Study of the distribution of doses in tumors with hypoxia through the PENELOPE code

Abstract

Cells with normal oxygenation are more sensitive to the effects of ionizing radiation than those with hypoxic conditions, because O2 molecules react rapidly with free radicals, produced by irradiation, originating highly reactive radicals. Thus, the different concentrations of hypoxia in tumors can modulate the response of the irradiation through the radioresistance they present. The objective of this work is to study the dose distributions in cranial tumors with hypoxia through the simulation of the PENELOPE-Monte Carlo code, simulating a cranial tumor with various concentrations of oxygen. The obtained results were evaluated in terms of oxygen enhancement ratio (OER), energy deposited and beam profiles of the dose distributions of the tumors with different concentrations of oxygen. From the simulation data, it was shown that the code is able to evidence the effect of oxygen in dose distribution. A maximum difference of 7.29% were found when compared values of tumor with different concentrations of oxygen and with normal oxygenation conditions. We can assume that PENELOPE can be simulated the dose response of the tumors with different concentrations of oxygen, proving that, its oxygen concentration modulates the treatment response and carrying with it the risk of survival of the treated tumor cells.