A new imaging approach has been identified and studied in a preliminary way by simulation. The new approach is prompt gamma-ray imaging (PGI) and it is suggested for use on small animals. The approach consists of irradiating the small animal with neutrons, either in a thermal neutron beam from a nuclear reactor or with other sources like 252 Cf or machine sources. The neutrons can also be used directly to provide very sensitive imaging of the small animal, which can be used for registration of the prompt gamma-ray imaging. Characteristic prompt gamma rays are emitted in coincident chains that exhibit some angular correlation. Therefore, the imaging algorithms that can be employed in this case include aspects of both SPECT and PET. However, the approach is more general in some aspects than either SPECT or PET in that one can examine elements already present in the animal, or specific elements that are injected as tracers.