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Indium-111,  111In
Name, symbolIndium-111,111In
Nuclide data
Complete table of nuclides

Indium-111 (111In) is a radioactive isotope of Indium (In), atomic number (number of protons) of 49. The difference among the various isotopes of In is the number of neutrons (i.e. they have different atomic mass numbers). The naturally occurring isotopes of Indium are stable (non-radioactive): 113In (4.25%) and 115In (95.75%).[2]

111In chloride (Cl) solution is produced by proton irradiation ((p,2n) of a cadmium (Cd) isotope (112Cd) OR (p,n) 111Cd enriched target) in a cyclotron, as recommended by International Atomic Energy Agency (IAEA).[3] The former method is more commonly used as is results in a high level of radionuclide purity. 111In has a half-life (t1/2) of 2.81 days (67.32 hours) decaying by electron capture (EC) to 111Cd, which is stable (non-radioactive).[4]

It is commonly in Nuclear Medicine Diagnostic Imaging by radio-labeling targeted molecules or cells, During its radioactive decay, it emits low energy gamma (γ) photons which can be imaged using planar or SPECT (Single Photon Emission Computed Tomography) gamma cameras (primary energies (ε) of 171.3 keV (91%) and 245.4 keV (94%) )[4]

Example Clinical uses in Nuclear Medicine

When formulated as an 111In Cl solution, it can be used to bind antibodies 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; ZevlinTM 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, OctreoscanTM )
    • Octreotide is an somatostatin receptor inhibitor pharmaceutical which binds with high affinity to somatostatin receptors (SSRs) 2 and 5, interfering with normal receptor function. It is used as a drug to treat several neuroendocrine tumors (NET) in which SSRs 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 SSR2,5 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[edit]


  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. ^ Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna; Loss, Robert D. (2016-01-01). "Isotopic compositions of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry. 88 (3). doi:10.1515/pac-2015-0503. ISSN 1365-3075.
  3. ^ 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.
  4. ^ a b "FDA Label Document:Indium In-111 Chloride Sterile Solution". Retrieved 20 Aug 2018.
  5. ^ "PubChem In-111 Oxyquinoline". 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.