I123

Iodine-123, often abbreviated as I-123, is a radioactive isotope of the element iodine used primarily in diagnostic nuclear medicine. It has a half-life of 13.2 hours and decays by electron capture to tellurium-123, emitting gamma radiation with a principal energy of 159 keV. This emission is well suited to detection by standard gamma cameras and single-photon emission computed tomography (SPECT) systems, enabling high-quality diagnostic imaging.

Production and formulation aspects vary by facility, but I-123 is typically produced in nuclear reactors or accelerator facilities and then chemically separated and purified for clinical use. It is incorporated into radiopharmaceuticals or used as sodium iodide for imaging, with strict quality control to ensure radiochemical purity and appropriate specific activity for patient safety and image quality.

Medical applications focus on the thyroid and related systems. The most common use is thyroid scintigraphy and thyroid uptake studies to evaluate gland anatomy and function, helping diagnose hyperthyroidism, thyroid nodules, and other thyroid disorders. I-123 is also employed in radiopharmaceuticals such as I-123 MIBG for imaging certain neuroendocrine tumors and adrenergic tissue, demonstrating the versatility of the isotope in functional imaging. Compared with iodine-131, I-123 provides diagnostic information with a lower radiation dose and without the longer-lived beta emissions, facilitating safer and more precise assessment.

Safety and regulatory considerations accompany all radiopharmaceuticals. I-123 is administered under controlled conditions in licensed facilities, with attention to radiation safety, patient history, and relevant contraindications, including pregnancy. Hydration and adherence to timing for imaging help optimize image quality and reduce radiation exposure.