Robustly optimized hybrid intensity-modulated proton therapy for craniospinal irradiation

Area of Science:

• Radiation Oncology
• Medical Physics
• Cancer Treatment

Background:

• Intensity-modulated proton therapy (IMPT) offers precise dose delivery for complex treatments like craniospinal irradiation (CSI).
• Robust optimization is crucial in IMPT to account for uncertainties in patient setup and proton range.
• Developing efficient and reliable planning strategies for CSI is essential for minimizing toxicity and maximizing treatment efficacy.

Purpose of the Study:

• To investigate a novel hybrid robust optimization planning approach for IMPT in adult craniospinal irradiation (CSI).
• To evaluate the robustness of the proposed technique against setup and range uncertainties.
• To assess the dosimetric outcomes, including target coverage and organ at risk (OAR) sparing.

Main Methods:

• Five adult CSI IMPT plans were created using the Raystation treatment planning system.
• A hybrid strategy combined robust optimization for clinical target volume (CTV) with minimax optimization for planning target volume (PTV).
• Dosimetric outcomes were analyzed under nominal conditions and 16 error scenarios (±3 mm setup, ±3.5% range).

Main Results:

• The hybrid approach achieved homogeneous dose distribution in the target volume, including junction regions.
• Excellent coverage of the cribriform plate and reduced lens doses were observed.
• Target and OAR doses met predefined clinical goals even in worst-case error scenarios.

Conclusions:

• The proposed hybrid robust optimization technique is efficient and robust against uncertainties in IMPT for CSI.
• This planning approach can be effectively adopted by other proton therapy centers.
• The technique demonstrates potential for improved outcomes in CSI patients treated with IMPT.