Indium-111

Indium-111 (111In) is a radioactive isotope of indium (In). It decays by electron capture to stable cadmium-111 with a half-life of 2.8 days.[3] Indium-111 chloride (111InCl) solution is produced by proton irradiation of a cadmium target (112Cd(p,2n) or 111Cd(p,n)) in a cyclotron, as recommended by International Atomic Energy Agency (IAEA).[4] The former method is more commonly used as it results in a high level of radionuclide purity.

Indium-111, 111In
General
Symbol111In
Namesindium-111, In-111
Protons49
Neutrons62
Nuclide data
Natural abundancesyn
Half-life2.8049 d[1]
Decay products111Cd
Decay modes
Decay modeDecay energy (MeV)
EC0.860[2]
Isotopes of indium
Complete table of nuclides

Indium-111 is commonly used in Nuclear Medicine Diagnostic Imaging by radiolabeling targeted molecules or cells. During its radioactive decay, it emits low energy gamma (γ) photons which can be imaged using planar or Single-photon emission computed tomography (SPECT) gamma cameras (primary energies (ε) of 171.3 keV (91%) and 245.4 keV (94%))[3]

Uses in nuclear medicine

When formulated as an 111InCl solution, it can be used to bind antibodies, peptides, or other molecular targeted proteins or other molecules, typically using a chelate to bind the radionuclide (in this case 111In) to the targeting molecule during the radiosynthesis/ radiolabeling process, which is tailored to the desired product.

111In labeled antibodies
  • Ibritumomab Tiuxetan; Zevlin For dosimetry estimates prior to 90Y immunotherapy for lymphoma
  • 111In Prostoscint—PSMA antibody imaging of prostate cancer

111In labeled peptides
  • 111In pentetreotide (a.k.a. 111In (diethylenetriaminopentaacetic- (DTPA)-(octreotide), 111In octreotide DTPA, Octreoscan)
    • Octreotide is an somatostatin receptor inhibitor pharmaceutical which binds with high affinity to somatostatin receptors 2 and 5, interfering with normal receptor function. It is used as a drug to treat several neuroendocrine tumors in which somatostatin receptors are overexpressed or overactive. Examples include:
      • Sympathoadrenal system tumors: pheochromocytoma, neuroblastoma, ganglioneuroma, paraganglioma
      • Gastroenteropancreatic (GEP) tumors: Carcinoid, insulinoma
      • Medullary thyroid cancer, pituitary adenoma, small cell lung cancer
    • 111In pentetreotide imaging can identify the presence, levels of somatostatin receptor 2,5 expression, extent of disease and response to therapy

111In can also be formulated in the chemical form 111In oxyquinoline (oxine)[5] for labeling blood cells and components

See also

References
  1. Table of Radionuclides, Vol. 3 (PDF). Bureau international des poids et mesures. 2006. p. 75. ISBN 92-822-2218-7. Retrieved 26 June 2017.
  2. Wang, M.; Audi, G.; Kondev, F. G.; Huang, W. J.; Naimi, S.; Xu, X. (2017). "The AME2016 atomic mass evaluation (II). Tables, graphs, and references" (PDF). Chinese Physics C. 41 (3): 030003-1–030003-442. doi:10.1088/1674-1137/41/3/030003.
  3. "FDA Label Document:Indium In-111 Chloride Sterile Solution". www.accessdata.fda.gov. Retrieved 20 Aug 2018.
  4. Takács, S.; Tárkányi, F.; Hermanne, A. (Dec 2005). "Validation and upgrading of the recommended cross-section data of charged particle reactions: Gamma emitter radioisotopes". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 240 (4): 790–802. doi:10.1016/j.nimb.2005.06.209. ISSN 0168-583X.
  5. "PubChem In-111 Oxyquinoline". pubchem.ncbi.nlm.nih.gov. Retrieved 20 Aug 2018.
  6. "IN-111 FACT SHEET" (PDF). Nordion(Canada), Inc. Archived from the original (PDF) on 3 December 2011. Retrieved 23 September 2012.
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