Performance characteristics of a second generation micro crystal element (MiCE2) detector

This work reports on performance characteristics of a second generation micro crystal element (MiCE2) detector for a dedicated PET system to image mice. Our MiCE2 detector consists of a 22×22, array of 0.8×0.8×6 mm mixed lutetium silicate (MLS) crystals. Five sides of the crystals are polished with one 0.80.8 mm face left unpolished. The crystals are placed within a grid made of a highly reflective polymer film material. The grid optically isolates the crystals and also functions as a reflective wrap. The detector unit is directly coupled to a 6+6 cross-anode position sensitive PMT. The crystal of interaction is determined using simple Anger style logic. Crystal maps have been created for a 22×22 crystal array. All 484 crystals are visualized in the full detector module´s crystal map. The average peak to valley ratio between neighboring crystals was 6.4. There was greater than a factor of two difference between the photopeak energy channel for high versus low light collection efficiency crystals. The energy resolution for individual crystals varied between 14% and 23%. Partial detector arrays (e.g., 22×4) using 0.8×0.8×10 mm crystals with an etched surface finish have also been built and decoded. A miniature line source phantom consisting of five 1 mm diameter lines with 2 mm center-to-center spacing has been imaged using two partial MiCE2 detectors. All lines are distinguished and. the average peak to valley ratio between lines is 2.7.