60Co irradiation effects in Gd2O3 and Er2O3 nanoparticles

Abstract

Enhanced radiosensitization in tissues using high-Z materials has been observed since 80’s, and the application of nanoparticles (NPs) for this purpose has been widely studied in the past years. NPs use in radiotherapy procedures implies to submit them to high dose radiation beams which might cause damage to these particles resulting in the release of toxic material to the biological environment. In order to verify radiation effect in Gd2O3 and Er2O3 NPs doses from 3 Gy to 20 Gy produced by a 60Co source were tested. The study with X-ray diffraction (XRD) showed, for Gd2O3-NP samples, a change in peaks positions featuring a decrease in the lattice parameter as function of dose increase up to 5 Gy. From this point lattice parameter presented no significant change. For Er2O3-NP the lattice parameters do not present a behavior in function of dose. A peak change can be noticed for samples irradiated with 5 Gy and 20 Gy, and samples irradiated with 3 Gy, 7 Gy and no irradiated presented no significant peak displacement. Perturbed angular correlation (PAC) gamma-gamma spectroscopy was performed using 111In(111Cd) as probe nuclei. Despite non-symmetric site C parameters presented no substantial change results showed a slight variation of eta parameter for the symmetric site D for both samples, which may indicate a distortion at that site caused by the radiation. This study showed that radiation doses used in radiotherapy procedures may cause damage to nanoparticles structures. However, this damage is not great enough to break the nanoparticle and liberate toxic Gd3+ or Er3+ into patient organism.