Dual-Energy Low-Dose X-Ray Computed Tomography Scanner Using a Room-Temperature Cadmium Telluride Detector

To obtain two kinds of tomograms at two different X-ray energy ranges simultaneously, we have constructed a dual-energy (DE) X-ray photon counter with a room-temperature cadmium telluride (CdTe) detector. X-ray photons are detected using the CdTe detector system, and the event pulses from amplifiers are sent to three comparators simultaneously to regulate three threshold energies of 33, 50 and 54 keV. The DE counter consists of energy-range and -region selectors, and the energy ranges are 33-54 and 50-100 keV, the maximum energy corresponds to the tube voltage. We performed DE computed tomography (DE-CT) at a tube voltage of 100 kV. Using a 0.6-mm-diam lead pinhole, K-edge tomograms using iodine and gadolinium media were obtained simultaneously at two energy ranges of 33-54 and 50-100 keV, respectively. At a tube voltage of 100 kV and a current of 100 A, the count rate was 25 kilocounts per second (kcps), and the minimum count rates after penetrating objects in DE-CT were regulated to approximately 2 kcps by the tube current.