Learning by Research

Her Thesis Title: X-Ray Phase Contrast and Dark-Field Imaging on Laboratory Equipment: How X-ray Dark-Field relates to Small Angle X-ray Scattering (SAXS)?

Clara’s thesis focuses on the technological transition of next-generation X-ray imaging modalities—phase contrast imaging (PCI) and dark-field imaging (DF)—from synchrotron facilities to conventional laboratory settings. Unlike conventional radiography, these modalities exploit the wave nature of X-rays (refraction and scattering).

Objectives and Physical Foundations

Clara’s project aimed to implement these modalities on compact equipment and to study the correlations between the dark-field signal and small-angle X-ray scattering (SAXS).

• Phase Contrast: Sensitive to variations in refractive index, it distinguishes interfaces in low-absorbing soft tissues.
• Dark Field: Provides structural information on sub-pixel-sized features through sub-resolved scattering.
• MoBI Methodology: Rests on a modulating filter (membrane) and the Low Coherence System (LCS) algorithm to extract absorption, phase, and dark field signals pixel by pixel.

Major Innovations and Results

Clara’s work led to the optimization of a spiral topology for modulation masks, validated through simulation and experimentation. This innovation resulted in a patent application and the commercialization of a PCI/DF option by Xenocs. Her thesis demonstrates that the dark-field signal results from multiple refraction and scattering. Its sensitivity, which is related to the propagation distance, makes it possible to locally reconstruct SAXS curves from multi-distance measurements.

Applications and Commercialization

This technology opens up significant new possibilities in industrial and medical imaging, making soft tissue visible in X-ray imaging for the first time (aiding in pulmonary, dental, and oncological diagnostics). In particular, the directional approach enables the study of complex anisotropic structures such as dentin.

Startup Project: arXimed

Building on her results, Clara is currently developing the arXimed project, a startup dedicated to medical imaging based on this technological breakthrough. The excellence of this work has been recognized with several prestigious awards, including the Thesis Prize in Biomedical Engineering (SGBM/AGBM Special Mention for Innovation) and the Grand Prize in the BPI France i-PhD competition.

Key words: small-angle X-ray scattering, X-Ray phase contrast imaging, dark-field imaging, speckle based imaging, X-ray micro-tomography, image processing and analysis