Abstract
We present an alternative laboratory implementation of x-ray phase-contrast tomography through a beam-tracking approach. A nonmicrofocal rotating anode source is combined with a high-resolution detector and an absorbing mask to obtain attenuation, phase, and ultra-small-angle scattering tomograms of different specimens. A theoretical model is also presented which justifies the implementation of beam tracking with polychromatic sources and provides quantitative values of attenuation and phase, under the assumption of low sample attenuation. The method is tested on a variety of samples featuring both large and small x-ray attenuation, phase, and scattering signals. The complementarity of the contrast channels can enable subtle distinctions between materials and tissue types, which appear indistinguishable to conventional tomography scanners.
Highlights
X-ray imaging is a widely used technique for the study and investigation of specimens’ internal structure in different fields of application
We present an implementation of beamtracking phase-contrast computed tomography (CT) with a nonmicrofocal laboratory setup
The method can reconstruct the three-dimensional maps of attenuation, phase, and ultra-small-angle x-ray scattering (USAXS) of a given sample
Summary
X-ray imaging is a widely used technique for the study and investigation of specimens’ internal structure in different fields of application. X rays traveling through matter are partially attenuated, and the degree of attenuation depends on the sample’s chemical composition and density. This is the only contrast mechanism in standard, attenuation-based x-ray imaging. An alternative approach is represented by x-ray phase-contrast imaging (XPCI). In x-ray imaging, a sample can be described in terms of its complex refractive index n 1⁄4 1 − δ þ iβ. The parameter β is responsible for x-ray attenuation, while δ describes phase effects
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