Photon counting Detectors: Concept, technical Challenges, and clinical outlook.

Photon counting detectors in Computed Tomography overcome several drawbacks of classical detectors used in Computed Tomography. Classical detectors measure X-rays by converting them into visible light during the initial absorption inside a pixel (individual scintillator cube which is separated mechanically from neighboring pixels) and then collecting the emitted visible light per pixel with a photo diode. High resolution imaging with scintillator-based detector experiences a limit due to the dose usage capabilities, low dose applications suffer from classical electronic noise and true material separation inside the scan object can only be performed, if the data acquisition was selected prior the scan examination (dual energy protocols).