Monte Carlo assessment of low energy electron range in liquid water and dosimetry effects

SENIWAL, BALJEET; MENDES, BRUNO M.; MALANO, FRANCISCO; PÉREZ, PEDRO; VALENTE, MAURO; FONSECA, TELMA C.F.

PHYSICA MEDICA

IST EDITORIALI POLGRAFICI INT

Lugar: Roma; Año: 2020 vol. 80 p. 363 - 372

1120-1797

The effects of low energy electrons in biological tissues have proved to lead to severe damages at the cellular andsub-cellular level. It is due to an increase in the relative biological effectiveness (RBE) of these electrons with adecrease in their penetration range. That is, lower the range higher will be its RBE.Therefore, accurate determination of low energy electron range becomes a key issue for radiation dosimetry. This work reports on in-waterelectron tracks evaluated at low kinetic energy (1?50 keV) using isotropic mono-energetic point source approachsuitably implemented by different general-purpose Monte Carlo codes. For this aim, simulations were performedusing PENELOPE, EGSnrc, MCNP6, FLUKA and Geant4-DNA Monte Carlo codes to obtain the particle range, R,R90, R50. Finally, evaluation of dose point kernel (DPK), as used for internal dosimetry, was carried out as anapplication example. Scaled dose point kernels (sDPK) were estimated for a range of mono-energetic low energyelectron sources. The non-negligible differences among the calculated sDPK using different codes were obtainedfor energy electrons up to 5 keV. It was also observed that differences of in-water range for low-energy electrons,due to the different general-purpose Monte Carlo codes, affected the DPKs used for dosimetry by convolutionapproach. Finally, the 3D dosimetry was found to be almost not affected at macroscopic clinical scale, whereasnon-negligible differences appeared at the microscopic level. Hence, a thorough validation of the used sDPKshave to be performed before they could be used in applications to derive any conclusions