ESTRO 2020 Abstract book

S364 ESTRO 2020

the MR-Linac system using previous imaging to prepare a patient specific plan template, this takes approximately 1 hour. The patient was positioned, and an initial MR image was taken. The clinician contoured the GTV on the MR and expanded 5mm to get the PTV. A pseudo-CT was prepared using bulk density overrides of bones, air, lung, fat, and soft tissue for dose calculation. A step-and-shoot IMRT treatment plan was optimised, and approved by the clinician, while the patient stayed on the table. Online QA (monte-carlo recalculation (gamma agreement score 2mm/2%) and point dose calculation using the Clarkson method) was performed. Finally, the single fraction dose was delivered to the patient. Each plan was later measured on a Delta 4 Phantom (ScandiDos) and evaluated using a criterion of 3%/2mm. Evaluation of the pseudo CT technique was performed prior to the development of this workflow. Mean dose difference to the PTV when calculated with a CT based electron density map was compared with a bulk density override based calculation for 20 patients treated in the pelvis, lung, and abdomen. Results A total 7 treatments were performed with this method, all evaluated treatments were prescribed a single fraction of 12Gy based on the size of the tumour. The first 4 were performed over a two day procedure to trial the workflow, then a following 3 treatments were performed with the final single day workflow. The first patient treated in the single day workflow took a total time of 66 minutes, the following two were treated in less than 1 hour. Evaluation of the Pseudo-CT method showed a median dose difference in the PTV compared to CT based calculation of 0.75% (-0.09% – 4.46%). For 6 of the treatments the online QA gave a median passing rate of 98.9%(94.01%-99.07%), and for all 7 treatments a delta4 measurement passed with median passing rate of 99.7% (95.2%-100%) with the criterion of 3%/2mm. The point dose calculation using Clarkson method had a median of -3.8% (-14.4%-0.6%) to the MC calculated point dose. Conclusion One-day radiosurgery with on-table treatment planning has been successfully implemented. A pseudo-CT technique was used, which accurately estimates electron density compared to CT based calculations, and eliminates the need for a planning CT. All treatments were verified with patient specific QA which passed. Patients can now receive treatment for painful non-spinal bone metastases in a single day and single appointment on an MR-Linac as part of a prospective study protocol regarding patient comfort, clinical feasibility, and compliance. OC-0593 Alexithymia, empathy and burn-out amongst RTTs: results from the PRO BONO survey P. Franco 1 , V. Tesio 2 , J. Bertholet 3 , A. Gasnier 4 , E. Gonzalez del Portillo 5 , M. Spalek 6 , J. Bibault 7 , G. Borst 8 , W. Van Elmpt 9 , D. Thorwarth 10 , L. Mullaney 11 , K. Roe Redalen 12 , L. Dubois 13 , M. Bittner 14 , C. Chargari 15 , S. Perryck 16 , J. Heukelom 8 , S. Petit 17 , M. Lybeer 18 , L. Castelli 2 1 University of Turin, Department of Oncology- Radiation Oncology, Turin, Italy ; 2 University of Turin, Department of Psychology, Turin, Italy ; 3 The Institute of Cancer Research and the Royal Marsden NHS Foundation Trust, Joint Department of Physics, London, United Kingdom ; 4 Gustave Roussy Cancer Campus, Department of Medical Physics, Villejiuif, France ; 5 University Hospital of Salamanca, Department of Radiation Oncology, Salamanca, Spain ; 6 Maria Sklodowska-Curie Institute - Oncology Center, Department of Soft Tissue/Bone Sarcoma and Melanoma, Warsaw, Poland ; 7 Hopital

Europeen Georges Pompidou- Universite Paris Descartes, Department of Radiation Oncology, Paris, France ; 8 The Netherlands Cancer Institute- Antoni van Leeuwenhoek Hospital, Department of Radiation Oncology, Amsterdam, The Netherlands ; 9 GROW – School for Oncology and Developmental Biology- Maastricht University Medical Center, Department of Radiation Oncology, Maastricht, The Netherlands ; 10 University Hospital for Radiation Oncology Tubingen, Section for Biomedical Physic, Tubingen, Germany ; 11 Trinity College Dublin, Applied Radiation Therapy Trinity Research Group- Discipline of Radiation Therapy- School of Medicine, Dublin, Ireland ; 12 Norwegian University of Science and Technology, Department of Physic, Trondheim, Norway ; 13 GROW – School for Oncology and Developmental Biology- Maastricht University Medical Center, Department of Radiation Oncology, , The Netherlands ; 14 Arctoris, Arctoris, Oxford, United Kingdom ; 15 Gustave Roussy Cancer Campus, Department of Radiation Oncology, Villejiuf, France ; 16 University Hospital Zurich and University of Zurich, Department of Radiation Oncology, Zurich, Switzerland ; 17 Erasmus Medical Center, Department of Medical Physics, Rotterdam, The Netherlands ; 18 ESTRO, ESTRO Office, Brussels, Belgium Purpose or Objective Burn-out syndrome (BOS) is a frequent observation amongst oncology professionals. It influences performance at work, as well as physical and mental well-being. Specific personality traits may predispose to BOS. Alexithymia is a psychological dimension characterized by dysfunctional emotion processing and awareness. Empathy is the ability to share and understand another’s ‘state of mind’ or emotion. The PROject on Burn-Out in RadiatioN Oncology (PRO BONO study) was developed to explore BOS in the field of radiation oncology and to investigate the correlation between alexithymia and empathy and the likelihood to experience BOS. Material and Methods An anonymous online survey was distributed to European Society for Radiotherapy and Oncology (ESTRO) members. Each participant was requested to complete 3 validated questionnaires to evaluate alexithymia, empathy and BOS: the Toronto Alexithymia Scale (TAS-20), the Interpersonal Reactivity Index (IRI) and the Professional Quality of Life Scale (ProQoL), respectively. The present analysis focuses on the population of Radiation TherapisTs (RTTs). Compassion satisfaction (CS), a measure of professional satisfaction, secondary traumatic stress (STS) and BOS (the 3 ProQoL subscales) were evaluated and their correlation with alexithymia and empathy (empathic concern, perspective taking and personal distress) was investigated with generalized linear modelling. Covariates found to be significant on univariate linear regression analysis were included in the multivariate linear regression model. R 2 and adjusted R 2 were used to assess model fit. Results A total of 399 RTTs, 71.2% female and 28.8% male, completed all requested questionnaires. Mean age was 39.9 years (SD:9.9). Point prevalence of alexithymic trait in this cohort was 10.5%, while borderline alexithymia was observed in 19.8%. With respect to professional quality of life, high levels of STS and BOS were observed with 24.1% and 25.6% of respondents, respectively. On the other hand, up to 30.6% of RTTs scored high in the CS domain of ProQoL. A higher level of alexithymia was associated to significantly decreased CS (β:-0.201;SE:0.027;p<0.001), increased STS (β:0.202;SE:0.028;p<0.001) and BOS