A Monte Carlo Simulation Tool for Physics, Biology and Clinical Research

Welcome to the TOPAS Collaboration official site!

July 23, 2024: OpenTOPAS User meeting at AAPM2024.

For a full list of posters and oral presentations using TOPAS please refer to the AAPM website

What is OpenTOPAS ?

The NIH-funded TOPAS project made radiation therapy simulations using the Monte Carlo method easily accessible for the radiotherapy community. The code has been released previously as open source. This repository brings TOPAS to a new, open release stage, called OpenTOPAS.

OpenTOPAS wraps and extends the Geant4 Simulation Toolkit to provide an easier-to-use application for the medical physicist. OpenTOPAS’s unique parameter control system lets you assemble and control a rich library of simulation objects (geometry components, particle sources, scorers, etc.) with no need to write C++ code and without knowledge of the underlying Geant4 Simulation Toolkit. Please visit our User guide for mode details.

OpenTOPAS basic concepts were originally created out of an NIH-funded collaboration of Massachusetts General Hospital, University of California San Francisco, and SLAC National Accelerator Laboratory for the development of the TOPAS software. The current collaboration between University of California San Francisco and Massachusetts General Hospital continues to support and develop TOPAS under the name of OpenTOPAS since 2024.

OpenTOPAS is designed for simulation of medical applications of ionizing radiation with the Monte Carlo method. The free availability of OpenTOPAS is intended to aid and stimulate research by medical physicists, radiobiologists, and clinicians with emphasis on all modalities of radiotherapy. We recommend new users look at the key publications to explore its potential.

OpenTOPAS is fully open-access. Advanced users remain free to implement their own simulation objects in C++ code, and add them to OpenTOPAS via fork mechanism. While user-written extensions benefit from underlying functionality of OpenTOPAS base classes and the OpenTOPAS parameter system, they can exploit the full flexibility of Geant4.


How to cite?

Please cite these two key references when using Open TOPAS:

Future of the TOPAS Collaboration

The NIH-funded TOPAS team feels a need to address a recent addition to the topasmc website on May 6, 2024. This address can be found here.