Time resolved X-ray Dark-Field Tomography Revealing Water Transport in a Fresh Cement Sample

Grating-based X-ray dark-field tomography is a promising technique for biomedical and materials research. Even if the resolution of conventional X-ray tomography does not suffice to resolve relevant structures, the dark-field signal provides valuable information about the sub-pixel microstructural properties of the sample. Here, we report on the potential of X-ray dark-field imaging to be used for time-resolved three-dimensional studies. By repeating consecutive tomography scans on a fresh cement sample, we were able to study the hardening dynamics of the cement paste in three dimensions over time. The hardening of the cement was accompanied by a strong decrease in the dark-field signal pointing to microstructural changes within the cement paste. Furthermore our results hint at the transport of water from certain limestone grains, which were embedded in the sample, to the cement paste during the process of hardening. This is indicated by an increasing scattering signal which was observed for two of the six tested limestone grains. Electron microscopy images revealed a distinct porous structure only for those two grains which supports the following interpretation of our results. When the water filled pores of the limestone grains empty during the experiment the scattering signal of the grains increases

Quantitative detection of drug dose and spatial distribution in the lung revealed by Cryoslicing Imaging

AbstractAdministration of drugs via inhalation is an attractive route for pulmonary and systemic drug delivery. The therapeutic outcome of inhalation therapy depends not only on the dose of the lung-delivered drug, but also on its bioactivity and regional distribution. Fluorescence imaging has the potential to monitor these aspects already during preclinical development of inhaled drugs, but quantitative methods of analysis are lacking. In this proof-of-concept study, we demonstrate that Cryoslicing Imaging allows for 3D quantitative fluorescence imaging on ex vivo murine lungs. Known amounts of fluorescent substance (nanoparticles or fluorophore–drug conjugate) were instilled in the lungs of mice. The excised lungs were measured by Cryoslicing Imaging. Herein, white light and fluorescence images are obtained from the face of a gradually sliced frozen organ block. A quantitative representation of the fluorescence intensity throughout the lung was inferred from the images by accounting for instrument noise, tissue autofluorescence and out-of-plane fluorescence. Importantly, the out-of-plane fluorescence correction is based on the experimentally determined effective light attenuation coefficient of frozen murine lung tissue (10.0±0.6cm−1 at 716nm). The linear correlation between pulmonary total fluorescence intensity and pulmonary fluorophore dose indicates the validity of this method and allows direct fluorophore dose assessment. The pulmonary dose of a fluorescence-labeled drug (FcγR-Alexa750) could be assessed with an estimated accuracy of 9% and the limit of detection in ng regime. Hence, Cryoslicing Imaging can be used for quantitative assessment of dose and 3D distribution of fluorescence-labeled drugs or drug carriers in the lungs of mice

Gitterbasierte Röntgendunkelfeldbildgebung: Theorie und Anwendungen in den Materialwissenschaften

In this work, we present a theoretical framework for grating-based X-ray dark-field imaging. This framework is based on the mathematical formalism of small-angle scattering, and relates the dark-field signal to physical quantities such as the microstructure's form- and structure-factor. Furthermore, application examples of dark-field imaging in materials research are presented, including studies on cement-based building materials and fiber reinforced composites.In dieser Arbeit wird ein theoretisches Modell für die gitterbasierte Röntgendunkelfeldbildgebung vorgestellt. Das Modell wird aus den theoretischen Grundlagen der Kleinwinkelstreuung entwickelt und erlaubt es, mit Hilfe des Dunkelfeldsignales, Mikrostruktureigenschaften wie den Form- und Strukturfaktor zu untersuchen. Zudem werden Anwendungsbeispiele in den Materialwissenschaften vorgestellt. Dies umfasst Studien an zementbasierten Materialien sowie faserverstärkten Verbundwerkstoffen