ASN Report 2020

ASN considers the radiation protection situation associated with the radionuclide distribution activity to be satisfactory on the whole. The large majority of licensees meet the main requirements and assume their responsibilities adequately (verifications prior to supply, technical verifications of the supplied sources, setting up the source recovery streams, transmission of information to the IRSN). These inspections also served to inform source suppliers of forthcoming changes in the regulations, particularly those concerning the protection of radioactive sources they hold, either for their own use of for future supply to customers, against malicious acts. However, these inspections and the analyses of significant events reports have also revealed points requiring particular attention, including: ∙ the ability of the suppliers to fully and exhaustively track the sealed radioactive sources from initial supply through to end-of- life recovery. This is because tracking is often incomplete and the expired or soon-to-expire sources (ten-year administrative limit counting from the date of the first registration figuring on the supply form) are not identified sufficiently far in advance, which slows down the recovery procedure; Cyclotrons A cyclotron is a device 1.5 to 4 metres (m) in diameter, belonging to the circular particle accelerator family. The accelerated particles are mainly protons, with energy levels of up to 70 megaelectronvolts (MeV). A cyclotron consists of two circular electromagnets producing a magnetic field and between which there is an electrical field, allowing the rotation of the particles and their acceleration at each revolution. The accelerated particles strike a target which is activated and produces radionuclides. Low and medium energy cyclotrons are primarily used in research and in the pharmaceutical industry to produce positron emitting isotopes, such as fluorine-18 or carbon-11. The radionuclides are then combined with molecules of varying complexity to form radiopharmaceuticals used in medical imaging. The best known of them is 18 F-FDG (fluorodeoxyglucose marked by fluorine-18), which is an industrially manufactured injectable drug, commonly used for early diagnosis of certain cancers. Other radiopharmaceutical drugs manufactured from fluorine-18 have also been developed in recent years, such as 18 F-Choline, 18 F-Na, 18 F-DOPA, along with other radiopharmaceuticals for exploring the brain. To a lesser extent, the other positron emitters that can be manufactured with a cyclotron of an equivalent energy range to that necessary for the production of fluorine-18 and carbon-11 are oxygen-15 and nitrogen-13. Their utilisation is however still limited due to their very short half-life. The approximate levels of activities involved for the fluorine-18 usually found in pharmaceutical facilities vary from 30 to 500 gigibecquerels (GBq) per production batch. The positron emitting radionuclides produced for research purposes involve activities that are usually limited to a few tens of gigabecquerels. ASN Report on the state of nuclear safety and radiation protection in France in 2020 263 08 – SOURCES OF IONISING RADIATION AND THEIR INDUSTRIAL, VETERINARY AND RESEARCH APPLICATIONS 08 Simplified diagram of the operation of a cyclotron Semi-cylindrical D-shaped hollow electrodes Magnetic field generated by two electromagnets Progressively accelerated particles Electric field AC voltage generator Beam extraction channel Isotopes transferred and then used in shielded cells Target in which the isotopes are generated Source of electrically charged particles Electromagnet Semi-cylindrical hollow electrode