reporting portal managed by the Ministry of Solidarity and Health. Depending on the type of event reported, the notification is sent automatically to ASN (regional division and Department of ionising Radiation and Health – DIS), to the ARS for all events concerning the patient and to the ANSM for events relating to medical devices vigilance or drug safety monitoring. A draft ASN resolution on “Procedures for reporting significant events and codifying the reporting criteria” was submitted for public consultation in 2022, along with the updated ASN Guide No. 11 for the medical sectors, which details the event reporting procedures. The resolution and guide should be published in the course of 2024. The ASN-SFRO scale for rating events concerning patients undergoing radiotherapy or brachytherapy treatment remains unchanged. The aim of this scale, developed in collaboration with the French Society for Radiation Oncology (SFRO), is to inform the public about radiation protection events affecting patients in the course of a radiotherapy or brachytherapy treatment, taking into account, in addition to the confirmed consequences, the potential effects of the event and the number of patients exposed (see chapter 3). In addition to this, the incident notices are published on asn.fr. To encourage sharing of the lessons learned from the feedback from medical professionals, ASN publishes the newsletter “Patient safety - Paving the way for progress”, first issued in March 2011, “LFE” sheets further to ESRs, and circular letters addressed to the RNAs. Produced by multidisciplinary working groups coordinated by ASN, the “Patient safety” newsletter offers a thematic presentation of the good practices of medical departments and the recommendations developed by the learned societies of the discipline concerned and the health and radiation protection institutions. The aim of the “LFE” sheet is to alert the health professionals to a particular ESR incident reported to ASN to prevent it from occurring in another healthcare facility. 2 Nuclear-based medical activities 2.1 EXTERNAL-BEAM RADIOTHERAPY Radiotherapy, along with surgery and chemotherapy, is one of the key techniques employed to treat cancerous tumours. Radiotherapy uses ionising radiation to destroy malignant cells and also dysfunctional non-malignant cells. The ionising radiation necessary for the treatments is produced by an electric generator or emitted by radionuclides in sealed sources. We distinguish external-beam radiotherapy, where the source of radiation (particle accelerator or a radioactive source such as Gamma Knife®) is external to the patient, from brachytherapy, where the source is placed as close as possible to the cancerous lesion, either via the natural cavities or by catheters (see point 2.2). The radiation sessions are always preceded by the preparation of a treatment plan which serves to set the conditions for achieving a high dose in the target volume while preserving the surrounding healthy tissues. The treatment plan defines the dose to deliver, the target volume(s) to treat, the volumes at risk to be protected, the ballistics of the radiation beams and the predicted dose distribution (dosimetry). Preparation of the treatment plan requires close cooperation between the radiation oncologist, the medical physicist and, if necessary, the dosimetrists. The main radiation protection risk is linked to the dose delivered to the patient; the change of treatment techniques with the development of hypofractionated radiotherapy (see point 2.1.1), which consists in delivering higher doses during a given session, makes it all the more crucial to control delivery of the dose. This is why ASN’s oversight focuses on both the ability of the centres to control delivery of the dose to the patient and to learn lessons from the malfunctions that have occurred or could occur. Implementation of the treatment quality and safety management system, skills management, mastery of the equipment, ESR recording and follow-up are the focal points of the ASN inspections. As technical, organisational and human changes have been identified as potential risk-generating situations, particular attention is also given to change management during the inspections. 2.1.1 Description of the techniques Several external-beam therapy techniques are currently used in France: The SFRO considers three-dimension conformal radiotherapy to be the basic technique in its Guide to Recommendations for the practise of external-beam radiotherapy and brachytherapy (Recorad), updated in February 2022. This technique uses three-dimensional images of the target volumes and neighbouring organs obtained with a CT scanner, sometimes in conjunction with other imaging examinations (Positon Emission Tomography – PET, Magnetic Resonance Imaging – MRI, etc.). For several years now, however, the proportion of treatments performed using this techniques is decreasing in favour of Intensity‑Modulated Radiotherapy (IMRT), which saw the day in France in the early 2000s and allows better adaptation to complex tumoral volumes and better protection of neighbouring organs at risk, thanks to modulation of the intensity of the beams during irradiation. Following on from IMRT, Intensity-Modulated Volumetric Arc Therapy (IMVAT) is now being used increasingly frequently in France and is the reference technique for prostate and head and neck cancers. This technique consists in irradiating a target volume by continuous modulated irradiation rotating around the target volume and therefore around the patient. Helical radiotherapy, or tomotherapy, enables radiation treatment to be delivered by combining the continuous rotation of an electron accelerator with the longitudinal movement of the patient during the treatment. The possibility of modulating radiation intensity allows equally well the irradiation of large complex-shaped volumes as of highly-localised lesions, if necessary in mutually independent anatomical regions. The system requires the acquisition of images under the treatment conditions of each session for comparison with reference computed tomography images in order to reposition the patient. Stereotactic radiotherapy is a treatment method that aims at delivering high-dose radiation to intra- or extracranial lesions (whether cancerous or not) with millimetric accuracy through multiple mini-beams which converge at the centre of the target. The total dose is delivered either in a single session or in a hypofractionated manner, depending on the disease being treated. The term “radiosurgery” is used to designate treatments carried out in a single session. This technique demands great precision in defining the target volume to irradiate and uses specific identification techniques in order to localise the lesions with millimetric accuracy. This therapeutic technique essentially uses three specific types of equipment, such as: ∙ Gamma Knife®, which uses more than 190 cobalt-60 sources. It acts like a veritable scalpel over an extremely precise and delimited zone; 212 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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