Experimental validation of image contrast correlation between ultra-small-angle X-ray scattering and grating-based dark-field imaging using a laser-driven compact X-ray source: Experimentelle Verifizierung des Zusammenhangs zwischen Röntgen-Kleinwinkelstreuung und gitter-basierter Röntgen-Dunkelfeldbildgebung unter Verwendung eines laser-getriebenen Kompaktsynchrotrons

X-ray phase and dark-field contrast have recently been the source of much attention in the field of X-ray imaging, as they both contribute new imaging signals based on physical principles that differ from conventional X-ray imaging. With a so-called Talbot grating interferometer, both phase-contrast and dark-field images are obtained simultaneously with the conventional attenuation-based X-ray image, providing three complementary image modalities that are intrinsically registered. Whereas the physical contrast mechanisms behind attenuation and phase contrast are well understood, a formalism to describe the dark-field signal is still in progress. In this article, we report on correlative experimental results obtained with a grating interferometer and with small-angle X-ray scattering. Furthermore, we use a proposed model to quantitatively describe the results, which could be of great importance for future clinical and biomedical applications of grating-based X-ray imagin

Development of higher efficiency photocathodes for gas filled<br />detectors

This work concerned the development of a new generation of photocathodes for X-rays gas filled detectors. The thesis contains a description of the monte carlo studies, as well as experimental tests of various photocathodes which were carried out during the thesis work. Last, interesting results concerning CsI3 as an interesting precursor to CsI (as a secondary emitter) are given.Ce travail a concerné le développement d'une nouvelle génération de photocathodes pour détecteur gazeux (dans le domaine du X). La thèse comprend une description de l'étude par monte carlo ainsi que des tests expérimentaux qui ont été menés au cours de ce travail.Enfin, des résultats intéressant concernant le CsI3 utilisé comme précurseur au CsI (comme émetteur secondaire) sont présentés

Développement de photocathode de meilleures efficacitées quantiques pour détecteurs à gaz

Ce travail a concerné le développement d'une nouvelle génération de photocathodes pour détecteur gazeux (dans le domaine du X). La thèse comprend une description de l'étude par monte carlo ainsi que des tests expérimentaux qui ont été menés au cours de ce travail. Enfin, des résultats intéressant concernant le CsI3 utilisé comme précurseur au CsI (comme émetteur secondaire) sont présentés.This work concerned the development of a new generation of photocathodes for X-rays gas filled detectors. The thesis contains a description of the monte carlo studies, as well as experimental tests of various photocathodes which were carried out during the thesis work. Last, interesting results concerning CsI3 as an interesting precursor to CsI (as a secondary emitter) are given.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Multimodal hard X-ray imaging of a mammography phantom at a compact synchrotron light source

The Compact Light Source is a miniature synchrotron producing X-rays at the interaction point of a counter-propagating laser pulse and electron bunch through the process of inverse Compton scattering. The small transverse size of the luminous region yields a highly coherent beam with an angular divergence of a few milliradians. The intrinsic monochromaticity and coherence of the produced X-rays can be exploited in high-sensitivity differential phase-contrast imaging with a grating-based interferometer. Here, the first multimodal X-ray imaging experiments at the Compact Light Source at a clinically compatible X-ray energy of 21 keV are reported. Dose-compatible measurements of a mammography phantom clearly demonstrate an increase in contrast attainable through differential phase and dark-field imaging over conventional attenuation-based projections

Coherent superposition in grating-based directional dark-field imaging.

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. Here we present a description of the signal formation for thick samples with many overlying structures and show its validity in experiment. In contrast to existing experimental work this description follows from theoretical predictions of a numerical study using a Fourier optics approach. One can easily extend this description and perform a quantitative structural analysis of clinical or materials science samples with directional dark-field imaging or even direction-dependent dark-field CT

X-ray phase-contrast tomosynthesis for improved breast tissue discrimination.

Attenuation-based tomosynthesis has proven to successfully resolve the glandular tissue overlap present in mammography. However, the ability of tomosynthesis to differentiate tumorous and glandular tissue remains limited, due to the small differences in X-ray attenuation in breast tissue. One possibility to overcome this limitation and to further increase the diagnostic value of tomosynthesis exams, is the application of recently developed grating-based phase-contrast methods, which provide complementary information on the phase shift and the local scattering power of the sample. In this study, we report on first phase-contrast breast tomosynthesis results of a mastectomy sample slice with an invasive ductal carcinoma