Radioactive isotopes, or radioisotopes, are chemical elements that are produced through the natural decay of atoms. Exposure to radiation is harmful to the human body, but radioisotopes are highly valuable nuclear medicine, particularly in the diagnosis and treatment of disease. Nuclear medicine uses small amounts of radiation to provide information about a person’s body and the functioning of specific organs, ongoing biological processes, or the disease state of a specific illness. In most cases the information is used by physicians to make an accurate diagnosis. In certain cases radiation can be used to treat diseased organs or tumours.