Energy deposition in biological tissues by 7Li and 4He due to neutron capture calculated with the FLUKA code

SEBASTIAN TRIVINO; DARÍO GRAÑA; MAURO VALENTE

MONTEVIDEO

Congreso; X - LATIN AMERICAN SYMPOSIUM OF NUCLEAR PHYSICS AND APPLICATIONS; 2013

COM LATINOAMERICANA DE FISICA - JEFFERSON LAB USA - UNIV. REPUBLICA URUGUAY

Boron Neutron Capture Therapy (BNCT) is a promising cancer therapy, currently be-ing investigated and optimized, relying on the high thermal neutron capture cross sec-tion of the 10 B nuclide, which undergoes the reaction 10 B (n, α) 7 Li [Q = 2.79M eV σ =3837 · 10−24 cm2 ]. Q is mostly converted into kinetic energy shared between the reactionproducts 7 Li and α particles releasing energy in tissue in a range around 10μm, approxi-mately typical cell dimensions. Thereby, converting BNCT as a therapy capable of quiteselectively targeting cancer at a cellular level. Neutrons are themselves not directly ion-izing particles and the mechanisms through which energy is lost and further release ina medium are very complex. Different types of secondary radiation carry out specificLinear Energy Transfer - LET and Radiobiological Effectiveness - RBE thereby beingnecessary to separate dose components. Relative contributions to the total dose arisingfrom secondary components are dependent on neutron energy spectrum, beam geometryas well as irradiated material its size and dimensions.Quite uniform absorbed dose spatial distribution within the whole volume of the treatedorgan constitutes the main goal requiring accurately evaluations of both therapeutic doseand deposition in healthy tissues become necessary. However, dose components, likephotons and protons generated in marginal reactions have to be accounted thereforeaffecting and distorting the desired therapeutic dose distribution.The present work presents a study aimed to characterize energy deposition due to 7 Liand the α as well as corresponding pathlengths through different biological tissues. Sim-plified expressions for energy loss are described by the Bethe theory thus energy depositionand particle range are compared with theoretical models of the FLUKA Monte Carlo code[1],[2] by subroutines adapted at the Laboratorio de Investigaciones e Instrumentaci ́on enxF ́ısica Aplicada a la Medicina e Im ́agenes por Rayos X - LIIFAMIR ).[1] A. Ferrari et al.FLUKA: a multi-particle transport code CERN-2005-10, INFN/TC05/11, SLAC-R-773 (2005)[2] G. Battistoni et al.The FLUKA code: Description and benchmarking Proc. HadronicShower Simulation Workshop Fermilab 6-8 Sept AIP Conf. Proc. 896, 31-49, (2007)