An analysis of correction methods for emission contamination in PET postinjection transmission measurement

Three techniques for estimation of emission contamination in PET postinjection transmission scans (PITSs) were evaluated and compared. For PET scanners with electronic windowing of events that intersect the transmission rod source locations, the emission contamination can be estimated by: (1) the emission data taken either before or after the transmission scan, using a sinogram window mask to correct for the rod position and window width; (2) the emission data taken concurrently with the transmission data and a similar sinogram window mask; (3) utilizing a windowed transmission scan with cold rods, or "mock" scan. These techniques have been evaluated with phantom experiments to simulate a wide range of residual activities and object sizes.