based on the recommendations of the manufacturers or medical professionals. Maintenance of the afterloaders (for the HDR and PDR applica– tions) –This is ensured by the manufacturers, particularly when replacing sources. The brachytherapy departments rely on these verifications to guarantee correct operation of the devices. The source activity is verified at each delivery, and verifications are also carried out on source removal. 2.2.3.5 Significant events in brachytherapy In 2021, 8 ESRs were reported in brachytherapy under criterion 2.1 (exposure of patients for therapeutic purposes), including one rated level 3 on the ASN‑SFRO scale concerning unintentional exposure of a female patient during an HDR brachytherapy treatment. In addition, one event is linked to the loss of seeds of iodine-125 during treatment preparation, which led to an atypical exposure of the workers without exceeding dose limits. The analysis of these events underlines that the control of risks in brachytherapy must be based on appropriate quality controls and the implementation of organisational measures to better manage the informing of the patient, the sources and emergency situations. SUMMARY ASN did not note any failure to comply with the radiation protection rules regarding treatment safety in brachytherapy in the centres inspected. The radiation protection of medical staff and the management of high-activity sealed sources are considered satisfactory. The training drive for medical professionals where high-activity sources are held must be maintained, and increased in some centres. ASN notes that the new requirements relative to safeguarding access to high-activity sources are being progressively deployed, in particular regarding measures to prevent unauthorised access to these sources. The reported events highlight the importance of a having an active events recording system in order to identify malfunctions as early as possible, to assess the risks in degraded situations (staff shortages), to formalise and record device quality controls. 2.3 Nuclear medicine Nuclear medicine is a medical discipline that uses radionuclides in unsealed sources for diagnostic purposes (functional imaging in vivo or medical biology in vitro) or therapeutic purposes (ITR). Thanks to the expansion of new radionuclides and vectors, nuclear medicine has considerably developed over the last few years, for diagnostic and therapeutic purposes alike. Nuclear medicine forms part of ASN’s inspection priorities. The main radiation protection risks are linked in particular to the use of unsealed sources, which generate radioactive waste and effluents, and can lead to contaminations. Nuclear medicine is moreover the main contributor to doses at the extremities of professionals in the nuclear sector (see point 1.2.1) During inspections, particular attention is focused on management of the sources, waste and effluents, occupational radiation protection, control of drug dispensing, through quality assurance obligations and the experience feedback process. 2.3.1 Presentation of the techniques In vivo diagnostic nuclear medicine allows the production of functional imaging which is complementary to the purely morphological imaging obtained by the other imaging techniques. This technique consists in examining a function of the organism using a specific radioactive substance called a RadioPharmaceutical Drug (RPD) which is administered to a patient. The nature of the RPD used depends on the organ or function to be studied. The RPD conventionally consists of a radionuclide which can be used directly (in this case the radionuclide constitutes the RPD) or be attached to a vector (molecule, hormone, antibody, etc.). In the latter case, it is the specific attachment of the vector that determines the studied function. Table 3 presents some of the principal radionuclides used in various explorations. It is by detecting the ionising radiation emitted from the radio– nuclide by using a specific detector that the RPD can be located in the organism and images of the functioning of the explored tissues or organs can be obtained. The majority of detection devices allow tomographic acquisitions and cross-sectional imaging and a three-dimensional reconstruction of the organs. The imaging techniques depend on the type of radionuclide used: Single Photon Emission Computed Tomography (SPECT), sometimes called “gamma-camera”, uses radionuclides emitting gamma radiation, while Positron Emission Tomography (PET) uses radionuclides emitting positrons. In order to make it easier to merge functional and morphological images, hybrid appliances have been developed. They combine PET cameras or gamma cameras with a CT scanner (PET-CT or SPECT-CT). According to a survey conducted by ASN in 2018 on the installed base of SPECT and “Cadmium-Zinc-Telluride” (CZT) semiconductor cameras in 2017, the inventory comprised: ∙ 423 SPECT cameras, of which 70% are coupled to a computed tomography (CT) scanner, accounting for 924,000 procedures per year; ∙ 51 CZT semiconductor cameras, of which 7 are coupled to a CT scanner, accounting for 125,000 procedures per year. The installed base of PET cameras comprised: ∙ 158 PET cameras, all coupled to a CT scanner, accounting for 486,000 procedures per year; ∙ 4 PET cameras coupled to an MRI scanner, performing some 2,000 procedures per year. In vitro diagnostic nuclear medicine is a medical biology technique used to assay certain compounds contained in the biological fluids sampled beforehand from the patient (e.g. hormones, tumoral markers, etc.); it is used frequently because it has the highest detection sensitivity of the techniques using ionising radiation. This technique uses assaying methods based on immunological reactions (reactions between antigens and antibodies marked with iodine-125), hence the name Radio Immunology Assay or radioimmunoassay –RIA). However, the number of in vitro diagnostic laboratories is decreasing due to the use of techniques offering greater detection sensitivity, such as immunoenzymology or chemiluminescence. At the end of 2019, about fifty in vitro diagnostic laboratories were licensed by ASN. Nuclear medicine for therapeutic purposes, or ITR, uses the administration of the RPDs to deliver a high dose of ionising radiation to a target organ for curative or palliative purposes. Two areas of therapeutic application of nuclear medicine can be identified: oncology and non-oncological diseases. Human Subject Research (HSR) in nuclear medicine has been particularly 216 ASN Report on the state of nuclear safety and radiation protection in France in 2021 07 – MEDICAL USES OF IONISING RADIATIONS
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