Modeling and incorporation of system response functions in 3D whole body PET

Appropriate application of spatially variant system models can correct for degraded resolution response and mispositioning errors. This work explores the detector blurring component of the system model for a whole body PET system and extends this factor into a more general system response function to account for other system non-idealities such as the influence of FORE rebinning. We model the system response function as a 3 dimensional function that blurs in the radial and axial dimension and is spatially variant in radial location. This function is derived from Monte Carlo simulations and incorporates inter-crystal scatter, crystal penetration, and the blurring due to FORE rebinning. The improved system model is applied in a modified OSEM algorithm to reconstruct FORE rebinned, fully 3D PET data into images with improved resolution and quantitative accuracy.