ABSTRACT
Barbara Y. Croft Nuclear medicine can be defined as the practice of making patients radioactive for diagnostic and
therapeutic purposes. The radioactivity is injected intravenously, rebreathed, or ingested. It is the internal circulation of radioactive material that distinguishes nuclear medicine from diagnostic radiology and radiation oncology in most of its forms. This section will examine only the diagnostic use and will concentrate on methods for detecting the radioactivity from outside the body without trauma to the patient. Diagnostic nuclear medicine is successful for two main reasons (1) It can rely on the use of very small amounts of materials (picomolar concentrations in chemical terms) thus usually not having any effect on the processes being studied, and (2) the radionuclides being used can penetrate tissue and be detected outside the patient. Thus the materials can trace processes or “opacify” organs without affecting their function.
