ESTRO 2022 - Abstract Book

S410

Abstract book

ESTRO 2022

delineation as it consistently generates delineations with high clinical acceptability (higher even than contours by clinical experts) at a fraction of the time (less than 30 seconds as compared to 15min for the expert). Funding: European Union’s Horizon 2020 (No. 880314)

OC-0464 A new model of care for rapid lung SABR treatment planning: Evaluation of the advanced RTT role.

R. Wooder 1 , N. Bayman 2 , C. Chan 2 , J. Coote 2 , C. Faivre-Finn 2 , R. Goldstraw 3 , M. Harris 2 , L. Pemberton 2 , A. Salem 2 , H. Sheikh 2 , P. Whitehurst 4 , D. Woolf 2 1 The Christie NHS Foundation Trust, Christie medical physics and engineering , Manchester, United Kingdom; 2 The Christie NHS Foundation Trust, Networked services, clinical oncology, Manchester, United Kingdom; 3 The Christie NHS Foundation Trust, Christie medical physics and engineering, Manchester, United Kingdom; 4 The Christie NHS Foundation Trust,, Christie medical physics and engineering, Manchester, United Kingdom Purpose or Objective Lung SABR treatment is managed by a multidisciplinary team to ensure optimal delivery of care. The incorporation of a lung SABR advanced practitioner (specialist RTT) role to delineate target volumes and organs at risk (OAR) aims to improve service efficiency. This study evaluated inter-observer variability as well as target volume and OAR delineation acceptance. Materials and Methods An initial pilot study assessed if there was a statistically significant difference in OAR delineation between advanced practitioners and radiation oncologists. Following a training session and the provision of a supporting OAR atlas 2 advanced practitioners and 5 radiation oncologists delineated the heart, oesophagus, trachea, proximal bronchial tree and brachial plexus on 8 lung SABR patient CT scans. These structure sets were analysed in ADMIRE (Advanced Medical Imaging Registration Engine, Elekta AB, Stockholm, Sweden). The advanced practitioners OAR were compared against a STAPLE (Simultaneous Truth and Performance Level Estimation) volume generated from the radiation oncologist’s volumes. Inter- observer variability was measured using distance to agreement metrics. PTV and OAR delineation competency was assessed separately by the completion of 10 Supervised Learning Event for Radiotherapy Planning Skills (SLERPS). All clinical lung SABR plans delineated by the advanced practitioner were then subject to peer review. After 6 months the advanced practitioner peer review acceptance rate (proportion of cases accepted without changes during peer review) was compared against that of the radiation oncologists. Results The pilot study showed there was no significant difference in OAR delineation between the advanced practitioners and radiation oncologists, except for the brachial plexus (p = 0.014), highlighting this as an area for training development (Table 1). A review of complex lung SABR plans (n=29) found the advanced practitioner peer review acceptance rate (68%) was comparable with the radiation oncologists (69%). Over a 6 month period the advance practitioner delineated 168 patients; this was 79.6% of the SABR patient workload. Table 1. The median of the max distance to agreement and range for each OAR across all patients is shown. Results are compared with an independent t-test. Median mDTA (mm) Consultant Oncologist Median mDTA (mm) Advanced Practitioner p Brachial Plexus 3.6 (2.5 – 4.2) 5.0 (3.4 – 17.1) 0.014 Oesophagus 1.0 (0.8 – 1.5) 1.0 (0.8 – 1.4) 0.82 Heart 1.3 (1 – 1.5) 1.5 (0.8 – 2.4) 0.49 PBT 1.2 (0.6 – 1.7) 1.3 (0.9 – 1.7) 0.8 Trachea 1.2 (0.8 – 1.6) 1.2 (0.6 – 1.8) 0.78

Conclusion With appropriate training the advanced practitioner is competent delineating OAR and planning target volumes for lung SABR. The lung SABR advanced practitioner role has successfully reduced clinician workload.

OC-0465 A comparison of doctor and therapeutic radiographer (RTT) prostate contours on T2 weighted MRI

G. Smith 1 , A. Dunlop 1,2 , S. Alexander 1 , H. Barnes 1 , T. Herbert 1 , R. Lawes 1 , J. Murray 1,3 , A. Pathmanathan 1,3 , P. Patel 1,3 , K. Sritharan 1,3 , N. Sundahl 1,3,4 , R. Westley 1,3 , A. Tree 1,3 , H. McNair 1,3 1 Royal Marsden NHS Foundation Trust, Radiotherapy, London, United Kingdom; 2 Institute of Cancer Research, Physics, London, United Kingdom; 3 Institute of Cancer Research, Radiotherapy, London, United Kingdom; 4 Ghent University Hospital, Radiation Oncology, Ghent, Belgium Purpose or Objective MR-linac (MRL) systems enable daily online re-contouring and treatment plan re-optimisation. Currently this requires the presence of a doctor, however, it is anticipated that therapeutic radiographers (RTTs) will take over the re-contouring