Optimizing Gantry Breakpoint Angles in Proton Therapy: Enhancing Efficiency and Patient Experience

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• The standard 180° gantry breakpoint in 360° radiotherapy systems is an arbitrary setting.
• This conventional breakpoint may lead to inefficient gantry rotation and prolonged patient setup times.
• Systematic evaluation is needed to determine an optimal breakpoint for full-gantry proton therapy systems.

Purpose of the Study:

• To identify an optimal gantry breakpoint angle for a full-gantry proton therapy system.
• The primary goal is to minimize gantry movement and enhance treatment delivery efficiency.

Main Methods:

• Analysis of 70 months of proton therapy plans (9152 plans, 131,883 fractions).
• Categorization by treatment site and mapping of fields to a full-gantry orientation.
• Computation of minimum total gantry rotation angle as a function of breakpoint position (0°-360°), with and without a 20° overlap allowance.

Main Results:

• A 130° breakpoint was identified as optimal, balancing rotational efficiency and practical considerations.
• This 130° breakpoint reduced average gantry rotation by 41.4° per fraction compared to the 180° breakpoint (with 20° overlap).
• Significant reductions in average gantry rotation were observed for gastrointestinal (192.2°), thoracic (56.3°), and pediatric (44.9°) sites.

Conclusions:

• A 130° gantry breakpoint is superior to the conventional 180° for full-gantry proton therapy.
• This optimization is particularly beneficial for gastrointestinal, pediatric, and thoracic cancer treatments.
• Adjusting the breakpoint can streamline delivery, reduce mechanical wear, and improve treatment precision by minimizing patient movement.