Neutron measurements in the vicinity of a self-shielded PET cyclotron

The radionuclides used in positron emission tomography (PET) are short-lived and generally must be produced on site using a cyclotron. A common end product of the nuclear reactions used to produce the PET radionuclides is neutron radiation. These neutrons could potentially contribute to the annual effective dose received by hospital personnel. A Bonner sphere spectrometer was used to measure neutron energy spectra at three locations near a self-shielded PET cyclotron. This cyclotron accelerates protons to 11 MeV. The neutron measurements reported were made during the production of 18F via the 18O(p,n)18F reaction (Q = -2.4 MeV). Neutron spectra were obtained with the BUMS unfolding code and converted to dose equivalent rates.