Fit Function Modeling for Bragg Curves of Heavy Ion Beams

Le résumé fourni par la source

This study aims to develop a novel fitting function to accurately determine the beam range of heavy-ion beams, addressing challenges arising from secondary fragmentations in Bragg curve fitting. Monte Carlo simulations were conducted using the TOPAS toolkit to model Bragg curves for heavy ions in a water phantom. Various parameters, including depth step size, beam energy, energy spread, and the number of particle histories, were adjusted to evaluate the stability and accuracy of the fitting function. The proposed fitting function included modifications to the traditional Bortfeld function to account for secondary contributions from neutron scattering and nuclear fragmentation through additional terms. Experimental validation was performed using data from the Brookhaven National Laboratory, comparing simulated and measured Bragg curves. The enhanced fitting function improved the accuracy and robustness of beam ranges for heavy ions. The deviations in the fitted beam range for 80 % of the dose maximum were reduced to within$\pm 0.2 \text{mm}$across the entire fitting region, compared to deviations exceeding$\pm 1 \text{mm}$with traditional methods in the partial fitting region. The fitting function accurately captured complex depth dose distributions and secondary particle effects, especially in regions with high energy or broad energy spreads as shown in Figure 1. The novel fitting function improves Bragg curve estimations without requiring inefficient measurement procedures or high-resolution equipment, thereby enhancing the accuracy and reliability of heavy ion therapy.

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