TOPAS Tool for Particle Simulation

Welcome to TOPAS MC Inc., a non-profit organization to support and extend the TOPAS Tool for Particle Simulation.

29 April 2024: Open Call for New Funding Ideas

Support for the TOPAS project is in crisis. Unless we can identify new funding sources over the next few months, all of the user support services operated by the TOPAS non-profit will be frozen or shut down - including the web site, the new user lectures, the code repository and the user forum. Our code is open source, available from our downloads page, so our users will never lose access to the source code. But we need funding to continue providing all the other services that have made TOPAS such a success. Please see details in the attached Call for New Funding Ideas.

TOPAS wraps and extends the Geant4 Simulation Toolkit to make advanced Monte Carlo simulation of all forms of radiotherapy easier to use for medical physicists. TOPAS can model x-ray and particle therapy treatment heads, model a patient geometry based on CT images, score dose, fluence, etc., save and replay a phase space, provides advanced graphics, and is fully four-dimensional (4D) to handle variations in beam delivery and patient geometry during treatment. TOPAS users configure pre-built components (such as nozzles, patient geometry, dosimetry and imaging components) to simulate a wide variety of radiation therapies with no required knowledge of the underlying Geant4 Simulation Toolkit or any programming language. All aspects of the simulation, including all 4D behaviors, are controlled from a unique, TOPAS Parameter Control System. TOPAS was engineered from the ground up to be flexible, yet easy to use, reliable and repeatable. The code includes a strong focus on “engineering-in” safety, employing a variety of techniques to make it harder for users to make mistakes. Two very brief introduction to TOPAS videos can be found here and here.

TOPAS is further described in the open-access manuscript: Perl J, Shin J, Schumann J, Faddegon B, Paganetti H. TOPAS: an innovative proton Monte Carlo platform for research and clinical applications. Med Phys. 2012 Nov; 39(11):6818-37. (View in: PubMed). This manuscript has has been cited 996 times in Google Scholar – proof that TOPAS enables extensive and varied cancer solutions.

TOPAS basic concepts were originally created out of an NIH-funded collaboration of the SLAC National Accelerator Laboratory, Massachusetts General Hospital and the University of California at San Francisco. TOPAS MC Inc. serves as a central resource for TOPAS users. At last count, our TOPAS User and Development Community included 2773 users at 674 institutions in 70 countries.

TOPAS is applied in all areas of radiation therapy research and is also actively used in medical imaging research, radiation biology, materials science and education. Other potential applications include studies of radiation damage to electronics, particle physics, nuclear physics and astrophysics.

Our mission is to make TOPAS into a tool that fits comfortably into the hands of every scientist and engineer.

TOPAS MC Inc. is a nonprofit public benefit corporation and is recognized by the IRS as a tax exempt public charity under section 501(c)(3).