I) is a radioactive isotope
used in nuclear medicine
imaging, including single photon emission computed tomography
Iodine-123 is produced in a cyclotron by proton irradiation of enriched xenon. Its half-life is 13.22 hours; the decay emits gamma radiation with predominant energies of 159 keV and 27 keV. In medical applications this radiation can be detected by a gamma camera.
Iodine-123 is supplied as a solution of sodium iodide
. This is administered to a patient by intravenous injection or as a drink1
. The iodine is taken up by the thyroid gland
and a gamma camera
is used to form functional images of the thyroid
for diagnosis. Quantitative measurements of the thyroid can be performed to calculate the iodine uptake for the diagnosis of hypothyroidism
Iodine-123 is also used as a label in other radiopharmaceuticals e.g.metaiodobenzylguanidine (MIBG).
1. Sharp PF, Gemmell HG, Smith FW (eds). Practical nuclear medicine 2nd edition. 1998 Oxford University Press.