Semiconductor pixel detectors for gamma-ray imaging in nuclear medicine

Semiconductor pixel detectors hold great promise for replacing scintillation cameras in nuclear medicine; improvements in spatial resolution, energy resolution and sensitivity should result. The current status of this subject is briefly reviewed. The fabrication of hybrid, 48 x 48 CdZnTe pixel arrays for use in gamma-ray imaging is described. Each detector array is indium-bump bonded to a Hughes 48 x 48 multiplexer chip; the design is similar to that of an infrared focal-plane array. The 48 x 48 CdZnTe array is shown to perform well as a gamma-ray imaging system with 125 mu m spatial resolution (at 60 keV), equivalent to the pixel spacing. A correction technique for charge spreading between pixels is demonstrated. The implications of macroscopic crystal defects on array performance are briefly discussed.