Estudo das distribuições de dose em meios não homogêneos usando feixes clínicos de elétrons através do método de Monte Carlo

Abstract

This work studies the electron beam dose distribution for clinical use applying Monte Carlo method, especifically, the PENELOPE code. The Monte Carlo method is found in different areas of the exact sciences, being a common resource in the area of medical physics. This method is essentially simple in its approach, reaching a solution to a macroscopic system through simulation of its microscopic interactions, representing an attempt to model nature through direct simulation of the essential dynamics of the system in question. The first objective of the work is to validate the simulations through the comparison with measured distribution of dose along the central axis (PDD). The first objective of this work is to validate the simulations through the comparison with experimental curves of clinical electron beam (PDD curves). The measurements are done as part of the commissioning of the TPS Eclipse eMC algorithm. A first approximation is considered the electron beam as monoenergetic, and then, building its spectra that best reproduce the data measured from relevant parameters that characterize the PDD curves. The spectra are modeled in such a way that they reproduce with good agreement the experimental PDD curves, having been used as criterion that the beam quality and the range of the electron beam are within 1mm difference between the measured and the simulated data. The next objective of this work is to use the optimized spectra in the simulations of two cases where the target is non-homogeneous. The study continues with the plots of the characteristic dose distributions curves as the isodose, PDD and profile. The simulated heterogeneities presented results of overdosage and underdosage that have to be taken into account when administering the dose to the patient