Phase-Contrast CT Sample Clauses

Phase-Contrast CT. Absorption-based imaging techniques are limited in the size of the sample (total attenuation). Phase-Contrast CT is viable alternative to image larger samples. Our current experimental setup yields an isotropic voxel size of 0.65µm3. The reconstruction of the phase-contrast sinograms involves additional postprocessing, most notably Paganin filtering, limiting the effective spatial resolution to about 1µm3. Data quality is most critically limited by imperfect sample preparation (incomplete filling of vessels due to occlusions or air-bubbles) and potential structural/positional changes of the sample during the acquisition lasting multiple hours (dislocation, shrinkage, sample-beam interaction). We have conducted multiple pilot studies and were able to significantly optimise the preparation and acquisition protocol including the choice of proper contrast agents. Besides the pilot studies, we have scanned an entire mouse brain of 1cm3 volume perfused with 50% Indian ink and embedded in glue to ensure stability (effective resolution 1um3, 16bit grayscale, 792 local tomographies, 30h scanning time, 7TB raw data). The local tomographies have been reconstructed and stitched together to form a consistent 3-D volume in a common coordinate frame.