Comparison of Bi2S3 and Ta2O5 as alternative materials to gold in nanoparticles used as agents to increase the dose in radiotherapy

Abstract

Radiotherapy is an essential component in the treatment of all types of cancer. Radiotherapy uses ionizing radiation to destroy tumor tissue while reducing the damage to normal tissue as much as possible. In this work we study the effects of the spherical Bi2S3 and Ta2O5 nanoparticles (NPs) used as a radio-sensitization agent to increase local doses around the nanoparticle in a water medium. For low energy X-rays the dominant interaction is the photoelectric effect, which involves the absorption of a photon and the subsequent production of photoelectrons, characteristic X-rays and Auger electrons. Using a GEANT4 based simulation was determined the kinetic energy spectra of secondary electrons produced by the interaction of X-ray beam and Au, Bi2S3 and Ta2O5 NPs, after that was calculated the interaction processes, energy deposited, absorbed dose and the effective range distributions for the secondary electrons generated by the interaction of 100 million incident photons in the nanoparticles. The size of the nanoparticles was 20 nm and the energy distribution of the photons corresponds to the spectrum of a tube of x-rays with Tungsten anode and a peak voltage applied of 40 kV. This study demonstrates that Bi2S3 and Ta2O5 NPs are a viable alternative to Au NPs as a dose enhancing agent in radiotherapy.