Performance analysis of an improved 3-D PET Monte Carlo simulation and scatter correction

We are developing an accelerated Monte Carlo simulation of positron emission tomography (PET) that can be used for scatter correction of three-dimensional (3-D) PET data. Our Monte Carlo technique accurately accounts for single, multiple, and dual Compton scatter events, attenuation through the patient bed, and activity from outside the field of view. We have incorporated innovative sampling techniques that are compatible with our simulation approach, increasing computational efficiency by a factor of seven while improving accuracy through more sophisticated stratification and by incorporating the true energy response of the scanner. The required execution time to acquire 10 million scatter coincidence events for a 3-D thorax PET scan is only 4 min on a 300-MHz Sun dual-processor workstation. We demonstrate that for a low-noise thorax phantom study, image data corrected using the Monte Carlo 3-D PET scatter correction demonstrate no statistically significant deviation from the true activity concentration provided corresponding input data are accurate. The speed and accuracy of our simulation makes it an efficient research tool for studying scatter effects in PET and a practical scatter correction for 3-D PET clinical imaging.