Iodine-123 a patient in capsule form, by intravenous injection, or (less commonly due to problems involved in a spill) in a drink. (I is usually administered in a drink, due to the heavy radiation dose to local tissues which results before a capsule could dissolve). The iodine is taken up by the thyroid gland and a gamma camera is used to functional images of the thyroid for diagnosis. Quantitative measurements of the thyroid can be performed to calculate the iodine uptake (absorption) for the diagnosis of hyperthyroidism and hypothyroidism. Dosing can vary; is recommended for thyroid imaging while an uptake test
Isotopes of iodine other form of direct radiation). The protective effect of KI lasts approximately 24 hours, so must be dosed daily until a risk of significant exposure to radioiodines from fission products no longer exists. Iodine-131 (the most common radioiodine contaminant in fallout) also decays relatively rapidly with a half-life of eight days, so that 99.95% of the original radioiodine has vanished after three months. Isotopes of iodine There are 37 known isotopes of iodine (I) from I to I; all undergo radioactive decay except I, which is stable. Iodine is thus a monoisotopic element. Its longest-lived radioactive isotope, I, has a