Cyclotron isotope production (F-18, Ga-68, Cu-64, Zr-89, At-211)

A medical cyclotron accelerates protons (or for a few isotopes deuterons or alpha particles) into a target whose nuclei absorb them and emit neutrons. Fluorine-18 (half-life 110 minutes) is made from oxygen-18-enriched water in almost every PET-producing radiopharmacy and cyclotron centre, then built into FDG, PSMA and other tracers by automated synthesis modules; distribution is limited to a few hours' travel. Gallium-68 (68 minutes) has two routes: a germanium-68/gallium-68 generator that a hospital elutes several times a day for about a year (made by Eckert & Ziegler, IRE ELiT and ITM among others), or direct cyclotron production from zinc-68 targets, which regulators have accepted for PSMA kits in the United States and which frees users from generator allocation. Copper-64 (12.7 hours, from nickel-64) and zirconium-89 (78 hours, from yttrium-89) allow central manufacture and national shipping, so copper-64 dotatate is made at a few sites and flown to scanners across the United States. Astatine-211 for alpha therapy needs an alpha beam of about 28 MeV on bismuth, which only a handful of cyclotrons in the world can deliver, and actinium-225 can be made from radium-226 targets on medium-energy cyclotrons (covered in the actinium record).

The machines and the shielded hot cells and synthesis modules are covered in the existing cyclotron record; this record is about the isotopes and their supply. Capacity constraints are target material (enriched oxygen-18 water, zinc-68, nickel-64 and above all radium-226), beam time shared between commercial tracers, and the GMP burden on hospital sites under 21 CFR 212 and EU Annex 3. The cyclotron makers are IBA, GE HealthCare, Siemens Healthineers (through PETNET) and Sumitomo, and the commercial networks (PETNET, Cardinal Health, SOFIE, Curium, Jubilant) run most of the daily production.