ESTRO 2023 - Abstract Book

S1456

Digital Posters

ESTRO 2023

analyzed just after the fraction end, and corrective actions were taken when needed. Moreover, proactive preventions were further introduced to reduce the risk of future failures. The error occurrence rate was analyzed to evaluate the effectiveness of proactive actions. Results A total of 330 fractions have been analyzed. Considering all fractions analyzed in both phases, the average PTV differences were (-1.1 ± 3.8) %, (3.8% ± 7.3) % and (-0.7 ± 3.9) % for mean, minimum and maximum doses, respectively (FIG1). In the ipsilateral lung the average mean dose difference was (0.9 ± 8.5) %. In the first phase 13 errors have been identified. In the active phase, 12 errors were detected, 5 of which needed corrective actions; in 4 patients the actions taken corrected the error. Several preventions and barriers have been introduced to reduce the risk of future failures: the planning checklist was updated; the procedure for vacuum pillows was improved; and the use of the respiratory compression belt was optimized. A decrease of the failures rate was observed, showing the effectiveness of procedural adjustment.

Fig1 Histogram of dose differences in PTV and in the ipsilaterl lung for all the analyzed 330 fractions.

Fig2. Errors found and corrective actions taken in the first Observational phase (Fig2A), and in the second Active phase (Fig2B). Conclusion The use of IVD allowed to improve the quality of lung SBRT treatments. Patient specific and procedural corrective actions were successfully taken, leading to an overall improvement of the dosimetric accuracy.

PO-1737 Profile of centres participating in paediatric radiotherapy clinical trials: initial QUARTET report

A. Turcas 1,2,3 , S. Kelly 4,5 , E. Clementel 6 , M. Gaze 7 , L. Gandola 8 , G. Horan 9 , L. Padovani 10 , C. Corning 11 , T. Boterberg 12 , H. Mandeville 13 1 European Organisation for. Research and Treatment of Cancer , (EORTC) Headquarters, Brussels, Belgium; 2 The European Society for Paediatric Oncology (SIOPE), QUARTET project, Brussels, Belgium; 3 University of Medicine and Pharmacy "Iuliu Hatieganu", Oncology Department, Cluj-Napoca, Romania; 4 The European Society for Paediatric Oncology, QUARTET project, Brussels, Belgium; 5 European Organisation for. Research and Treatment of Cancer , (EORTC) Headquarters, Brussels, Belgium; 6 The European Organisation for Research and Treatment of Cancer (EORTC) Headquarters, Data Management/RTQA, Brussels, Belgium; 7 University College London Hospitals NHS Foundation Trust, Department of Oncology, London, United Kingdom; 8 Fondazione IRCCS-Istituto Nazionale Dei Tumori, Department of Radiation Oncology, Milan, Italy; 9 Cambridge University Hospitals NHS Trust, Oncology Centre, Cambridge, United Kingdom; 10 Assistance Publique Hoˆpitaux de Marseille, Department of Radiation Oncology, Marseille, France; 11 The European Organisation for Research and Treatment of Cancer (EORTC) Headquarters, Data Management/RTQA , Brussels, Belgium; 12 Ghent University Hospital, Department of Radiation Oncology, Ghent, Belgium; 13 The Royal Marsden Hospital and the Institute of Cancer Research, Department of Radiotherapy, Sutton, United Kingdom

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