For more than a century now, medicine has made use of ionising radiation produced either by electric generators or by radionuclides in sealed or unsealed sources for both diagnostic and therapeutic purposes. These techniques represent the second source of exposure of the population to ionising radiation (behind exposure to natural ionising radiation) and the leading source of artificial exposure (see chapter 1). The exposure of patients to ionising radiation for diagnostic or therapeutic purposes is distinguished from the exposure of workers, the public and the environment, for which there is no direct benefit. The principle of dose limitation does not apply to patients due to the need to adapt the delivered dose to the diagnostic or therapeutic end-purpose. The principles of justification and optimisation are fundamental, even if the radiation protection risks differ according to the medical uses. In radiotherapy (external-beam or brachytherapy) as in Internal Targeted Radiotherapy (ITR) which is developing strongly at present, the major risk is linked to the administered dose and, if applicable, the high dose rates used. There are specific risks linked to the use of sealed radionuclide sources (in brachytherapy, with high-activity sources) and unsealed sources (in nuclear medicine), associated in the latter case with the doses delivered to the patient’s carers and family, as well as the management of waste and effluents. The ever-continuing expansion of Fluoroscopy-Guided Interventional Procedures (FGIPs) carried out using increasingly sophisticated devices can lead to significant exposure of the patient for whom the procedure brings health benefits, but also for the personnel in the immediate vicinity. Lastly, Computed Tomography (CT) examinations, although they do not present a major risk in terms of delivered dose or dose rate for an individual, contribute very significantly to population exposure resulting from medical diagnostic procedures due to their frequency of use, underlining the importance of justification for each procedure using ionising radiation. 1 Radiation protection and medical uses of ionising radiation 1. Internal Targeted Radiotherapy aims to administer a RadioPharmaceutical Drug (RPD) or implant a radioactive medical device so that the ionising radiation delivers a high dose as close as possible to the organ that needs to be treated (also called the target organ) for curative or palliative purposes. The majority of these treatments are dispensed within nuclear medicine departments. 1.1 The different activity categories Medical nuclear activities can be divided into two broad categories, namely those for diagnostic purposes and those for therapeutic purposes. The medical diagnostic activities that use ionising radiation comprise radiology – which includes computed tomography, conventional radio- logy and dental radiology, and diagnostic nuclear medicine. Situated at the boundary between diagnostic and therapeutic activities are the Fluoroscopy-Guided Interventional Practices (FGIPs), which bring together various techniques used essentially for invasive medical or surgical procedures carried out for diagnostic, preventive or therapeutic purposes guided via an image obtained using X-rays. The majority of therapeutic activities such as external-beam radiotherapy, radiosurgery, brachytherapy and therapeutic nuclear medicine (called “Internal Targeted Radiotherapy” – ITR(1) are devoted to the treatment of cancers. These different activities and the techniques used are presented in sections 2.1 to 2.6. 1.2 Exposure situations in the medical sector 1.2.1 Exposure of health professionals Medical professionals are subject in particular to the risk of external exposure created by the Medical Devices (MDs – devices containing radioactive sources, X-ray generators or particle accelerators) or by sealed or unsealed sources. When using unsealed sources, the risk of contamination must also be taken into consideration in the risk assessment (in nuclear medicine and in the biology laboratory). According to the data collected in 2023 by Institute for Radiation Protection and Nuclear Safety (IRSN), the medical and veterinary sectors account for the majority of the people monitored: 47%, i.e. 122,228 people, were subject to individual dosimetric monitoring. The monitored personnel headcount (classified and non-classified) has dropped by nearly 8% overall compared with 2022. This drop can be explained by the fact that employers are no longer obliged to register non-classified workers in the Ionising radiation exposure monitoring information system (Siseri). This trend should continue in the coming years. ASN Report on the state of nuclear safety and radiation protection in France in 2024 211 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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