Proton and carbon-ion minibeam therapy: from modeling to treatment

TL;DR

This study models proton and carbon-ion minibeam therapy using Geant4, comparing dose distributions and patterns to evaluate uniformity and effectiveness in tissue-like media.

Contribution

It provides a detailed simulation comparison of proton and carbon-ion minibeams, analyzing dose uniformity and pattern effects in tissue-like media.

Findings

Protons achieve more uniform dose distribution due to greater lateral scattering.

Minibeam size influences dose distribution and pattern effects.

Different grid patterns affect dose-volume histograms in target volume.

Abstract

Arrays of minibeams of protons and $^{12}$C in tissue-like media were modeled with Geant4 toolkit. A set of beam energies was used in simulations to provide a Spead-out Bragg peak (SOBP) extended by 6 cm in depth for protons as well as for $^{12}$C. In both cases, beams of 0.3 mm or 0.5 mm FWHM were arranged at the entrance to a water phantom either on a rectangular or an hexagonal grid to compare two kinds of projectiles and different minibeam patterns. Differential and cumulative dose-volume histograms (DVH) were calculated and compared for protons and $^{12}$C as dose uniformity metrics. A uniform dose distribution was easily achieved with protons due to an enhanced lateral scattering of these projectiles in comparison to $^{12}$C. The cumulative DVHs calculated for 0.3 mm or 0.5 mm minibeams almost coincide in the target volume, but diverge for different grid patterns. In contrast, cumulative entry DVHs were found similar for both grid patterns, but different for 0.3 mm and 0.5 mm minibeams.