Towards faster plan adaptation for proton arc therapy using initial treatment plan information.

Area of Science:

• Medical Physics
• Radiation Oncology
• Image-Guided Therapy

Background:

• Proton arc therapy (PAT) is an advanced radiation technique using continuously rotating proton beams.
• Current PAT planning is time-intensive, hindering timely online adaptation for patients.

Purpose of the Study:

• To develop and evaluate an accelerated workflow for adapting PAT plans.
• To reduce the time required for online plan adaptation in proton arc therapy.

Main Methods:

• A novel workflow transfers treatment spots from initial CT scans to daily CT scans.
• Energy layers are updated, and selected spots are re-optimized based on initial weights and objective function impact.
• A retrospective study compared the proposed 'smart-adapted' workflow against a de novo 'reference' plan on five head and neck cancer patients.

Main Results:

• Smart-adapted PAT plans demonstrated comparable mean dose to organs at risk versus reference plans.
• The smart-adaptation method reduced average planning time by 3.4-fold (from 19184s to 5626s).
• All smart-adapted plans met clinical objectives for target coverage in nominal and worst-case scenarios.

Conclusions:

• The proposed smart-adaptation workflow significantly reduces PAT plan generation time.
• This accelerated method achieves similar plan quality to traditional de novo planning.
• The workflow is suitable for online adaptation, improving efficiency in proton arc therapy.