An investigation on the capabilities of the PENELOPE MC code in nanodosimetry

Abstract

The Monte Carlo (MC) method has been widely implemented in studies of radiation effects on human genetic material. Most of these works have used specific-purpose MC codes to simulate radiation transport in condensed media. PENELOPE is one of the general-purpose MC codes that has been used in many applications related to radiation dosimetry. Based on the fact that PENELOPE can carry out event-by-event coupled electron-photon transport simulations following these particles down to energies of the order of few tens of eV, we have decided to investigate the capacities of this code in the field of nanodosimetry. Single and double strand break probabilities due to the direct impact of gamma rays originated from Co60 and Cs137 isotopes and characteristic x-rays, from Al and C K-shells, have been determined by use of PENELOPE. Indirect damage has not been accounted for in this study. A human genetic material geometrical model has been developed, taking into account five organizational levels. In an article by Friedland et al. [Radiat. Environ. Biophys. 38, 39-47 (1999)], a specific-purpose MC code and a very sophisticated DNA geometrical model were used. We have chosen that work as a reference to compare our results. Single and double strand-break probabilities obtained here underestimate those reported by Friedland and co-workers by 20%-76% and 50%-60%, respectively. However, we obtain RBE values for Cs137, AlK and CK radiations in agreement with those reported in previous works [Radiat. Environ. Biophys. 38, 39-47 (1999)] and [Phys. Med. Biol. 53, 233-244 (2008)]. Some enhancements can be incorporated into the PENELOPE code to improve its results in the nanodosimetry field.

Geant4 interaction model comparison for dose deposition from gold nanoparticles under proton irradiation

“…This selection is based on the original paper presenting the suitability of the "Penelope" models for nanodosimetric (i.e. DNA damage) studies (Bernal and Liendo 2009). On the other hand, simulations based on the "Livermore Physics List" have demonstrated good agreement in reproducing energy spectra of gold nanoparticles or thin foils under photon or proton irradiation (Casta et al 2014.…”

An implementation of discrete electron transport models for gold in the Geant4 simulation toolkit

“…[3][4][5] A dose enhancement from using GNPs in radiotherapy has already been demonstrated using Monte Carlo simulations; 6 however these simulations are of limited accuracy at micrometer scales, as the continuous physics models used to date break down at small spatial resolutions. 7,8 As one moves towards more accurate microdosimetric measurements of the impact of GNPs, discrete physics models become necessary as they improve the spatial resolution in simulation. As the physical effects of GNP boosted radiotherapy occur across energy scales that descend down to 10 eV, Monte Carlo simulations require discrete physics models down to these very low energies in order to avoid underestimating absorbed dose and secondary particle generation.…”

Nanoscale radiation transport and clinical beam modeling for gold nanoparticle dose enhanced radiotherapy (GNPT) using X-rays

“…For convenience, we arrange the literature according to the following order: general radiation transport aspects relevant for nanoscale simulations, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] macroscopic dose enhancement in contrast agents and dose perturbation at high-Z material interfaces, radiation transport for nanoscopic dose enhancement of GNP, [46][47][48][49][50][51][52][53][54][55][56][57][58] radiobiological and clinical aspects of GNPT, [59][60][61][62][63][64][65][66][67] application of Monte Carlo (MC) simulations to cellular environment, [68][69][70] modification of linear accelerator spectra to maximize dose enhancement 71 and GNPT using other than X-ray therapeutic beams (proton, electron). …”