Timm Weitkamp

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X-ray radiographic absorption imaging is an invaluable tool in medical diagnostics and materials science. For biological tissue samples, polymers or fibre composites, however, the use of conventional X-ray radiography is limited due to their weak absorption. This is resolved at highly brilliant X-ray synchrotron or micro-focus sources by using(More)
Using a high-efficiency grating interferometer for hard X rays (10-30 keV) and a phase-stepping technique, separate radiographs of the phase and absorption profiles of bulk samples can be obtained from a single set of measurements. Tomographic reconstruction yields quantitative three-dimensional maps of the X-ray refractive index, with a spatial resolution(More)
A computer program named ANKAphase is presented that processes X-ray inline phase-contrast radiographs by reconstructing the projected thickness of the object(s) imaged. The program uses a single-distance non-iterative phase-retrieval algorithm described by David Paganin et al. [(2002), J. Microsc. 206, 33-40]. Allowing for non-negligible absorption in the(More)
We report on the design and experimental realization of a 2D x-ray grating interferometer. We describe how this interferometer has been practically implemented, discuss its performance, and present multidirectional scattering (dark-field) maps and quantitative phase images that have been retrieved using this device.
X-ray phase-contrast imaging has received growing interest in recent years due to its high capability in visualizing soft tissue. Breast imaging became the focus of particular attention as it is considered the most promising candidate for a first clinical application of this contrast modality. In this study, we investigate quantitative breast tissue(More)
To explore the potential of grating-based x-ray phase-contrast computed tomography (CT) for preclinical research, a genetically engineered mouse model of pancreatic ductal adenocarcinoma (PDAC) was investigated. One ex-vivo mouse specimen was scanned with different grating-based phase-contrast CT imaging setups covering two different settings: i)(More)
This study used synchrotron X-ray microtomography on a micron scale to compare three-dimensional (3D) bone ingrowth after implantation of various calcium phosphate bone substitutes in a rabbit model. The advantage of using this new method for the study of biomaterials was then compared with histomorphometry for analysis of interconnection and bone ingrowth.(More)
Human brain tissue belongs to the most impressive and delicate three-dimensional structures in nature. Its outstanding functional importance in the organism implies a strong need for brain imaging modalities. Although magnetic resonance imaging provides deep insights, its spatial resolution is insufficient to study the structure on the level of individual(More)
A key issue in developing strategies against diseases such as cancer is the analysis of the vessel tree in comparison to the healthy one. In the search for parameters that might be characteristic for tumor capillaries we study the vascularization in mice for cancerous and healthy tissues using synchrotron radiation-based micro computed tomography in(More)
We report a quantitative measurement of the full transverse coherence function of the 14.4 keV x-ray radiation produced by an undulator at the Swiss Light Source. An x-ray grating interferometer consisting of a beam splitter phase grating and an analyzer amplitude grating has been used to measure the degree of coherence as a function of the beam separation(More)