IODINE I-123 is a radioactive isotope of iodine used in nuclear medicine imaging, including single photon emission computed tomography (SPECT) and X-ray computed tomography (X-Ray CT) scans. Iodine-123 is usually supplied as sodium iodide (NaI) and hypoiodite (OI−) in dilute sodium hydroxide solution, at high isotopic purity. 123I is the most suitable isotope of iodine for the diagnostic study of thyroid diseases. The half-life of approximately 13.13 h (hours) is ideal for the 24-h (hour) iodine uptake test and 123I has other advantages for diagnostic imaging thyroid tissue and thyroid cancer metastasis. The iodine is taken up by the thyroid gland and/or cancer metastasis 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. This is administered to a patient in capsule form, by intravenous injection, or in a drink.