PROGRESS IN DEVELOPING FOCAL-PLANE-MULTIPLEXER READOUT FOR LARGE CDZNTE ARRAYS FOR NUCLEAR-MEDICINE APPLICATIONS

We report on the construction and initial testing of a 48 x 48 CdZnTe array with 125 mu m pixel spacing and multiplexer readout. Large porti ons of the array function well but there was a loss of pixels near one corner of the array due to non-interconnecting indium bumps. This pro blem is readily correctable. Excellent single-pixel spectra were obtai ned with a (TC)-T-99m source using an adjustment technique that accoun ts for energy deposited in neighboring pixels. A point-spread function (PSF) taken at 140 keV yielded a spatial resolution of 230 mu m, much better than required for nuclear medicine applications. No problems w ere found that are not readily correctable or of much less significanc e for CdZnTe arrays having larger pixel spacing. We are now constructi ng 64 x 64 CdZnTe arrays with 380 mu m pixel spacing for use in an ult ra-high resolution brain SPECT imaging system.