Dual-energy x-ray computed tomography scanner using a room-temperature cadmium-telluride detector and a range-region counter

To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have constructed a dualenergy (DE) X-ray photon counter with a room-temperature cadmium telluride (CdTe) detector. X-ray photons are detected using the CdTe detector system, and event pulses from an amplifier module are sent to three comparators simultaneously to determine three threshold energies of 33, 48 and 50 keV. The DE counter has energy-range and - region selectors, and the energy range and region are 33-48 and beyond 50 keV (50-100 keV); the maximum energy corresponds to the tube voltage. We performed DE computed tomography (DE-CT) using four lead pinholes at a tube voltage of 100 kV. In Gd-K-edge CT at a range of 50-100 keV, Gd media were observed at high contrasts. The spatial resolutions were 0.5×0.5 mm 2 , and the exposure time for DE-CT was 19.6 min at a total rotation angle of 360°. At a tube voltage of 100 kV and a current of 0.22 mA, the count rate was 36 kilocounts per second.