Abstract
Limited-angle computed tomography (CT) has great impact in some clinical applications. Existing iterative reconstruction algorithms could not reconstruct high-quality images, leading to severe artifacts nearby edges. Optimal selection of initial image would influence the iterative reconstruction performance but has not been studied deeply yet. In this work, we proposed to generate optimized initial image followed by total variation (TV) based iterative reconstruction considering the feature of image symmetry. The simulated data and real data reconstruction results indicate that the proposed method effectively removes the artifacts nearby edges.
Highlights
Computed tomography (CT) has been applied extensively in clinical diagnosis
We propose an initialization procedure for limited-angle CT iterative image reconstruction when an object’s outer contour is roughly axis-symmetrical
For numerical experiments, compared with zero image and Filtered back projection (FBP) image as initial images for projections onto convex sets (POCS)-total variation (TV), results by our method are better with 92% (0.0002 < 0.0024) gains in terms of mean square error (MSE) measure and with 46% (22.99 dB > 12.42 dB) gains in terms of signal to noise ratio (SNR) measure
Summary
Computed tomography (CT) has been applied extensively in clinical diagnosis. Under some CT applications, limited-angle scan mode has deserved wide interest [1] since it has to be used in several practical cases such as large object size [2], short exposure time [3], and restricted scanning [4]. Advanced iterative algorithms have been developed, such as singular value decomposition [6], wavelet decomposition [7], and projections onto convex sets (POCS) [8] These methods cannot well solve edge distortions, smooth artifacts nearby edges are effectively reduced. POCS-TV and other TV based methods still cannot produce satisfactory results, and large amount of iterations is needed to make the reconstruction converge. We propose an iterative image reconstruction algorithm with optimized initial image for limited-angle CT. The artifacts-removed image is regarded as initial image for iterative reconstruction (POCS-TV is applied in this paper). We addressed limited-angle artifacts in POCS-TV, already evidenced in the cited paper [18], proposing a novel initialization procedure.
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