Electron vs proton FLASH radiation on murine skin toxicity

Area of Science:

• Radiation Oncology
• Medical Physics
• Preclinical Research

Background:

• Fast, high-dose-rate (FLASH) radiation therapy demonstrates a dose-sparing effect for acute toxicity.
• Previous studies established this effect for proton FLASH, but electron FLASH data for both acute and late effects were lacking.

Purpose of the Study:

• To quantify the dose-response modification of electron FLASH irradiation for acute skin and late fibrotic toxicity in mice.
• To enable a quantitative comparison of acute skin response between electron and proton FLASH.

Main Methods:

• Female C3D2F1 mice underwent horizontal electron irradiation (16 MeV) at conventional (CONV, 0.162 Gy/s) or FLASH (233 Gy/s) dose rates.
• Mice received single doses ranging from 19.4-57.6 Gy, with 8-10 mice per group.
• Acute skin toxicity was assessed daily for 28 days; late fibrotic toxicity was assessed via leg extension up to 52 weeks.

Main Results:

• Electron FLASH demonstrated a significant skin-sparing effect with a dose-modifying factor (DMF) of 1.45-1.54.
• A smaller fibrotic-sparing effect was observed with a DMF of 1.15 for late toxicity.
• Acute skin toxicity development was comparable between CONV and FLASH groups when using DMF-based biological equivalent doses.

Conclusions:

• Electron FLASH provides a considerable skin-sparing effect, comparable to proton FLASH.
• The acute skin toxicity response to electron FLASH is similar to previously reported proton FLASH data.
• FLASH irradiation shows potential for reducing radiation-induced toxicities in preclinical models.