X-ray photon counting using two different energy-selection electronics and a cadmium telluride detector

Abstract

To obtain two tomograms at two different photon energy ranges simultaneously, we have developed a dualenergy X-ray photon counter consisting of a cadmium telluride（CdTe）detector system, three comparators, two microcomputers（MCs）, and two frequency-voltage converters（FVCs）. X-ray photons are detected using the CdTe detector,and the event pulses are input to three comparators simultaneously to determine threshold energies. At a tube voltage of 100 kV, the three threshold energies are 33, 50 and 60 keV, and two energy ranges are 33-60 and 50-100 keV. X-ray photons in the two ranges are counted using MCs, and the logical pulses from the two MCs are input to two FVCs. In dualenergy computed tomography（DE-CT）, the tube voltage and current were 100 kV and 22 μA, respectively. Two tomograms were obtained simultaneously at two energy ranges. The energy ranges for K-edge CT using iodine and gadolinium media were 33-60 and 50-100 keV, respectively. The maximum count rate was 6.5 kilocounts per second with energies ranging from 10 to 100 keV, and the exposure time for tomography was 19.6 min.