 Decay over 24 hours | |
| General | |
|---|---|
| Symbol | 18F |
| Names | fluorine-18, 18F, F-18, Fluorine-18 |
| Protons(Z) | 9 |
| Neutrons(N) | 9 |
| Nuclide data | |
| Natural abundance | Radioisotope |
| Half-life(t1/2) | 109.771(20) min |
| Isotope mass | 18.0009380(6)Da |
| Spin | 1+ |
| Excess energy | 873.431±0.593keV |
| Binding energy | 137369.199±0.593 keV |
| Decay products | 18O |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
| Positron emission (97%) | 0.6335 |
| Electron capture (3%) | 1.6555 |
| Isotopes of fluorine Complete table of nuclides | |
Fluorine-18 (18F, also called radiofluorine) is afluorineradioisotope which is an important source ofpositrons. It has a mass of 18.0009380(6) u and itshalf-life is 109.771(20) minutes. It decays bypositron emission 96.7% of the time andelectron capture 3.3% of the time. Both modes of decay yield stableoxygen-18.
18
F is a naturaltrace radioisotope produced bycosmic ray spallation of atmospheric argon as well as by reaction of protons with natural oxygen:18O + p →18F + n.[1]
In theradiopharmaceutical industry, fluorine-18 is made using either acyclotron orlinear particle accelerator to bombard a target, usually of natural or enriched [18O]water[2] with high energyprotons (typically ~18MeV). The fluorine produced is in the form of a water solution of [18F]fluoride, which is then used in a rapid chemical synthesis of various radio pharmaceuticals. The organic oxygen-18 pharmaceutical molecule is not made before the production of the radiopharmaceutical, as high energy protons destroy such molecules (radiolysis). Radiopharmaceuticals using fluorine must therefore be synthesized after the fluorine-18 has been produced.
First published synthesis and report of properties of fluorine-18 were in 1937 by Arthur H. Snell, produced by the nuclear reaction of20Ne(d,α)18F in the cyclotron laboratories ofErnest O. Lawrence.[3]
Fluorine-18 is often substituted for ahydroxyl group(–OH) in a radiotracer parent molecule, due to similarsteric andelectrostatic properties. This may however be problematic in certain applications due to possible changes in the moleculepolarity.
Fluorine-18 is one of the early tracers used inpositron emission tomography (PET), having been in use since the 1960s.[4]Its significance is due to both its short half-life and the emission of positrons when decaying. A major medical use of fluorine-18 is: in positron emission tomography (PET) to image the brain and heart; to image the thyroid gland; as a radiotracer to image bones and seeking cancers that have metastasized from other locations in the body and in radiation therapy treating internal tumors.
Tracers includesodium fluoride which can be useful for skeletal imaging as it displays high and rapid bone uptake accompanied by very rapid blood clearance, which results in a high bone-to-background ratio in a short time[5] andfluorodeoxyglucose (FDG), where the18F substitutes ahydroxyl.New dioxaborolane chemistry enables radioactive fluoride (18F) labeling ofantibodies, which allows forpositron emission tomography (PET) imaging ofcancer.[6] AHuman-Derived,Genetic,Positron-emitting andFluorescent (HD-GPF) reporter system uses a human protein,PSMA and non-immunogenic, and a small molecule that is positron-emitting (18F) and fluorescent for dual modality PET and fluorescence imaging of genome modified cells, e.g.cancer,CRISPR/Cas9, orCAR T-cells, in an entire mouse.[7] The dual-modality small molecule targetingPSMA was tested in humans and found the location of primary andmetastaticprostate cancer, fluorescence-guided removal of cancer, and detects single cancer cells in tissue margins.[8]
| Lighter: fluorine-17 | Fluorine-18 is an isotope offluorine | Heavier: fluorine-19 |
| Decay product of: neon-18 | Decay chain of fluorine-18 | Decays to: oxygen-18 |