ESTRO 2022 - Abstract Book

S557

Abstract book

ESTRO 2022

Results Prescribed doses expressed as equivalent doses in 2 Gy per fraction (EQD2) for D 50% were 82±4 Gy in the HTV, 72±3 Gy in GTV-HTV, and 68±2 Gy in CTV-GTV. 97% of the plans were clinically feasible considering brain stem, spinal cord, and mandible constraints. Parotids could be spared in only 57% of the cases, since they were inside the PTV, and target coverage was prioritized. The TCP accounting for the planned dose distribution and image-derived radiosensitivity maps was higher than 95% control for the nominal plan in all the targets for 87% of the cases (Figure 2). For four remaining cases lower TCP values, seemingly attributable to voxels receiving low doses at the target periphery, were however observed requiring further investigation and potential a posteriori adjustment.

Conclusion Automated treatment planning with integrated boost targeting hypoxia and considering a heterogeneous density of clonogens in the tumour based on functional imaging has shown clinical feasibility and high tumour control prediction.

OC-0628 Proton therapy treatment verification with prompt gamma rays and fast neutrons – a feasibility study

H.E.S. Pettersen 1 , E. Alagoz 2,3 , L.B. Hysing 1 , T. Kögler 4 , D. Lathouwers 5 , W. Lionheart 6 , J. Obhodas 7 , G. Pausch 8 , H.M. Ratliff 3 , M. Rovituso 9 , S. Schellhammer 4 , L.M. Setterdahl 3 , K. Skjerdal 3 , D. Sudac 10 , J.A. Turko 4 , K.S. Ytre-Hauge 11 , I. Meric 3 1 Haukeland University Hospital, Department of Oncology and Medical Physics, Bergen, Norway; 2 University of Bergen, Department of Earth Science, Bergen, Norway; 3 Western Norway University of Applied Sciences, Department of Computer Science, Electrical Engineering and Mathematical Sciences, Bergen, Norway; 4 OncoRay — National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden, Dresden, Germany; 5 Delft University of Technology, Section of Nuclear Energy and Radiation Applications, Department of Radiation, Science and Technology, Delft, The Netherlands; 6 University of Manchester, Department of Mathematics, Manchester, United Kingdom; 7 Ru đ er Bo š kovi ć Institute, Division of Experimental Physics,