Expanding the versatility of a more accurate accelerated Monte Carlo simulation for 3D PET: data correction of PET emission scans using 124I

Our Monte Carlo PET simulation for a 3D PET scan is able to simulate ~5 million coincidence events per minute per minute on 300MHz Sun dual processor workstation. This Is over two orders of magnitude faster than most other available Monte Carlo simulations for 3D PET and is fast enough to be employed as a scatter correction for 3D PET imaging. We have improved the accuracy of our simulation of a clinical ECAT HR+ scanner by analyzing the effect of the energy response of the detectors on simulated sinograms. We created a modified version of our simulation for 3D PET scans using ¹²⁴I. Our initial version was five times slower than our simulation for FDG scans. We analyzed the distribution of the simulated detected coincidence events involving gamma rays and proposed an analytical method that corrected for these events. We found that this correction is subject to errors that can be exacerbated when used in conjunction with an analytical scatter correction that scales to the measured sinogram´s scatter tail. To reduce error, we have developed a faster, more detailed simulation for ¹²⁴I. We are currently investigating the possibly of a fully Monte Carlo correction for both scatter and gamma ray coincidences in the future