System integration of the MiCES small animal PET scanner

A small animal positron emission tomography scanner for small animals has been developed based on the University of Washington micro-crystal element (MiCE2) detector module design. The scanner, MiCES, uses 72 MiCE2 modules, each consisting of a 22×22 array of 0.8×0.8×10 mm MLS crystals coupled to a Hamamatsu R5900-00-C12 PMT. Alternate rows of detectors (in the axial direction) are offset by the axial gap between crystal arrays and the entire detector and electronics system is continuously rotated. The system electronics is based on the use of the IEEE 1394a (FireWire) standard for transmitting data from detector nodes to the host computer. The electronics are organized around rows of four detector modules. Each module is connected to a threshold summing board that converts the 12 PS PMT signals to 4 position signals. The signals are then digitized and acquired by the host computer in a list mode format. Each set of electronics (supporting four modules) is essentially independent with its own control processor and field programmable gate arrays. Each electronics module receives basic commands from a single control processor, which in turns communicates with the host computer. In addition, during acquisition, data specific commands are sent to the electronics modules via FireWire (each module supports a control and a data logical unit). This paper provides an overview of the MiCES system and provides details of system integration and testing.