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. The future resolution will update the checks performed on 2D mammography units and will introduce EQCs for the tomosynthesis devices. Computed tomography Computed tomography (CT) scanners use a beam of X-rays emitted by a tube which moves in a spiral around the body of the patient (helical CT scanner). These scanners produce a three- dimensional reconstruction of the organs with very much better image quality than that of conventional radiology devices. The number of rows of detectors (multidetector-row CT scanner, also known as a multislice or volumetry CT scanner) has been increased in recent machines, enabling thinner slices to be produced. An examination can comprise several helical image acquisitions of a specific anatomical region (with or without injection of a contrasting agent) or of 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 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(6). 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). Technical progress has nevertheless brought a new mode of image reconstruction in the form of iterative re-construction. Computed tomography can thus provide consistent image quality at reduced doses. The devices can also be equipped with dose-reduction tools. Teleradiology Teleradiology provides the possibility of guiding the performance and interpreting the results of radiology examinations carried out in another location. The interchanges must be carried out in strict application of the regulations (relating to radiation protection and the quality of image production and transfer in particular) and professional ethics. Essentially two interchange methods are used: ∙ Telediagnosis, which enables a doctor on the scene (e.g. an emergency doctor), who is not a radiologist, to perform the radiological examination and then send the results to a radiologist in order to obtain an interpretation of the images. If necessary the radiologist can guide the radiological operator during the examination and imaging process. In this case, the doctor on the scene is considered to be the doctor performing the procedure and assumes responsibility for it. ∙ Tele-expertise, which is an exchange of opinions between two radiologists, where one asks the other –the “expert radiologist” (teleradiologist)– for a remote confirmation or contradiction of a diagnosis, to determine a therapeutic orientation or to guide 6. 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. a remote examination. The data transmissions are protected and preserve medical secrecy and image quality. Teleradiology involves many responsibilities which must be specified in the agreement binding the practitioner performing the procedure to the teleradiologist. The teleradiology procedure is a medical procedure in its own right, like all other imaging procedures, and cannot be reduced to a simple remote inter– pretation of images. Teleradiology therefore fits into the general health care organisation governed by the Public Health Code and obeys the rules of professional ethics in effect. The Teleradiology Charter published by the French professional council of radiology (G4) was re-updated in 2020. It details the organisation of the two parts of teleradiology (telediagnosis and tele-expertise). In addition, a guide to good practices concerning the quality and safety of teleimaging procedures was published in May 2019 by the HAS. In this guide the HAS makes important clarifications concerning the proper use of “medical imaging examinations with remote interpretation”. It has the particularity of also addressing nuclear telemedicine, deployed with the aim of providing uniform coverage of the country. This guide does not consider mammography, which cannot be done by tele– radiology because it necessitates clinical examination of the patient, including palpation. 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 about 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 Cone-beam computed tomography (3D) 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). 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. 2.5.2 Technical fitting out rules for medical and dental radiodiagnosis facilities Radiology facilities A conventional radiological facility usually comprises a generator (high-voltage unit, X-ray tube), associated with a support (the stand) for moving the tube, a control unit and an examination table or chair. Mobile facilities, but which are often used in the same given room, such as the X-ray generators used in operating theatres, are to be considered as fixed facilities. 226 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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