A MACINTOSH-BASED MULTIENERGY DATA ACQUISITION-SYSTEM FOR GAMMA CAMERAS

A multi-energy data acquisition system based on the Macintosh II computer and a commercial ADC subsystem has been developed to allow the application of sophisticated Compton-scatter correction procedures. The system digitizes position and energy signals from the camera to 12 bits, bins the data into images, and transfers the data via an Ethernet interface to an extensive computer network for reconstruction and analysis. The system also provides the necessary gantry control signals for tomographic acquisition. In a preliminary application, the system has been used along with polynomial nonlinear spectral fitting (PNSF), which can account for shifts in the energy spectrum, to estimate scatter fractions for a hot, off-axis sphere in a cold, cylindrical phantom. The radioisotope is Tc-99m. The resultant scatter fractions display the expected symmetry with camera angle and dependence on the amount of scattering material between the source and camera.