Computerized Biological Brain Phantom for Evaluation of PET and SPECT Reconstruction

A digital brain phantom was created from available primate autoradiographic (AR) data for use in emission computed tomography studies. The tissue was radio-labelled with a functional analogue of the PET agent [18F]-fluoro-deoxyglucose (FDG). Following sacrifice of the animal, film records from serial 20 m thickness sections were digitized and calibrated to obtain ground truth 2D spatial distributions of relative radionuclide density. A 3D version was constructed by using a video subtraction method to align consecutive slices. In order to assess the effects of accurate modelling of activity, the AR data, containing cortical and basal ganglia structures, was used as a phantom in the context of a partialvolume correction method for obtaining accurate regional quantitation. A second phantom, less realistic in terms of activity assignment, was constructed and also tested. The results indicate that quantitation errors due to effects of nonuniform activity in the AR phantom are significant and comparable in magnitude to errors due to non-phantom effects.