Self-normalization of emission data in 3D PET

Demonstrates that dead-time mismatch between the normalization and emission acquisitions in 3D positron emission tomography (PET) can introduce high-frequency circular image artifacts. We describe a simple correction scheme for this problem, where appropriate correction factors are calculated from the emission data itself, thus avoiding the necessity of acquiring normalization data at a range of different count-rates. In this scheme, "pseudo-detector efficiencies" are calculated from the emission data by the application of a conventional normalization algorithm. The mean systematic variation in these pseudo-efficiencies with position within the block detector is then calculated, and appropriate correction factors are applied to the original emission data. We show that this "self-normalization" scheme can remove normalization artifacts in both uniform and non-uniform phantom studies, and that it is also effective in vivo.