PET Detector Ring Aperture Function Calculations Using Monte Carlo Techniques

A Monte Carlo simulation of gamma-ray transport within a single-slice positron emission tomography (PET) ring camera has been developed. Included in the simulation are the radioactive source distribution, collimators, and detectors with inter-crystal septa. The modelling code has been used to study the effect of the septa and BGO detector width on system sensitivity and intrinsic resolution. It is concluded that if the detectors are close-packed, there is a decreasing incentive in using detectors less than 1 cm in width in a high sensitivity camera designed for head scans. It is also found that by using tungsten-alloy inter-crystal septa, near optimum ring sensitivity can be achieved over a wide range of ring radii while maintaining a uniform intrinsic resolution function over the image area.