ESTRO 2025 - Abstract Book

S2306

Interdisciplinary – Health economics & health services research

ESTRO 2025

1 Center for Proton Therapy, Paul Scherrer Institute, Viligen-PSI, Switzerland. 2 Research Department, Leo Cancer Care, Horley, United Kingdom. 3 Department of Medical Physics and Biomedical Engineering, University College London, London, United Kingdom. 4 Research and Development, RaySearch Laboratories, Stockholm, Sweden. 5 Department of Human Oncology, University of Wisconsin Madison, Madison, USA. 6 Department of Accelerator and Medical Physics, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan. 7 Heidelberg Ion beam Therapy center, Heidelberg University Hospital, Heidelberg, Germany. 8 Medical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany. 9 Dept of Physics & Astronomy, University College London, London, United Kingdom. 10 Department of Radiation Oncology, Heidelberg University Hospital, Heidelberg, Germany. 11 Department of Physics, ETH Zurich, Zurich, Switzerland. 12 Biophysics, GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany. 13 Department of Electrical Engineering and Information Technology, TU Darmstadt, Darmstadt, Germany. 14 Division of Biomedical Physics in Radiation Oncology, German Cancer Research Center (DKFZ), Heidelberg, Germany. 15 Research and Development, P-Cure Ltd./Inc, Shilat, Israel. 16 Department of Basic and Applied Science for Engineering, Universita' di Roma "Sapienza", Roma, Italy. 17 Department of Radiation Oncology (Maastro), GROW School for Oncology, Maastricht University Medical Centre+, Maastricht, Netherlands. 18 Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic. 19 OncoRay-National Center for Radiation Research in Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Helmholtz-Zentrum Dresden-Rossendorf, Dresden, Germany. 20 Radiation Research Unit, European Institute of Oncology IRCCS, Milan, Italy Purpose/Objective: Recently, there is growing interest in gantry-less irradiation within the radiotherapy community. Rotating patients upright through a fixed RT beam is appealing, offering reduced treatment room costs, particularly for particle therapy, alongside potential anatomical and comfort benefits [1]. Advances in upright imaging enable treatment planning and daily positioning verification in the same position as during radiation therapy, addressing the key concern of upright treatment in the past. This has led several radiotherapy centers worldwide to develop or adopt upright patient immobilization systems. However, many aspects of upright radiotherapy are yet to be addressed, before streamlined for clinical implementation. Material/Methods: The 2024 ESTRO physics workshop on “Gantry-less Radiotherapy: Challenges and Opportunities” brought together 22 participants for in-depth discussions on the open questions and existing solutions. Four invited speakers gave excellent presentations on past and present implementations of gantry-less radiotherapy, such as upright carbon ion RT (QST, Japan); the possibility of MR-guided proton and ion therapy leveraging either upright (Dresden, Germany) or horizontal patient rotation (Heidelberg, Germany); and the challenges of establishing any paradigm shift within modern radiotherapy (Wisconsin, USA). Representatives from industry presented current and future commercial solutions for upright radiotherapy. Results: Recommendations for early adopters of upright patient positioning emphasized necessary workflow adjustments alongside unchanged elements. Ongoing research projects showcase significant progress in addressing current challenges to successfully implement upright treatment (Figure 1). Consensus outlined (1) A wishlist-to-vendor for immediate clinical needs, and (2) long-term innovations enabled by upright positioning and gantry elimination was formulated (Table 1). Limited upright imaging data (CT/MRI) and challenges in data sharing or generation were noted as major barriers to clinical assessment. Proposed solutions include developing physical/numerical phantoms simulating motion from supine to upright posture, alongside anatomically guided deformable registration algorithms to align supine and upright images, for which AI's potential was deemed critical. Virtual trials were identified as essential for evaluating suitable clinical indications for upright radiotherapy.