ASN Report 2020

in only 58% of the cases do the centres have adequate command of project management, and in only 69% of the cases do they have adequate command of the installation of the new equipment. These figures nevertheless show distinct progress with respect to 2019, where only 40% and 25% of the departments had an adequate command of project management and the installation of new equipment respectively. 2.3.3 Significant events in external-beam radiotherapy In 2020, 124 significant radiation protection events were reported in radiotherapy. If the reduction in Significant Radiation Protection Events (ESRs) reported in 2020 can probably be partly attributed to a drop in activity, ASN has noted a distinct reduction in ESRs reported by radiotherapy departments over the last few years. In effect, some 200 ESRs were reported per year in 2014 and 2015. GRAPH 6 Percentage of conformity of the facilities concerning the management of events giving rise to corrective actions in 2020 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Reporting culture and organisation Analysis, defining corrective actions, building on lessons learned Assessing corrective action effectiveness “Fractionation” errors: example of overdose during a breast cancer treatment Between 2018 and 2020, ASN received about one hundred reports of Significant Radiation Protection Events (ESRs) linked to a problem of fractionation or protraction of the dose to deliver. The importance of protecting these data in the Record and Verify Systems is all the greater given that the number of hypofractionated stereotactic treatments is bound to increase significantly in the coming years. ASN published a Patient Safety newsletter dedicated to this subject in 2017 (No. 10). A marking event in 2020 concerning a fractionation error which led to a significant overdose during radiotherapy treatment of a breast cancer was rated level 3 on the ASN-SFRO scale. The radiotherapist prescribed delivery of a dose of 50 grays (Gy) to the tumour in the right breast, fractionated in 25 sessions. The administration of a higher dose was detected at the 23rd session, after taking a CT scan to prepare for the end of treatment. At this stage, a dose exceeding 76 Gy had been delivered, instead of the 50 Gy planned for the entire treatment. There was therefore an over-irradiation of 53% with deterministic effects (oedema of the breast) and an overdose at the right lung which had received more than 20 Gy, a dose beyond which the respiratory capacity is irreversibly diminished. The error resulted from consecutive and discordant manual entries concerning the treatment data. The entry of an incorrect number of sessions in the Treatment Planning Software (TPS) (1) led to the programming of excessively high doses per session. This error was not detected during the transfer and validation of the treatment plan in the Record & Verify software (2) , in which the initial prescription was correct. As soon as this event was reported, ASN immediately initiated an inspection which revealed several contributing factors. Differences were found between practices and the procedures in place, notably concerning the dosimetry validation procedure before the treatment phase, which was not fully adhered to. Furthermore, the risk relating to the manual transcription of the fractionation in the TPS had not been identified in the centre’s prospective risks analysis. 1. The Treatment Planning Software (TPS) enables the medical physicists and dosimetrists, after the target volumes and the organs at risk have been contoured by the radiotherapists, to plan the treatment, that is to say to position the beams such that the tumour is irradiated optimally while preserving the healthy and critical tissues insofar as possible, and perform the provisional calculations of the dose to deliver. 2. The Record &Verify software is a medical aid for recording and reducing the risk of errors in the treatment parameters. 218 ASN Report on the state of nuclear safety and radiation protection in France in 2020 07 – MEDICAL USES OF IONISING RADIATION