The microscopic dose enhancement factor measurment of bismuth nanoparticles in external radiation therapy using MRI polymer gel dosimetery

Introduction: Bismuth-based nanoparticles having high atomic number and electron density, besides of being utilized as CT contrast agent, stand as a strongly proposed method for dose enhancement in radiotherapy. Embedded nanoparticle in polymer gel dosimeter poses the first step to assess the dose enhancement capability in nanoparticles. To this end, MAGICA gel dosimeter, which is a modified kind of agarose-added magic gel to obtain more stiffness and stability is appropriate method. This study aims at determining the dose enhancement capability of bismuth nanoparticles in this gel under conventional external radiotherapy. Materials and Methods: In current study, the synthesized bismuth nanoparticles approximately with 20 nanometers in diameter and 0.1mM in concentration were injected into MAGICA gel and exposed to 6 MV X-rays beams from linear accelerator simultaneously with control gel samples irradiated in different five doses from 2-10Gy. Results: MAGICA polymer gel response against radiation was characterized by comparing R2 in samples lacking nanoparticles and with Bi-NPs. MAGICA response was found to be linear over the entire dose range explored from 2Gy up to 10 Gy. Results indicated the average dose enhancement factor around 9.8% ± 0.02 in the presence of Bi-NPs. Conclusion: This study investigated the dose enhancement capability of bismuth nanoparticles in external radiotherapy. As well as, MAGICA polymer gel combined with Bi-NPs was approved as a suitable tool for measuring the enhancement of radiation.