Abstracts ASN Report 2019

ׯ٫ ڲ Medical and dental radiodiagnosis ӌє Ļĸ ŇĸŅŀ ѢļŁķļĶĴŇļłŁѣ ŀĸĴŁņ Ĵ ĶĿļŁļĶĴĿ ņļĺŁё ĴŁ ļĿĿŁĸņņ łŅ Ĵ ņļŇňĴŇļłŁ Ĵ֊ĸĶŇļŁĺ Ĵ ŃĴŇļĸŁŇ ŊĻļĶĻ ĽňņŇļ֍ĸņ ŇĻĸ ʼnĴĿňĸ łĹ Ĵ ŀĸķļĶĴĿ ŇŅĸĴŇŀĸŁŇ łŅ Ĵ ŀĸķļĶĴĿ ĸŋĴŀļŁĴŇļłŁє ה ِ׏ …ɮƺȸɮǣƺɯ Ȓǔ Ɏǝƺ ƺȷɖǣȵȅƺȇɎ Medical diagnostic radiology is based on the principle of differential attenuation of X-rays by 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 comprises various techniques (conventional radiology, radiology associated with interventional practices, computed tomography, mammography) and a very wide variety of examinations (radiography of the thorax, chest- abdomen-pelvis computed tomography scan, etc.). The request for a radiological examination by the 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. A guide intended for general practitioners ( Guide to Good Medical Imaging Examination Practices ) indicates the most appropriate examinations to request according to the clinical situations. ה ِ׏ِ׏ xƺƳǣƬƏǼ ȸƏƳǣȒƳǣƏǕȇȒɀǣɀ • !ȒȇɮƺȇɎǣȒȇƏǼ ȸƏƳǣȒǼȒǕɵ 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. • ȇǕǣȒǕȸƏȵǝɵ This technique, used for exploring blood vessels, involves injecting a radio-opaque contrast agent into the vessels which enables the arterial tree (arteriography) or venous tree (venography) to be visualised. Angiography techniques benefit from computerised image processing (such as digital subtraction angiography). • xƏȅȅȒǕȸƏȵǝɵ Given the composition of the mammary gland and the fineness of the details required in order to make a diagnosis, specific devices (mammography units) are used. They operate at low voltage and provide high resolution and high contrast. They are used in particular in the National Breast Cancer Screening Programme. ASN was consulted and gave a favourable opinion on the draft resolution relative to the internal and external quality controls of digital mammography facilities. This resolution updates the controls performed on the 2D mammographs and provides for external quality controls on tomosynthesis devices. Tomosynthesis is a new three-dimensional breast imaging technique that is developing in Europe without any form of quality control. The evaluations of this technique, currently in progress in several European countries, should enable its advantages compared with the traditional planar technique to be determined. At present, this technique is not validated for use in organised breast cancer screening. • !ȒȅȵɖɎƺƳ ɎȒȅȒǕȸƏȵǝɵ 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 (spiral or helical CT scanner). Based on a computerised image acquisition and processing system, 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. ŁׇĸŋĴŀļŁĴŇļłŁ ĶĴŁ ĶłŀŃŅļņĸ ņĸʼnĸŅĴĿ ĻĸĿļĶĴĿ ļŀĴĺĸ ĴĶńňļņļŇļłŁņ of a specific anatomical region (with or without injection of a contrasting agent) or of different anatomical regions. This technique can, like Magnetic Resonance Imaging (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 led to an increase in exploration possibilities (example of dynamic volume acquisitions) and in the indications (9) . The placing of mobile computed tomography 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 chapter 1). Computed tomography can thus provide consistent image quality at reduced doses. The devices can also be equipped with dose-reduction tools. • ÁƺǼƺȸƏƳǣȒǼȒǕɵ 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 methods of interchange 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 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 224 ASN Report on the state of nuclear safety and radiation protection in France in 2019 ׎ ٲ ו MEDICAL USES OF IONISING RADIATION