Proton Therapy

Problem Description

This problem illustrates a highly simplified version of proton therapy.

In this example a simplified human skeleton is modeled with a tumor embedded in adipose tissue and covered with skin on the back. A circular proton beam of 70 MeV energy is centered on the tumor. The total ionizing dose on the skin, fat, tumor and torso are all recorded.

For materials, the ICRP models built into RSim are used.

Opening the Simulation

The proton therapy example is accessed from within RSimComposer by the following actions:

• Select the New → From Example… menu item in the File menu.
• In the resulting Examples window expand the RSim for Basic Radiation option.
• Expand the Basic Examples option.
• Select Proton Therapy and press the Choose button.
• In the resulting dialog, create a New Folder if desired, and press the Save button to create a copy of this example.

All of the properties and values that create the simulation are now available in the Setup Window as shown in protontherapysetupwingras. You can expand the tree elements and navigate through the various properties, making any changes you desire. The right pane shows a 3D view of the geometry, if any, as well as the grid, if actively shown.

Setup Window for the proton therapy example.

Simulation Properties

This example demonstrates two physics features, and how CSG and CAD can be incorporated into RSim Simulations.

Under the Basic Settings tab the number of events to be simulated can be selected, as well as the simulation model. Right now the only supported model is gras.

The particle source selected is an elliptic plane. In this case it is a 1D Beam with 3 degrees of dispersion, and a monoenergetic energy distribution.

Running the Simulation

After performing the above actions, continue as follows:

• Proceed to the Run Window by pressing the Run button in the left column of buttons.
• To run the file, click on the Run button in the upper left corner of the Logs and Output Files pane. You will see the output of the run in the right pane. The run has completed when you see the output, “Engine completed successfully.” This is shown in protontherapyrunwingras.

The Run Window at the end of execution.

Visualizing the Results

Visualization is not possible in RSim at this time.

Further Experiments

Try altering the energy of the beam to see an increase in the dose on the “tumor” or increasing the thickness of the fat block to see how it may reduce the ionizing dose.