X-ray microtomography setup for absorption and diffraction tomography

Abstract

The results of studying silicon single crystals and gallstones on a laboratory X-ray microtomograph with a spatial resolution of 10 µm (developed at the Federal Scientific Research Centre for «Crystallography and Photonics» of the Russian Academy of Sciences) are reviewed. The method of tomographic experiment included the use of a monochromatic «parallel beam» with subsequent three-dimensional reconstruction based on a set of two-dimensional projections. Topotomographic measurements were performed in the mode of rotation of the samples under study around the normal to the reflecting plane adjusted to the Laue diffraction reflection geometry, which made it possible to identify and study single dislocations in perfect silicon crystals. Simulation of the dislocation loops was carried out on the basis of numerical solution of the Takagi-Taupin equations. In-vitro microtomographic study of human gallstones revealed the layered structure of the gallstones which are close in composition to modifications of calcium carbonate. The internal structure of the stones is heterogeneous and contains numerous cavities and cracks formed upon their growth. At the same time, the evaluation of the porosity of gallstones is necessary, since the latter can affect the rate of stone dissolution in their treatment by litholytic methods. Linear attenuation coefficients of x-ray radiation of cholesterol-type gallstones were calculated from the measurement results. The good agreement of the experimentally obtained results and calculations based on tabular data for pure cholesterol is demonstrated which proved that the tomographic method can be used for in vivo diagnosis of cholesterol-type gallstones.