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Radiation Protection of Patients in Nuclear Medicine: Diagnostic Reference Levels and Accuracy of Activity Meters

8 June 2022


Moderator: Jenia Vassileva (IAEA), Peter Knoll (IAEA)

Presenters: Mario Marengo (Italy)

About the webinar

Optimization in diagnostic nuclear medicine means keeping the exposure of patients to the minimum necessary to achieve the required diagnostic objective and clinical outcome. The IAEA Safety Standards define several components of optimization of protection, including the use of appropriate and well-designed medical radiological equipment and associated software, appropriate selection of the best available radiopharmaceutical and its activity, as well as the appropriate acquisition parameters to acquire diagnostic image quality at minimum patient dose.

An important tool for optimization is the use of diagnostic reference levels (DRLs), which are usually set at national or regional level and then used for benchmarking local practices. This cycle of establishment of national or regional DRLs, their use by nuclear medicine departments to compare their local values, corrective actions by imaging facilities, and periodic review of national or regional DRLs brings about a steady improvement in the optimization of patient protection.

The webinar will review DRL concept as applied to nuclear medicine. The role of international recommendations, national and local DRLs will be discussed, as well as the appropriate quantities to be used in nuclear medicine, including multi-modality imaging studies. For the nuclear medicine component of the study, DRLs are set up to monitor and assess the radiopharmaceutical dose administered to patient. In the nuclear medicine facility, the administered activity should be verified by means of an activity meter, calibrated at appropriate intervals. The role of radionuclide activity meters in radiation protection of patient will be discussed, starting with a recap of the principles of operation up to a critical analysis of the modality to obtain a calibration traceable to the international standards of the unit for activity.

Learning objectives

  • To review the concept of DRL and responsibilities for their establishment
  • To learn which quantities are used for DRLs in nuclear medicine
  • To review the principle of operation of activity meters
  • To discuss traceability of calibration of activity meters to the international safety standards


Dr. Mario Marengo is a Medical Physicist and Radiation Protection Expert, former Director of the Medical Physics Department of the University Hospital of Bologna, S. Orsola–Malpighi. After his retirement in September 2018, he continues his professional activities as an Adjunct Professor for the University of Bologna and as a Technical Expert for the International Atomic Energy Agency. After he draduated in Physics and PhD in Medical Physics from the University of Bologna, he contributed to the design and construction of the PET Center of the S. Orsola Hospital, as well as of other PET and Nuclear Medicine Centers, both nationally and internationally. Dr. Marengo is an expert in quality systems in medicine and quality auditor. He is the author of on the Italian publication on— Physics in Nuclear Medicine — and has contributed to the IAEA publications on physics in nuclear medicine. He has co-authored over 90 original publications in peer reviewed scientific journals and numerous reports at national and international congresses.

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