Dual-energy radiography of bone tissues using ZnSe-based scintielectronic detectors

Detectors of the scintillator-photodiode type were obtained on the basis of CsI(Tl), CdWO4 and ZnSe(Te) crystals, and their comparative study was carried out, aiming at their use in X-ray computer tomography (CT). Because of their low afterglow level (10 ppm after 10 ms), CWO and ZnSe crystals are preferable for this application. A drawback of CWO is its lower (by 3 times) light output as compared with CsI(Tl). ZnSe has low transparence to intrinsic radiation; however, up to energies of 60–70 keV it is superior, as for the whole complex of its parameter, to materials traditionally used for CT detectors. The use of a dual-energy receiving–detecting circuit with a detector pair ZnSe/CsI or ZnSe/CdWO allows efficient distinction between muscular and bone tissues, which supports our earlier theoretical assumptions that this method could be successfully used for separate detection of materials differing in their effective atomic number Zeff and local density (e.g., calcium contents in bone densitometry).