The high resolution gamma imager (HRGI): a CCD based camera for medical imaging

We describe the High Resolution Gamma Imager (HRGI): a Charge Coupled Device (CCD) based camera for imaging small volumes of radionuclide uptake in tissues. The HRGI is a collimated, scintillator-coated, low cost, high performance imager using low noise CCDs that will complement whole-body imaging Gamma Cameras in nuclear medicine. Using 59.5 keV radiation from a Am-241 source we have measured the spatial resolution and relative efficiency of test CCDs from E2V Technologies (formerly EEV Ltd.) coated with Gadox (Gd2O2S(Tb)) layers of varying thicknesses. The spatial resolution degrades from 0.44 to 0.6mm and the detection efficiency increases ( x 3) as the scintillator thickness increases from 100 to 500 mum. We also describe our first image using the clinically important isotope Tc-99m. The final HRGI will have intrinsic sub-mm spatial resolution (similar to 0.7 mm) and good energy resolution over the energy range 30-160 keV. (C) 2003 Elsevier B.V. All rights reserved.