Radionuclide impurities in proton-irradiated [18O]H2O for the production of 18F-: Activities and distribution in the [18F]FDG synthesis process

Proton- and neutron-induced activation products in the components of a high-pressure [O-18]H2O target vessel used for the production of F-18(-) in a medical cyclotron have been identified using high resolution gamma spectrometry. The activities leached from the target vessel into the [O-18]H2O during irradiation, and the distribution of the identified radionuclide impurities in the various cartridges and solutions used in the [F-18]FDG synthesis process have been measured and are discussed from the perspective of waste disposal. The results indicate that, at the energies and beam currents employed, only a few, relatively short-lived radionuclides are present in the irradiated [O-18]H2O, and that the activities involved (< 10kBq in each case) are well below typical exemption limits. Activities of beta-emitting H-3 in irradiated [O-18]H2O, produced via the O-18(p,H-3)O-16 reaction, have also been determined using liquid scintillation spectrometry. Measured activity concentrations, in the range 150-180 kBq g(-1), are consistent with those reported by other workers. Analyses of the synthesised [F-18]FDG confirm the radiochemical purity of the product. both for H-3 and for gamma-emitting radionuclides in the energy range 25-1650 keV. (C) 2008 Elsevier Ltd. All rights reserved.