Design of Acquisition Schemes and Setup Geometry for Anisotropic X-ray Dark-Field Tomography (AXDT)

Y Sharma,F Pfeiffer,F Schaff,T Lasser,M Wieczorek

doi:10.1038/s41598-017-03329-0

Abstract

Anisotropic X-ray Dark-field Tomography (AXDT) is a new imaging technique for reconstructing the three-dimensional scattering profile within a sample using the dark-field signal measured in an X-ray grating interferometry setup. As in any tomographic measurement, the acquisition geometry plays a key role in the accurate reconstruction of the scattering information. More- over, the anisotropic nature of the dark-field signal poses additional challenges for designing the acquisition protocols. In this work, we present an efficient approach to measure scattering orientations spread over the unit sphere and prove its efficacy using the knowledge from conventional tomography. In addition, we conclude (using analytical and experimental results) that placing the gratings such that the grating bars make an angle of 45 degrees with respect to the vertical direction is the optimal setup configuration for AXDT.

Highlights

Malecki et al.[16] presented the first fully three-dimensional directional dark-field imaging method and termed it “X-ray Tensor Tomography” (XTT)
We present an analysis of the acquisition schemes designed in the previous section with respect to the setup geometry and its limitations
We use null space analysis to demonstrate the correlation of these schemes with the Anisotropic X-ray Dark-field Tomography (AXDT) reconstruction

Summary

Introduction

Malecki et al.[16] presented the first fully three-dimensional directional dark-field imaging method and termed it “X-ray Tensor Tomography” (XTT). The tensor approximation, is insufficient for recovering multiple scattering orientations in a single volume element which is especially relevant since the structures probed with this technique are typically smaller than the spatial resolution To overcome this limitation, Wieczorek et al.[18] presented a technique termed “Anisotropic X-ray Dark-field Tomography” (AXDT) which reconstructs the scattering profile as a spherical function represented using spherical harmonics. Wieczorek et al.[18] presented a technique termed “Anisotropic X-ray Dark-field Tomography” (AXDT) which reconstructs the scattering profile as a spherical function represented using spherical harmonics This method provides a more accurate and robust representation of the three-dimensional scattering profile and allows for the extraction of multiple scattering orientations in a single volume element. We corroborate the theoretical findings with experimental results for an industrially relevant fiber composite sample

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Conclusion