Program Information
Algorithm-Enabled Varying Illumination Coverage Scan for Spectral CT
B Chen*, Z Zhang , E Sidky , D Xia , X Pan , The University of Chicago, Chicago, IL
Presentations
TH-AB-601-2 (Thursday, August 3, 2017) 7:30 AM - 9:30 AM Room: 601
Purpose: To demonstrate the potential of an optimization-based, one-step image reconstruction algorithm for enabling non-standard scanning configurations for spectral CT that involves no or minimum hardware modification.
Methods: An optimization-based, one-step inversion approach was developed to reconstruct basis images directly from measured spectral data. The approach consists of a non-linear data model, a non-convex optimization program, and a heuristic algorithm for numerically solving the non-convex optimization program. We have derived first-order optimality conditions and defined practical convergence conditions based on the former. We further investigated two non-standard dual-energy scanning configurations enabled by the developed algorithm, with split- and block-illumination coverage from low and high kVp at each view. These two scan configurations were considered as they can be readily implemented on existing conventional CT scanners with only minimum hardware modifications. Data from the two non-standard scan configurations, as well as a standard two-full-rotation configuration, were simulated from a numerical chest phantom. Inconsistencies, including noise and decomposition errors, are considered. Reconstructed basis images and monochromatic images at different energy levels are visually assessed and compared to the results from the standard two-full-rotation scan data. Profiles from the monochromatic images are also plotted for a quantitative impression of the results.
Results: While the basis images from split- and block-illumination scan data show some cross-talks as compared to the two-full-rotation scan, the monochromatic images are comparable to the two-full-rotation scan results. Profiles plots reveal that the truth and reconstructed monochromatic images agree reasonably well quantitatively
Conclusion: The work demonstrates the potential of an optimization-based, one-step image reconstruction method for enabling scanning configuration of practical significance. The study results suggest that the non-standard configurations considered, with split- and block-illumination coverage, yield monochromatic images visually comparable to those of the standard full-rotation scan configuration and also quantitatively close to the truth monochromatic images.
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