MODEL RELEASED. Gamma camera scanning. Patient undergoing a gamma or radionuclide scan. 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 the gamma camera (behind the patient, left), which produces a coloured image showing the functioning of specific organs and physiological systems. Gamma scans are also known as scintigrams.