Improving the dose distributions in minibeam radiation therapy: Helium ions vs protons.

摘要: Purpose Charged particle minibeam radiation therapy is a novel therapeutic strategy aiming at reducing the normal tissue complication probability by combining sparing of submillimetric, spatially fractionated beams with improved dose deposition ions. This may allow safe escalation in tumor and other targets. In particular, proton has already proven remarkable increase index for high‐grade gliomas animal experiments. The reduced multiple Coulomb scattering nuclear fragmentation helium ions compared to protons heavier ions, respectively, make them good candidate (MBRT). purpose present work was perform comprehensive dosimetric comparison between MBRT (pMBRT HeMBRT). Methods Proton minibeams same range (7.7 cm) have been simulated water phantom CT images an anonymized human head. Monte Carlo simulation toolkit GATE v8.0 used. Different beam sizes (1 3 mm) spacings were evaluated. Depth curves, lateral profiles, peak‐to‐valley ratios (PVDR), dose‐averaged linear energy transfer (LET) assessed. Furthermore, evaluations secondary products valley regions carried out basic example treatment plan pMBRT HeMBRT considered. Results Compared protons, yield significantly Bragg‐peak‐to‐entrance ratio (BEDR) higher PVDR equal spacing. At time, due lower scattering, homogenization target becomes more difficult than protons. To achieve homogeneous HeMBRT, spacing be which turn decreases tissues values those observed LET maps show up 20%–30% peak all evaluated cases. Helium lead depths, including entrance region. However, this compensated shallow depths thanks BEDR HeMBRT. Conclusions Helium might offer choice therapy. They provide pronounced spatial fractionation without possible drawbacks linked biological experiments are needed evaluate whether heterogeneity volume would still efficient control, as case pMBRT.