Dual‐energy X‐ray computed tomography using a YAP（Ce）‐multipixel‐photon detector and an energy‐selecting device

Abstract

Dual‐energy photon counting was performed using an energy‐selecting device （ESD） and a detector, consisting of a cerium‐doped yttrium aluminum perovskite [YAP（Ce）] crystal and a multipixel photon counter （MPPC）. The ESD is used to determine a low‐energy‐channel range for CT and consists of two comparators and a microcomputer （MC）. The two threshold channels in proportion to 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‐channel range for CT, 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 computed tomography was accomplished at a tube voltage of 60 kV and a maximum count rate of 67 kilo‐counts per second, and two‐different‐energy tomograms were obtained simultaneously.