Comparison of methodologies for creating spread-out Bragg peaks in proton therapy using TOPAS and MCNP codes
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2023
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Radiation Physics and Chemistry
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In proton beam treatments, the superposition of several weighted Bragg curves with different incident energies is
required to homogeneously irradiate a large tumor volume, creating a spread-out Bragg peak (SOBP). This paper
confirms on the suitability of two different methods to create SOBPs – Bortfeld/Jette’s and MCMC (Monte Carlo
calculations and Matrix Computations), using Monte Carlo simulations performed with TOPAS and MCNP6.1. To
generate the SOBPs, algorithms were developed for implementation of the two methods, which enabled to find
the weights for thirty variations of SOBPs, categorized according to their width and maximum depths. The
MCMC method used weight optimization in designing SOBPs to avoid negative values. In contrast, the Bortfeld/
Jette’s method yielded the SOBPs according to the variation of a power-law parameter (p) introduced by the
range-energy relationship. Optimal values of p, from MCNP and TOPAS, were selected in order to retrieve SOBPs
with the best smoothness and then related to those obtained from the literature. In comparing both methods and
codes, dose homogeneity parameters (HOM) were used to examine the SOBP flatness and gamma analyses were
employed to assess the dose deposition along its full extension. The results showed that the SOBPs designed using
the MCMC method had better HOM values and computational performance for both codes when compared to the
Bortfeld/Jette’s method. The gamma analyses highlighted significant differences between the entrance doses
comparing the two different methods, for SOBPs with intermediate and high depths and small width. This
evaluation was not possible with the HOM values alone, which stresses the relevance of a broad analysis to avoid
unintended doses in healthy tissues.
Como referenciar
BRANCO, I.S.L.; BURIN, A.L.; PEREIRA, J.J.N.; SIQUEIRA, P.T.D.; SHORTO, J.M.B.; YORIYAZ, H. Comparison of methodologies for creating spread-out Bragg peaks in proton therapy using TOPAS and MCNP codes. Radiation Physics and Chemistry, v. 211, p. 1-14, 2023. DOI: 10.1016/j.radphyschem.2023.111043. Disponível em: https://repositorio.ipen.br/handle/123456789/47895. Acesso em: 13 May 2024.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.