Simulation of the detective quantum efficiency for a hybrid pixel detector

A simulation tool has been developed for the analysis of the performance of an X-ray imaging hybrid pixel detector. The photon transport and charge collection were simulated with the aid of the Monte Carlo based code GEANT and the readout signal processing was simulated in a program written in the LabView programming environment. Results of the spatial frequency-dependent detective quantum efficiency are presented and the influence of charge sharing, the threshold settings, level of exposure, the noise sources on the detector performance are studied. The detector was found to operate quantum limited down to an exposure of 0.08 μGy, below which it is limited by the readout noise. The threshold setting has a strong influence on both the efficiency and the spatial resolution due to charge sharing, and a compromise between the two is necessary. The optimized threshold value corresponds to half of the mean energy of the input spectrum.