SPULTRA: Low-Dose CT Image Reconstruction with Joint Statistical and Learned Image Models

Abstract

Low-dose CT image reconstruction has been a popular research topic in recent years. A typical reconstruction method based on post-log measurements is called penalized weighted-least squares (PWLS). Due to the underlying limitations of the post-log statistical model, the PWLS reconstruction quality is often degraded in low-dose scans. This paper investigates a shifted-Poisson (SP) model based likelihood function that uses the pre-log raw measurements that better represents the measurement statistics, together with a data-driven regularizer exploiting a Union of Learned TRAnsforms (SPULTRA). Both the SP induced data-fidelity term and the regularizer in the proposed framework are nonconvex. The proposed SPULTRA algorithm uses quadratic surrogate functions for the SP induced data-fidelity term. Each iteration involves a quadratic subproblem for updating the image, and a sparse coding and clustering subproblem that has a closed-form solution. The SPULTRA algorithm has a similar computational cost per iteration as its recent counterpart PWLS-ULTRA that uses post-log measurements, and it provides better image reconstruction quality than PWLS-ULTRA, especially in low-dose scans.

arXiv commentAccepted to IEEE Transaction on Medical Imaging

References in corpus (7)

• Learned Primal-dual Reconstruction
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Cited by in corpus (4)

• Transform Learning for Magnetic Resonance Image Reconstruction: From Model-based Learning to Building Neural Networks
• Unified Supervised-Unsupervised (SUPER) Learning for X-ray CT Image Reconstruction
• Multi-layer Residual Sparsifying Transform (MARS) Model for Low-dose CT Image Reconstruction
• Deep learning based dictionary learning and tomographic image reconstruction