LES ACTIVITÉS NUCLÉAIRES : RAYONNEMENTS IONISANTS ET RISQUES POUR LA SANTÉ ET L’ENVIRONNEMENT 2.5 Medical and dental radiodiagnosis Medical radiodiagnosis is based on the principle of differential attenuation of X-rays in the organs and tissues of the human body. The information is collected on digital media allowing computer processing of the resulting images, and their transfer and filing. Diagnostic X-ray imaging is one of the oldest medical applications of ionising radiation; it encompasses all the methods of morphological exploration of the human body using X-rays produced by electric generators. It occupies an important place in the field of medical imaging and encompasses various techniques (conventional radiology, radiology associated with interventional practices, computed tomography, mammography) and a very wide variety of examinations (retroalveolar, radiography of the thorax, chestabdomen‑pelvis computed tomography scan, etc.). The request for a radiological examination by the referring physician must be part of a diagnostic strategy taking account of the patient’s known medical history, the question posed, the expected benefit for the patient, the examination exposure level and the dose history and the possibilities offered by other non-irradiating investigative techniques. The French Society of Radiology and Medical Imaging issues a Guide for Radiology and Medical Imaging Examination Referrals (ADERIM) to enhance the relevance of the examinations requested by referring physicians. If the dose delivered does not in itself represent a radiation protection health risk, it is the large number of examinations carried out among the population that contributes significantly to the collective dose of medical origin. 2.5.1 – Description of the techniques 2.5.1.1 Medical radiodiagnosis Conventional radiology Conventional radiology (producing radiographic images, or radiographs), if considered by the number of procedures, represents the large majority of radiological examinations performed. The examinations mainly concern the bones, the thorax and the abdomen. Conventional radiology can be carried out in fixed facilities reserved for diagnostic radiology or, in certain cases, using portable devices if justified by the clinical situation of the patient. Angiography This technique, used for exploring blood vessels, involves injecting a radio‑opaque contrast agent into the vessels which enables the arterial (arteriography) or venous (venography) tree to be visualised. Angiography techniques benefit from computerised image processing (such as digital subtraction angiography). Mammography Given the composition of the mammary gland and the fineness of detail required, screening for breast cancer necessitates the use of mammography units, specific radiology devices providing high-definition and high-contrast images. Two complementary imaging techniques are currently available, planar imaging (2D) and tomosynthesis imaging (3D). At present, only planar imaging, which functions at a low voltage and gives high definition and high contrast images, is approved by the HAS for breast cancer screening. ASNR participated in a working group coordinated by the HAS which has assessed the position of tomosynthesis mammography in the breast cancer screening strategy. In 2019, the HAS published a first report on the technical performance of tomosynthesis mammography in breast cancer screening of average-risk women. A second report on the evaluation of the performance and the position of tomosynthesis mammography in the French organised breast cancer screening programme was published by the HAS in April 2023. It recommends integrating tomosynthesis mammography (3D) in the organised screening programme, on condition that it is always associated with 2D synthetic image reconstruction (2Ds) in order to improve the screening performance without increasing the dose of ionising radiation. The use of these devices is subject to quality controls defined by the ANSM. The planar imaging (2D) quality controls are defined by the ANSM resolution of 15 January 2020 which entered into effect on 15 January 2021. ASN was consulted in this context and gave a favourable opinion on the draft resolution relative to the internal and external quality controls of digital mammography facilities. This resolution is currently being updated. ANSM’s future resolution will update the checks performed on 2D mammography units and will introduce external quality controls for the tomosynthesis devices. ASN has asked the GPRP to update the collection methods and the DRLs for 2D-DR mammography and to establish them for tomosynthesis mammography. The opinion issued by the GPRP in June 2023 will allow the updating of ASN resolution 2019-DC-0667 of 18 April 2019 on the methods of evaluating the ionising radiation doses delivered to patients during radiology, FGIP or nuclear medicine procedures, and the updating of the associated DRLs. Computed tomography Computed Tomography (CT) scanners use a beam of X-rays emitted by a tube that rotates around the patient’s body as the bed moves linearly, describing a helical scan. These scanners produce a three-dimensional reconstruction of the organs with very much better image quality than that of conventional radiology devices. An examination can comprise multiphase image acquisitions on the same given anatomical location or on different anatomical regions. This technique can, like MRI, be associated with functional imaging provided by nuclear medicine in order to obtain fusion images combining functional information with structural information. administrative personnel in the centres is still necessary to give them a clearer perception of the risks, especially for operating theatre personnel. Finally, analysis of the 49 significant radiation protection events notified during the period highlights situations of overexposure involving not only isolated cases, but also inappropriate practices leading to numerous repeated non-optimised exposures within the same activity. This is particularly the case for an ESR concerning exposure of a cohort of 44 patients who had undergone uterine fibroid embolisation procedures, for whom the dose levels delivered were found to be elevated and, in some cases, exceeded the reference values expected for this type of procedure. These events highlight the importance of better implementation of the optimisation principle, systematic monitoring of individual and cumulative dosimetric indicators, and in-depth analysis to identify contributing factors (procedure complexity, procedure duration, acquisition parameters and team organisation). They also highlight the need to establish a structured system for the post-exposure follow-up of patients and for shared OEF, particularly for activities involving a risk of delivering high doses, in order to prevent the recurrence of similar overexposures. Finally, in the case of professionals, the dose limit values are exceeded, in one case on the hands, and in the other case at the lens of the eye – once again highlights the challenges of radiation protection in this area and the need to regularly update individual dosimetry assessments and optimise practices. 220 ASNR Report on the state of nuclear safety and radiation protection in France in 2025
RkJQdWJsaXNoZXIy NjQ0NzU=