EGSnrc: software tool to model radiation transport

Overview of the software

NRC’s electron gamma shower (EGS) software toolkit can meet your specific requirements relating to modelling the passage of electrons and photons through matter. EGSnrc relies on Monte Carlo, which is the most accurate method to model the transport of radiation. The included BEAMnrc software component can meet your requirements relating to modelling beams travelling through consecutive material components, ranging from a simple slab to the full treatment head of a radiotherapy linear particle accelerator (linac).

EGSnrc is used to address a broad range of questions about the propagation of radiation in materials. It is particularly well-suited for medical physics purposes, such as the research and development of devices that allow medical professionals to detect radiation, image a patient’s anatomy using x-rays, or deliver a prescribed radiation dose to a tumour while sparing healthy tissue. But given its flexible, modular design and companion utilities, EGSnrc can also be used for a vast range of applications, including the simulation of research and industrial linac beams, x-ray emitters, radiation shielding, and more.

NRC also trains Canadian and international physicists on use of the software.

NRC contributes to the development and application of the Monte Carlo method in the modelling of radiation transport since the early 1980s. The EGSnrc software is now downloaded more than 5,000 times per year by academic, medical and industrial researchers worldwide.

Targeted audience

  • Medical physicists, universities and hospitals.
  • Companies that develop radiotherapy equipment and software.
  • Universities and industries working with radiation, including radiation measurement, radiotherapy, radiation protection, radiation processing, medical imaging, and other electron and photon radiation applications.

Description of the software

EGSnrc is a general-purpose software toolkit that can be applied to build Monte Carlo simulations of coupled electron-photon transport, for particle energies ranging from 1 keV to 10 GeV. The included BEAMnrc component includes the dose scoring utility DOSXYZnrc to estimate radiation dose in a voxel geometry, such as patient medical imaging data. It also includes data processing tools to analyze the beam characteristic in detail and generate radiation dose profiles.

EGSnrc is an extended and improved version of the EGS4 code system developed jointly by NRC and the Stanford Linear Accelerator Center in the 1980s (WR Nelson, H Hirayama, DWO Rogers. The EGS4 code system, Report SLAC-265, 1985). The EGSnrc implementation improves the accuracy and precision of the charged particle transport mechanics and the atomic scattering cross-section data (I Kawrakow. Accurate condensed history Monte Carlo simulation of electron transport. I. EGSnrc, the new EGS4 version. Medical physics 27, 2000). It also comprises a C++ geometry library for defining the geometry of complex simulation environments and particle sources. The BEAMnrc component is an improved version of the original BEAM package developed by NRC and the University of Wisconsin-Madison in the 1990s (DWO Rogers et al. BEAM: A Monte Carlo code to simulate radiotherapy treatment units. Medical physics 22, 1995).

System requirements

EGSnrc works on Linux, OS X and Windows. EGSnrc is a set of source files and utilities to build your own Monte Carlo simulations. As such, it is not a stand-alone software and requires the following:

  • Fortran, C and C++ compilers
  • The GNU make utility
  • The Tcl/Tk interpreter and GUI toolkit
  • Grace (to display results graphically)


EGSnrc is trusted by researchers worldwide for simulation accuracy and speed. It is widely regarded as the most accurate computer program for electron and photon transport simulation. The EGS code has been used extensively by medical physicists over the past four decades, resulting in thousands of publications in scientific journals. Through this rigorous peer-review process it has evolved into a reliable and well-benchmarked software. EGSnrc continues to be referenced in around 30 per cent of all Monte Carlo related publications in the leading journals Medical Physics and Physics in Medicine and Biology. Commercial partners around the world also rely upon EGSnrc for the design of radiation equipment and software.


EGSnrc is distributed as free software under the terms of the GNU Affero General Public Licence. Please review this licence before downloading the software. In practice, this licence imposes no restriction on using EGSnrc. However, if you want to further convey verbatim or modified versions of the code, or any work based on any EGSnrc component (including any such work operated remotely over a network), you must do so under the same licence terms. Please contact us if you wish to licence EGSnrc under different terms.


For technical inquiries

Dr. Frédéric Tessier
Telephone: 613-993-9352 ext. 237

Dr. Ernesto Mainegra-Hing
Telephone: 613-993-9352 ext. 260

For business inquiries


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