New Cross-Calibration Ion Chamber and Calibration Method for Radionuclide Activity Meters

Direct quality assurance with short-lived clinical isotopes


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).


  • Direct, manufacturer independent, standards lab traceable calibration
  • Ion chamber fits into the well of a dose calibrator, utilizing existing shielding
  • Activity of decaying source continually displayed to allow comparing to dose calibrator reading
  • Calibration transferable to any container or form factor
  • Easily transported between sites
  • Design minimizes variability due to sample position and volume present in the syringe
  • Highly accurate calibration facilitates quantitative imaging, a growing trend in nuclear medicine

Protection Status

US Provisional Patent

Product Number


Contact Information

Megha Bajaj
Technology Management Group
TEC Edmonton – University of Alberta
Phone: 780-492-7739