1 Radiation protection and medical uses of ionising radiation 1. Internal Targeted Radiotherapy (ITR) 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 nuclear activities for diagnostic purposes such as computed tomography, conventional radiology, dental radiology and diagnostic nuclear medicine, interventional practices using ionising radiation (FGIPs), which bring together different techniques used primarily for invasive medical or surgical procedures for diagnostic, preventive or therapeutic purposes, and activities for therapeutic purposes, most of which are dedicated to cancer treatment, such as externalbeam radiotherapy, radiosurgery, brachytherapy and ITR(1). 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 2022 by Institute for Radiation Protection and Nuclear Safety (IRSN), the medical and veterinary sectors account for the majority of the people monitored: 52.5%, i.e. 204,614 people were subject to dosimetric monitoring of their exposure. These figures have decreased overall by nearly 3% compared with 2021. The average individual annual dose received is 0.33 millisievert (mSv) in the medical sector and 0.20 mSv in the dental sector. This figure remained relatively stable between 2015‑2022, with the exception of 2020, when it dropped by 17% due to the Covid-19 pandemic. The average individual dose in the medical sector nevertheless increased by 7% in 2022 compared with 2021 (0.31 mSv). Among the health personnel liable to be exposed and therefore subject to dosimetry monitoring, those working in radiology (71% of the medical personnel monitored, in diagnostic radiology and intervention radiology alike) receive an average individual annual dose of 0.20 mSv. The nuclear medicine personnel, who represent 5% of the monitored health personnel, are exposed to an average individual annual whole body dose that is four time greater, estimated at 0.83 mSv. The medical activities sector accounts for the majority of exposures of worker extremities. Consequently, 16,645 people were subject to dosimetric monitoring of the extremities by ring or wrist dosimeter. This represents 60% of the workers monitored in this way and contributes to 68% of the total dose to the 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 comforters, 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. 07 206 ASN Report on the state of nuclear safety and radiation protection in France in 2023 • 07 • Medical uses of ionising radiation
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