radioactive substance – an RPD – to the patient. The choice of RPD depends on the studied organ or function. The RPD conventionally consists of a radionuclide which can be used alone (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 radionuclide 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. Depending on the type of radionuclide used, the term SPECT, still called “gamma-camera”, is used for radionuclides emitting gamma radiation and PET for radionuclides emitting positons. 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). A PET camera can also be coupled with an MRI scanner, but this is rarer. 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 labelled 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. 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 dynamic in recent years, primarily in the field of oncology therapy with the emergence of new vectors and radionuclides. This research is leading to the gradual introduction of new treatments which are intended to be proposed to a growing number of patients in the coming years, raising radiation protection issues which are currently being examined by ASN. ITR treatments can be administered either by mouth (e.g. capsule of iodine-131) or by systemic route (intravenous injection or via a catheter). Some treatments – depending on the administered activity or the nature of the radionuclide used – require patients to be hospitalised for several days in specially fitted-out rooms in the nuclear medicine department to ensure the radiation protection of the personnel, of people visiting the patients and of the environment. The radiological protection of these rooms is adapted to the nature of the radiation emitted by the radionuclides, and the contaminated urine of the patients is collected in tanks. When treatments are administered on an out-patient basis or in hospital rooms external to the nuclear medicine department, a circuit must also be provided to channel the patients’ urine to decay tanks, knowing that ASN’s circular letter of 12 June 2020 provides for, in the case of treatments based on lutetium-177, provisional derogation measures to give departments without these tanks time to install them. Out-patient treatment also implies, in certain cases, decay management of the waste produced by the patients in their home prior to disposal via the household waste route. Forty-five (45) nuclear medicine departments have a combined total of 170 ITR rooms for therapeutic purposes (see Graph 5). GRAPH 5 Overview of the national nuclear medicine base in 2024 0 10 20 30 40 50 60 Licensed centres Departments with out-patient therapies Departments with therapies with hospitalisation in ITR rooms ITR rooms Strasbourg Paris Orléans Nantes Marseille Lyon Lille Dijon Châlons-enChampagne Caen Bordeaux 33 5 27 15 13 2 7 4 2 2 5 16 3 10 31 4 14 23 7 26 5 17 5 22 6 23 4 11 2 5 1 11 3 20 4 56 7 20 21 28 8 9 9 9 TABLE 3 Main radionuclides used in diverse in vivo nuclear medicine explorations Type of examination Radionuclides used Thyroid metabolism Iode-123, technetium-99m Myocardial perfusion Rubidium-82, technetium-99m, thallium-201 Lung perfusion Technetium-99m Lung ventilation Krypton-81m, technetium-99m Osteoarticular process Fluor-18, technetium-99m Renal exploration Technetium-99m Oncology – search for metastases Fluor-18, gallium-68, technetium-99m Neurology Fluor-18, technetium-99m ASN Report on the state of nuclear safety and radiation protection in France in 2024 227 Medical uses of ionising radiation 07 01 02 03 04 05 06 08 09 10 11 12 13 14 15 AP
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