Although no radiation protection events linked to cyberattacks were reported to ASN in 2023, unlike 2022 and 2021 (three radiotherapy centres, one in 2021 and two in 2022, and one nuclear medicine centre in 2022), the risk of such attacks, leading to paralysis of the computing systems and serious disruptions in the organisation of treatments, is very real. Cybersecurity does not lie within ASN’s scope of competence, but it is nevertheless informed of cyberattack situations which form the subject of a notification if they lead to an ESR. As these cyberattacks call into question the current practices of “all electronic” patient medical records, ASN had encouraged the medical professionals to conduct a reflection on this subject. The SFRO set up a working group in 2023, in which ASN participated, and in December 2023 it published recommendations for anticipating and limiting the risks associated with cyberattacks in a context of increasing digitising of data. This article underlines the importance of retaining a minimum amount of “hard copy” data so that treatment can be continued if the electronic (computerised) data are not available: patient’s contact details, summary of the medical record, dose-volume histograms, number of sessions carried out, description of the treatment plan, etc. In radiotherapy, the inspections carried out by ASN in 40% of the radiotherapy units in 2023, considered alongside those carried out over the period 2019-2022, enabling all the departments to be covered, confirm that the safety fundamentals are in place: organisation of medical physics, equipment verifications, training in the radiation protection of patients, deployment of quality assurance procedures. ASN also underlines the progress in clinical peer reviews, with performance of the first such reviews in radiotherapy at the end of 2023 and encourages their rapid extension to radiosurgery. However, the analysis of the 2019-2023 period confirms that assessing the effectiveness of corrective actions is still the weak point of the ILS procedures and is struggling to become more widely adopted. Furthermore, the learning from experience approaches are losing momentum, with fewer CREX meetings and less thorough ESR analyses. The number of ESRs reported to ASN has dropped significantly since 2015. Although this drop can be partly attributed to improved treatment safety, the risk of routinisation and the need to give renewed meaning to these procedures in order to maintain the interest of the medical professionals and the collective dynamic were underlined at the national seminar of radiotherapy actors organised by ASN on 15 March 2023. In addition, the prospective risk analyses are still insufficiently updated prior to organisational or technical changes or after analysing the lessons learned from events. The occurrence of events such as laterality and positioning errors, delineation of organs at risk and/or target organs and calibration errors, still reveals organisational weaknesses and the need to regularly assess practices. The assessment of new techniques and practices is still an important subject, to allow, among other things, an assessment of long-term radiation induced effects (hypofractionation, flash therapy, etc.) and the demonstration of their benefits compared with the existing techniques. It is in this context that ASN initiated a study in 2023 to define and collect the data necessary for the assessment of adaptive radiotherapy. In 2024, it will continue the analysis of the radiation protection risks associated with flash therapy, included in the Canpri studies. Lastly, in 2024, in a context of increasing complexity, fewer resources, extensive innovation and organisational changes, ASN will define the directions of its next four-yearly inspection programme in collaboration with the stakeholders and drawing the lessons from the inspection practices of its counterparts and other authorities in charge of activities involving risks. In this context, ASN once again urges the decision makers, RNAs and medical professionals to be vigilant regarding the need to assess the impact of the changes on the safety of treatments. SUMMARY 2.2 BRACHYTHERAPY Brachytherapy can be used to treat certain pathologies and cancerous tumours in particular either specifically or as a complement to another treatment technique. This technique consists in placing radionuclide sources, in the form of sealed sources, either in contact with or inside the solid tumours to be treated. The main radionuclides used in brachytherapy are iridium-192 and iodine-125. Brachytherapy uses three techniques (detailed below), which differ more specifically in the dose rate applied according to the indications. As with radiotherapy, the radiation protection issues are linked to the intensity of the dose delivered to the patient and, if applicable, the high dose rates and the mastery of the equipment. Furthermore, as high-activity sources are involved, the management of emergency situations in the event of source jamming, as illustrated by the feedback from events reported to ASN, and the security of the sources, constitute specific issues of brachytherapy. That is why the ASN checks focus on the management of source security in addition to those on external-beam radiotherapy. 2.2.1 Description of the techniques The radiation protection risks in brachytherapy, apart from the problem of managing sealed sources, depend on the dose rate associated with the technique, the method of delivering the radiation to the tumour (permanent or temporary implantation, or temporary application). The use where necessary of source afterloaders means that the medical personnel do not have to handle the sources and allows the patient to be treated without irradiating the personnel. On the other hand, it is necessary to make provisions for accident situations associated with malfunctioning of the source afterloader and the high dose-rate delivered by the sources used. Low Dose‑Rate (LDR) brachytherapy is carried out at present using sealed sources of iodine-125 in the form of permanently implanted seeds, or caesium-137 applied temporarily. The dose rates are between 0.4 and 2 grays per hour (Gy/h). A new medical technique called “DaRT” (Diffusing alpha emitters Radiation Therapy) is currently being tested in a clinical investigation into the treatment of skin cancers. This technique consists in implanting sealed radium-224 sources which emit alpha particles in the tumour using an afterloader; the sources are left in the tumour for 15 to 20 days. Pulsed Dose‑Rate (PDR) brachytherapy delivers dose rates of between 2 and 12 Gy/h and uses sources of iridium-192 with a maximum activity of 18.5 gigabecquerels (GBq), which are applied with a specific source afterloader. It is based on the use of a single radioactive source which moves in steps, and stops in predetermined positions for predetermined times. The doses are delivered in sequences of 5 to 20 minutes, sometimes even 50 minutes, every hour for the entire duration of the treatment, hence the name pulsed dose-rate brachytherapy. ASN Report on the state of nuclear safety and radiation protection in France in 2023 219 • 07 • Medical uses of ionising radiation 07 05 15 08 11 04 14 06 13 AP 03 10 02 09 12 01
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