Measurement of the residual radioactivity induced in the front foil of a target assembly in a modern medical cyclotron

The levels of residual radioactivity induced in Havar® foils at the entrance of a high-pressure 18O-enriched water target used for the production of 18F− in a medical cyclotron with 16 MeV protons have been determined using high-resolution γ-ray spectrometry. Whole body and skin dose rates arising from exposure to these foils during their periodic replacement have been estimated. The results indicate that irradiated foils do not represent a significant radiological hazard for the cyclotron operating staff and that no waste disposal difficulties should be encountered after an appropriate ‘cooling’ period of 2 years.