Publications by authors named "Guillaume Potdevin"
Article Synopsis
- X-ray dark-field vector radiography (XVR) is a new imaging technique that produces high-quality dark-field scatter images using standard X-ray tubes.
- This method provides valuable information about the directional scattering of X-rays related to the microstructure of trabecular bone, without needing to directly visualize tiny structures that cause this scattering.
- In a preliminary study, researchers found that the level of anisotropy measured by XVR was linked to the strength of femoral bones in individuals with osteoporosis.
Article Synopsis
- - The study aimed to determine if x-ray vector radiographic (XVR) parameters can predict the biomechanical failure load of vertebrae, which is important for assessing osteoporosis risk.
- - Researchers used thoracic vertebrae from human cadavers, assessing factors like bone density and XVR measurements to find correlations between these factors and vertebral failure load.
- - Results showed significant correlations between XVR parameters and failure load, indicating that incorporating XVR data, especially in combination with bone mineral density, enhances the prediction of vertebral strength compared to using BMD alone.
Article Synopsis
- Grating-based differential phase-contrast imaging can work well with standard X-ray sources, despite challenges posed by their polychromatic spectrum.* -
- By using energy-sensitive detectors, this study corrects phase-wrapping artifacts and enhances image quality through maximum likelihood estimation across different energy levels.* -
- The findings demonstrate that spectral imaging improves contrast-to-noise ratios and reduces beam hardening, making it a key advancement for pre-clinical and clinical applications involving differential phase-contrast imaging.*
Article Synopsis
- The study uses X-ray grating interferometry to gather information about the internal structure and scattering of a wood sample without needing to visualize tiny features directly.
- Researchers found a correlation between the wood's biomechanical elasticity (Young's modulus) and the directional dark-field parameters they measured.
- This method combines imaging and mechanical testing, suggesting that directional dark-field imaging could significantly advance materials science applications.
X-ray imaging using a Talbot-Lau interferometer, consisting of three binary gratings, is a well-established approach to acquire x-ray phase-contrast and dark-field images with a polychromatic source. However, challenges in the production of high aspect ratio gratings limit the construction of a compact setup for high x-ray energies. In this study we consider the use of phase gratings with triangular-shaped structures in an x-ray interferometer and show that such gratings can yield high visibilities for significantly shorter propagation distances than conventional gratings with binary structures.
View Article and Find Full Text PDFExploiting spatio-temporal redundancies in sub-Nyquist sampled dynamic MRI for the suppression of undersampling artifacts was shown to be of great success. However, temporally averaged and blurred structures in image space composite data poses the risk of false information in the reconstruction. Within this work we assess the possibility of employing the composite image histogram as a measure of undersampling artifacts and as basis of their suppression.
View Article and Find Full Text PDFArticle Synopsis
- The strength of trabecular bone is influenced by its microstructure, but traditional CT imaging can't capture fine details due to dose limits.
- A new technique called X-ray vector radiography (XVR) can image bone microstructure using X-ray scattering, without needing to see each tiny bone structure directly.
- Research using XVR on thick human femoral bone samples shows it can provide valuable information about trabecular microstructure, potentially aiding in early diagnosis of bone diseases like osteoporosis.*
Article Synopsis
- Attenuation-based tomosynthesis is effective in resolving glandular tissue overlap in mammograms, but struggles to distinguish between tumorous and non-tumorous breast tissue due to similar X-ray attenuation.
- The study introduces a new approach using grating-based phase-contrast methods, which can provide additional insights into the tissue's phase shift and scattering properties.
- Initial results demonstrate that phase-contrast tomosynthesis enhances soft-tissue discrimination and depth resolution, allowing for clearer visualization of features like necrotic tissue that may be obscured in standard images.
X-ray dark-field scatter imaging allows to gain information on the average local direction and anisotropy of micro-structural features in a sample well below the actual detector resolution. For thin samples the morphological interpretation of the signal is straight forward, provided that only one average orientation of sub-pixel features is present in the specimen. For thick samples, however, where the x-ray beam may pass structures of many different orientations and dimensions, this simple assumption in general does not hold and a quantitative description of the resulting directional dark-field signal is required to draw deductions on the morphology.
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- Early detection of pulmonary diseases like emphysema and fibrosis is challenging with traditional X-ray techniques, which struggle to reveal changes in lung tissue.
- A new method using dark-field imaging, which captures small-angle scattering of X-rays, offers better differentiation between healthy and emphysematous lung tissues.
- The research employs a compact synchrotron X-ray source and shows that dark-field images significantly enhance diagnosis by correlating the dark-field signal with the size of alveoli in lung tissues.
Article Synopsis
- - The Compact Light Source is a small synchrotron that generates X-rays by using a technique called inverse Compton scattering, combining a laser pulse with an electron bunch.
- - It produces a highly coherent X-ray beam that has impressive monochromaticity and can be used for advanced imaging techniques, particularly high-sensitivity differential phase-contrast imaging.
- - Recent experiments using this technology at a clinically relevant X-ray energy of 21 keV showed enhanced contrast in imaging tests compared to traditional methods, highlighting its potential for better medical diagnostics.
Article Synopsis
- Understanding large biophysical systems requires detailed knowledge of their microstructure, which is challenging to obtain, especially in living organisms due to limitations of current imaging methods.
- A new technique called x-ray vector radiography (XVR) provides valuable information on the orientation, anisotropy, and size of microstructures within a sample.
- Initial experiments using XVR on human vertebrae have shown that it can successfully reveal trabecular structures at a pixel resolution of 0.5 mm, paving the way for safer, low-dose imaging methods for studying bone disorders like osteoporosis in vivo.
X-ray lasers offer new capabilities in understanding the structure of biological systems, complex materials and matter under extreme conditions. Very short and extremely bright, coherent X-ray pulses can be used to outrun key damage processes and obtain a single diffraction pattern from a large macromolecule, a virus or a cell before the sample explodes and turns into plasma. The continuous diffraction pattern of non-crystalline objects permits oversampling and direct phase retrieval.
View Article and Find Full Text PDFX-ray crystallography provides the vast majority of macromolecular structures, but the success of the method relies on growing crystals of sufficient size. In conventional measurements, the necessary increase in X-ray dose to record data from crystals that are too small leads to extensive damage before a diffraction signal can be recorded. It is particularly challenging to obtain large, well-diffracting crystals of membrane proteins, for which fewer than 300 unique structures have been determined despite their importance in all living cells.
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