Towards the reconstruction of 3D orientation information from direction-sensitive X-ray projections

For medical in vivo applications the resolution of a computed tomography (CT) scan is limited by the acceptable patient received dose. Thus it does not allow to image microstructures in the body. Novel X-ray contrast mechanisms provide two additional signal channels, phase contrast and dark-field contrast. In this study we report on our progress to use the dark-field signal to gain micro-structural information by reconstructing a tensor field describing the local sample scattering power. For that purpose we developed an experimental setup composed of an X-ray tube, a Talbot Lau interferometer, an Euler cradle to orient the sample and a detector. This setup allows a direct measurement of the sample scattering strength in all directions. The reconstruction of several test samples is done using filtered back-projection or the algebraic reconstruction technique. The definition of the physical model behind the reconstructed quantity is obtained from a second ansatz by using 3D density map (micro-CT) data as an input to a computer simulation of the whole setup. We consider this project important for diagnostic improvements in the case of bone pathologies. (orig.)