Investigation of the dose enhancement effect of spherical bismuth oxide nanoparticles in external beam radiotherapy

Objective(s): External radiotherapy is the most common method of radiotherapy which the most important problem associated with is that there is no difference between healthy and tumor tissues in dose absorption. One way to differentiate the dose sensitivity is to use metal-based nanoparticles. Bismuth oxide nanoparticles are good candidates for cancer radiotherapy. In this study, the dose enhancement effect of the synthesized spherical Bi2O3 NPs was investigated in 6 MV external radiotherapy. Methods: Bi2O3 were synthesized and GENIPIN gel dosimeter was produced and divided into two equal portions, one part to fill vials containing pure gel and the other part to be added to a specified amount of nanoparticles to give a concentration of 0.1 mM. Then, the irradiation of the pure gel and gel vials containing the NPs was performed one day after manufacture by a 6 MV external radiotherapy device. Gel readout was performed using spectrophotometer and absorption-dose curves were achieved. Results: Results show that spherical Bi2O3 NPs cause a decrease in GENIPIN absorbance range compared to gel without NPs. The slope of the absorbancedose curve in presence of NPs is -0.038 which is more than this slop in the pure gel (-0.029) which indicates a DEF of 1.31 in the usage of these NPs in the tumor. Conclusions: We can conclude that by applying these spherical Bi2O3 NPs, dose absorption of the tumor will increase up to 31% which means the efficacy of radiotherapy can be maintained by lower applied dose to the tumor and healthy cells.