Abstract
The simulation model for MCNP5 code was used to study the effect of the gold nanoparticle (AuNPs) in cancer breast samples. The dose rate distribution of AuNPs in water and breast phantom was calculated using MCNP5 code. For inhomogeneities, cone cells were designed to calculate dose distribution around Ir-192 source in breast and inhomogeneous medium that includes gold nanoparticles at different concentration. Both barometers, the track length energy deposition tally (F6) and pulse height tally (*F8), were used. The result indicated that the F6 is better than *F8 for radiation dose calculation. Angular doses distribution in water was compared with data published for tally F6 and*F8 with the different percentage range of 0.0136 to 0.3019% for tally F6 at the average angle of 5 degrees and 175 degrees respectively. For *F8 tally, different percentage range of - 0.0014 to 0.8253 % was obtained at an average angle of 75 degrees and 5 degrees respectively. For breast phantom, the result of the F6 tally with the *F8 tally was compared. The difference in calculations between the two tallies in the angular anisotropic distribution was found to be in the range from 0.0514 to 0.4596% at the average angle of 15 degrees and 175 degrees respectively. The obtained results showed that the AuNP dose increases when the concentration increases up to ten percent (100 mg/ml), and then decreases for concentration higher than ten percent. The concentration of AuNPs greater than ten percent is not recommended. The results indicated that tally F6 is a good tool to calculate the effect of inhomogeneities due to breast cancer on brachytherapy.