Color X-ray photon counting image sensing

Present state of the art medical X-ray image sensors are “charge integration” based, which results in an overall noise that is composed of the quantum limited photon shot noise, electronic read noise and excess noise due to the non-reproducible charge packet sizes per absorbed X-ray. Ultimate sensitivity and signal to noise ratio is obtained when each incoming photon is counted, the so-called quantum limit. Another advantage of photon counting is that one can classify the incoming photons according to their energy, and in that way realize spectral sensitivity or “color X-ray” [5] without having a penalty in dose or multiple exposures.