  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.
