2016 Volume 3 Issue 6 Pages 16-00308
Dual-energy photon counting was performed using an energy-selecting device (ESD) and a cadmium telluride detector. The ESD is used to determine a low-energy range for computed tomography (CT) and consists of two comparators and a microcomputer (MC). The two threshold energies are determined using low and high-energy comparators, respectively. The MC in the ESD produces a single logical pulse when only a logical pulse from the low-energy comparator is input to the MC. To determine the high-energy range, logical pulses from the high-energy comparator are input to the MC outside the ESD. Logical pulses from the two MCs are input to frequency-voltage converters (FVCs) to convert count rates into voltages. The output voltages from the two FVCs are sent to a personal computer through an analog-digital converter to reconstruct tomograms. Dual-energy CT was accomplished at a tube voltage of 70 kV and a maximum count rate of 4.5 kilocounts per second, and two-different-energy tomograms were obtained simultaneously using iodine media.