TG-195 - case 1 - CSR: exercise of intercomparison between two Monte Carlo codes

An exercise of intercomparison between two computational Monte Carlo (MC) codes was carried out. The American Association of Physicists in Medicine (AAPM) "Case 1" - Research Group 195 (TG 195) called ^Monte Carlo Reference Data Sets for Imaging Research was used. The problem presented in "case 1" consists of verifying the accuracy of the X-ray spectrum, basic attenuation of the material to calculate the semi-reducing layer (CSR) and fourth-reducing layer (CQR) parameters. The MC Electron Gamma Shower (EGSnrc) and Monte Carlo N-Particle Transport Code eXtended (MCNPX) codes were used in the modeling and simulation of the ^case1^. Simulations were carried out with two 30 and 100 keV monoenergetic sources and two X-ray spectra using Molybdenum/Molybdenum (Mo/Mo) and Tungsten/Aluminium (W/Al) combination of 30 and 100 kVp tube voltages. The results obtained for both MC codes were compared with the results provided by the TG 195. The relative error of the simulations provided by the MC code was kept below 1% in all simulations. The average percentage variation (Δ%) between the simulation results and those published by the TG 195 report ranged from 1 to 5% for monoenergetic sources and spectra. The exercise of intercomparison between the MC codes EGSnrc and MCNPX showed a good agreement when compared with the values reported in "case 1" of TG 195