also reduce the relative reconstruction error of images.
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references
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