Current Directions in Biomedical Engineering · Published 2025-09-01 · DOI 10.1515/cdbme-2025-0101
Introduction: Energy modulators (EM) have gained increasing attention due to their relevance in FLASH proton therapy. Current EM designs are fragile, necessitating thin ridges and limited sizes. Production requires advanced and costly 3D printers, as basic filament printers are inadequate, leading to expensive outsourcing. We propose an innovative EM design to address these limitations. Methods: The novel design consists of boxes stacked one on top of the other. Each box is created with two distinct infillratios: one for the inner cube and one for the larger cube surrounding it. The size of the inner and outer cubes is optimized along with the infill ratio. This structure is repeated periodically for box-like targets or varied to achieve the desired dose distribution.We design, slice, and print the EM using a Bambu Lab-X1C filament printer and polylactic acid filament. The simulation was performed using a GPU-based Monte Carlo simulation (FRED), where the EM was modeled as a combination of cubes with variable heights, with the infill ratio mapped to the material height. The simulation design was validated through depth-dose curve measurements using PSI Gantry 2. Results: EM for box-like targets of 35mm depth were designed and manufactured by varying the infill ratio between 30% and 100%. We chose cubic infill for isotropic periodicity, ensuring that impinging particles encounter uniform material distribution. Manufacturing constraints require 100% (concentric) infill in areas smaller than 1.5mm2. The simulations were validated by depth dose curve measurements with shape and distal range agreement to within detector uncertainties (<1mm). Conclusion: We realized a 3D-printed EM that is easier to produce and more resistant to physical damage than current alternatives. This design demonstrates the potential for a costeffective, easily manufacturable, and scalable EM.
Abstract from DOAJ. Public domain (CC0 1.0).
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