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Autori: Costel Rizescu, Calin Besliu, Alexandru Jipa
Editorial: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Volume A 465, Issues 2-3, p.584 - 599, 2001.
This paper presents the theoretical and experimental results obtained at the Research Institute for Electrical Engineering, Bucharest, Romania, in determining local density and effective atomic number by a newly developed CT method using dual-energy gamma radiation from the 192-Ir radioisotope.
The applied method is based on modeling total effective cross-section of gamma radiation in the natural materials in function of the atomic number (Z from 1 to 92), in terms of the photoelectric and Compton cross-sections. Also, a new parameter (composition factor k) given by the ratio of th elinear attenuation coefficients from the two tomograms is introduced. We investigated 16 materials with effective atomic number Zeff between 6 and 72.2 and bulk density ranging from 2.15 to 10.51 g/cm3, using 310.5 and 469.1 keV gamma radiation.
Our results show very good accuracy of the dual-energy CT method for most materials. The error in determining the effective atomic number is less than 5% for Zeff >25 and less than 10% for light materials (Zeff <15), while the error in density estimation is always smaller than 3%.
Cuvinte cheie: Tomography, Gamma ray, Dual-energy CT method, 192-iridium source