Comparison of a Multi-Scenario Robustness Evaluation Method with Measurements for Proton Teletherapy.

Area of Science:

• Medical Physics
• Radiation Oncology
• Dosimetry

Background:

• Proton teletherapy plan robustness is crucial for effective cancer treatment.
• Multi-scenario calculational methods are used to evaluate robustness, but their accuracy requires validation.
• Few studies have assessed the accuracy of these predictive calculational methods.

Purpose of the Study:

• To evaluate the accuracy of a multi-scenario calculational method for proton teletherapy.
• To compare computational predictions with physical measurements in phantoms simulating uncertainties.
• To assess the robustness of treatment plans under various uncertainty scenarios.

Main Methods:

• Proton therapy plans were created using four phantoms sensitive to positional and penetration uncertainties.
• Nine uncertainty scenarios were simulated computationally, and calculations were compared to physical measurements.
• Dose distributions were measured using films in phantoms with induced alignment displacements.

Main Results:

• The nine-scenario method's calculated dose envelope contained most phantom measurements.
• Under uncertainty, minimum dose decreased >20 Gy and V95% coverage fluctuated >10%.
• Maximum dose parameter changed <5 Gy; some dose profile mismatches occurred for specific phantoms.

Conclusions:

• The nine-scenario method adequately evaluates the robustness of simple mono-directional proton teletherapy plans.
• The study confirms the utility of multi-scenario calculations for predicting plan performance under uncertainty.
• Further refinement may be needed for complex phantom geometries or dose profiles.