ESTRO 2023 - Abstract Book

S370

Sunday 14 May 2023

ESTRO 2023

Purpose or Objective For rectal cancer patients, anatomical changes can be significant and daily plan adaptation allows for a reduction of treatment margins. Adjustments of the target volume are normally performed by Radiation Oncologists (RO), requiring their presence during each fraction. Auto-contouring can help streamline the process, but for target volumes such solutions are not widely available. To reduce the burden for the RO nonetheless, we trained RTTs to take over this task. The contours generated by RTTs during online adaptation were used to develop an auto-contouring solution for the mesorectum. Since the auto-contour still needs to be verified before clinical use, it does not remove the need for the RO to be present. The aim of this study was to show that the combination of auto-contouring with a verification by trained RTTs, leads to an efficient online adaptive workflow. Materials and Methods The training program consisted of education by a radiologist, delineation instructions plus a demonstration by an RO and written instructions. After training, ten patients were randomly selected for re-delineation by an RTT, using the deformed target volume as prior. These re-delineations were checked by an RO and after approval RTTs were allowed to perform the re-delineation online, followed by an offline check before the next fraction. An in-house developed auto-contouring algorithm was trained for the mesorectum based on the on-line contours. Trained RTTs verified and/or corrected the auto contour in an offline setting and scored the accuracy of the auto-contouring as well as the timing for verification and/or correction. To evaluate the potential time gain of this workflow, the timing of re-delineation was also scored during online adaptation. The timing for manual re-delineation was performed for 13 patients (51 fr), validation of the auto contour was performed for 18 patients (50 fr). Results Four RTTs were trained to perform online re-delineation. In total 45 patients (190 fr) were re-delineated by RTTs, all delineations were considered clinically acceptable. Online re-delineation of the target volume took on average 7:34 min. Minimal time was 2:40 min, maximum time 14:58 min. For offline validation of the auto-contour these numbers were resp. 2:45 min, 0:35 min and 8:35 min. Only for 2 fractions the auto-contour was judged unacceptable. No corrections were required for 9 fractions; while the remaining fractions only required minimal correction (29) or a mix of large and small corrections (9). Conclusion RTTs are skilled to delineate the target volume in rectal cancer patients during the MRI-guided adaptive process in absence of an RO. This allows for a reduction in logistic complexity and cost, making online adaptive radiotherapy available for more patients. Auto-contouring of target volumes can assist RTTs in this process to reduce delineation time. Trained RTTs remain important to guarantee correct contours as a start for online plan adaptation. 1 The University of Manchester, Division of Cancer Sciences , Manchester, United Kingdom; 2 The Christie NHS Foundation Trust , Department of Clinical Oncology, Manchester, United Kingdom; 3 Guy's and St Thomas' NHS Foundation Trust, Department of Clinical Oncology, London, United Kingdom; 4 Brighton and Sussex University Hospitals NHS Trust, Department of Clinical Oncology, Brighton, United Kingdom; 5 The Northern Ireland Cancer Centre, Department of Clinical Oncology, Belfast, United Kingdom; 6 Torbay and South Devon NHS Foundation Trust, Department of Clinical Oncology, Torquay, United Kingdom; 7 Weston Park Hospital, Department of Clinical Oncology, Sheffield, United Kingdom; 8 University College London Hospitals, Department of Clinical Oncology, London, United Kingdom; 9 Oncology Centre, Addenbrooke's Hospital, Cambridge University Hospitals NHS Foundation Trust, Department of Clinical Oncology, Cambridge, United Kingdom; 10 University Hospitals North Midlands, Department of Clinical Oncology, Stoke-on-Trent, United Kingdom; 11 Royal Wolverhampton NHS Trust, Department of Clinical Oncology, Wolverhampton, United Kingdom; 12 Oxford Universities NHS Trust, Department of Clinical Oncology , Oxford, United Kingdom; 13 The James Cook University Hospital, Department of Clinical Oncology, Middlesbrough, United Kingdom; 14 Clatterbridge Cancer Centre, Department of Clinical Oncology, Bebington, United Kingdom; 15 Velindre Cancer Centre, Department of Clinical Oncology, Cardiff, United Kingdom; 16 Aberdeen Royal Infirmary, Department of Clinical Oncology, Aberdeen, United Kingdom; 17 Swansea Bay University Hospital, Department of Clinical Oncology, Swansea, United Kingdom; 18 Royal Devon and Exeter NHS Foundation Trust, Department of Clinical Oncology, Exeter, United Kingdom; 19 The University of Manchester, Division of Cancer Sciences, Manchester, United Kingdom; 20 University Hospitals Southampton NHS Foundation Trust, Department of Clinical Oncology, Southampton, United Kingdom; 21 University Hospitals Birmingham, Department of Clinical Oncology, Birmingham, United Kingdom; 22 Beatson West of Scotland Cancer Centre, Department of Clinical Oncology, Glasgow, United Kingdom; 23 The Christie NHS Foundation Trust, Department of Clinical Oncology, Manchester, United Kingdom Purpose or Objective Previous work found that during the first wave of the COVID-19 pandemic, 34% of patients with lung cancer treated with curative-intent radiotherapy (RT) in the UK had a change to their centre’s usual standard of care treatment (Banfill et al. 2021). 17.5% of patients had a different RT dose/fractionation, generally increased hypofractionation as was recommended by UK guidelines (Faivre-Finn et al. 2020). 10.7% of patients with stage 3 lung cancer considered for chemotherapy had it omitted, and 6.7% had a reduced dose. We present the impact of these changes on patient outcomes. Materials and Methods The COVID-RT Lung database was a prospective multicentre UK cohort study including patients with stage 1-3 lung cancer referred for and/or treated with radical RT between April and October 2020. Data was collected on patient demographics, RT and systemic treatments, toxicity, recurrence, and death. The effect of having a change to RT dose/fractionation and developing ≥ grade 3 acute toxicity was assessed using logistic regression and survival was assessed using cox regression, both adjusting for age, sex, performance score, chemotherapy and dose per fraction. The effect of omitting chemotherapy Mini-Oral: Lung MO-0467 Impact of the COVID-19 pandemic on patient outcomes after curative-intent radiotherapy in the UK I. Fornacon-Wood 1 , K. Banfill 2 , S. Ahmad 3 , A. Britten 4 , C. Carson 5 , N. Dorey 6 , M. Hatton 7 , C. Hiley 8 , K. Thippu Jayaprakash 9 , A. Jegannathen 10 , P. Koh 11 , N. Panakis 12 , C. Peedell 13 , A. Pope 14 , C. Powell 15 , C. Stilwell 16 , B. Thomas 17 , E. Toy 18 , K. Wicks 19 , V. Wood 20 , S. Yahya 21 , A. Peters 22 , G. Price 19 , C. Faivre-Finn 23,19