Purpose: Radiotherapy aims to realize tumor control using ionizing radiation sources, preserving adjacent healthy tissues. Recent studies aim to deliver the dose in a more conformed way to tumor tissues. Among new strategies to enhance dose in tumor volume, the use of high-Z materials combined with radiotherapy emerged as a proposal for this. Thus, the combination of radiotherapy with gold nanoparticles as an alternative to maximize the efficiency of the treatment, aiming to reduce the toxicity. Therefore, this work analyzed the increase in dose deposition resulting from the effects of the interaction between gold nanoparticles and radiation from different clinical radiotherapy beams, using Monte Carlo Simulation with PENELOPE code.
Methods: A homogeneous model of gold incorporation in water was used to quantify the interaction effect of gold with ionizing radiation (Ir-192; photon beam - 6 MV; electron beam - 6 MeV). The Dose Enhancement Factor (DEF) was calculated for all simulated conditions.
Results: The results showed that DEF increases according to the increase in gold concentration, being also dependent on the spectrum of primary radiation used. The DEF values using the highest concentration studied for the 192Ir, 6 MV, e 6 MeV were 2.82 ± 0.09, 1.41 ± 0.08 and 1.0297 ± 0.0002, respectively. Thus, the work showed that the use of gold nanoparticles for electron beams does not result in a significant DEF value.
Conclusion: The use of gold nanoparticles can provide a more effective tumor control, minimizing toxicity in adjacent healthy tissues, increasing the dose around the gold nanoparticles. This is a preliminary study with a simplified model for a previous analysis of DEFs in different types of radiation. Studies with more realistic cell models are needed to estimate an increase in local dose at different energies and beams.