Development of Compton lens design for increased dose rate in linear accelerator based SRS

Area of Science:

• Medical Physics
• Radiation Oncology
• Radiosurgery Technology

Background:

• Stereotactic radiosurgery (SRS) requires precise dose delivery, especially for small targets.
• Current collimator designs may limit dose rate efficiency in small field SRS.
• Utilizing scattered photons presents an opportunity to improve SRS dose delivery.

Purpose of the Study:

• To develop a novel SRS collimator design.
• To leverage Compton scattered photons for increased isocenter dose rate.
• To enhance dose delivery for small field SRS treatments.

Main Methods:

• A new collimator design incorporating conical slits was proposed.
• The design featured an interaction plate and Compton slit region.
• Monte Carlo N-Particle (MCNP6) simulations were used for geometric optimization.

Main Results:

• An optimized 6-slit collimator design was developed for a 4 mm target.
• A 3.5% increase in dose rate at the isocenter was achieved.
• Off-axis dose increases were limited to less than 1% between 1-5 cm.

Conclusions:

• The preliminary design demonstrates proof of concept for increased SRS dose rates.
• The design achieves dose rate enhancement while limiting peripheral dose.
• Further optimization and clinical validation are warranted for this SRS collimator.