{"entity":{"id":"o-15","kind":"isotope","name":"Oxygen-15","aka":["15O"],"tldr":"A radioactive form of oxygen with a two-minute lifetime, made into water and injected to measure blood flow to the brain or heart; used almost exclusively in research because it decays too fast for routine hospital use in the US.","summary":"Oxygen-15 has the shortest half-life of any radionuclide used in PET, 122 seconds (about two minutes), and decays by pure positron emission. Labelled as [15O]water, it diffuses freely across cell membranes and its uptake is not confounded by metabolism, which makes it the physics gold standard for quantifying regional cerebral or myocardial blood flow; the very short half-life also allows repeat rest and stress or activation scans in the same session only 10-15 minutes apart, with a very low cumulative radiation dose.\n\nProduction requires an on-site cyclotron: nitrogen gas is bombarded with deuterons, 14N(d,n)15O, to give [15O]oxygen gas, which is then reacted over a heated palladium catalyst to form [15O]water vapour that is dissolved into saline for injection. Because a scan can only happen within a couple of minutes' walk of the cyclotron, [15O]water PET is confined to a small number of specialised academic centres worldwide.\n\n[15O]water PET myocardial and cerebral blood flow imaging is clinically approved and reimbursed in a number of European countries but, as of the mid-2020s, has not received FDA approval for routine US clinical use, so its US role remains research and investigational protocols rather than everyday practice.","status":"emerging","asOf":"2026-09-22","links":[{"label":"PMC: EANM procedural guidelines for PET/CT quantitative myocardial perfusion (O-15/N-13/Rb-82/F-18-flurpiridaz comparison table)","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC7603916/"},{"label":"PMC: frugal and translatable [15O]O2 production for human research","url":"https://pmc.ncbi.nlm.nih.gov/articles/PMC11083888/"}],"tags":["positron emitter","shortest-lived PET isotope","cerebral blood flow"],"related":[],"indications":[],"sections":[],"technologies":["pet","cyclotron-isotope-production"],"targets":[],"drugs":[],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":[],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"symbol":"15O","element":"Oxygen","massNumber":15,"halfLife":"122 seconds (about 2 minutes)","emissions":["β+ 100% (mean energy ~735 keV)","annihilation γ 511 keV"],"emissionClass":"positron","use":"imaging","production":"Cyclotron: 14N(d,n)15O on nitrogen gas target, converted to [15O]water over a heated palladium catalyst; 15N(p,n)15O and 16O(p,pn)15O are alternative routes.","supply":"research-only","supplyNote":"The 122-second half-life confines use to sites with an on-site cyclotron directly adjacent to the scanner; not FDA-approved for routine US clinical use as of the mid-2020s, though it is approved and reimbursed in parts of Europe.","chelators":[],"pairedWith":[],"since":1970},"route":"/isotopes/o-15/","neighbours":{"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/"}],"drug":[{"id":"n-13-ammonia","kind":"drug","name":"Ammonia N-13","route":"/drugs/n-13-ammonia/"}],"section":[{"id":"f-cardiac-imaging","kind":"section","name":"Cardiac imaging","route":"/fronts/f-cardiac-imaging/"}],"term":[{"id":"decay-correction","kind":"term","name":"Decay correction","route":"/terms/decay-correction/"}]}}