  Cadmium Telluride (CdTe) is a high-Z material with excellent photon radiation
absorption properties, making it a promising material to include in radiation
detection technologies. However, the brittleness of CdTe crystals as well as
their varying concentration of defects necessitate a thorough quality
assessment before the complex detector processing procedure. We present our
quality assessment of CdTe as a detector material for multispectral medical
imaging, a research which is conducted as part of the Consortium Project
Multispectral Photon-counting for Medical Imaging and Beam characterization
(MPMIB). The aim of the project is to develop novel CdTe detectors and obtain
spectrum-per-pixel information that make the distinction between different
radiation types and tissues possible. To evaluate the defect density inside the
crystals -- which can deteriorate the detector performance -- we employ
infrared microscopy (IRM). Posterior data analysis allows us to visualise the
defect distributions as 3D defect maps. Additionally, we investigate front and
backside differences of the material with current-voltage (IV) measurements to
determine the preferred surface for the pixelisation of the crystal, and
perform test measurements with the prototypes to provide feedback for further
processing. We present the different parts of our quality assessment chain and
will close with first experimental results obtained with one of our prototype
PC detectors in a small tomographic setup.
