Epp (Easy particle propagation) is a user code for the EGSnrc code system to run Monte Carlo simulations of particles propagating through an arbitrary geometry. The photons leaving the simulation geometry can be propagated to a virtual detector, and separate images for primary and scattered photons can be generated allowing a detailed analysis of the amount and distribution of x-ray scattering. The deposited dose in a voxelized phantom can also be recorded, similar to DOSXYZnrc.

For more information about Epp, see the following paper:

Jonas Lippuner, Idris A. Elbakri, Congwu Cui and Harry R. Ingleby (2011), Epp: A C++ EGSnrc user code for x-ray imaging and scattering simulations, Med. Phys. 38, 1705; doi:10.1118/1.3555296

Download & Installation

The source code along with a user manual and some sample input files can be downloaded below. Currently Epp only supports Linux. Detailed installation instructions can be found in the user manual and the file INSTALL.

Note that EGSnrc 2.3.1 must be installed and fully configured before Epp can be installed. EGSnrc can be downloaded free of charge here.

Source code, user manual and example input files: Epp_1.4.3.tar.gz (GZ, 247 kB)
Only the user manual for Epp: Epp_User_Manual_1.4.3.pdf (PDF, 208 kB)


If you encounter the following error while compiling Epp:

/usr/bin/ld: Epp_x86_64-unknown-linux-gnu.o: undefined reference to symbol ‘_ZNSs4_Rep10_M_destroyERKSaIcE@@GLIBCXX_3.4’
//usr/lib/x86_64-linux-gnu/libstdc++.so.6: error adding symbols: DSO missing from command line
collect2: error: ld returned 1 exit status
Makefile:122: recipe for target ‘/home/jlippuner/egsnrc_mp/bin/x86_64-unknown-linux-gnu/Epp’ failed

Change $(F77) to $(CXX) on line 122 in Makefile and run make again.


Epp is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version.

Epp is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.