“…Experiments indicate that for a-Se W ± strongly depends on the field and weakly on the photon energy. Over typical Xray imaging ranges, one can write [23], W ± (eV) ≈ W It should be apparent that the overall conversion efficiency of incident radiation to collected charge relies on three processes: (a) the attenuation of the X-rays in the photoconductor, determined by A Q , and the absorption of the radiation energy, determined by (α en /α)E ph , where α en is the energy absorption coefficient, per attenuated photon, (b) the conversion of absorbed radiation to electron and hole pairs, determined by W ± , and (c) the collection of the charge carriers, determined by η CC . If we define the X-ray sensitivity, S x , as the charge collected per unit incident radiation (per unit Roentgen), then at one specific photon energy E ph ,…”