Mineral composition of urinary stones by single energy desktop microtomography

Urinary stone is a common clinical problem whose most frequent chemical compositions are calcium oxalate, calcium phosphate, uric acid and cystine. In this work we propose a new method for quantification of urinary stones using single-energy computed tomography (SECT). The results were validated with X-ray powder diffraction (XRPD). The proposed SECT method consists of obtaining a calibration curve that relates the gray levels of the sample with its density and effective atomic number. XRPD results showed that one of the samples is purely composed of uracite, another is a mixed stone composed of hydroxyapatite and struvite, and the last one is composed of hydroxyapatite and calcium oxalate monohydrate (whewellite). X-ray computed microtomography (micro-CT) results showed that the standard samples presented an excellent correlation. The gray levels of the studied samples were determined theoretically through the calibration curve and its values agreed with the experimental results. The XRPD results reinforced the data obtained by micro-CT.