Clinical high-purity germanium gamma-camera

A 3,072-element, high purity germanium camera with a 2-mm spatial resolution, an energy resolution of 2 to 3 percent for/sup 99m/Tc, and a clinically useful area of 123 sq cm for imaging the average adult heart, breast or brain is being developed. To this end a 100-element prototype was constructed and images of rats and mice were obtained with the use of single and multiple isotopes. A second prototype with 512 elements was also completed and tested. The 512 elements are derived from an array of electrodes, on the bottom of two germanium crystals, orthogonal to 16 electrodes on the top. The top electrodes are electrically in parallel and have a common electronic readout. The p-contact is palladium over germanium oxide, and the n-side is gold over the lithium diffusion. Cooling for the detector is accomplished through a sapphire motherboard by way of indium contacts which are also the electrical contacts for the n-side. The isolation between the strips on the p-and the n-sides is adequate to attain good energy resolution.