Noise correlation in PET, CT, SPECT and PET/CT data evaluated using autocorrelation function: a phantom study on data, reconstructed using FBP and OSEM. - Pasha Razifar; Mattias Sandström; Harald Schneider; Bengt Långström; Enn Maripuu; Ewert Bengtsson; Mats Bergström (BMC Medical Imaging, 2005)