ESTRO 2024 - Abstract Book

S93 ESTRO 2024 2021 ) . Until these multiple variables are considered to optimize the combination, the synergy of radiation and immunotherapy will remain underestimated. Invited Speaker

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Radiotherapy indications in early rectal cancer

Femke P. Peters

Netherlands Cancer Institute, Radiotherapy, Amsterdam, Netherlands

Abstract:

cT1-3b, MRF-, EMVI-, N0, M0 tumors are considered early rectal cancer. In routine rectal cancer care, where TME surgery is still the standard treatment for early rectal cancer, there is no indication for radiotherapy. Primary organ preservative treatment with (chemo)radiotherapy is, however, increasingly used and gaining in evidence and is on the verge of becoming an accepted standard indication. Research and development in this field is now aimed at identifying the optimum treatment strategy with an increasingly wide variety of options and techniques being investigated. On the other hand, radiotherapy for organ preservation might be overtaken by developments in systemic treatment with chemotherapy and/or immunotherapy.

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RAPTOR project: Imaging

Andreas Smolders

Paul Scherrer Institute, Centre for Proton Therapy, Villigen, Switzerland. ETH Zurich, Department of Physics, Zurich, Switzerland

Abstract:

Particle therapy is especially sensitive to set-up and anatomical variations due to the characteristic depth-dose curve, known as the Bragg peak. It can therefore likely benefit even more from online and real-time adaptation than photon therapy. However, the particles’ characteristics require different accuracy standards and solutions for the processes and algorithms involved. RAPTOR, a consortium supported by the European Union’s Horizon 2020, is dedicated to advancing online and Real-time Adaptive Particle Therapy of cancer (RAPTOR). With 15 PhD projects spanning Europe, RAPTOR focuses on refining treatment adaptation processes covering imaging, intervention, and verification. Online and real-time adaptation largely relies on imaging data acquired shortly before the delivery. Therefore, five PhD projects aim to quickly and reliably analyze this imaging data to further incorporate it into the treatment. In this presentation, we report on the major goals and findings of this work package. Promising modalities for online volumetric imaging include CT, CBCT and MRI. Both CBCT and MRI imaging have the drawback that they cannot straightforwardly be used for particle dose calculation, which nowadays mostly relies on CT. However, gantry-mounted CBCT scanners are more common than in-room CT scanners, and MRI scans have better soft-tissue contrast. Therefore, two PhD projects have developed deep-learning strategies to enhance or convert CBCT and MRI scans into synthetic CTs, suitable for particle dose calculation. Since the purpose of these algorithms is to use them in a time-sensitive online workflow, both projects aimed to incorporate an integral