# Indium-111

Source: https://nuclide.cc/isotopes/in-111/  
Nuclide record `in-111` (Isotope). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

A radioactive metal used, attached to octreotide, as the original scan for neuroendocrine tumours (Octreoscan) before gallium-68 PET took over, and still used to label white blood cells for infection imaging.

## Summary

Indium-111 decays by electron capture to stable cadmium-111 with a 2.805-day half-life, emitting gamma photons suited to gamma-camera and SPECT imaging. For two decades it was the standard somatostatin-receptor imaging agent as 111In-pentetreotide (Octreoscan), used to select neuroendocrine tumour patients before peptide receptor radionuclide therapy, first with 90Y-labelled and later with 177Lu-labelled somatostatin analogues; SPECT-based Octreoscan has since been largely replaced by 68Ga- or 64Cu-DOTATATE PET, which has better resolution and quantification, but 111In-pentetreotide remains on label and in use where PET access is limited.

It is produced on a cyclotron by proton bombardment of an enriched cadmium target, either 112Cd(p,2n)111In or 111Cd(p,n)111In, the latter giving higher radionuclidic purity. Its 2.8-day half-life is long enough to ship internationally and to track slower-clearing tracers such as labelled leukocytes and antibody fragments, which is why it is also used for infection and inflammation imaging (111In-labelled white cells) and in some antibody biodistribution and dosimetry studies.

## Fields

- Kind: Isotope
- Status: established
- Last checked: 2026-09-22
- Also known as: 111In
- Tags: gamma emitter; legacy somatostatin imaging

## Sources

- FDA/DailyMed label: OctreoScan (indium In 111 pentetreotide): https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=93d8f3b2-1216-41dc-a63d-0e812b33891d
- Wikipedia: indium-111 (production routes): https://en.wikipedia.org/wiki/Indium-111

## Connected records

- drugs: [Actinium-225 FPI-2068](https://nuclide.cc/drugs/ac-225-fpi-2068/), [Gallium-68 DOTATATE (and Cu-64 DOTATATE)](https://nuclide.cc/drugs/ga68-dotatate/), [Indium-111 pentetreotide](https://nuclide.cc/drugs/in-111-pentetreotide/), [Lutetium-177 dotatate](https://nuclide.cc/drugs/lutathera/), [Technetium Tc-99m PSMA agents (PSMA-I&S)](https://nuclide.cc/drugs/tc-99m-psma-imaging/)
- indications: [Neuroendocrine tumours](https://nuclide.cc/indications/neuroendocrine/)
- technologies: [Auger-electron therapy](https://nuclide.cc/technologies/auger-electron-therapy/), [Cyclotron isotope production (F-18, Ga-68, Cu-64, Zr-89, At-211)](https://nuclide.cc/technologies/cyclotron-isotope-production/), [Somatostatin receptor PET (68Ga/64Cu-DOTATATE)](https://nuclide.cc/technologies/sstr-pet/), [SPECT & bone scan](https://nuclide.cc/technologies/spect/), [SPECT/CT](https://nuclide.cc/technologies/spect-ct/)
- trials: [Study Evaluating Dosimetry, Randomized Dose Optimization, Dose Escalation and Efficacy of Ac-225 Rosopatamab Tetraxetan in Participants With PSMA PET-Positive Castration-Resistant Prostate Cancer (CRPC)](https://nuclide.cc/trials/nct06549465/)
- companies: [BWXT Medical](https://nuclide.cc/companies/bwxt-medical/)
- pairings: [68Ga-DOTATATE PET before Lutathera (177Lu-DOTATATE)](https://nuclide.cc/pairings/ga68-dotatate-then-lutathera/)
- roadmaps: [PSMA theranostics roadmap: antigen discovery → PSMA PET → 177Lu-PSMA-617 → earlier lines and alpha](https://nuclide.cc/roadmaps/psma-theranostics-roadmap/), [SSTR theranostics roadmap: octreotide scintigraphy → 68Ga-DOTATATE → 177Lu-DOTATATE → alpha](https://nuclide.cc/roadmaps/sstr-theranostics-roadmap/)
- targets: [Bradykinin B1 receptor (B1R)](https://nuclide.cc/targets/bradykinin-b1-receptor/), [CCK2 receptor (gastrin receptor)](https://nuclide.cc/targets/cck2-receptor/)
- terms: [Chelator (bifunctional chelating agent)](https://nuclide.cc/terms/chelator-term/), [Krenning score](https://nuclide.cc/terms/krenning-score/)

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