CMOS detector readout electronics for an emission-transmission medical imaging system

We have built a prototype medical imaging system in which transmission X-ray data provide anatomical information while emission radionuclide data yield physiological information. We have developed a CMOS integrated circuit for readout of the system's high-purity germanium detector. The circuit can be operated in three different modes. The first is a slow pulse-counting mode for detection of radionuclide events at 10⁴ cps with 1-2 keV energy resolution. Next, there is a fast pulse-counting mode for simultaneous acquisition of emission and transmission data or for acquisition of dual-energy X-ray data at 10⁶ cps with 5-7 keV energy resolution. Finally, current mode operation allows fast acquisition of X-ray transmission data. The circuit architecture includes a common preamplifier, selectable pulse shaping stages, and a common output buffer