Quantifying the x-ray dark-field signal in single-grid imaging

TL;DR

This paper introduces a new method to quantify x-ray dark-field signals in single-grid imaging, relating the signal to microstructure count, enabling quantitative analysis with minimal exposures.

Contribution

A novel approach models sample-induced changes to extract and quantify dark-field signals from single-grid x-ray imaging data.

Findings

Dark-field scattering angle proportional to N^{2.19/2}

Deviation from the theoretical √N model observed

Method effective for small samples with limited exposures

Abstract

X-ray dark-field imaging reveals the sample microstructure that is unresolved when using conventional methods of x-ray imaging. In this paper, we derive a new method to extract and quantify the x-ray dark-field signal collected using a single-grid imaging set-up, and relate the signal strength to the number of sample microstructures, $N$. This was achieved by modelling sample-induced changes to the shadow of the upstream grid, and fitting experimental data to this model. Our results suggested that the dark-field scattering angle from our spherical microstructures is proportional to $^{2.19}\sqrt{N}$, which deviated from the theoretical model of $\sqrt{N}$, but was not inconsistent with results from other experimental methods. We believe the approach outlined here can equip quantitative dark-field imaging of small samples, particularly in cases where only one sample exposure is possible, either due to sample movement or radiation dose limitations. Future directions include an extension into directional dark-field imaging.