Contrast-to-noise of a non-ideal multi-bin photon counting x-ray detector

The contrast-to-noise (CNR) is optimized over the weights and energy threshold settings of energy bins in a photon counting detector using "delta-pulse" model simulations. Comparison is made to single-bin photon counting and energy integration detectors. The CNR2 for iodine imaging is about a factor of 2.5X higher for a perfect, photon counting detector compared to energy integration. Monte Carlo simulations are used to determine the impact of pile-up and other factors that degrade the spectral performance. The benefits of multi-bin photon counting vanish at about 40-60% tail fraction and 20-30 keV RMS noise. Because of pile-up, the CNR2 benefit also decreases as the incident count rate approaches the maximum periodic rate (MPR). However the impact of pile-up is less for a three-bin detector than for a two-bin detector when the multiple bins are weighted optimally.