Study of Properties of Materials by Absorption and Diffraction X-Ray Microtomography

Resumo

Single crystals of silicon and gallstones are studied on a laboratory X-ray microtomograph with a spatial resolution of 10 μm. The tomographic experiment included the use of a monochromatic “parallel beam” with subsequent three-dimensional reconstruction based on two-dimensional projections. The topo-tomographic measurements were performed in the rotation mode of the samples around the normal to the reflection plane tuned by the Laue diffraction reflection geometry, which allowed identification and study of single dislocations in perfect silicon crystals. The dislocation loops were simulated by means of a numerical solution of the Takagi–Taupin equations. Human gallstones were studied in vitro with microtomography. We found that the stones have a layered formation, whose composition may involve calcium carbonate modifications. The internal structure of the stones is heterogeneous and contains numerous cavities and cracks formed during their growth. The assessment of the porosity of gallstones, however, is necessary, because it can affect the dissolution rate of the stone during litholytic treatment. Linear attenuation coefficients of X‑ray radiation of cholesterol-type gallstones were found from the results of measurements. A good agreement between the experimental and calculated absorption coefficients for pure cholesterol suggests that the tomographic method can be used for in vivo diagnosis of cholesterol-type gallstones.