Tomographic phase and attenuation extraction for a sample composed of unknown materials using X-ray propagation-based phase-contrast imaging

TL;DR

This paper introduces a novel PB-PCXI algorithm that extracts attenuation and refraction properties of unknown materials in a sample using single-distance, phase-contrast imaging without prior sample information, demonstrated on breast tissue.

Contribution

The method enables accurate extraction of material properties from unknown samples using a single-distance phase-contrast approach without prior knowledge.

Findings

Achieved 0.6-2.4% accuracy in refraction measurement for breast tissue.

Requires only one exposure per tomographic angle, reducing radiation dose.

Applicable to samples with unknown material composition.

Abstract

Propagation-based phase-contrast X-ray imaging (PB-PCXI) generates image contrast by utilizing sample-imposed phase-shifts. This has proven useful when imaging weakly-attenuating samples, as conventional attenuation-based imaging does not always provide adequate contrast. We present a PB-PCXI algorithm capable of extracting the X-ray attenuation, $\beta$, and refraction, $\delta$, components of the complex refractive index of distinct materials within an unknown sample. The method involves curve-fitting an error-function-based model to a phase-retrieved interface in a PB-PCXI tomographic reconstruction, which is obtained when Paganin-type phase-retrieval is applied with incorrect values of $\delta$ and $\beta$. The fit parameters can then be used to calculate true $\delta$ and $\beta$ values for composite materials. This approach requires no a priori sample information, making it broadly applicable. Our PB-PCXI reconstruction is single distance, requiring only one exposure per tomographic angle, which is important for radiosensitive samples. We apply this approach to a breast-tissue sample, recovering the refraction component, $\delta$, with 0.6 - 2.4\% accuracy compared to theoretical values.