Recent progress in the development of a micro crystal element (MiCE) PET system

This work reports on the continuing development of a small animal PET system designed to image mice. The key component of the system is our micro crystal element (MiCE) detectors. Each MiCE detector consists of a 22×22 array of 0.8×0.8×10 mm mixed lutetium silicate (MLS) crystals. The crystals are placed within a grid made of a highly reflective polymer film material. The grid optically isolates the crystals and additionally functions as a reflective wrap. The detector unit is directly coupled to a 6+6 cross-anode position sensitive PMT. The PMT signals are fed to a simple resistor network and front end amplifier card that produces four (X+, X-, Y+, V-) position and the summed energy signals. A partial ring consisting of six detector modules has been built. Tomographic data sets have been acquired by rotating the source object within the limited field of view. A simplified data acquisition system designed using a field programmable gate array and commercial NIM and CAMAC electronic modules has been assembled. Using a two detector module coincidence setup, a reconstructed image resolution of 1.0 mm full width at half maximum has been achieved for a line source centered within the field of view. Mouse images have been acquired using the full evaluation system. These images illustrate the resolution capabilities of the MiCE scanner. The final system will consist of four rings of detector modules (i.e., 72 modules) and utilize a high bandwidth firewire (i.e., EEEE 1394a) based acquisition system. This system is currently under development.