Dual-energy high-count-rate X-ray computed tomography scanner using a cerium-doped yttrium aluminum perovskite crystal and a small-photomultiplier tube

Abstract

To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have constructed a dual-energy X-ray photon counter with a high-count-rate detector system, three comparators, two microcomputers, and two frequency-voltage converters. The detector system consists of a cerium-doped yttrium aluminum perovskite [YAP(Ce)], a photomultiplier tube, an inverse amplifier, and a pulse-width extender. X-ray photons are detected using the detector system, 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 35, 55 and 60 keV. X-ray photons in the two ranges are counted using microcomputers, and the logical pulses from the two microcomputers are input to two frequency-voltage converters. In dual-energy computed tomography (CT), the tube voltage and current were 100 kV and 0.25 mA, respectively. Two tomograms were obtained simultaneously at two energy ranges. The energy ranges for iodine and gadolinium K-edge CT were 35–60 and 55–100 keV, respectively. The maximum count rate of dual-energy CT was 85 kilocounts per second with energies ranging from 21 to 100 keV, and the exposure time for tomography was 9.8 min.