title: Analytical evaluation of the signal and noise propagation in x-ray differential phase-contrast computed tomography.
abstract: We analyze the signal and noise propagation of differential phase-contrast computed tomography (PCT) compared with conventional attenuation-based computed tomography (CT) from a theoretical point of view. This work focuses on grating-based differential phase-contrast imaging. A mathematical framework is derived that is able to analytically predict the relative performance of both imaging techniques in the sense of the relative contrast-to-noise ratio for the contrast of any two materials. Two fundamentally different properties of PCT compared with CT are identified. First, the noise power spectra show qualitatively different characteristics implying a resolution-dependent performance ratio. The break-even point is derived analytically as a function of system parameters such as geometry and visibility. A superior performance of PCT compared with CT can only be achieved at a sufficiently high spatial resolution. Second, due to periodicity of phase information which is non-ambiguous only in a bounded interval statistical phase wrapping can occur. This effect causes a collapse of information propagation for low signals which limits the applicability of phase-contrast imaging at low dose.
authors.affiliation: Siemens AG Healthcare Sector, H IM CT R&D PA, Siemensstrasse 1, D-91301 Forchheim, Germany. rainer.raupach@siemens.com
authors.forename: Rainer
authors.initials: R
authors.lastname: Raupach
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Flohr
mesh_terms: D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D014057:Tomography, X-Ray Computed / Q000379:methods*