Normalisation of emission and transmission data taken with a large-area positron camera, PETRRA

Prior to reconstruction, emission and transmission data must be normalised to account for crystal non-uniformities and for geometric effects. The method described in this work for emission scans is based on the inversion of flood images that are acquired with ether a point or a plane source. The correction is applied in the event by backprojection (BP) of the list mode data obtained with PETRRA, a novel PET scanner that comprises two large area detectors. For transmission images linear interpolation was used unsuccessfully to predict values of the missing areas of the detectors that correspond to gaps between the crystals and the crystal support frame. Iterative reconstruction methods did not solve the problem either. Simulation data showed that more than one source position could remove circular artifacts in transmission imaging.