Rapid Switching of a C-Series Linear Accelerator Between Conventional and Ultrahigh-Dose-Rate Research Mode With...

Area of Science:

• Medical Physics
• Radiation Oncology
• Accelerator Physics

Background:

• FLASH radiation therapy requires ultrahigh-dose-rate (UHDR) electron beams.
• Conventional linear accelerators need modification for UHDR beam generation.
• Rapid and reliable switching between beam modes is crucial for clinical translation.

Purpose of the Study:

• To configure a C-series linear accelerator for rapid switching between conventional and UHDR electron beams.
• To establish a stable and reliable UHDR beamline for FLASH radiation therapy.
• To achieve consistent dose delivery for experimental FLASH applications.

Main Methods:

• Modified a C-series linear accelerator for dual-mode operation (conventional and UHDR).
• Implemented a system for rapid (within 2 minutes) switching between electron beam modes.
• Utilized a pulse counting system and custom dosimetry for precise beam control and measurement.
• Retracted the X-ray target for UHDR electron beam production.

Main Results:

• Achieved a stable UHDR electron beam with average dose rates of 432 Gy/s at the isocenter.
• Successfully limited pulse overshoots and eliminated ramp-up time.
• Demonstrated reliable conversion with no machine downtime over one year.
• Measured beam profiles using Gafchromic film and pulse-by-pulse dosimetry.

Conclusions:

• Stable 10 MeV UHDR electron beams were successfully generated for FLASH radiation therapy.
• The developed system allows for consistent dose delivery with a reliable pulse-counting system.
• The configuration supports various experimental parameters, facilitating future clinical translation of FLASH therapy.