Pyramid Filter: Design of a 3D Range Spreader for FLASH Irradiations

Popescu-Boboc, Clara (2025) Pyramid Filter: Design of a 3D Range Spreader for FLASH Irradiations. Bachelor's Thesis, Biomedical Engineering.

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Abstract

The thesis investigates the design and optimisation of pyramid-shaped proton range modulator filters to improve dose distribution uniformity in high-speed FLASH radiotherapy. To address this, the study asks: (1) How does the spatial configuration of pyramid filters affect dose distribution and SOBP uniformity in proton therapy? (2) What is the effect of introducing a collimator in combination with pyramid filters on beam shaping and dose conformity? (3) How do variations in the base layer design influence proton beam penetration range and modulation for targeting irregularly-shaped tumours? To answer these questions, Python-based models were developed and validated using TOPAS Monte Carlo simulations. A 17 x 17 array of pyramids significantly improved dose uniformity across the SOBP, compared to a single pyramid setup. Integrating a copper collimator with a 3 x 3 cm² air-gap effectively confined the modulated beam to the tumour region, without degrading the SOBP. Additionally, adjusting the filter's base layer thickness modulated penetration depth, and a split base design enabled lateral range variation for better conformity to asymmetric tumour geometries. Based on these results, the project recommends tailored pyramid configurations and collimation for achieving homogeneous, conformal dose delivery in FLASH proton therapy. In conclusion, the work shows that a simulation-driven filter design can strengthen FLASH treatment precision, while sparing surrounding he

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Gerbershagen, A. and Dendooven, P.G.
Degree programme:	Biomedical Engineering
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	09 Jul 2025 12:33
Last Modified:	09 Jul 2025 12:33
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/36024

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