F-18 Half-Life and Decay Mode
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Question
F-18 (fluorine-18) is the most widely used PET radionuclide. What is its physical half-life and primary mode of production?
- APhysical half-life 110 minutes; produced by a cyclotron via proton bombardment of O-18 enriched water
- BPhysical half-life 75 seconds; produced from a strontium-82 generator
- CPhysical half-life 68 minutes; produced from a germanium-68 generator
- DPhysical half-life 10 minutes; produced by a cyclotron from N-14
Show the answer and explanation
A. Physical half-life 110 minutes; produced by a cyclotron via proton bombardment of O-18 enriched water
F-18 has a physical half-life of 109.77 minutes (~110 minutes). It decays by positron emission (97%) to O-18. F-18 is produced by cyclotron via proton bombardment of O-18-enriched water: ¹⁸O(p,n)¹⁸F. The 110-minute half-life is long enough to allow off-site production and regional distribution (unlike N-13 at 10 min or Rb-82 at 75 sec, which require on-site production), yet short enough for reasonable patient radiation dose and efficient department scheduling. F-18 FDG (fluorodeoxyglucose) is produced by nucleophilic substitution of a precursor molecule with F-18 in an automated synthesis module.
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