{"entity":{"id":"c-11","kind":"isotope","name":"Carbon-11","aka":["11C"],"tldr":"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.\n\nThe 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.\n\nCholine 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.","status":"established","asOf":"2026-09-22","links":[{"label":"FDA label: Choline C 11 Injection (NDA 203155, approved 12 Sep 2012)","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=61f00cb4-ea53-4ba6-a890-78586095d2f6"},{"label":"PMC: synthesis, isolation and purification of [11C]-choline","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC5013686/"}],"tags":["positron emitter","ultra-short-lived","on-site only"],"related":["choline-c11"],"indications":["prostate"],"sections":[],"technologies":["pet","cyclotron-isotope-production","choline-metabolism-in-cancer"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"11C","element":"Carbon","massNumber":11,"halfLife":"20.4 minutes","emissions":["β+ ~99.8% (max 0.96 MeV)","electron capture ~0.2%"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 14N(p,α)11C on nitrogen gas target (with trace oxygen for [11C]CO2 or trace hydrogen for [11C]CH4), converted to [11C]methyl iodide or [11C]methyl triflate for labelling.","supply":"research-only","supplyNote":"The 20.4-minute half-life rules out shipping entirely; every dose is made and used at the same site, so availability is limited to institutions with an on-site cyclotron and radiochemistry, mostly academic centres.","chelators":[],"pairedWith":[],"since":1973},"route":"/isotopes/c-11/","neighbours":{"drug":[{"id":"choline-c11","kind":"drug","name":"Choline C-11","route":"/drugs/choline-c11/"}],"indication":[{"id":"primary-aldosteronism","kind":"indication","name":"Primary aldosteronism","route":"/indications/primary-aldosteronism/"},{"id":"prostate","kind":"indication","name":"Prostate cancer","route":"/indications/prostate/"}],"technology":[{"id":"cyclotron-isotope-production","kind":"technology","name":"Cyclotron isotope production (F-18, Ga-68, Cu-64, Zr-89, At-211)","route":"/technologies/cyclotron-isotope-production/"},{"id":"pet","kind":"technology","name":"PET (positron emission tomography)","route":"/technologies/pet/"}],"pathway":[{"id":"choline-metabolism-in-cancer","kind":"pathway","name":"Choline metabolism in cancer","route":"/pathways/choline-metabolism-in-cancer/"}],"roadmap":[{"id":"neuro-imaging-roadmap","kind":"roadmap","name":"Neuro-oncology imaging roadmap: FDG PET → amino acid PET → SSTR2 theranostics in meningioma","route":"/roadmaps/neuro-imaging-roadmap/"}],"target":[{"id":"amyloid-beta","kind":"target","name":"Amyloid beta plaques","route":"/targets/amyloid-beta/"},{"id":"dlg4-psd95","kind":"target","name":"DLG4 (PSD-95)","route":"/targets/dlg4-psd95/"}]}}