VMATc: VMAT with constant gantry speed and dose rate

Area of Science:

• Medical Physics
• Radiation Oncology
• Computational Biology

Background:

• Volumetric Modulated Arc Therapy (VMAT) is an advanced radiotherapy technique.
• Optimizing VMAT plans, especially with constant parameters (VMATc), presents computational challenges.
• Current VMAT optimization involves complex trade-offs between plan quality and delivery efficiency.

Purpose of the Study:

• To develop and evaluate a heuristic framework for optimizing VMAT with constant gantry speed and dose rate (VMATc).
• To simultaneously optimize multi-leaf collimator positions, gantry speed, and dose rate for VMATc.
• To compare the quality of VMATc plans against Intensity-Modulated Radiation Therapy (IMRT) and full VMAT.

Main Methods:

• A heuristic framework based on hierarchical decomposition was proposed.
• An iterative algorithm was employed to optimize dose rate and gantry speed.
• Leaf position optimization subproblems were solved heuristically at each iteration.
• The framework was applied to clinical patient cases.

Main Results:

• VMATc plans demonstrated comparable quality to full VMAT plans.
• The proposed heuristic framework provided high-quality VMATc plans.
• VMATc plans generally required higher total monitor units compared to VMAT.
• Achieving VMATc plans incurred longer computation times.

Conclusions:

• VMATc is a viable radiotherapy technique capable of producing high-quality treatment plans.
• The developed heuristic approach effectively optimizes VMATc parameters.
• Trade-offs exist, including increased computation time and monitor units for VMATc plans.