MODEL-BASED SCATTER CORRECTION FOR FULLY 3D PET

A method is presented that directly calculates the mean number of scat tered coincidences in data acquired with fully 3D positron emission to mography (PET). This method uses a transmission scan, an emission scan , the physics of Compton scatter, and a mathematical model of the scan ner in a forward calculation of the number of events for which one pho ton has undergone a single Compton interaction. The distribution of ev ents for which multiple Compton interactions have occurred is modelled as a linear transformation of the single-scatter distribution. Comput ational efficiency is achieved by sampling at rates no higher than tho se required by the scatter distribution and by implementing the algori thm using look-up tables. Evaluation studies in phantoms with large sc atter fractions show that the method yields images with quantitative a ccuracy equivalent to that of slice-collimated PET in clinically usefu l times.