Investigation of accelerated Monte Carlo techniques for PET simulation and 3D PET scatter correction

The authors have been developing Monte Carlo Techniques for calculating primary and scatter photon distributions in PET. Their first goal has been to accelerate the Monte Carlo Code for fast PET simulation. Their second goal has been to use the simulation to analyze scatter effects in PET and explore the potential for use in scatter correction of clinical 3D PET studies. The authors have reduced the execution time to about 30 minutes or /spl sim/1 million coincidences per minute on a dual 300 MHz processor UltraSparcII workstation. The short execution time makes it feasible to use this technique for 3D PET scatter correction in the clinic. Fast simulation also allows the authors rapid feedback for the close examination of the accuracy of the method. They present techniques used to improve computational efficiency of Monte Carlo PET simulations. They use the simulation to analyze how scatter from within the body, outside the FOV, and from scanner shielding as well as the chosen energy threshold affect 3D PET sinograms.