Dosimetry and Medical Radiation Physics

E2.10.05 Harmonization of quality practices for nuclear medicine radioactivity measurements

Background

The practice of nuclear medicine involves the injection of drugs, labelled with radioactivity, that target specific diseased tissues. It permits either the extent of the disease to be visualized with modern nuclear medicine imaging techniques, or delivers radiation doses to those tissues to kill the disease while minimizing damage to healthy tissue. The safety and effectiveness of these drugs depend on the ability of the radiopharmacy or clinic to accurately determine the amount of radioactivity (which ultimately determines the dose to the patient) contained in the drug prior to its administration. If insufficient activity is given, the drug may have insufficient effect or could possibly even cause the disease to progress; too much activity could result in an excessive radiation dose and possibly death. As countries adopt these techniques, it is necessary for them to have a uniform, effective quality assurance network that can ensure the accuracy of radioactivity measurements of radiopharmaceuticals. To achieve this, it is necessary for each radiopharmacy and clinic to have the capability to calibrate their measurement devices using sources that can be traced to national and international standards. This can be carried out on a national or regional basis by establishing measurement laboratories in those countries or regions that will interact closely with the Agency through measurement comparisons. These laboratories will, in turn, provide calibration services to radiopharmacies and clinics ("end users") as secondary laboratories. The challenges that currently exist include lack of metrology laboratories to service the countries or regions that currently practice nuclear medicine, as well as a lack of uniform guidance regarding exactly how the measurements are to be performed and how audits should be carried out to verify measurement quality.

There are currently few countries that have national measurement laboratories that routinely provide measurement services to end-users. Among the countries that do have active programmes, the services that are provided and the procedures that are used often differ considerably. The challenge for this CRP will be to develop a set of measurement and auditing procedures that can be used by all Member States that still meet all of their respective regulatory requirements.

The IAEA does not yet have the ability to provide radioactivity standards of short-lived radionuclides at activity levels required by the instrumentation used by most clinics and radiopharmacies, but efforts are now being directed at changing this situation. Although the Agency has, at various times, been involved with the production and distribution of radioactivity standards, a program specifically directed towards radioactivity standards and auditing of radioactivity measurement procedures for nuclear medicine has never been undertaken. The Agency has a great deal of experience providing dosimetry calibration and auditing services to radiotherapy clinics throughout the world via its SSDL program and is uniquely suited as an international organization to apply this experience to coordinate research into the development of a uniform code of practice for clinical radioactivity measurements and audits.