Calculating photon beam characteristics with Monte Carlo techniques

摘要: This study describes the results from a simulation of 10 MV photon beam medical linac using BEAM code. To check quality generated beam, characteristics this (depth dose curve, cross profiles, and output factors) have been calculated compared to measured data. By splitting up radiation head in two parts, target section collimator calculation times were long, but acceptable when aiming at phase space files containing some 5 million particles. Given number particles evaluated, accuracy all data was around 2%. Analysis for different field size supports previous studies about contaminant sources scattered beams linacs. The total scatter factor Scp as well Sc within 2% measurements. Also, ratio between reference point full situation no-scatter has correctly. All depth curves profiles also correctly, although with only moderate statistics. Improvements are possible by increasing simulations (up 50 largest size) least 4-8 times, will increase same factor. Nevertheless, method proved itself reliable. Still, should be improved 1% or better. is necessary we plan use Monte Carlo benchmark three-dimensional radiotherapy planning systems. subsequently each simulation, achieved. easy way files, which already recycled ten reused (this study) 40 more not work, it introduces artifacts, especially profiles.