A portable ion chamber system has been designed for direct calibration of radionuclide activity meters in nuclear medicine and research. The cylindrical chamber accommodates a syringe filled with a specified volume of radionuclide, allowing dose calibrators to be measured against a known quantity of the short-lived radio isotopes actually used in the clinic (e.g. for PET imaging). Following the establishment of an isotope-specific calibration factor at a standards lab, the portable ion chamber is easily shipped to a nuclear medicine clinic or research site, where the same isotope can be measured using an identical syringe.
Results: Chamber sensitivity was 12.1, 12.5 and 29.4 pA/100MBq for ¹³¹I, ⁹⁹ᵐTc and ¹⁸F, respectively. The uncertainty budget for the ion chamber yields an overall uncertainty of better than 1%, with the greatest contribution arising from constancy and linearity (0.5% each).