Preliminary characterizations of a new hybrid CdTe structure for x-ray dental imaging

A new 2D imaging system structure is being studied in CEA-LETI for medical and industrial applications, beginning with dental applications. It consists of a bulk CdTe:Cl detection medium connected to a 2D electronic read-out circuit using the indium bumps techniques developed for infrared imaging. The feasibility of such a structure was tested first with 64 X 64 pixels, 100 micrometers pitch. The 900 micrometers thick CdTe sample suits well for x rays up to 100 keV. High absorption efficiency and high spatial resolution can be reached together by using this new x-ray detector. Due to the fact that the electric field channelizes the created charges, unlike structures using scintillators, this new structure requires no compromise in defining the thickness of the x-ray detector medium. Characterization was performed with 70 kV x rays from a standard dental x ray source. The performances (linearity, signal-to-noise ratio, spatial resolution) and the images obtained with the first prototypes confirm the advantages of such detectors. Based on these results, a 20 X 30 mm 2 imager for dental applications is now being developed by SOFRADIR and CEA- LETI.