Monte Carlo Study of Photon Dose Distributions Produced By 12 MV Linear Accelerator

BEAMnrc is a Monte Carlo code for simulation of photon and electron transport in the radiotherapy field. The purpose of this paper was to develop a technique to derive best estimates for the energy and intensity distribution of the incident electron beam by comparing calculated and measured values for the linear accelerator Saturne 43 machine. We varied the initial electron energy and full width half maximum of the radius of the electron beam incident on the tungsten target to find the percentage depth dose, dose profile curves, the tissue-phantom ratio TPR 20/10, the energy fluence distribution and angular distribution for a square field size 10 × 10 cm 2. It is found that our results were quantitatively in good agreement with experimental PDD and lateral profiles at 10 cm depth. The TPR 20/10 was agreed well with the literature publisher works. Furthermore, we could reduce the discrepancy between measured and calculated data photon dose distributions to 1.5%/1mm in the gamma index method for the energy 11.8 MeV and full width half maximum equal to 0.07 cm. Monte Carlo simulation of the treatment head of the Saturne 43 machine was successfully done changing the initial properties of electron source in the Monte Carlo BEAMnrc code. That shows the efficacy and accuracy of the technique used in this paper. Keywords: Monte Carlo; Photon dose distribution; BEAMnrc; Tissue-Phantom Ratio