Application of the monte carlo method to shielding analysis in medical linear accelerators

Abstract

In radiotherapy installations using accelerators it is very important to produce an accurate estimation of the shielding requirements to keep doses lower than established limits. Shielding thickness is directly proportional to the tenth-value thickness, which depends on the shielding material and the energy of the incident radiation. The tenth-value thickness can be obtained from curves recommended by the DIN-6847 standard and also estimated in terms of dose rates calculated for two different values of shielding thickness. MCNP code based on the Monte Carlo method is applied to perform this estimation. Authors presented in former papers the methodology and model developed using previous versions of the MCNP code. In this paper, the latest version -MCNP 4B- of the code is used for the simulation. Two different models for dose estimation have been considered, including recent data for dose conversion factors. Results are discussed taking into account older simulation data and finally they are also compared with the values recommended by the DIN-6847 standard. © 2014 Atomic Energy Society of Japan. All rights reserved.