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 integr ated circuit for readout of the system's high-purity germanium detecto r. The circuit can be operated in three different modes. The first is a slow pulse-counting mode for detection of radionuclide events at 10( 4) cps with 1-2 keV energy resolution. Next, there is a fast pulse-cou nting mode for simultaneous acquisition of emission and transmission d ata or for acquisition of dual-energy x-ray data at 10(6) cps with 5-7 keV energy resolution. Finally, current mode operation allows fast ac quisition of x-ray transmission data. The circuit architecture include s a common preamplifier, selectable pulse shaping stages, and a common output buffer.