Cycloidal-spiral sampling for three-modal x-ray CT flyscans with two-dimensional phase sensitivity

TL;DR

This paper introduces a novel cycloidal-spiral sampling method for three-modal X-ray CT flyscans with two-dimensional phase sensitivity, enabling continuous scanning and reducing scan times without sacrificing image quality.

Contribution

The authors develop a cycloidal-spiral sampling scheme that allows continuous flyscans in three-modal X-ray CT, overcoming limitations of step-and-shoot methods.

Findings

Enables continuous flyscans with three-modal X-ray CT

Reduces scan times significantly compared to traditional methods

Maintains high image quality and isotropic resolution

Abstract

We present a flyscan compatible acquisition scheme for three-modal X-Ray Computed Tomography (CT) with two-dimensional phase sensitivity. Our approach is demonstrated using a "beam tracking" setup, through which a sample's attenuation, phase (refraction) and scattering properties can be measured from a single frame, providing three complementary contrast channels. Up to now, such setups required the sample to be stepped at each rotation angle to sample signals at an adequate rate, to prevent resolution losses, anisotropic resolution, and under-sampling artefacts. However, the need for stepping necessitated a step-and-shoot implementation, which is affected by motors overheads and increases the total scan time. By contrast, our proposed scheme, by which continuous horizontal and vertical translations of the sample are integrated with its rotation (leading to a "cycloidal-spiral" trajectory), is fully compatible with continuous scanning (flyscans). This leads to greatly reduced scan times while largely preserving image quality and isotropic resolution.