High-throughput, high-resolution X-ray phase contrast tomographic microscopy for visualisation of soft tissue

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.