A Monte Carlo Study of the Photon Spectrum due to the Different Materials Used in the Construction of Flattening Filters of LINAC

Abstract

Different types the spectrum of photons were studied; they were emitted from the flattening filter of a LINAC Varian 2100 C/D that operates at 15 MV. The simplified geometry of the LINAC head was calculated using the MCNPX code based on the studies of the materials of the flattening filter, namely, SST, W, Pb, Fe, Ta, Al, and Cu. These materials were replaced in the flattening filter to calculate the photon spectra at the output of this device to obtain the spectrum that makes an impact with the patient. The different spectra obtained were analyzed and compared to the emission from the original spectra configuration of the LINAC, which uses material W. In the study, different combinations of materials were considered in order to establish differences between the use of different materials and the original material, with the objective of establishing advantages and disadvantages from a clinical standpoint.

Se estudiaron diferentes tipos del espectro de fotones; fueron emitidos por el filtro aplanador de un LINAC Varian 2100 C/D que opera a 15 MV. La geometría simplificada del cabezal LINAC se calculó utilizando el código MCNPX basado en los estudios de los materiales del filtro de aplanamiento, a saber, SST, W, Pb, Fe, Ta, Al y Cu. Estos materiales fueron reemplazados en el filtro aplanador para calcular los espectros de fotones a la salida de este dispositivo para obtener el espectro que impacta al paciente. Los diferentes espectros obtenidos se analizaron y compararon con la emisión de la configuración de espectros original del LINAC, que utiliza material W. En el estudio se consideraron diferentes combinaciones de materiales para establecer diferencias entre el uso de diferentes materiales y el material original. , con el objetivo de establecer ventajas y desventajas desde el punto de vista clínico.