indium111

Indium-111 is a radionuclide of the element indium used in diagnostic nuclear medicine. It has an atomic number of 49 and a mass number of 111. It decays to cadmium-111 by electron capture with a half-life of about 2.8 days. It emits gamma rays with energies of 171 keV and 245 keV, making it suitable for gamma camera and SPECT imaging.

Production and forms: Indium-111 is produced by irradiation of cadmium targets in nuclear reactors or cyclotrons and is then chemically separated. It is available in various chemical forms, such as indium(III) chloride, or complexed with chelating agents to label biomolecules for imaging applications. One common approach is labeling with oxine to form Indium-111-oxine for leukocyte labeling.

Applications in medicine: Indium-111 is used to label radiopharmaceuticals for diagnostic imaging. Classic applications include infection and inflammation imaging with Indium-111 labeled leukocytes, which help localize occult infections. It is also used in tumor imaging, notably Indium-111 pentetreotide (octreotide analog) for somatostatin receptor imaging (OctreoScan), and Indium-111 capromab pendetide (ProstaScint) for prostate cancer imaging. Additional uses involve labeling various monoclonal antibodies or peptides for targeted imaging. The 2.8-day half-life enables imaging over one to several days after administration, which can be advantageous for certain slow-distributing agents but entails longer radiation exposure.

Safety and regulation: Like other radiopharmaceuticals, Indium-111 imaging requires specialized facilities and trained personnel, with regulatory oversight and dose optimization to balance image quality and patient safety. Adverse reactions are generally rare and related to the labeled compound rather than the isotope itself.