X-ray absorption, phase and dark-field tomography through a beam tracking approach

Area of Science:

• Physics
• Materials Science
• Imaging Technology

Background:

• Computed tomography (CT) typically measures X-ray absorption.
• Advanced CT techniques aim to extract more information, such as refraction and scattering (dark-field).
• Existing methods often require complex setups or highly coherent sources.

Purpose of the Study:

• To develop a versatile computed tomography method using beam-tracking.
• To enable simultaneous retrieval of absorption, refraction, and dark-field signals.
• To reconstruct 3D maps of these properties from experimental data.

Main Methods:

• Implementation of a beam-tracking approach within a computed tomography framework.
• Utilizing an absorbing mask and high-resolution detector to monitor beam intensity variations.
• Employing multi-Gaussian interpolation to decouple absorption, refraction, and dark-field signals.
• Reconstruction of 3D maps using standard filtered back projection.

Main Results:

• Successful demonstration of 3D mapping of absorption, refraction, and dark-field signals.
• The method retrieves the real and imaginary parts of the refractive index and the dark-field signal.
• The technique shows potential for implementation with less coherent laboratory X-ray sources.

Conclusions:

• The developed beam-tracking computed tomography method offers a comprehensive approach to material characterization.
• It provides simultaneous quantitative information on absorption, refraction, and dark-field.
• The low coherence requirement broadens the applicability of this advanced imaging technique beyond synchrotron facilities.