Scatter correction in the transaxial slices of a whole-body positron emission tomograph

A procedure for scatter correction in a whole-body positron emission tomograph (PET) is presented. The method is based on measured scatter distributions of line sources. It extends the method originally developed by Bergstrom et al. (1983) for brain scanners to large objects. Scatter distributions were measured with line sources at different positions in cylindrical water containers with diameters ranging from 20 to 35 cm. The projection data were approximated by a monoexponential function, the scatter distribution function f. The parameters of this function depended on the projected distance of the source from the centre and on the diameter of the phantom. For scatter correction, the scatter distributions in emission scans were calculated by integral transformation of the measured projection data with the spatially variant scatter distribution function, and then subtracted from the measured projection data. The method was tested using cylindrical phantoms of different diameters and the EEC body phantom with arms, both with uniform activity distributions.