High DQE performance X-and gamma-ray fast imagers:: Emergent concepts

Challenges for the design of quantum sensitive 2D imaging detectors for high-energy photons are reviewed. Conception rules and universal data plot are presented. They allow the optimization of pixel dimensions versus incident fluence and the contrast of the radiant image for several interesting materials such as photoconductors, scintillators and metallic X-converters. Firstly, a 2D very sensitive CdZnTe imaging matrix and its performance are presented. Secondly, the performance of a large size gaseous detector (Parallel Plate Avalanche Chamber), coupled with a structured high stopping power metallic X-ray converter are reviewed. Finally, we make comparison to performances obtained with more classical technologies made of segmented heavy scintillators.