Abstract

The use of conventional absorption based X-ray microtomography can become
limited for samples showing only very weak absorption contrast. However, a wide range of
samples studied in biology and materials science can produce significant phase shifts of the Xray
beam, and thus the use of the phase signal can provide substantially increased contrast and
therefore new and otherwise inaccessible information. The application of two approaches for
high-throughput, high-resolution X-ray phase contrast tomography, both available on the
TOMCAT beamline of the SLS, is illustrated. Differential Phase Contrast (DPC) imaging uses
a grating interferometer and a phase-stepping technique. It has been integrated into the
beamline environment on TOMCAT in terms of the fast acquisition and reconstruction of data
and the availability to scan samples within an aqueous environment. The second phase contrast
approach is a modified transfer of intensity approach that can yield the 3D distribution of the
phase (refractive index) of a weakly absorbing object from a single tomographic dataset. These
methods are being used for the evaluation of cell integrity in 3D, with the specific aim of
following and analyzing progressive cell degeneration to increase knowledge of the
mechanistic events of neurodegenerative disorders such as Parkinson’s disease.