CMOS readout electronics for an emission-transmission medical imaging system

We have developed a CMOS chip for readout of a germanium detector in an emission-transmission medical imaging system. The chip can be operated in three different modes. First, there is a slow pulse counting mode for acquisition of radionuclide data at 10/sup 4/ cps/channel and 1-2 keV energy resolution. Next, there is a fast pulse counting mode for collection of dual-energy X-ray data or for simultaneous accumulation of radionuclide emission and X-ray transmission counts at 10/sup 6/ cps and 5-7 keV energy resolution. Finally, there is a current mode readout for fast acquisition of X-ray transmission data. The new readout electronics offer the potential for improved quantitation of SPECT data. Monte Carlo simulations indicate that 2 keV energy resolution is sufficient to reduce the uncertainty due to scatter to below the level of uncertainty due to photon statistics. In addition, the X-ray data can be used to generate an object-specific attenuation map at the radionuclide energy. Thus, the new electronics offer the possibility of virtually scatter-free, attenuation-corrected quantitative SPECT images.<
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