Radiation dose distribution around a mobile linear accelerator Mobetron using Monte Carlo simulation

The aim of this work is to analyze the scattered radiation produced by the mobile accelerator Mobetron. To do so detailed Monte Carlo simulation using two different codes, Penelope2011 and Geant4, were performed. Experimental measurements were also done to validate them. To quantify the attenuation of the internal structures present in the accelerator head on the scattered radiation produced, some of the main structural shielding in the Mobetron has been incorporated into the simulation. Results are compared with experimental measurements. Some discrepancies between the calculated and measured dose values were found. These differences can be traced back to the importance of the radiation component due to low energy scattered electrons. This encourages us to perform additional simulations to separate the role played by this component. Dose due to the neutron radiation produced with the 12 MeV energy has been measured. The values obtained agrees well with the experimental values existing in the literature, being much smaller than those registered in conventional accelerators. This theoretical study is a useful tool for the clinical user to investigate the radiation protection issues arising with the use of these accelerators in operating rooms without structural shielding. In doing so they will be able to assess the suitability of facilities for carrying out these techniques before the acquisition of the accelerator.