Streamlined Pin-Ridge-Filter Design for Single-energy Proton FLASH Planning.

Area of Science:

• Medical Physics
• Radiation Oncology

Background:

• Proton FLASH radiotherapy offers potential for improved tumor control and reduced normal tissue toxicity.
• Implementing single-energy proton therapy requires efficient dose delivery techniques.

Approach:

• Developed an inverse planning framework for single-energy proton FLASH planning using a streamlined pin-shaped ridge filter (pin-RF).
• Integrated a spot reduction process to optimize pencil beam directions and energy layers.
• Translated the optimized plan into pin-RFs and validated on three lung cancer cases.

Key Points:

• The pin-RF plans closely matched the reference intensity-modulated proton therapy plans in dose conformity.
• Significant reductions (up to 33%) in maximum dose to organs at risk were observed in high-dose regions.
• Benefits in moderate-to-low dose regions were marginal, with some increases in lung dose metrics.

Conclusions:

• A streamlined pin-RF design is feasible for single-energy proton FLASH planning.
• This approach demonstrates clinical benefits for organs at risk in high-dose areas.
• The simplified pin-RF design suggests potential for cost-effective and efficient production.