Parametrization of dose profiles of therapeutic minibeams of protons, 4 He, 12 C, and 16O

Single minibeams of protons, 4 He, 12 C and 16 O in water were modeled with Geant4, and their dose distributions were parameterized with double-Gauss-Rutherford (DGR) functions. Dose distributions from arrays of 16 parallel minibeams centered on a rectangular or hexagonal grid were constructed from the parameterized minibeam profiles to simulate the lateral convergence of the minibeams resulting in a homogeneous dose field in the target tumor volume. Peak-to-valley dose ratios (PVDR) and dose-volume histograms (DVH) were calculated for the parameterized dose distributions and compared with those obtained directly from Geant4 modeling of minibeam arrays. The similarity of the results obtained by these two methods suggests that the fast calculation of dose profiles of minibeam arrays based on the DGR parameterizations proposed in this work can replace the time-consuming MC modeling in future preclinical studies and also in the development of treatment planning systems for minibeam therapy.