Characterisation of the secondary neutron field generated by a compact PET cyclotron with MCNP6 and experimental measurements

The production of the most common used PET radioisotope Fluorine-18 with commercial cyclotrons is obtained from the ¹⁸O(p,n)¹⁸F nuclear reaction when ¹⁸O-enriched water is bombarded with a proton beam. We present the characterization of the secondary neutron field spectra produced by this reaction in different locations around the cyclotron, through a comparison between MCNP6 Monte Carlo simulation results and experimental data obtained with Neutron Activation Analysis (NAA) of thin target foils of different materials. - Highlights: • An alternative method of neutron spectra characterization of commercial cyclotrons is proposed. • Detailed Monte Carlo simulation of cyclotron structure is presented. • Characterization of neutron field is essential for future decommissioning of the cyclotron and health physics program. • Estimation of ambient dose is presented.