Dose Distribution and Dose Enhancement by Using Gadolinium Nanoparticles Implant in Brain Tumor in Stereotactic Brachytherapy

Background: The photoelectric and pair production processes increase when high-energy photons interact with materials with high atomic number Z. The energy loss results in a dose enhancement at the target implanted with these materials. This will lead to a higher active dose to be delivered to tumor, while sparing healthy tissues around the target volume. Objective and method: The objective of this work was to compute the radial dose enhancement, using GEANT4 based Monte Carlo simulations, at and near a 1×1×1 cm³ brain tumor implanted with different concentrations of gadolinium nanoparticles when using ¹⁹²Ir, ¹³⁷Cs and ⁶⁰Co, brachytherapy sources with parallel beam geometry. Results: Our outcomes show a dose enhancement factor of 1.45 for a concentration of 70 mg of gadolinium in the tumor when irradiated with 0.38 MeV γ-photon from ¹⁹²Ir source. It was also observed that this dose enhancement increased with increasing gadolinium concentration in the target and with photon energy. Conclusion: Gadolinium nanoparticles are groundbreaking agents with strong advantageous potential in cancer radiotherapy due to the fact that they enhance the radiation dose within the tumor. - Highlights: • High atomic number elements have high photoelectric cross section. • Radiation dose is enhanced in tumor injected with gadolinium nanoparticles. • Dose enhancement factor increases with increasing gadolinium concentration. • Dose enhancement factor increases with decreasing irradiation energy. • Dose enhancement factor increases with increasing tumor depth.