11Ccarbon

Carbon-11, often abbreviated as 11C, is a radioactive isotope of carbon with six protons and five neutrons, yielding a mass number of 11. It is a short-lived nuclide that decays primarily by positron emission to stable boron-11. Its half-life is about 20.3 minutes, which means it must be produced and used quickly in short-lived radiotracers for imaging.

Production and handling of 11C typically occur in a cyclotron. The isotope is commonly generated by irradiating nitrogen-14 with protons in the reaction 14N(p,α)11C. The resulting 11C is then incorporated into chemical compounds to form radiotracers suitable for positron emission tomography (PET). Because 11C is chemically indistinguishable from stable carbon, it can be introduced into a wide range of organic molecules including carbon dioxide, carbon monoxide, formyl groups, and methyl groups, enabling the creation of many different tracers.

In practical use, 11C radiotracers are employed for PET imaging to study biological processes such as brain function, metabolism, and protein synthesis. Common applications include mapping receptor distributions in the brain, tracking metabolic pathways, and evaluating tumor activity. The short half-life of 11C allows for high-contrast imaging with relatively low long-term radiation exposure, but it also requires on-site production and rapid radiochemical synthesis, limiting distribution to facilities with appropriate infrastructure.

Safety and regulatory considerations center on radiopharmacy practices, equipment for cyclotron production, and radiation protection. Proper handling, shielding, and waste management are maintained to protect patients and staff, while the transient nature of 11C minimizes long-term environmental impact.