Nuclear Medicine involves the diagnostic and therapeutic use of the radioactive materials. In Nuclear Medicine, ionising radiation is administered in the form of a radionuclide, which is chemically tagged to a pharmaceutical. The design of a Nuclear Medicine facility needs to take into consideration numerous regulatory requirements as well as allowing good clinical working practices. The radioactive agents given to patients are mostly manufactured within a hospital Radiopharmacy – an aseptic unit conforming to standards outlined by the “orange guide” published by the Medicines and Health Regulatory Agency. Technetium-99m is the main radionuclide used in the Nuclear Medicine. Radionuclide calibrators are used to measure radioactivity during the preparation of radiopharmaceutical kits and prior to administration to patients. Clinical Scientists specialising in Nuclear Medicine are expected to have a detailed understanding of the design and function of the gamma camera used to detect emitted gamma photons.