Epp - A C++ Monte Carlo simulation EGSnrc user code for dose calculation and imaging

Epp (Easy particle propagation) is a Monte Carlo simulation EGSnrc user code that we have developed for dose calculation in a voxelized volume, and to generate images for an arbitrary geometry irradiated by a particle source. The dose calculation aspect is a reimplementation of the function of DOSXYZnrc with the performance being significantly improved. The functionality can be readily extended to trace other kinds of particles. Epp is based on the EGSnrc C++ class library (egspp) that offers great simplicity for setting up particle sources and simulation geometries, compared to DOSXYZnrc. Using an XML format for the input file makes the file parsing at least 1,000 times faster than the original input file format of egspp. Compared to DOSXYZnrc, Epp is at least two times faster. Photon (other particles possible with minor extension to the current program) propagation to the image plane is integrated into Epp. When only the resultant images are needed, there is no need to save the particle data. This results in significant savings of data storage space, network load, and time for file I/O. Epp was validated against DOSXYZnrc by comparing their simulation results with the exact same input. Epp can thus be used for faster Monte Carlo simulation for radiation dose applications and imaging applications.