Given this context, ASN wanted to encourage an initiative to assess this new technique. To this end, in late 2023 it initiated a study with the SFRO and the National Council of Radiation Oncologists (CNPO) to collect the data necessary for a largescale assessment before the technique becomes widely adopted in France. A steering committee in which participate the HAS, the DGS, the General Directorate of the Healthcare Offering (DGOS), the National Cancer Institute (INCa), IRSN, the SFRO and the CNP, has been set up by ASN to conduct and follow-up this study in compliance with the rules of good assessment practice. All the centres with an adaptive radiotherapy machine expressed their interest in participating in the project, for which the assessment methodology was finalised at the end of 2024. The MRI-Linac and CBCT-Linac techniques are to be assessed separately, by assessing a tumoral location of interest for each technique: unresectable pancreatic cancers on the MRI-Linac machines and urothelial carcinomas (bladder cancer) on the CBCT‑Linac machines. 2.1.2 Technical rules applicable to external-beam radiotherapy facilities On account of the high dose rate and high energy of the beams when delivering the dose to the patient, the devices must be installed in rooms specially designed to guarantee radiation protection of the staff, turning them into veritable bunkers in which the wall thickness can vary from 1 to 2.5 metres of ordinary concrete. A radiotherapy installation comprises a treatment room including a technical area containing the treatment device, a control station outside the room and, for some accelerators, auxiliary technical premises. 6. In 2021, 214,000 cancer patients were treated by radiotherapy with 4.3 million treatment sessions (soruce: INCa Observatory). The protection of the premises, in particular the treatment room, must be determined in order to respect the annual exposure limits for the workers and/or the public around the premises. The current conditions of design of these rooms were reviewed in 2019. A specific study must be carried out for each installation by the machine supplier, together with the medical physicist and the Radiation Protection Advisor (RPA). This study defines the thicknesses and nature of the various protections required, which are determined according to the conditions of use of the device, the characteristics of the radiation beam and the use of the adjacent rooms, including those vertically above or below the treatment room. This study must be included in the file submitted to ASN to support the application for a license to use a radiotherapy installation. In addition, a set of safety systems informs the operator of the machine operating status (exposure in progress or not) and switches off the beam in an emergency or if the door to the irradiation room is opened. The bunker with shielding baffle remains the reference insofar as it reduces the shielding required at the ventilation duct and electrical duct inlets and provides greater security in the event of failure of the door motorisation system or if anyone gets accidentally locked inside. However, if the space available to the licensee is limited, which compromises the installation of the accelerator, a smaller shielding baffle, or even none at all, can be envisaged under certain restrictive conditions. Moreover, the arrival of self-shielded MDs such as the ZAP-X® platform could make it possible to consider having an installation with fewer architectural constraints (no bunker), and to meet the healthcare offering needs of certain regions more directly. In its opinion 2024-AV-0447 of 22 October 2024, ASN recommends that medical-economic studies by carried out to confirm the justification of this MD compared with the other existing devices used in France. Furthermore, the conditions of installation and use of this platform should enable the level of ionising radiation exposure of the personnel working on this platform and in adjacent rooms to be optimised. ASN considers that the ionising radiation exposure levels of these professionals should not be higher than those found at present when using medical particle accelerators installed in bunkers. 2.1.3 Radiation protection situation in external-beam radiotherapy The installed base of external-beam radiotherapy facilities in 2024 comprises 577 particle accelerators installed in 171 radiotherapy centres subject to ASN licensing (see Graph 1). More than 220,000 patients(6) are treated each year, which represents 4.12 million radiation sessions (in 2023). The French Radiotherapy Observatory (INCa) lists 953 radiotherapists (headcount in 2023). ASN issued 112 licences in 2024, slightly fewer than in 2023 (121). ASN nevertheless notes the maintaining of a drive to modernise and enlarge the radiotherapy centres (relocation, increase in the number of bunkers, replacement of accelerators, etc.). Given the significant number of accelerators aged over 10 years (20 to 30% of the installed base in some regions), accelerator replacement requests could increase in the next few years. Furthermore, the rise in the number of stereotactic treatments in radiotherapy departments across the country is continuing, with an increase in extra-cranial stereotactic indications (lung, liver, spine, GRAPH 1 Breakdown, by ASN regional division, of the number of centres and external-beam radiotherapy accelerators inspected and the number of new licenses or license renewals issued by ASN in 2024 0 10 20 30 40 50 60 70 80 90 100 110 Licensed centres (legal entities) Accelerators New licences or license renewals Strasbourg Paris Orléans Nantes Marseille Lyon Lille Dijon Châlons-enChampagne Caen Bordeaux 85 21 20 4 24 4 20 9 19 22 15 14 64 13 9 24 4 25 4 31 14 106 67 77 57 28 26 8 8 7 8 16 7 ASN Report on the state of nuclear safety and radiation protection in France in 2024 219 Medical uses of ionising radiation 07 01 02 03 04 05 06 08 09 10 11 12 13 14 15 AP
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