ESTRO 2024 - Abstract Book

S4617

Physics - Optimisation, algorithms and applications for ion beam treatment planning

ESTR0 2024

[7] Batth, S. S., et al. "Clinical-dosimetric relationship between lacrimal gland dose and ocular toxicity after intensity modulated radiotherapy for sinonasal tumours." The British journal of radiology 86.1032 (2013): 20130459.

[8] Dutz, A., et al. "Modelling of late side-effects following cranial proton beam therapy." Radiotherapy and Oncology 157 (2021): 15-23.

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Digital Poster

Towards MR-only based proton dose calculation with bulk density override in extremities

Franciska Lebbink 1,2,3 , Marisa Cobanaj 1,4 , Hermann Fuchs 5 , Dietmar Georg 5 , Aswin L. Hoffmann 1,3,4 , Esther G.C. Troost 1,3,4 , Petra Trnkova 5 1 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. 2 National Center for Tumor Diseases (NCT/UCC), German Cancer Research Center (DKFZ), Heidelberg, Germany; Medizinische Fakultät and University, Hospital Carl Gustav Carus Technische Universität Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany. 3 Department of Radiotherapy and Radiation Oncology, Faculty of Medicine and University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany. 4 Helmholtz-Zentrum Dresden-Rossendorf, Institute of Radiooncology – OncoRay, Dresden, Germany. 5 Medical University of Vienna, Department of Radiooncology, Vienna, Austria For real-time magnetic resonance imaging (MRI) integrated proton beam therapy (PBT), the calculation of dose distributions directly on MRI data is ultimately required [1]. Due to the lack of electron density information in MRI data, some form of post-processing of these images is needed if they are to be used for dose calculation. The most common methods for this are based on the generation of synthetic computed tomography (sCT) images, using deep learning [2]. These methods, however, demand large patient data training sets including both MRI and dual energy CT (DECT) scans, which may be limited for many body sites. As an alternative to sCT generation, the bulk density override (BDO) method assigns a certain electron density value to each tissue structure. Since proton range calculation is sensitive to the accuracy of tissue density determination, BDO may not provide accurate dose calculation for PBT in general. However, for patients with soft-tissue tumors of the extremities, BDO may be sufficient for accurate PBT dose calculation, due to the simplicity of the anatomy. Purpose/Objective:

The aim of this treatment planning study was to investigate the impact of BDO on the accuracy of MRI-only based proton dose calculation by comparison with the current standard of dose calculation.

Material/Methods: