The University of Birmingham has pioneered and adapted the use of the medical imaging technique known as positron emission tomography (PET) to the study of particulate, granular and multiphase flows in industrial and physical processes. This paper provides a review of the PET and complimentary positron emission particle tracking (PEPT) techniques and details their application to the study of particulate systems. The current state of the art, recent developments and example results from many of the applications to which these techniques have been applied are highlighted. The University of Birmingham has pioneered and adapted the use of the medical imaging technique known as positron emission tomography (PET) to the study of particulate, granular and multiphase flows in industrial and physical processes. This paper provides a review of the PET and complimentary positron The current state of the art, recent developments and example results from many of the applications to which these techniques have been applied are highlighted.