fluoru18

Fluorine-18, often written as 18F, is a positron-emitting radioisotope of fluorine with mass number 18 and atomic number 9. It decays to stable 18O by positron emission with a half-life of about 109.8 minutes, emitting positrons that annihilate with electrons to produce two 511 keV gamma photons. Because of its relatively short half-life and favorable positron energy, 18F is well suited for medical imaging.

Production and radiochemistry

18F is typically produced in a medical cyclotron by irradiating 18O-enriched water with protons, via the 18O(p,n)18F reaction. The produced fluoride is captured as [18F]fluoride in aqueous solution and transported to a radiopharmacy. In radiochemistry, 18F is incorporated into tracer molecules through nucleophilic substitution or other labeling methods, yielding high-purity radiopharmaceuticals suitable for PET imaging.

Common radiotracers and applications

The most widely used 18F-labeled tracer is fluorodeoxyglucose labeled with fluorine-18 [18F]FDG, which reflects tissue glucose metabolism and is integral to oncologic, neurologic, and cardiologic PET imaging. Other 18F-labeled tracers include [18F]FLT for cellular proliferation, [18F]FDOPA for dopaminergic systems, and various amino-acid or receptor-targeted compounds. The choice of tracer depends on the clinical question and the biological process of interest.

Advantages, limitations, and safety

18F offers a favorable combination of a moderate half-life and high-energy positrons, enabling high-quality images and practical distribution to PET facilities. Limitations include the need for on-site or nearby production and strict radiation-safety controls. Handling requires trained personnel, shielding, and regulatory oversight to minimize radiation exposure to patients and staff.

See also

PET imaging; radiopharmaceuticals; cyclotron production.