ESTRO 2025 - Abstract Book

S3575

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

ESTRO 2025

copper or polypropylene spheres, respectively. Collimator functionality can be improved using Copper-filled Metal Composite HTPLA filament for the cylinder surface of the bore. We performed simulations in TOPAS-MC[1,2] and designed the elements using the modified Python package Porespy[3]. We evaluated the collimator's performance by comparing a solid collimator with the new proposed approach. As a feasibility study, we designed a PS setup of an eco-friendly compensator and collimator. Results: We validated the computational model for reproducing the new elements via depth dose curve and beam size measurement (Fig.1). The observed discrepancy between TOPAS and measurement falls within the detector’s inherent uncertainty. Simulations of collimating and compensating elements and experiments agree with a mean square error below 2%. We did not observe a difference in the dose profile between the solid and eco-friendly collimators for low energy. For higher energies (Fig.2A), the PLA in the inner cylinder affects the dose distribution, generating a dose halo around the aperture. The usage of more dense filaments (Copper-filled HTPLA) improves the results.

To demonstrate the feasibility of this new PS approach, we designed and validated an “eco-friendly” setup for simple geometrical phantoms and more complex and challenging small structures like murine brain tumours (Fig.2B). 3D-printing allows the design of complex elements with low costs and within a short time (the total time required was <20min, and the filament costs <1$).