ASN Report 2021

be improved so as to better integrate certain geological factors that could facilitate radon transfer to buildings (karst zones in particular). Furthermore, the fourth Radon Plan provides for the updating of knowledge of exposure of the French population by organising the collection of measurement data obtained in particular during the local awareness-raising operations organised by the ARS and the regional authorities to cover the areas for which insufficient data are available. These operations consist in proposing screening kits to the inhabitants of a given region to raise their awareness of the radon risk. Lastly, line 3 aims to take better account of the management of the radon risk in buildings. In order to help members of building trade organisations improve their skills, these organisations have recently developed training courses dealing with methods to prevent and reduce concentration levels and various media to address the needs. The various French-language aids have been listed. To complete the offering, a guide intended for professionals and private individuals will establish prevention recommendations for new constructions and remedial measures in existing buildings. The progress made in understanding the effectiveness of construction standards in reducing radon concentrations in indoor air shall be consolidated. A system of specific indicators, chosen according to their relevance and the available data allowing them to be monitored, has been put in place to evaluate the effectiveness of the national strategy implemented under the national action plan. The way the indicators evolve will be analysed each year by the steering committee that monitors the new action plan. 3.3 Doses received by patients In France, exposure for medical purposes represents the greatest part of the artificial exposures of the public to ionising radiation. Medical exposure has been increasing over the last thirty years or so due to the rise in the number of radiological examinations –and computed tomography examinations in particular, to the ageing of the population, and to the strategies implemented to ensure better patient care, particularly in the context of patient monitoring after cancer treatment and coronary diseases. It has been regularly reviewed by IRSN since 2002. The average effective dose per inhabitant resulting from diagnostic radiological examinations has been evaluated at 1.53 mSv for the year 2017 (IRSN ExPRI study 2020) for some 85 million diagnostic procedures performed in 2017 (81.6 million in 2012), i.e. 1,187 procedures for 1,000 inhabitants per year. It is to be noted that as before, the individual exposure in 2017 is very varied. Consequently, although about 32.7% of the French population underwent at least one procedure (dental procedures excluded), half the patients received a dose of 0.1 mSv or less, 75% received 1.5 mSv or less, while the most exposed 5% of patients received a dose exceeding 18.1 mSv. Conventional radiology (55.1%), computed tomography (12.8%) and dental radiology (29.6%) account for the largest number of procedures. It is the contribution of computed tomography to the effective collective dose that remains preponderant and more significant in 2017 (75%) than in 2012 (71%), whereas that of dental radiology remains very low (0.3%). In adolescents, conventional and dental radiology procedures are the more numerous (about 1,000 procedures for 1,000 individuals in 2017). Despite their frequency, these procedures in this population represent only 0.5% of the collective dose. Lastly, it is noteworthy that: ∙ A national headcount estimated at more than 30, 000 patients was exposed to a cumulative effective dose of more than 100 mSv in 2017 due to multiple computed tomography examinations. This figure reaches 500,000 if a cumulative period of six years is considered. This highly exposed population seems to be increasing in size regularly and relatively rapidly since 2012. Although most people in this population are old, a quarter of them are aged under 55 years. The question of possible radiation-induced effects is therefore raised for this specific population. It is worth pointing out that these patients are often suffering from serious pathologies and that the computed tomography examinations are important for their care. ∙ Based on a sample of 120,000 children born between 2000 and 2015, IRSN reports that in 2015, 31.3% of the children in the sample were exposed to ionising radiation for diagnostic purposes (up by 2% compared with 2010). The average effective dose is estimated at 0.43 mSv and the median at 0.02 mSv (down for the average but equivalent for the median value). This median value varies greatly according to the age category. For infants of less than one year, it is 0.55 mSv (highest value) and between 6-10 years it is 0.012 mSv. The substantial uncertainties in these studies with regard to the average effective dose values per type of procedure must nevertheless be taken into account, which justifies the need for progress in estimating doses in the next exposure study of the general population. Particular attention must be exercised to check and reduce the doses associated with medical imaging, particularly when alternative techniques can be used for a same given indication. Controlling the doses of ionising radiation delivered to persons during a medical examination remains a priority for ASN. A second plan of action was published in July 2018. This plan extends the first one (2011-2017), drawn up in collaboration with the stakeholders (institutional and professional). TABLE Number of procedures and associated collective effective dose for each imaging method (rounded values) in France in 2017 IMAGING METHOD PROCEDURES TOTAL COLLECTIVE EFFECTIVE DOSE: 102,198 Sv NUMBER % % Conventional radiology (dentistry excluded) 46,681,000 55.1 11.8 Dental radiology 25,023,000 29.6 0.3 Computed tomography 10,866,000 12.8 74.2 Diagnostic interventional radiology 435,000 0.5 2.4 Nuclear medicine 1,662,000 2 11.3 Total 84,667,000 100.0 100.0 Source: IRSN 2020. 5 114 ASN Report on the state of nuclear safety and radiation protection in France in 2021 01 – NUCLEAR ACTIVITIES: IONISING RADIATION AND HEALTH AND ENVIRONMENTAL RISKS

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