From Event: SPIE Optical Engineering + Applications, 2016
To obtain four tomograms with four different photon energy ranges simultaneously, we have developed a quad-energy Xray
photon counter with a cadmium telluride (CdTe) detector and four sets of comparators and frequency-voltage
converters (FVCs). X-ray photons are detected using the CdTe detector, and the event pulses from a shaping amplifier are
sent to four comparators simultaneously to regulate four threshold energies of 20, 35, 50 and 65 keV. Using this counter,
the energy ranges are 20-100, 35-100, 50-100 and 65-100 keV; the maximum energy corresponds to the tube voltage. Xray
photons in the four ranges are counted using the comparators, and the logical pulses from the comparators are input
to the FVCs. The outputs from the four FVCs are input to a personal computer through an analog-digital converter (ADC)
to carry out quad-energy imaging. To observe contrast variations with changes in the threshold energy, we performed
spectral computed tomography utilizing the quad-energy photon counter at a tube voltage of 100 kV and a current of 8.0
μA. In the spectral CT, four tomograms were obtained simultaneously with four energy ranges. The image contrast varied
with changes in the threshold energy, and the exposure time for tomography was 9.8 min.
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