# Carbon-11

Source: https://nuclide.cc/isotopes/c-11/  
Nuclide record `c-11` (Isotope). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

A radioactive form of ordinary carbon that lasts only about 20 minutes, so it has to be made and used in the same building; it can label real body molecules like choline without changing their chemistry.

## Summary

Carbon-11 decays by positron emission (about 99.8% of the time) with a physical half-life of only 20.4 minutes, the shortest half-life of any radionuclide in routine clinical use. Because carbon is the backbone atom of biological molecules, replacing a stable carbon-12 with carbon-11 gives a radiotracer that is chemically indistinguishable from its natural counterpart, unlike fluorine- or metal-based tracers that are typically synthetic analogues.

The half-life is so short that C-11 cannot be shipped: it must be produced, synthesised into a tracer, quality-tested and injected within the same facility, on the same clock, which is why C-11 programmes exist only at large academic or hospital sites with an on-site cyclotron and radiochemistry suite immediately adjacent to the PET scanner. Almost all clinical C-11 comes from the 14N(p,α)11C reaction, bombarding nitrogen gas with protons to give [11C]carbon dioxide or, with added hydrogen, [11C]methane, which is then converted to the reactive methylating agent [11C]methyl iodide or [11C]methyl triflate to label a precursor molecule such as choline or methionine.

Choline C-11 was approved by the FDA in September 2012 for PET imaging of suspected recurrent prostate cancer with non-informative conventional imaging, and remains one of the few full-NDA radiopharmaceuticals that can only be produced and used on site.

## Fields

- Kind: Isotope
- Status: established
- Last checked: 2026-09-22
- Also known as: 11C
- Tags: positron emitter; ultra-short-lived; on-site only

## Sources

- FDA label: Choline C 11 Injection (NDA 203155, approved 12 Sep 2012): https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=61f00cb4-ea53-4ba6-a890-78586095d2f6
- PMC: synthesis, isolation and purification of [11C]-choline: https://pmc.ncbi.nlm.nih.gov/articles/PMC5013686/

## Connected records

- drugs: [Choline C-11](https://nuclide.cc/drugs/choline-c11/)
- indications: [Primary aldosteronism](https://nuclide.cc/indications/primary-aldosteronism/), [Prostate cancer](https://nuclide.cc/indications/prostate/)
- technologies: [Cyclotron isotope production (F-18, Ga-68, Cu-64, Zr-89, At-211)](https://nuclide.cc/technologies/cyclotron-isotope-production/), [PET (positron emission tomography)](https://nuclide.cc/technologies/pet/)
- pathways: [Choline metabolism in cancer](https://nuclide.cc/pathways/choline-metabolism-in-cancer/)
- roadmaps: [Neuro-oncology imaging roadmap: FDG PET → amino acid PET → SSTR2 theranostics in meningioma](https://nuclide.cc/roadmaps/neuro-imaging-roadmap/)
- targets: [Amyloid beta plaques](https://nuclide.cc/targets/amyloid-beta/), [DLG4 (PSD-95)](https://nuclide.cc/targets/dlg4-psd95/)

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