ESTRO 2025 - Abstract Book

S3549

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

ESTRO 2025

3934

Digital Poster Quality analysis and correction of ultra-precise 3D-printed patient specific range modulators in particle therapy Moritz Westermayer 1,2 , Uli Weber 2,3 , Yuri Simeonov 3 , Hong-Ha Nguyen 4 , Marta Rovituso 5 , Klemens Zink 1,6 , Christoph Schuy 2 1 Institute of Medical Physic, University of Applied Sciences, 35390 Giessen, Germany. 2 Biophysics Division, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany. 3 Institute of Medical Physics and Radiation Protection (IMPS), University of Applied Sciences, 35390 Giessen, Germany. 4 Biophysics, GSI Helmholtzzentrum for heavy ion research, 64291 Darmstadt, Germany. 5 R&D, HollandPTC, 2629 JH Delft, Netherlands. 6 Medical Physics, Marburg Ion Beam Therapy Center (MIT), 35043 Marburg, Germany Purpose/Objective: At present, one of the most promising ways to realize FLASH irradiation in particle therapy are patient-specific 3D range modulators (3DRMs) allowing to exploit Bragg peak properties under ultra-high dose rates (UHDR) conditions [1]. 3DRMs are precisely designed and manufactured with high quality 3D printers. Depending on the desired spread-out Bragg peak (SOBP) and beam energy, the precisely designed and sharp pins of 3DRMs exhibiting high aspect ratios (of typically 1:10–1:20). Already smallest deviations in the range of few 10 μm in diameter in the steep flanks of the pins cause an undesired and clinically relevant tilt in the depth dose profile, particularly prominent for proton or carbon beams. Therefore, specialized procedures are required to ensure precise printing and, if necessary, to optimize the design and manufacturing chain. Material/Methods: The quantification of the 3D printing precision and modulation properties was performed by micro-CT imaging with a resolution of 5-10 μm (ProJet MJP 2500 Object3D, 3D-Systems). Additionally, direct depth-dose measurements of particle beams were used to deduce geometric deviations using the in-house software SPIDER (Sensitivity of Pin Deformation on the Depth Dose Profile). The used energies for depth dose measurements were 150.15 Mev for protons and 277.8 MeV/u for C12 ions. Results: Micro-CT-based volumetric analysis was found to be an appropriated method for the fast quality assurance of highly filigree 3DRM in FLASH particle therapy. In the case study of the characterised printer a constant offset of 35 μm in the pin radius was quantified and compensated in the corrected pin design. The corrected pin design showed afterwards excellent agreement with the planned SOBP (Fig. 1). Furthermore, same deviations and corrections could be derived by analysing depth-dose measurements using SPIDER.