A DATA-ACQUISITION SYSTEM FOR COINCIDENCE IMAGING USING A CONVENTIONAL DUAL HEAD GAMMA-CAMERA

A low cost data acquisition system (DAS) was developed to acquire coin cidence data from an unmodified General Electric Maxxus dual head scin tillation camera. A high impedance pick-off circuit provides position and energy signals to the DAS without interfering with normal camera o peration. The signals are pulse-clipped to reduce pileup effects. Coin cidence is determined with fast timing signals derived from constant f raction discriminators. A charge-integrating FERA 16 channel ADC feeds position and energy data to two CAMAC FERA memories operated as ping- pong buffers. A Macintosh PowerPC running Labview controls the system and reads the CAMAC memories. A CAMAC 12-channel scaler records single s and coincidence rate data. The system dead-time is approximately 10% at a coincidence rate of 4.0 kHz.