Estudio por simulación del comportamiento de la dosis absorbida en la interfaz entre dos medios irradiados con haces de electrones externos con energía en el rango de 500 keV a 20 MeV

Abstract

The work studies by MC simulation the absorbed dose around the interface between two media of different Z irradiated by monoenergetic beams of electrons of 0.5 to 20 MeV that impact perpendicularly on two contiguous plates composed of WT, Al, Cu and Pb. The first plate has depth R50 and R100; and the second plate a semi-infinite depth. The interface was fixed in the XY plane crossing the origin, electronic creep and absorbed dose detectors were stacked around it. Backscattering of electrons at the interface causes a dose increase in the low Z region and a decrease in the high Z region, relative to the homogeneous case. These dose changes are increased when the difference between the Zs of the media is greater and are not significantly altered by varying beam energy. In a medium similar to human muscle tissue WT, variations of 10% in WT-Al, 22% in WT-Cu and 45% in WT-Pb are obtained; values to consider when planning radiotherapy in patients with permanent metal implants. Backscattered and incident fluence were fitted with exponential curves; achieving correlations greater than 0.9.