Physics and Imaging in Radiation Oncology · Published 2026-07-01 · DOI 10.1016/j.phro.2026.101032
Angela Corvino, Tim Schneider, Yolanda Prezado
Background and purpose: Proton minibeam radiotherapy (pMBRT) uses a 1D array of narrow beams to widen the therapeutic window of difficult-to-treat tumors. With the aim of identifying tumor locations that could benefit most from pMBRT, we evaluated how irradiation parameters shape 3D dose distributions. Materials and methods: Monte Carlo simulations were used to compute dose distributions in water for different proton energies, beam widths (bws) and center-to-center distances (ctcs). Optimal parameter combinations were selected according to three criteria: (i) minimization of the bw in normal tissue; (ii) maximization of the valley dose in the target; and (iii) minimization of the peak dose in normal tissue. Results: For shallow tumors (≤ 2 cm), 0.5 mm beams with ctc = 3bw kept normal-tissue widths < 1 mm with Bragg-peak-to-entrance dose ratio (BEDR) > 1. For intermediate and deep-seated tumors (8–20 cm), 1.0–1.5 mm beams with ctc = 4–5bw kept normal-tissue widths < 7 mm with peak-to-valley dose ratio (PVDR) > 3 and achieved lateral dose homogeneity in the target. For very deep-seated tumors (> 20 cm), 2 mm beams with ctc = 4bw maintained normal-tissue widths < 10 mm with PVDR > 3 at the cost of BEDR ∼ 0.5. Conclusion: pMBRT may offer advantages over conventional proton therapy and GRID therapy for treating shallow and deep-seated tumors. For very deep-seated tumors (> 20 cm), feasibility will depend on tumor size and proximity of organs at risk.
Abstract from DOAJ. Public domain (CC0 1.0).
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Corvino, A., Schneider, T., Prezado, Y. (2026). Monte Carlo-based characterization of proton minibeam radiation therapy across clinically relevant beam parameters. Physics and Imaging in Radiation Oncology. https://doi.org/10.1016/j.phro.2026.101032