On radiation situation in vicinity of PET production cyclotron

Abstract

The medical cyclotrons intended for the production of medical isotopes are relatively widespread. The most common radioisotope product of these facilities is 18F which origins from 18O(p, n)18F reaction. Due to relatively large amounts of produced nuclei, the leakage neutron and gamma flux is a big issue in radiation safety in such cyclotron labs. Due to relatively high energies of accelerated protons, high energy gammas and neutrons are produced with energies above 10 MeV with high penetration properties. Neutron and gamma spectra around cyclotron IBA Cyclone 18/9 intended for production of 18F was measured with stilbene detector. It was compared to simulated neutron spectra with various Monte Carlo codes and with spectral indices calculated from reaction rates in activation detectors. Strong disagreement in simulation of spectra in backward angles was found for MC codes Geant4 and MCNP6.2.