A practical demand-based model for determining cyclotron irradiation time in routine 18F-FDG production

PURPOSE: The study aimed to develop and evaluate a practical model for determining cyclotron irradiation time based on planned fluorodeoxyglucose (FDG) supply in a hospital-based production setting. METHODS: Irradiation time was calculated using a composite coefficient of 2.8 min per GBq of planned clinical demand. The coefficient integrated a facility-specific conversion between required end-of-bombardment activity and irradiation time, a conservative synthesis yield of 55%, quality control activity consumption of 11.1%, radioactive decay during an approximately 30-min processing interval, and an operational safety factor of 1.2. RESULTS: During a fixed 24-month evaluation period, the model was applied on 516 consecutive scheduled FDG production days. Sufficient FDG activity was supplied for all scheduled examinations on all 516 days (100%), with no activity shortage attributable to underestimation of the required irradiation time. CONCLUSION: A demand-based irradiation model incorporating conservative yield assumptions, quality control consumption, and handling margins enables reliable FDG supply while maintaining an appropriate activity margin. This approach provides a practical framework for hospital-based radiopharmaceutical production.