The TOPAS development team is offering the free online course

“Monte Carlo simulation in medicine with TOPAS,” November 8-10, 2021.


Registration is now CLOSED as we have exceeded our capacity of 50 students.

Format/Educational methods: A 15-hour online course with lectures and practical examples divided evenly over three days (5 hours a day, with a 15-minute break). The students will use the TOPAS system hands-on to simulate the examples shown by the instructors and observe the effect of changing parameters used in the different simulations.


Target audience: Medical physicists with basic knowledge of Monte Carlo simulations. The course is designed for new as well as experienced TOPAS users.


Requirement: Before you attend the 3-day course, you are expected to have already completed the separate 2-hour online course, "Introduction to TOPAS,"

You are also expected to have already installed Topas version 3.7 or newer (which you can only do after you have completed the "Introduction to TOPAS"). Register for "Introduction to TOPAS" at

The above link is NOT to sign up for this 3 day course. Registration for the 3 Day course has reached capacity and that course is now closed.


Course objectives: To provide the background necessary for participants to reliably use the TOPAS Tool for Particle Simulation for Monte Carlo simulation in medicine. Participants will learn the fundamentals of the Monte Carlo method and its application in medicine, with focus on external beam radiotherapy. They will then learn through lectures and examples how TOPAS provides a simple, effective means to access the Geant4 Monte Carlo toolkit. Participants will leave the course with practical knowledge on how to use TOPAS for their own application.


Registration fee: There is no registration fee for this on-line course.


Registration period: October 1, 2021 at 9 am Pacific Time, closing when we reach 50 participants on a first come, first served basis. This course has reached capacity and registration has been closed.


Activity location: The course will be given online. The instructors and their institutions are listed below.


Zoom: Zoom login information and password will be distributed to registered participants by November 6, 2021, prior to the start of the course.


Sources of support: This course is partially supported by NIH grant U24CA215123.


Contact: Harald Paganetti,


            • Bruce Faddegon, TOPAS U24 PI, UCSF (Bruce)
            • Harald Paganetti, Director of Physics Research, MGH (Harald)
            • Joseph Perl, TOPAS Chief architect, SLAC (Joseph)
            • Jan Schuemann, Ph.D., Head of Multi-Scale Monte Carlo lab, MGH (Jan)
            • Jose Ramos Mendez, Ph.D., TOPAS Developer, UCSF (Jose)

            • Jhonatan Carrasco Hernandez, Ph.D., TOPAS Developer, UCSF (Jhonatan)
            • Alejandro Bertolet, Ph.D., TOPAS Developer, MGH (Alejandro)
            • Aimee McNamara, Ph.D., TOPAS Developer, MGH (Aimee)

Course outline:
Times given in Pacific Time
Each lecture includes time for questions.
Participants will participate in one of three breakout sessions for each of the examples 1-3 and 4-6 the following day, giving time to try out the examples before the breakout sessions.

Day 1 (Monday, November 8, 2021) Jan Schuemann, chair
Introduction to Monte Carlo and TOPAS simulation of x-ray and electron therapy
9:00 am     Overview: MC simulation in medicine with TOPAS (Joseph)
9:15 am     Lecture 1 - Review of fundamentals of the Monte Carlo method (Jose)
10:00 am   Lecture 2 - Monte Carlo in x-ray and electron therapy (Bruce)
11:00 am   Example 1 - Linac treatment head simulation (Jhonatan)
12:00 pm   Break
12:15 pm   Example 2 - Variance reduction for a generic x-ray linac (Jose)
1:15 pm     Example 3 - Importing patient CT in DICOM format (Alejandro)
2:15 pm     Adjourn - Participants work on problems from example sessions

Day 2 (Tuesday, November 9, 2021) Aimee McNamara, chair
TOPAS simulation of proton therapy
9:00 am     Breakout sessions: Examples 1-3 (Jhonatan, Jose, Alejandro, Aimee)
10:00 am   Lecture 3 - Monte Carlo in proton therapy (Harald)
10:45 am   Lecture 4 - TOPAS advanced capabilities, Part I (Joseph)
11:15 am   Example 4 - Using Time Features to rotate a range modulator (Joseph)
12:15 pm   Break
12:30 pm   Example 5 - Extensions (Jose)
1:30 pm     Example 6 - Proton patient dose, LET and RBE calculation using pre-made extensions (Jan)
2:15 pm     Adjourn – Participants work on problems from example sessions

Day 3 (Wednesday, November 10, 2021) José Ramos Méndez, chair
TOPAS advanced capabilities and examples
9:00 am     Breakout session: Examples 4-6 (Joseph, Jose, Jan)
10:00 am   Lecture 5 - Geant4 and TOPAS (Jan)
11:00 am   Lecture 6 - TOPAS advanced capabilities, Part II (Joseph)
11:30 am   Example 7 - Using Time Features to create a scanning beam (Joseph)
12:30 pm   Break
12:45 pm   Example 8 - TOPAS-nBio advanced extension (Aimee)
2:15 pm     Adjourn