Developments in room temperature cadmium telluride (CdTe) based solid state imaging arrays for energy-resolved
photon-counting in medical x-ray imaging are discussed. A number of x-ray imaging applications can benefit from these
developments including mammography, radiography, and computed tomography (CT). Energy-resolved photon-counting
can provide reduced dose through optimal energy weighting, compositional analysis through multiple basis
function material decomposition, and contrast enhancement through spectroscopic x-ray imaging of metal nanoparticles.
Extremely high flux can occur in x-ray imaging and energy integrating detectors have been conventionally used. To
achieve the benefits of energy resolved photon counting, imaging arrays with a large count rate range and good detection
efficiency are required. Compound semiconductor radiation detectors with pixellated anode arrays electrically connected
to application specific integrated circuits (ASICs) can provide fast, efficient, low-noise performance with adequate
energy resolution however this can only be achieved with a careful optimization of the CdTe sensors and ASICs
together. We have designed and constructed CdTe imaging arrays, 3 mm thick with a grid of electrical contacts inter-connected
to a multi-channel channel ASICs. Arrays with a pixel pitch of 0.5 mm have achieved a counting range up to
20 million counts per second per square mm. Additionally, ASICs with a two dimensional array of pads has been
fabricated and tested by connecting the inputs to 1 mm pitch CdTe sensors demonstrating 7 keV full width at half
maximum energy resolution across a dynamic range of 30 keV to 140 keV for clinical CT.