Monte Carlo simulation of photon transport in different materials

X-rays in the energy range of 4 to 20 MeV produced in linear accelerators used in medical applications are the most common photon beams used in the diverse radiation treatments of cancer. A number of groups have been applied Monte Carlo simulation programs for simulating the radiation therapy planning. In this work the Monte Carlo N-Particle eXtended (MCNPX) code has been employed to simulate the photon fluence from the 10 MeV X-rays beam produce in a VARIAN linear accelerator. The photon beam was simulated inside a sphere considering as if it was produced by a point source. The point source was placed at 1m from three concentric spheres simulating the patient head constituted by three layers of different tissues: adipose tissue, bone tissue and brain. The results for the photon fluence in different media showed how the variation in elemental composition among the tissues produces variations in the photon fluence. (author)