# Oxygen-15

Source: https://nuclide.cc/isotopes/o-15/  
Nuclide record `o-15` (Isotope). Data CC BY-NC 4.0, attribute "Data from Nuclide (nuclide.cc)"; commercial use needs a licence.

## TL;DR

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.

Production 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.

[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.

## Fields

- Kind: Isotope
- Status: emerging
- Last checked: 2026-09-22
- Also known as: 15O
- Tags: positron emitter; shortest-lived PET isotope; cerebral blood flow

## Sources

- PMC: EANM procedural guidelines for PET/CT quantitative myocardial perfusion (O-15/N-13/Rb-82/F-18-flurpiridaz comparison table): https://pmc.ncbi.nlm.nih.gov/articles/PMC7603916/
- PMC: frugal and translatable [15O]O2 production for human research: https://pmc.ncbi.nlm.nih.gov/articles/PMC11083888/

## Connected records

- 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/)
- drugs: [Ammonia N-13](https://nuclide.cc/drugs/n-13-ammonia/)
- fronts: [Cardiac imaging](https://nuclide.cc/fronts/f-cardiac-imaging/)
- terms: [Decay correction](https://nuclide.cc/terms/decay-correction/)

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