MODEL RELEASED. Gamma scan. Elderly woman undergoing a gamma or radionuclide scan of her abdomen, with a radiographer. This diagnostic technique is based on the detection of radiation emitted by radioactive substances known as radionuclides, which are introduced into the body. Specific radionuclides are swallowed by the patient. These are absorbed in different concentrations by different types of tissue, where they emit radioactive gamma rays. The rays are detected by a camera (upper centre) which produces a coloured image from which the functioning of the tissues is studied. Gamma scans are also known as scintigrams.