Intensity Modulated Proton Therapy PROTOTYPE DEMO [21-NOV-2011] Disclaimer: This is a work-in-progress and contains proprietary information owned by Philips.
This is a complex-shaped tumor wrapping around the spinal cord.
3 proton spot scanning beams will be used for this demo.
A target ROI is chosen for each beam where the spots will be placed.
Range shifters are needed for targets close to the patient surface in order to ensure efficient coverage.
The snout's size and placement can be edited as required.
CT-to-Stopping Power, Spot spacing, Spot placement margin, etc can be set in the details window.
The next two beams are created at 45 and 315 degrees.
A 3 mm dose grid is used for this demo.
All beams are initialized with equal weights.
One can choose from 3 dose engines. The fastest one is used here.
The other 2 dose engines are 3 to 4 times slower but more accurate.
Dose computation took about 45 seconds for ~ 2600 spots using 8 threads in a SmartEnterprise environment.
All spots are initialized with the same weight.
Objectives have been specified on the CTV and Spinal Cord for this demo.
Optimization parameters can be set in the IMRT parameters window.
Optimization is in progress.
Notice how the dose is shaped to avoid the spinal cord.
But with increased precision comes increased risk.
The uncertainty analysis tool can be used to study this risk.
A range uncertainty of 3 mm is studied in this demo.
Trials are being generated for an overshoot and an undershoot scenario.
One can study the scenarios for potential plan degradation.
In the overshoot scenario, the spinal cord is heavily overdosed.
In the undershoot scenario, the CTV is underdosed.
For the same objectives, a robust optimization will now be performed.
Robust objectives are enabled in the IMRT Parameters window.
Beam weights and spot weights are again reset.
Robust optimization is in progress.
The thick DVH corresponds to the plan being optimized and the other two belong to the two scenarios.
The scenario DVHs will be updated once the optimization is done.
After robust optimization, the two scenarios look similar to the original plan.
Notice how the dose coverage shifts while still sparing the spinal cord.
Thank you for watching this demonstration.