3D range modulators for fast, conformal carbon ion therapy: anthropomorphic phantom validation and robustness...

Area of Science:

• Medical Physics
• Radiation Oncology
• Biomedical Engineering

Background:

• Synchrotron-based ion beam therapy requires energy layer switching, causing treatment delays.
• Fast and precise ion beam delivery is crucial for clinical efficiency and motion management.

Purpose of the Study:

• Develop a rapid Monte Carlo (MC)-based workflow for patient-specific 3D range modulators (3D-RMs).
• Enable monoenergetic, conformal carbon irradiation at clinically viable speeds, eliminating energy layer switching times.
• Assess the dosimetric impact of setup and RM geometry deviations.

Main Methods:

• Extracted spots from intensity modulated particle therapy (IMPT) plans.
• Optimized RM geometry, performed fast MC dose verification (MonteRay), and 3D printed geometries.
• Validated SOBPs in water and targets in an anthropomorphic head phantom, assessing robustness to errors.

Main Results:

• RM geometry optimization took under one minute.
• RM-based plans achieved dose distributions comparable to IMPT.
• Depth dose profiles agreed within 1.2% local deviation; gamma pass rates >99% in phantom studies.
• Plans were robust to setup deviations up to 1 mm and manufacturing deviations up to 100 µm.

Conclusions:

• The rapid workflow enables clinically feasible conformal, monoenergetic carbon ion delivery with high dosimetric quality.
• Reduced treatment time facilitates motion mitigation and increases patient throughput.
• Provides a basis for exploring FLASH regimes in synchrotron-based ion beam facilities.