Analyzer-less X-ray Interferometry with Super-Resolution Methods

TL;DR

This paper introduces a super-resolution iterative reconstruction technique for analyzer-less X-ray interferometry, enabling high-quality imaging with reduced dose and larger fringe periods, even with detectors below the Nyquist rate.

Contribution

It presents a novel super-resolution method that allows for analyzer-less X-ray interferometry using detectors with sub-Nyquist pixel sizes, reducing X-ray dose and expanding imaging capabilities.

Findings

Robust super-resolution reconstruction with noisy data

Effective imaging with detectors of 30-75 micron pixels

Enables higher autocorrelation lengths without analyzers

Abstract

X-ray interferometry provides valuable information in terms of attenuation, small-angle scatter, and differential phase contrast. This multi-modal contrast can aid in many clinical applications, such as lung diseases and breast cancer. However, standard interferometry has an analyzer grating that can increase the dose requirement to maintain the same image quality as a standard X-ray. We propose the use of super-resolution methods for X-ray grating interferometry without an analyzer, with detectors that fail to meet the Nyquist sampling rate needed for traditional image recovery algorithms. We use the phase-steps judiciously to nominally recover the sampling and iteratively recover the visibility and the object parameters. This method enables Talbot-Lau interferometry without the X-ray absorbing analyzer. It also allows for smaller fringe periods (Pd) or higher autocorrelation lengths for the analyzer-less Modulated Phase Grating Interferometer. This will allow for reduced X-ray dose and higher autocorrelation lengths than previously accessible. We demonstrate the use of super-resolution methods to iteratively reconstruct attenuation, differential-phase, and dark-field images using simulations of two-dimensional lung phantoms with lesions. We tested a direct detector with 75 micron and 30 micron pixel size, modeled using a box-binning. We also tested scintillator-based detectors with 50 micron and 75 micron pixel sizes, modeled using Gaussian PSFs. We show that our super-resolution iterative reconstruction methods are robust to noise and can be used to improve grating interferometry for cases where traditional algorithms cannot be used.