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. ASN 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 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. The 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 2019DC-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 12. The term indication means a clinical sign, an illness or a situation affecting a patient which justifies the value of a medical treatment or a medical examination. 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. The technologies developed over the last few years (such as multi-energy photon-counting CT scanners) have made examinations easier and faster to perform, and have led to an increase in exploration possibilities (example of dynamic volume acquisitions) and in the indications(12). The placing of mobile CT systems on the market for intraoperative use is to be underlined, as is the increase in fluoroscopy-guided interventional CT procedures. On the other hand, these technological developments have led to an increase in the number of examinations, resulting in an increase in the doses delivered to patients and thus reinforcing the need for strict application of the principles of justification and optimisation (see point 1.3.4). Technological advances nevertheless allow a new mode of image reconstruction thanks to iterative reconstruction and deep learning of AI. CT can thus provide consistent image quality at reduced doses. Strict application of the principles of justification of the procedures and optimisation of the protocols remains as topical as ever. Teleradiology Teleradiology is a medical procedure in its own right defined in the Public Health Code, performed at a distance from the patient by a radiologist who performs the procedure at the request of a referring physician. Essentially two methods are used: ∙Telediagnosis, which is a remote radiological medical service for a patient when a radiologist is not present on site, either on a one-off basis in an emergency situation, or on a regular basis in non- emergency situations. The radiographer takes charge of the patient to perform the radiological or CT examination after receiving the instructions from the teleradiologist. At the end of the examination, the images are sent to the teleradiologist in order to formalise a results report in a manner comparable with what an on-site radiologist would have done. ∙Tele-expertise is defined as having recourse to a second opinion. The radiologist on the scene who performed and validated the examination, or a referring physician, asks for a second opinion on the images produced. Teleradiology is more than just a remote interpretation of images. Its development is becoming more widespread to allow continuity of out-of-hours service and to reduce the waiting times before receiving medical care. The organisation of the practice, the way it interfaces with the personnel on site and the many responsibilities are specified by contract between the healthcare facility and the teleradiology service provider. In May 2019 the HAS published a Guide to good practices concerning the quality and safety of tele-imaging procedures. Details are provided, with organisational, technical and operational recommendations. The French Professional Council of Radiology and Medical Imaging (G4) and the French Council of the Order of Physicians jointly published a teleradiology charter in February 2020, containing nine general recommendations. Lastly, the G4 also drafted baseline requirements for the profession and the skills of the radiologist in January 2023. It reinforces the position of teleradiology in the regional healthcare organisation and the availability, preferably in person, of the radiologist. ASN very recently completed (late 2024) a study it conducted with the French Nuclear Protection Evaluation Centre (CEPN), to assess the situation of teleradiology practices in France by conducting a survey with the teleradiology users and the teleradiologists. The conclusions will be published in 2025. 2.5.1.2 Dental radiodiagnosis Intra-oral radiography Intra-oral radiography generators, which are usually mounted on an articulated arm, are used to take localised planar images of the teeth (the radiological detector is placed in the patient’s mouth). They operate with low voltage and current and a very short exposure time, of a few hundredths of a second. This technique is usually associated with a digital system for processing and filing the radiographic image. Panoramic dental radiography Panoramic radiography (orthopantomography) gives a single picture showing both jaws in full, by rotating the radiation generating tube around the patient’s head for a few seconds. Cone-beam computed tomography 3D Cone-Beam Computed Tomography (CBCT) is developing very rapidly in all areas of dental radiology, due to the exceptional quality of the images produced (spatial resolution of about 100 microns – μm). The trade-off for this better diagnostic performance is that these devices deliver significantly higher doses than in conventional dental radiology. They must be used in accordance with the recommendations given by the HAS in 2009, the conclusions of which indicate that it should only be proposed in certain duly selected clinical indications and reiterate that whatever the case, the fundamental principles of justification and optimisation must be applied. ASN Report on the state of nuclear safety and radiation protection in France in 2024 239 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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