Beam hardening correction in polychromatic x-ray grating interferometry.

Aimin Yan,Hong Liu,Xizeng Wu

doi:10.1364/oe.25.024690

Aimin Yan, Hong Liu + Show 1 more

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https://doi.org/10.1364/oe.25.024690

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Abstract

The beam hardening is one of the two causes of the fringe shift distortion in polychromatic X-ray grating interferometry. Based on the assumption of the uniform energy dependence, we developed a novel analytic approach to accurately retrieve the monochromatic attenuation function and fringe phase shift from the polychromatic measurement. This approach provides a useful tool for precise measurement of sample electron density distribution in X-ray grating interferometry.

Highlights

In recent years, X-ray grating interferometry, a differential x-ray phase-contrast imaging technique, has been an active field of x-ray imaging research
As x-ray traverses the phantom, different projection-thickness generates different X-ray spectrum shifts. For this phantom design, the beam hardening effects will manifest itself as the uneven magnitudes of the polychromatic fringe shift φm,Poly(x) over the two slopes
In grating based X-ray phase contrast imaging, the most important task is to extract the monochromatic fringe phase shifts, which are critical to quantitative reconstruction of sample electron density distribution

Summary

Introduction

X-ray grating interferometry, a differential x-ray phase-contrast imaging technique, has been an active field of x-ray imaging research. This phase contrast imaging technique usually employs a Talbot-Lau interferometer [4, 20,21,22], which consists of an X-ray source, a source grating G0, a phase grating G1 and an imaging detector. Note that in another Talbot-Lau interferometer setup one employs an absorbing grating placed in front of the detector as the analyzer to extract the fringe shift generated by the sample [4, 20,21,22]. For one-dimensional phase grating interferometers with a monochromatic source of photon energy E, the Fourier expansion of the fringe intensity pattern I(Mg x, Mg y; E) is given by the following expression: I(Mg x, Mg y; E)

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