Megavoltage photon FLASH for preclinical experiments

Area of Science:

• Medical Physics
• Radiation Oncology
• Preclinical Research

Background:

• FLASH radiotherapy offers potential for greater therapeutic efficacy and targeting deep-seated tumors.
• Megavoltage (MV) photon beams are being explored for their application in FLASH techniques.
• Understanding FLASH mechanisms requires advanced preclinical irradiation capabilities.

Purpose of the Study:

• To demonstrate the facilitation of ultra-high dose rates (FLASH) using MV photons.
• To establish a setup for delivering FLASH with MV photons in preclinical experiments.
• To achieve FLASH irradiation over a field size of 12-15 mm using a preclinical electron linear accelerator.

Main Methods:

• Utilized a 6 MeV preclinical electron linear accelerator with a tungsten target and beam hardening filter.
• Optimized beam tuning and reduced source-to-surface distance (SSD).
• Measured dose rates, depth dose curves, and beam profiles using Gafchromic film and an ionization chamber.

Main Results:

• Achieved photon FLASH dose rates exceeding 40 Gy/s over 12-15 mm fields.
• Minimized electron contamination with a 0.55 mm tungsten target and 6 mm copper filter.
• Demonstrated comparable beam flatness and symmetry in both horizontal and vertical planes.

Conclusions:

• Successfully achieved ultra-high average dose rate MV photon beams for preclinical irradiation.
• The developed setup enables future preclinical FLASH radiation experiments.
• This advancement contributes to the investigation of FLASH radiotherapy mechanisms and applications.