ARE HYDROGENATED AMORPHOUS-SILICON ARRAYS USABLE FOR TOMOGRAPHIC IMAGING

X-ray detectors based on large-area, hydrogenated amorphous silicon ph otodiode arrays may be useful for performing transmission CT using an x-ray source to acquire the attenuation map for PET and SPECT. Questio ns regarding the required noise properties of these detectors for curr ent-integration mode transmission CT are answered in this investigatio n. A simple noise model is developed and from it the first- and second -order statistics are used to examine the propagation of signal and va riance through the reconstruction to estimates of the linear attenuati on coefficient. Simulation results for a-Si:H detectors are compared w ith those from a count mode ECT detector used for transmission scannin g. For the relatively undemanding application to ECT attenuation corre ction, these arrays will be usable.