Overlapping Scanning Arcs of Limited-Angular Range for Dual-Energy CT

Abstract

Dual-energy computed tomography (DECT) is useful for material differentiation and quantification i n medical and industrial imaging applications, in which low- and high-kVp data are often collected over two full rotations. DECT with limited-angular-range (LAR) data can potentially reduce dose and time, and avoid collision, and thus is of high practical interest. In this work, we investigate a directional-total-variation (DTV) algorithm for image reconstruction in DECT from low-and high-kVp data over overlapping scanning arcs of LAR that are less than 180°. Image reconstruction is formulated as a convex optimization problem in which data-ℓ <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> is minimized with constraints on image’s DTVs along orthogonal axes. A first-order primal-dual algorithm is tailored to solve the optimization problem and thus reconstruct images. Numerical studies are carried out with a digital breast phantom from data over LARs spanning from 14° to 180°. The results reveal that dual-energy images obtained with the DTV algorithm over LARs as low as 60° show substantially reduced artifacts that are otherwise observed in FBP images in DECT. The iodine-contrast concentrations estimated from LAR data are also in good agreement with those from the full-angular-range data. The results acquired in the work may engender insights into the design of DECT with LAR scanning configurations of practical application significance.