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 doserate brachytherapy. High Dose‑Rate (HDR) is carried out using high-activity (about 370 and 91 GBq respectively) sealed sources of iridium-192 or cobalt-60. The dose rates are higher than 12 Gy/h. Positioning is done using an afterloader containing the source. The treatments are delivered on an out-patient basis, in one or more sessions of a few minutes, spread over several days if necessary. 2.2.2 Technical rules applicable to brachytherapy facilities The rules for radioactive source management in brachytherapy are comparable to those defined for all sealed sources, regardless of their use (see point 1.3.1). In cases where permanent implant techniques are used (LDR), the applications are carried out in the operating theatre with ultrasonography monitoring, and do not require hospitalisation in a room with radiation protection. The PDR technique, which uses source afterloaders (usually 18.5 GBq of iridium-192), necessitates hospitalisation of the patient for several days in a room with radiological protection appropriate for the maximum activity of the radioactive source used. Lastly, with the HDR sources, as the maximum activity used in the source afterloaders is high (370 GBq of iridium-192 or 91 GBq of cobalt-60), the irradiations can only be carried out in a room with a configuration comparable to that of an external-beam radiotherapy room in terms of collective protection because of the high dose level used. The Order of 29 November 2019 sets the obligations concerning the protection of ionising radiation sources and batches of radioactive sources of categories A, B, C and D against malicious acts The requirements concerning the protection barriers and their resistance time for category A, B and C sources are enforceable since 1 July 2022 (see chapter 8, point 2.3.2). As some centres could not enlarge their premises or build new bunkers, ASN licensed two centres with “mixed-purpose” bunkers for joint external-beam radio- therapy and HDR brachytherapy practices on the basis of an expert assessment by IRSN concerning the design rules for premises housing both medical linear electron accelerators and HDR source projectors. The regulatory provisions to protect high- activity sources against malicious acts have been taken into account. ASN was particularly attentive to the analysis of the licensee’s provisions regarding the following main points: ∙organisation of the alternations between the different treatments and the quality control time slots (number of patients treated, organisation of the schedules, time slots for MD quality controls, time slots for treatments, etc.); ∙patient positioning that facilitates their evacuation in case of emergency; ∙specific safety systems preventing the simultaneous operation of two devices; ∙separate and clearly identified indicator lights and emergency stop controls for the two systems; ∙double zoning plan displayed at the entrance; ∙procedure if personnel get shut inside, for both devices. 2.2.3 Radiation protection situation in brachytherapy ASN has licensed 57 brachytherapy centres, 51 of which use the HDR technique. Nineteen licences were issued in 2024 (see Graph 3). The brachytherapy activity is stable, with HDR brachytherapy still representing the majority of treatments. ASN observes that some brachytherapy centres have difficulties in maintaining certain activities due to a lack of medical staff trained in brachytherapy techniques, even if they wish to maintain these activities in order to offer the patients the most appropriate treatments for their pathology. The INCa Observatory records 600 to 700 LDR treatments, 700 to 750 PDR treatments for gynaecological cancers and between 4,500 and 5,000 HDR treatments. In the same way as for external-beam radiotherapy, the safety of brachytherapy treatments has been a priority area of ASN oversight since 2007, because of the intensity of the doses delivered and, where applicable, the high dose rates. As brachytherapy is carried out within the radiotherapy departments, the inspection programme for the 2021‑2024 period is identical to that for external-beam radiotherapy, with a four-yearly frequency and checks similar to those applied in external- beam radiotherapy (see point 2.1.3.2). On account of the use of high activity sources, specific checks focus on medical staff training, such as knowledge of the action to take in the event of an emergency (source jamming), and the security of these sources (organisation in place for GRAPH 3 Breakdown, by ASN regional division, of the number of brachytherapy centres, of high dose-rate brachytherapy centres and the number of new licenses or license renewals in 2024 0 2 4 6 8 10 12 14 16 Licensed centres (legal entities) Including high dose-rate centres New licences or license renewals Strasbourg Paris Orléans Nantes Marseille Lyon Lille Dijon Châlons-enChampagne Caen Bordeaux 10 9 2 3 2 2 4 4 1 6 6 2 5 4 1 7 7 3 3 3 1 13 10 7 2 2 1 1 0 0 3 3 224 ASN Report on the state of nuclear safety and radiation protection in France in 2024 Medical uses of ionising radiation
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