In medical dual-energy CT, projection-domain decomposition is typically used to process the acquired two projection datasets. However, when a high atomic-number contrast-agent is introduced, its K-edge discontinuity challenges this method. In this work, we take advantage of the fact that the contrast agent and its solvent are known in advance and propose to first decompose the attenuation coefficient functions of the contrast agent and its solvent to estimate the attenuation contribution of the K-shell photoelectric. Then, the contribution of the K-edge attenuation to the projection data is eliminated and the problem is decomposed to determine the attenuation coefficient functions of the other biological materials. Numerical experiments are shown to verify that the proposed method can give better results with less artifacts than the result of the direct projection-domain decomposition. Moreover, the variances of the decomposition coefficients, which is the index of the noise level of the decomposition coefficient image on the contrast regions, are smaller.
Keywords: Computed tomography; Contrast agent; Dual energy; K-edge; Material decomposition.
Copyright © 2017. Published by Elsevier Ltd.