NCIt definition : A radioactive isotope of iodine, a nonmetallic element of the halogen group, with
an atomic mass of 124 and a half-life of 4.18 days with radioisotopic activity. Selectively
accumulating in thyroid tissue, iodine I 124 emits positrons that can be detected
by positron emission tomography (PET), allowing localization of thyroid tissue. This
radioisotope also emits gamma rays.;