Indium-111

Indium-111 (¹¹¹In) is a radioactive isotope of indium (In). It decays by electron capture to cadmium-111 with a half-life of 2.8 days.

Indium-111, ¹¹¹In

General
Symbol	^111In
Names	indium-111, In-111
Protons	49
Neutrons	62
Nuclide data
Natural abundance	syn
Half-life	2.8049 d[1]
Decay products	^111Cd
Decay modes
Decay mode	Decay energy (MeV)
EC	0.860[2]
Isotopes of indium Complete table of nuclides

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 it results in a high level of radionuclide purity. ¹¹¹In has a half-life (t_1/2) of 2.81 days (67.32 hours) decaying by electron capture (EC) to ¹¹¹Cd, which is stable (non-radioactive).[4]

It is commonly used 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]

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; 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^TM )
  • 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

• Platelets for thrombus detection
• Leukocytes for localization of inflammation and abscesses, detect and monitor osteomyelitis, and detect mycotic aneurysms, vascular graft and shunt infections and determination of leukocyte kinetics;[6]

See also

• Isotopes of indium
• Indium white blood cell scan

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. 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. "FDA Label Document:Indium In-111 Chloride Sterile Solution". www.accessdata.fda.gov. Retrieved 20 Aug 2018.
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.