RIS-ORANGIS RADIOTHERAPY CENTRE (CRRO): MANAGEMENT OF AN EMERGENCY SITUATION An inspection of the CRRO, concomitant with that of the ARS of Île‑de‑France, was carried out in August 2022, following the publication of articles in the mainstream press mentioning the departure of 4 of the centre’s radiotherapists after terminating their contract two years earlier, in a situation of private law conflict between CRRO senior management and the radiotherapists. With the new medical team arriving on 1 September 2022, the centre had to put in place a temporary organisation to ensure treatment continuity during the month of August 2022. It also had to plan for a period of skills build-up for the various medical teams. Further to this inspection, ASN made requests – which the centre has taken into account – concerning: ■ the completeness of the prospective risks mapping, more specifically by indicating certain barriers and the associated preventive or corrective actions and the continuation of its enrichment in view of the arrival of the new medical team as of September 2022; ■ the revival of the ILS approach, particularly the detection and reporting of adverse events; ■ monitoring of the new radiotherapists on arrival with the organisation of medical monitoring reinforced by occupational medicine for classified workers and training in occupational radiation protection appropriate for the practices of the department, dispensed by the radiation protection advisor. A follow-up inspection is scheduled in early 2023 to track the progress of the centre’s commitments. CALIBRATION ERRORS: LESSONS LEARNED FROM THE EVENT REPORTED IN 2022 Saint‑Jean de Saint‑Doulchard Oncology and Radiotherapy Centre (Corrèze département) On 30 May 2022, the Saint‑Jean de Saint‑Doulchard Oncology and Radiotherapy Centre (Corrèze département)(*) reported to ASN a significant event that occurred in its radiotherapy department of Moulins (Allier département), linked to an error in dose calibration under the reference conditions, as a result of an error in setting the parameters of a barometer. This incorrect parameter setting induced an overdosing of about 3%, with no expected clinical consequences, for all the patients treated between November 2010 and May 2022, which represents a cohort of about 5,800 patients. Following detection of this event, the department immediately checked the barometers and corrected the calibration of the doses of all the accelerator beams. However, this event adds on to another event in the same centre reported on 23 March 2022, which also led to overdosing of the ionising radiation delivered to five patients, with an error of 7.5% for one of them. Although such a difference is not likely to result in any clinical consequences, the patients’ follow-up consultations with their referring doctor(s) were brought forward. In response to ASN’s request, the centre has drawn up a retrospective clinical study protocol to look for any unexpected secondary effects in a representative sample from the cohort of patients concerned. The conclusions of this study have not yet been communicated to ASN. ASN rated this event level 1 on the ASN‑SFRO scale of radiotherapy events, graded from 0 to 7 in increasing order of severity. Léon Bérard Centre in Lyon (Rhône département) On 19 December 2022, the Léon Bérard Centre (CLB) in Lyon reported a significant event that occurred in its external-beam radiotherapy department concerning six patients who received higher-than-expected Total Body Irradiation (TBI) during treatments of malignant hemopathies. TBI is an external-beam radiotherapy treatment used mainly in preparation for an allogenic bone marrow transplant in patients suffering from blood cell cancers and their precursors (leukaemias, lymphomas, myelomas, etc.). In September 2022, after finding a drift in the calibration of the device delivering the prescribed dose to the patient, the centre’s medical physics team conducted a retrospective analysis of the impact of this drift on the treatment plans of the patients treated using this technique. For six patients, the doses delivered per treatment session were higher than expected. The CLB evaluated the dose to the lungs (sensitive organs) of these patients in priority. The estimated doses received at the lungs of all six patients remained below the doses considered to be associated with an increased toxicity risk. Following this event, the centre informed the patients concerned and put in place corrective actions. The practices for checking the doses delivered to the patients have been modified and stepped up. Furthermore, the use of a new measuring system with an ionisation chamber positioned directly on the patient during the treatment sessions is envisaged. In view of the confirmed overexposure of patients and the potential consequences, and after consulting the SFRO, ASN rated this event level 2+ on the ASN‑SFRO scale of radiotherapy events, graded from 0 to 7 in increasing order of severity. ASN has examined the corrective measures proposed and considers that they will limit the risks of a similar event occurring. Taking into account the SFRO’s recommendations, ASN has asked that the six patients concerned be subject to pulmonary monitoring every three months for 18 months. More generally, ASN underlines that the calibration of medical devices is critical for treatment safety and urges radiotherapy departments to question their practices by referring to the ASN publications drawn up on the basis of lessons learned from the analyses of several events associated with calibration errors. ASN points out that: ■ a circular letter of 19 May 2016 was sent to all the radiotherapy departments giving recommendations on the conditions for determining the absorbed dose, notably by using calibrated measuring instruments to measure the atmospheric pressure used to correct the response of the ionisation chamber; ■ an Experience feedback sheet published on 25 April 2022 concerning particle accelerator calibration errors sets out one centre’s analysis and its tips for reducing the risk of errors when calibrating an accelerator. * At the beginning of 2022, the Saint‑Jean Oncology and Radiotherapy Centre (Corrèze département) took over responsibility for the radiotherapy nuclear activity previously exercised by the Hospital Centre of Moulins (Allier département). ASN Report on the state of nuclear safety and radiation protection in France in 2022 217 • 07 • Medical uses of ionising radiation 07 01 08 13 AP 04 10 06 12 14 03 09 05 11 02
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