The present disclosure relates to increasing the spatial resolution of a clinical positron emission tomography (PET) scanner. The spatial resolution of the clinical PET scanner can be increased by placing a collimator, including a plurality of pinholes, inside the clinical PET scanner. Coincidence data of the annihilation photons are acquired by the PET scanner. A computer associates a pinhole location with the two detected locations of the coincident photons. All three locations are then used in the reconstruction of a high-resolution PET image.
