Phase retrieval in X-ray phase-contrast imaging suitable for tomography

TLDR

In‑line phase‑contrast X‑ray imaging produces images where absorption and refraction both contribute, and quantitative analysis requires numerical phase retrieval; many such methods exist, but those suitable for tomography are non‑iterative, single‑image per angle, and follow a common pattern derived in different ways. The authors aim to outline this common pattern and compare the methods solely on phase‑retrieval performance, excluding tomographic reconstruction effects. They detail the derivations, approximations, and assumptions of each method, illustrate their similarities, present a simple scheme for selecting a reconstruction method, and perform numerical phase retrieval for all methods. Numerical phase‑retrieval results for all methods were obtained, enabling a direct comparison of their performance and validating the proposed selection scheme.

Abstract

In-line phase-contrast X-ray imaging provides images where both absorption and refraction contribute. For quantitative analysis of these images, the phase needs to be retrieved numerically. There are many phase-retrieval methods available. Those suitable for phase-contrast tomography, i.e., non-iterative phase-retrieval methods that use only one image at each projection angle, all follow the same pattern though derived in different ways. We outline this pattern and use it to compare the methods to each other, considering only phase-retrieval performance and not the additional effects of tomographic reconstruction. We also outline derivations, approximations and assumptions, and show which methods are similar or identical and how they relate to each other. A simple scheme for choosing reconstruction method is presented, and numerical phase-retrieval performed for all methods.