title: Polyenergetic known-component CT reconstruction with unknown material compositions and unknown x-ray spectra.
abstract: Metal artifacts can cause substantial image quality issues in computed tomography. This is particularly true in interventional imaging where surgical tools or metal implants are in the field-of-view. Moreover, the region-of-interest is often near such devices which is exactly where image quality degradations are largest. Previous work on known-component reconstruction (KCR) has shown the incorporation of a physical model (e.g. shape, material composition, etc) of the metal component into the reconstruction algorithm can significantly reduce artifacts even near the edge of a metal component. However, for such approaches to be effective, they must have an accurate model of the component that include energy-dependent properties of both the metal device and the CT scanner, placing a burden on system characterization and component material knowledge. In this work, we propose a modified KCR approach that adopts a mixed forward model with a polyenergetic model for the component and a monoenergetic model for the background anatomy. This new approach called Poly-KCR jointly estimates a spectral transfer function associated with known components in addition to the background attenuation values. Thus, this approach eliminates both the need to know component material composition a prior as well as the requirement for an energy-dependent characterization of the CT scanner. We demonstrate the efficacy of this novel approach and illustrate its improved performance over traditional and model-based iterative reconstruction methods in both simulation studies and in physical data including an implanted cadaver sample.
authors.affiliation: Department of Biomedical Engineering, Johns Hopkins University, Baltimore MD, United States of America.
authors.forename: S
authors.initials: S
authors.lastname: Xu
authors.forename: A
authors.initials: A
authors.lastname: Uneri
authors.forename: A Jay
authors.initials: AJ
authors.lastname: Khanna
authors.forename: J H
authors.initials: JH
authors.lastname: Siewerdsen
authors.forename: J W
authors.initials: JW
authors.lastname: Stayman
mesh_terms: D000465:Algorithms; D016477:Artifacts; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008670:Metals / Q000528:radiation effects*; D019047:Phantoms, Imaging; D019736:Prostheses and Implants / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D014965:X-Rays
chemical_list: D008670:Metals