Spectral X-ray Imaging and Photon-Counting Detectors: a Biomedical Application and Advances in Timepix4 Technology

Spectral X-ray imaging is advancing biomedical imaging by using energy-resolved detection to provide quantitative and high-resolution visualization of biological tissues. Unlike conventional X-ray imaging, spectral methods differentiate materials through their energy-dependent attenuation, allowing improved contrast and material decomposition for 3D tissue characterization. This ability supports non-invasive and quantitative imaging in both preclinical and clinical contexts. Spectral micro Computed Tomography (CT) systems employing photon-counting detectors now permit in-depth analysis of tissue composition at very high spatial resolution (< 50 µm). By combining spectroscopic imaging with material decomposition algorithms, these systems generate quantitative 3D maps of biological samples, improving visualization of tissue heterogeneity and providing additional information relevant to biomedical studies.

Recent developments in photon-counting detectors, such as Medipix4 and Timepix4, produced through international collaboration at CERN, have driven these advances. These pixel detectors provide multi-threshold energy discrimination, high spatial and energy resolution to overcome limitations of conventional energy-integrating imaging detectors.

This seminar will present an application of spectral micro-CT for detecting calcium deposits in osteoarticular surgical samples. The approach complements traditional histology by enabling non-destructive and quantitative volumetric analysis of calcifications, contributing to the study of osteoarthritis. Ongoing activities on photon-counting detector development, particularly the characterization of the Timepix4 chip, will also be discussed. This detector offers high energy and spatial resolution and fast imaging capabilities, potentially improving spectral imaging performance.