ESTRO 2024 - Abstract Book

S3458

Physics - Dose calculation algorithms

ESTRO 2024

Nitrogen dose in RayStation refers to dose from the 14 N(n,p) 14 C reaction, which dominates non-boron dose in most tissues due to low energy (thermal) neutrons. Gamma dose collects all photon doses, and boron dose refers to dose from the ejectile and residual nucleus from neutron absorption by 10 B: 10 B(n,α) 7 Li. The hydrogen dose group’s usage is open to interpretation: it may refer only to the protons produced by elastic neutron scattering with hydrogen, but may include other reactions involving hydrogen. There are several key reactions that accounted for several percent of total physical dose that do not fall into these groups, for example elastic scattering of neutrons with carbon (0.8%) and oxygen (0.8%) and (n,α) reactions with 40 Ca (0.4%) in the cranium. In order to account for all dose components, we have assigned all elastic scattering dose to the hydrogen dose group, and all other non-boron and non-photon reactions are collected in the nitrogen group. Material definitions were also modified to include the specified 10 B concentrations neutron transport to accurately account for potential self-shielding effects.

Conclusion:

Testing has suggested OpenMC is a strong candidate for BNCT dose calculations, with results consistent with MCNP and reduced computation times. Next steps will involve continued benchmarking, including against measured phantom results in our first BNCT facility.

Keywords: BNCT, Monte Carlo, RBE

References:

1 Paul K. Romano, Nicholas E. Horelik, Bryan R. Herman, Adam G. Nelson, Benoit Forget, and Kord Smith, "OpenMC: A State-of-the-Art Monte Carlo Code for Research and Development", Ann. Nucl. Energy, 82, 90–97 (2015).

2 RaySearch Laboratories AB. RayStation 12A reference manual. Stockholm: RaySearch Laboratories AB; 2023.

3 C. J. Werner (editor), "MCNP User’s Manual - Code Version 6.2", Los Alamos National Laboratory, report LA-UR-17 29981 (2017).

4 T. Sato, et al., "Features of particle and heavy ion transport code system (phits) version 3.02", Journal 162 of Nuclear Science and Technology 55 (6) (2018) 684–690.