Calibration of ionization chamber for 18F and 68Ga

In order to maintain the results of primary activity standardizations carried out in 2011 the LNMRI has determined the calibration factors for a pressurized 4π-ionization chamber for the nuclides 18F and 68Ga. This ionization chamber is coupled to a 6517A Keithley electrometer which is controlled by a homemade LabVIEW program. This paper will describe the main issues related to the calibration of an ionization chamber system for positron emitters and short half-life radionuclides such as timing, current measurement, background, decay, and 226Ra check source measurements. - Highlights: • Calibration figures were determined for 18F and 68Ge/68Ga. • The main components of uncertainty were determined. • Use long-lived 68Ge/68Ga as replacement for 18F in quality control of calibrators. • Sent four 68Ge/68Ga reference solutions to manufacturers of radionuclide calibrators. • A standardized 68Ge/68Ga solution was submitted to the SIR at BIPM