Abstract
Contrast-enhanced computed tomography (CECT) helps enhance the visibility for tumor imaging. When a high-Z contrast agent interacts with X-rays across its K-edge, X-ray photoelectric absorption would experience a sudden increment, resulting in a significant difference of the X-ray transmission intensity between the left and right energy windows of the K-edge. Using photon-counting detectors, the X-ray intensity data in the left and right windows of the K-edge can be measured simultaneously. The differential information of the two kinds of intensity data reflects the contrast-agent concentration distribution. K-edge differences between various matters allow opportunities for the identification of contrast agents in biomedical applications. In this paper, a general radon transform is established to link the contrast-agent concentration to X-ray intensity measurement data. An iterative algorithm is proposed to reconstruct a contrast-agent distribution and tissue attenuation background simultaneously. Comprehensive numerical simulations are performed to demonstrate the merits of the proposed method over the existing K-edge imaging methods. Our results show that the proposed method accurately quantifies a distribution of a contrast agent, optimizing the contrast-to-noise ratio at a high dose efficiency.
Highlights
Contrast-enhanced computed tomography (CECT) is widely used in clinical applications, and helps enhance the visibility and detection of tumors, especially for precancerous conditions [1,2,3,4,5]
Compared with conventional CT, CECT seems better than conventional CT in detecting small lesions, showing the range of lesions and staging tumors [7]
Discussions and conclusion The existing methods for K-edge imaging rely on either projection decomposition or image subtraction [10,17]
Summary
Contrast-enhanced computed tomography (CECT) is widely used in clinical applications, and helps enhance the visibility and detection of tumors, especially for precancerous conditions [1,2,3,4,5]. CECT improves the imaging performance, there is a need for an efficient and effective method that can enhance contrast especially between tumor and normal tissue, and reduce dose of radiation and contrast agent while keeping the diagnostic performance [8]. There is a sudden increase in the attenuation coefficient when X-ray photons of energy just across the K-edge interact with the involved high-Z elements which can be used as contrast agents for clinical/pre-clinical X-ray imaging [10]. Using the differential information of the two kinds of X-ray transmission intensity data measured with photon counting detectors, in this paper a general Radon transform is established, and an iterative algorithm is proposed to reconstruct the contrast-agent distribution and tissue attenuation background simultaneously.
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