Making the EGSnrc/BEAMnrc system more efficient, accurate and realistic in simulating kilovoltage x-ray systems

This project aims to improve the performance of the EGSnrc/BEAMnrc system for kilovoltage medical physics applications, particularly for simulation of x-ray systems. This involves making the simulations more efficient , more accurate and more realistic.;For efficient simulations, a variance reduction technique is newly implemented which improves the efficiency of simulations involving bremsstrahlung targets by up to five orders of magnitude over analog simulations, and by up to a full order of magnitude over the state of the art of the system without the newly added technique. For accurate simulations, a comprehensive and stringent benchmark of the system against experimental measurements of charged particle backscatter shows excellent agreement between EGSnrc results and most of the experimental data. For realistic simulations, the ability to simulate voltage ripple and off-focal radiation are both added to the system. Other new features have also been introduced.