Introduction:

Dosimetry is used to ensure equality between the prescribed and delivered dose in radiotherapy treatments. However, performing it experimentally in brachytherapy becomes complex due to the high dose gradient near the source. Thus, Monte Carlo simulation is recommended to meet this demand.

Objective:

To analyze the response of two Monte Carlo codes: PENetration and Energy LOss of Positrons and Electrons (PENELOPE) and TOol for PArticle Simulation (TOPAS).

Method:

The dosimetric response of two scenarios, brachytherapy and teletherapy, was analyzed when irradiation occurred in three different materials: liquid water, solid water and perspex. Therefore, the simulations were performed following the same parameters in both codes, maintaining 5x108 simulated particles in a 30 cm side phantom. In the teletherapy scenario, photons and electrons were simulated and in the brachytherapy scenario, a palladium-103 source.

Results:

Through the analysis of the in-depth dose profiles for teletherapy, it was possible to validate the two codes, since both obtained behaviors in agreement with experimental values. Regarding the brachytherapy scenario, the curves obtained similar responses, with a punctual variation of 4 p.p. in relation to the literature. Finally, the simulation systems showed analogous between the curves for the change in the composition material of the phantom, having the largest variation of 4 p.p. and 15 p.p. for teletherapy and brachytherapy, respectively.

Conclusion:

Therefore, the simulation codes studied present themselves as promising tools for performing dosimetry.

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