S1928
Physics - Dose prediction/calculation, optimisation and applications for photon and electron planning
ESTRO 2026
Digital Poster 3253 The DoseRAD2026 Grand Challenge: Real-time radiotherapy dose calculation Guillaume Landry 1,2 , George Dedes 1,3 , Nikolaos Delopoulos 1 , Christopher Kurz 1 , Muheng Li 4,5 , Matteo Maspero 6 , Zoltan Perko 7,8 , Viktor Rogowski 9,10 , Adrian Thummerer 1 , Lennart Volz 11 , Niklas Wahl 12 , Fan Xiao 1 , Ye Zhang 4 1 Department of Radiation Oncology, LMU University Hospital, Munich, Germany. 2 Bavarian Cancer Research Center, (BZKF), Munich, Germany. 3 Department of Medical Physics, Faculty of Physics, Ludwig-Maximilians-Universität München, Munich, Germany. 4 Center for Proton Therapy, Paul Scherrer Institute (PSI), Villigen, Switzerland. 5 Department of Physics, ETH Zürich, Zürich, Switzerland. 6 Department of Radiotherapy, University Medical Center Utrecht, Utrecht, Netherlands. 7 Department of Radiation Science and Technology, TU Delft University of Technology, Delft, Netherlands. 8 Radformation, Inc., New York, USA. 9 Radiation Physics, Department of Hematology, Oncology, and Radiation Physics, Skåne University Hospital, Lund, Sweden. 10 Medical Radiation Physics, Department of Clinical Sciences Lund, Lund University, Lund, Sweden. 11 GSI Helmholtzzentrum für Schwerionenforschung, Biophysics Department, Darmstadt, Germany. 12 Division of Medical Physics in Radiation Oncology, Deutsches Krebsforschungszentrum (DKFZ), Heidelberg, Germany Purpose/Objective: The acceleration of radiotherapy dose calculation brings obvious benefits to treatment planning, online plan adaptation, quality assurance, and may ultimately foster real-time dose-guided radiotherapy [1]. Recent developments suggest that AI-based dose calculation directly on MRI may offer a pragmatic solution [2,3]. It remains to be seen what the optimal strategy is to achieve (near-)real-time dose calculation on 3D anatomy to combine accuracy and calculation speed. The DoseRAD2026 Grand Challenge aims to benchmark state-of-the-art methods for real-time dose calculations directly from images (both CT and MRI), in photon and proton radiotherapy. Material/Methods: The SynthRAD2025 open-source dataset [4] was used to obtain paired CT and MRI of patients treated for abdominal or thoracic lesions at a 0.35 T MRI-linac. Alignment was achieved with the ConvexAdam DIR framework [5] and curated by selecting exceptionally well-matched images as determined by visual overlay inspection. Ground truth dose distribution will be calculated using open-source Monte Carlo (MC) Geant4 photon and proton dose calculation (with low MC noise) on CTs, including a 0.35 T magnetic field. Generating several hundred beams per patient allows
registration vector maps between DIBH-EBH scans to sum dose contribution to the CTV and adjacent sliding OARs. To explore dose escalation, composite 3- fraction DIBH/2-fraction EBH plans (‘DIBH/IBH boost’) were created boosting different portions of the CTV furthest from sliding OARs during DIBH versus EBH scans (Figure-1). CTV and OAR dose statistics were evaluated for all plans. Goals were to escalate CTV dose, while not exceeding pre-defined OAR personalized dose constraints.
Figure-1: Variation of bowel OAR (red) in EBH (A) and DIBH (B), relative to CTV (green). In EBH, the CTV abuts the inferior bowel, sparing the superior bowel, compared to DIBH, where the inferior bowel is spared. Blue colour wash illustrates a CTV boost volume during EBH (A) vs DIBH (B). Results: Targets, OARs, dose constraints, and dose statistics are summarized in Table-1. In both cases, the boosted DIBH/EBH plans achieved higher CTV doses. Additionally, a lower maximum sliding OAR dose was seen with the boosted DIBH/EBH plan compared to individual DIBH, EBH, or non-boosted DIBH/EBH plans.
Table-1: Dose statistics of re-irradiation cases with DIBH, EBH and composite DIBH 3-fraction/EBH 2- fraction plans, with and without boosts. Conclusion: In this pilot study, we introduce and evaluate a novel concept (INEX), treating in two phases of breath hold to ‘spread’ dose and reduce the maximum dose to sliding OARs to improve the therapeutic ratio for upper abdominal cancers treated with SBRT. Using INEX, higher CTV doses were obtained while decreasing maximal doses to sliding OARs. Further optimizations (%DIBH versus %EBH, differential boosting), workflow, and clinical validation studies are ongoing. Keywords: therapeutic ratio, inhale/exhale breath hold, SBRT
Made with FlippingBook - Share PDF online