Neutron Activation of Air by a Biomedical Cyclotron and an Assessment of Dose to Neighbourhood Populations

An evaluation is presented of the production of 13N, 15O, 16N, 37S, 40Cl and 41Ar by activation of air using neutrons generated by a 40 MeV cyclotron, now being installed in a hospital in Milan. The amount of radioactivity released into the external environment depends on the duration of each run and on the number of air changes per hour in the room. Calculations are performed for three different ventilation rates, for the cyclotron vault and one typical target room. The delivery of the activity into the external atmosphere will occur through a chimney. An assessment of the annual dose to individuals living in the vicinity, based on a simple atmospheric dispersion model, shows that no significant radiological risk to the population will be produced and, because several cautious assumptions were made, the values should be regarded as upper limits.