A high-throughput focused collimator for OAR-sparing preclinical proton FLASH studies: commissioning and validation

Area of Science:

• Medical Physics
• Radiation Oncology
• Preclinical Research

Background:

• Proton therapy offers conformal dose delivery for deep-seated tumors.
• FLASH radiation therapy (FLASH-RT) shows potential for sparing normal tissues.
• Precise targeting in small animal models is crucial for FLASH-RT radiobiology studies.

Purpose of the Study:

• To fabricate and validate a novel focused collimator for preclinical FLASH-RT.
• To enable hemithoracic irradiation of mice using 250 MeV protons at ultra-high dose rates (UHDRs).
• To spare normal tissues and improve throughput in murine FLASH-RT studies.

Main Methods:

• A brass collimator with six 13 mm apertures was machined to shape 250 MeV UHDR proton beams.
• Film dosimetry characterized collimated field profiles and penumbrae.
• Neutron activation surveys assessed radiation safety for staff.

Main Results:

• The collimator produced radiation fields with 1.2 mm penumbrae, comparable to kV x-rays.
• Similar doses at an average rate of 52 Gy/s were delivered to all six mice concurrently.
• Staff safety was ensured through a parallel workflow, managing neutron activation risks.

Conclusions:

• The novel collimator platform enables high-throughput, cost-effective radiobiological studies of FLASH-RT.
• Sharp penumbrae are achieved, addressing challenges in precise targeting for small animal models.
• This technology is a benchmark for advancing FLASH-RT translation to clinical treatments.