S1523
Interdisciplinary - Quality assurance and risk management
ESTRO 2026
Proffered Paper 2677 Characterisation of SABR and SRS patient safety radiotherapy events John Rodgers, Helen Best, Cristiona Logan Medical Exposures Group, UKHSA, London, United Kingdom Purpose/Objective: The safety of stereotactic ablative radiotherapy and radiosurgery (SABR/SRS) requires seamless management along the patient pathway to eliminate issues that may affect treatment delivery.This study used a UK national event learning system (ELS) to investigate the origin, detection, contributory factors and severity of SABR/SRS patient safety radiotherapy events (RTE)1. Its primary aim was to characterise and provide thematic insights into drivers that enable events to occur. Material/Methods: A retrospective analysis of 24 months data voluntarily reported between May 2023 and April 2025 within the UK ELS was completed. Reports were filtered using search parameters and resulting reports were then selected by assessing their relevance within the SABR pathway. Descriptive statistical methods were applied. Results: There were 23,070 RTE reported nationally for this period. After selection, 972 reports met the study criteria and were included within the analysis. The severity of SABR/SRS events was compared with all submitted reports for the period. The proportion of SABR/SRS RTE of high/moderate harm were slightly lower than for all RTE (2.5% to 2.9%). There was a higher proportion of good catch/near miss RTE reported in the SABR/SRS group (29.8% to 24.1%).Figure 1 shows the SABR/SRS treatment pathway, associated activities and the volume of RTE generated, traversing, and detected within each area. The primary areas where events originate are verification imaging (17.7%), pretreatment planning (17.4%) and pretreatment prep/imaging (16.7%). The most effective areas for the detection of events are verification imaging (24.1%), pretreatment planning (17.7%), treatment delivery (16.6%) and treatment preview and setup (15.5%).
Conclusion: This is the first national analysis to evidence and identify the most effective methods employed to detect and mitigate the risk of incidents occurring along the radiotherapy pathway.Verification imaging is established as a vital safety tool1. This analysis provides evidence to confirm verification imaging reduces the risk of a radiation incident traversing to treatment delivery.The critical role of patient set up and positioning prior to treatment delivery is highlighted. These tasks may mitigate the risk of radiation incidents, emphasising the importance of patient engagement and comfort as well as RTTs judgement and skill in detecting errors.The efficacy of EOPC in mitigating the risk of RTE traversing across the patient pathway has also been demonstrated. References: 1. UKHSA, Advancing safer radiotherapy (2025) www.gov.uk/government/publications/radiotherapy- advancing-safer-radiotherapy (accessed 16.10.25)2. Ford EC, Evans SB. ‘Incident learning in radiation oncology: a review’ Medical Physics 2018: vol 45, pgs 100 to 1193.World Health Organization (WHO). Patient safety incident reporting and learning systems: technical report and guidance (who.int) 2020 (accessed 16.10.25)4.UKHSA Safer radiotherapy: national patient safety radiotherapy event taxonomy (2025). www.gov.uk/government/publications/safer- radiotherapy-national-patient-safety-radiotherapy-
event-taxonomy (accessed 16.10.25) Keywords: event, detection, learning
Figure 2 compares cited contributory factors of SABR/SRS reports to all submitted reports. A greater proportion of SABR/SRS events were attributed (at least in part) to individual factors. Technical causes,
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