Simulación de haces de fotones convergentes, una nueva técnica de radioterapia

Abstract

Se realiza una simulación por métodos Monte Carlo para generar una convergencia de fotones que puedan ser aplicables en un acelerador lineal de uso clínico. Los resultados muestran que la dosis depositada en un maniquí de agua dependen directamente del radio de apertura de los fotones, lo cual a nivel clínico implica una menor dosis absorbida en tejidos sanos y un máximo de dosis absorbida sobre tejido tumoral.

Abstract: In this work, a simulation is performed, using Monte Carlo methods to generate a convergence of photons that can be applied in a linear accelerator for clinical use. For this purpose, an electron beam with an energy spectrum, similar to that of energy spectrum of electrons for a real accelerator, is simulated. Therefore , the electron beam can be scattered by magnetic lenses, the opening made on the electron beam in these magnetic lenses will depend on the distribution of doses deposited by the photons in a water phantom. Once the electrons are dispersed they impinge on a second set of magnetic lenses whose function will be to focus the electron beam at a distance of 100 cm from the Tungsten-Copper target, the above with the objective of simulate an isocenter similar to that of a real accelerator. Finally, the beam of electrons, already convergent, hits a Tungsten-Copper target to produce photons from braking radiation. The photons produced tend to continue with the path of the incident electrons in the target, although another number of photons will be scattered in different directions. The results of the simulation show that the dose deposited in a water phantom depends directly on the opening radius of the electrons coming out of the first magnetic lens, where the electron beam opening will give an absorbed dose distribution similar to that of a Lorentzian distribution, which at a clinical level implies a lower dose drop in healthy tissues and a maximum net dose on tumor tissue.