Sensitive method for the determination of 18F attached to aerosol particles in a PET centre

A new grab sampling method has been developed for the measurement of 18F attached to aerosol particles. It is based on direct β-counting of filtered aerosol sample over successive time intervals by an end-window Geiger–Müller counter. The effect of the progeny of radon and thoron on the β-counting rate is separated by analysing the decay curve. The defined solid angle absolute counting was used to evaluate the efficiencies for 18F and for the progeny of radon and thoron one by one. Absolute activity concentration of 18F can be determined with less than 10% systematic error. Glass-fibre filter and high sampling flow rate are applied, leading to a detection limit for 18F of less than 1 Bq m−3. The method was tested under different circumstances in the PET centre of University of Debrecen, Hungary.