Gamma FLASH – Ultra-High Dose Rate Radiation Therapy Using Co-60: A Proof-Of-Principle Study of An Animal-Oriented FLASH Platform
Y Ma1*, S Wang2, L Zhuang1, (1) Northwestern Medicine Mchenry Hospital, Mchenry, IL (2) Saint Alphonsus Cancer Institute, Boise, ID
Presentations
TU-D1030-IePD-F4-5 (Tuesday, 7/12/2022) 10:30 AM - 11:00 AM [Eastern Time (GMT-4)]
Exhibit Hall | Forum 4
Purpose: By means of theoretical design, we are proposing a Co-60 γ-rays based system that generates a radiation field of ultra-high dose rate (FLASH) in water phantom. This is part I of a two-part report and a flat geometry is presented here.
Methods: The relative dose distribution is determined by Monte Carlo simulation with TOPAS Monte Carlo toolkit. In the simulation, twenty Co-60 rods are arranged within a flat geometry of 10x10x1 cm3 as source module. A box phantom, subdivided into 21x2x21 voxels (each 0.5x0.5x0.5 cm3), was positioned on top of a 2-mm-thick aluminum tray which seats 5 mm over the sources. A standalone baseline calculation was used to validate the results of Monte Carlo simulation. The baseline calculation ignores all scattered photons and takes only primary photons into account with the inverse square law and linear attenuations in phantom and tray explicitly treated. Absolute dose rate is calculated by scaling MC-determined dose distribution per photon with total number photons emitted per second by the sources.
Results: The flat design delivers up to 2000 Gy/s to the maximum dose point on central axis and about 130 Gy/s to the distal point on central axis. Baseline calculation results are in good agreement with the MC results. With a second layer of Co-60 rods used, the dose rate scales up by a factor of 1.6. With a third layer added, the dose rate gets doubled.
Conclusion: We have proved, based on theoretical computations, that Co-60 γ-rays, in a dedicated flat geometry, is able to create a radiation field of ultra-high dose rate, which is suitable for FLASH effect studies for small animal or cell lines.
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