  A hybrid pixel detector based on the concept of simultaneous charge
integration and photon counting will be presented. The second generation of a
counting and integrating X-ray prototype CMOS chip (CIX) has been operated with
different direct converting sensor materials (CdZnTe and CdTe) bump bonded to
its 8x8 pixel matrix. Photon counting devices give excellent results for low to
medium X-ray fluxes but saturate at high rates while charge integration allows
the detection of very high fluxes but is limited at low rates by the finite
signal to noise ratio. The combination of both signal processing concepts
therefore extends the resolvable dynamic range of the X-ray detector. In
addition, for a large region of the dynamic range, where counter and integrator
operate simultaneously, the mean energy of the detected X-ray spectrum can be
calculated. This spectral information can be used to enhance the contrast of
the X-ray image. The advantages of the counting and integrating signal
processing concept and the performance of the imaging system will be reviewed.
The properties of the system with respect to dynamic range and sensor response
will be discussed and examples of imaging with additional spectral information
will be presented.
