Optimization of collimators for imaging positron emitters by a gamma camera

The imaging of positron-emitting isotopes using a gamma camera requires special collimators. A ray-tracing method for simulating the point-spread function of collimators and, therefore, the total gamma camera system is presented. Simulated data obtained by this method showed good agreement with experimental data. Using this method, optimal lead and tungsten collimators for positron emitters were devised; at an object distance of B = 100 mm, these yielded a point-spread function with an FWHMtot = 9.1 mm using an intrinsic resolution of FWHMintr = 8.0 mm.