Lastly, nearly 87% of the personnel monitored for exposure to the lens of the eye work in the medical and veterinary sectors, and represent 5,219 workers with an average individual dose of 1.72 mSv. Nearly two-thirds of the personnel monitored for lens of the eye dosimetry work in the FGIP sector which accounts for 59% of the total dose in the medical and veterinary sectors. 1.2.2 Exposure of patients In medical applications for diagnostic purposes, optimisation of exposure to ionising radiation allows delivery of the minimum dose that produces the relevant diagnostic information or allows performance of the planned interventional procedure. With therapeutic applications, the highest dose possible must be delivered in order to destroy the targeted tumoral cells while preserving the surrounding healthy tissue as best possible. As the principle of limitation does not apply to patients, the principles of justification and optimisation (see point 1.3) must be applied all the more rigorously. In medical imaging, the principles of optimisation and justification (avoiding unnecessary examinations, or those whose result can be obtained using non-irradiating techniques that give an equivalent diagnostic level when available) are at the centre of the action plans for controlling doses delivered to patients. These action plans were developed by ASN in 2011 and 2018 in collaboration with the services of the Ministry responsible for health and the health professionals (see chapter 1, point 3.3). The action plan of 2018 will be updated in 2023 after reviewing the situation with all the stakeholders. The optimisation principle, defined by Article L. 1333‑2 of the Public Health Code (see chapter 2), known as the ALARA (As Low As Reasonably Achievable) principle, has led to the introduction, in the area of medical imaging using ionising radiation, of the concept of “Diagnostic Reference Levels” (DRL). These DRL, which must not be considered to be “dose limits” or “optimum doses”, are established for standard examinations and typical patients. DRL are therefore dosimetric indicators of the quality of practices, intended to identify the examinations on which optimisation efforts must be focused in priority. They should not be exceeded in standard procedures without justification. ASN resolution 2019-DC-0667 of 18 April 2019 sets the DRL values and requires heads of radiology and nuclear medicine departments to carry out (or have others carry out) periodic dosimetric evaluations and to send the results to IRSN. The data collected by IRSN are analysed with a view to updating the DRL. In 2022, ASN asked IRSN to propose new DRL values for Digital Radiography (DR) mammography and for tomosynthesis mammography. The ASN Advisory Committee for Radiation Protection (see chapter 2) was asked to give its opinion on these values with a view to updating ASN resolution 2019-DC-0667 of 18 April 2019 in 2023. The last “ExPRI” study, which analyses exposure of the French population to ionising radiation due to medical imaging examinations, was published by IRSN in late 2020. It presents the data for 2017, which are compared with those of 2012 to show how they have evolved. These analyses are carried out using diagnostic imaging procedures drawn from a representative sample of beneficiaries of the French health insurance system, by method of imaging (conventional, interventional and dental radiology, CT scans and nuclear medicine), by explored anatomical region, by age and by sex. On the whole the analyses reveal stability of exposure on average (see chapter 1, point 3.3). 2. ICRP Publication 84. Ann. ICRP 30. ICRP Supporting Guidance 2. Ann. ICRP 31. ICRP Publication 90. Ann. ICRP 33. ICRP Publication 103. Ann. ICRP 37, ICRP Publication 105. Ann. ICRP 37. 1.2.3 Exposure of the public The impact of medical applications of ionising radiation is likely to concern: ∙ members of the public who are close to facilities that emit ionising radiation; ∙ sewage network and wastewater treatment plant personnel who could be exposed to effluents or wastes produced by nuclear medicine departments; ∙ patients’ family, carers and comforters. The estimated doses for the public (people external to the health facility) resulting from discharges from nuclear medicine departments are a few tens of microsieverts (µSv) per year for the most exposed people, primarily the personnel working in the sewage networks and wastewater treatment plants (IRSN studies, 2005 and 2014). In 2015, IRSN developed an aid baptised CIDRRE (French acronym for “Calculation of the impact of radioactive discharges into wastewater networks”), which enables nuclear medicine departments and research laboratories to estimate, with reasonably penalising assumptions, conservative dose values for the sewage system workers based on the activities administered by the departments. In the case of an examination performed on a pregnant woman, the embryo or foetus exposed in utero is considered to be a member of the public and therefore subject to the dose limits for the public. Pregnant women unaware of their pregnancy represent one third of the Significant Radiation Protection Events (ESRs) reported annually to ASN, that is to say about 200 cases per year (see point 2.7). The doses delivered to the uterus by imaging examinations are usually less than 100 mGy, a value below which no increase in malformations or reduction in intellectual quotient has been detected to date in comparison with spontaneous risks (estimated at 3%)(2). In nuclear medicine, a radionuclide source is administered to the patient, who can then emit ionising radiation and expose the persons around them. To control this type of exposure, the regulations have introduced the notion of “dose constraints”. To verify compliance with these dose constraints, equivalent ambient dose rate measurements can be taken before discharging a patient who has received a nuclear medicine treatment or examination. In clinical practice, nuclear medicine departments make the discharging of patients having received a high activity (therapeutic application) conditional on an equivalent dose rate of about 20 microsieverts per hour (µSv/h) at a distance of 1 m (recommendations of the Advisory Group for Radiation Protection in Medical Applications – Oct. 2017). It is usually necessary to hospitalise the patient in a radiation-proof room while waiting for the activity to decay. 1.2.4 The environmental impact In nuclear medicine, the radioactive sources administered to the patients will undergo physical decay (period of time stemming from the physical-chemical properties of the sources) but also biological elimination (resulting from the biological metabolism, as with any medication). Patients having received an injection eliminate part of the administered radioactivity, mainly the urinary tract. Nuclear medicine departments are designed and organised for the collection, storage and disposal of the radioactive waste and effluents produced in the facility, particularly the radionuclides contained in patients’ urine (see point 2.3.2), and ASN Report on the state of nuclear safety and radiation protection in France in 2022 209 • 07 • Medical uses of ionising radiation 07 01 08 13 AP 04 10 06 12 14 03 09 05 11 02
RkJQdWJsaXNoZXIy NjQ0NzU=