Spectral Phase-Contrast X-ray Imaging: Methods and development with Synchrotron and Laboratory Sources

X-ray imaging is routinely used in medicine and scientific research, yet conventional techniques, based solely on absorption contrast, fail to provide sufficient soft tissue contrast or material specificity. Spectral and phase-contrast X-ray methods address these limitations by exploiting the energy-dependent attenuation and the wave nature of X-rays, delivering material quantification and enhanced image quality. This thesis explores spectral and phase-contrast X-ray imaging in laboratory and synchrotron environments, with a particular focus on crystal-based spectral imaging and beam tracking phase-contrast methods. The work is organized into two main sections: \textit{X-ray imaging} and \textit{Methods and Development}. \textit{X-ray imaging} introduces the theoretical and mathematical framework underlying X-ray imaging and describes in detail spectral and phase-contrast imaging principles and techniques implemented throughout this research. \textit{Methods and Development} presents the experimental and methodological studies using laboratory and synchrotron sources. Laboratory experiments include spectral micro-computed tomography using an energy resolving photon-counting detector for multiple material discrimination, as well as the development of a novel membrane-stepping approach for phase-contrast imaging which enhances image quality. Synchrotron-based studies include source-based spectral phase-contrast imaging with beam tracking, applied to thyroid tissue samples for the localization and quantification of iodine and calcium. The final, but central, part of this thesis focuses on crystal-based spectral imaging with beam tracking, supported by simulation studies, crystal and mask optimization and algorithm development. The optimization studies enhanced the performance and robustness of the spectral and phase-contrast techniques, which were then implemented in imaging experiments, using two distinct setups, demonstrating successful material detection and quantification, as well as effective spectral-phase decomposition that enabled simultaneous structural and elemental characterization of samples. Overall, these findings establish a framework for integrating spectral and phase-contrast information in X-ray imaging. The developed methods lay a foundation for quantitative, high-resolution, and material-specific imaging, paving the way toward more accurate X-ray imaging approaches for biomedical and materials applications.