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Updated: Jun 27, 2026
06:21
Diffuse Optical Spectroscopy for the Quantitative Assessment of Acute Ionizing Radiation Induced Skin Toxicity Using a Mouse Model
Published on: May 27, 2016
Ultra-High Dose-Rate Oxygen Depletion and Skin Response to Irradiation
Qianyi Huang1, Leo Gerweck1, Peigen Huang2
1Physics Division, Department of Radiation Oncology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
Cancers
|June 26, 2026
Summary
Transient oxygen depletion explains the skin sparing effect of ultra-high dose-rate (FLASH) irradiation. Reducing oxygen eliminates the FLASH sparing effect, indicating oxygen
Area of Science:
- Radiation oncology
- Radiobiology
- Medical physics
Background:
- Ultra-high dose-rate irradiation, known as FLASH irradiation, exhibits a skin sparing effect.
- The underlying mechanism of this effect is hypothesized to be transient oxygen depletion.
- Understanding this mechanism is crucial for optimizing radiation therapy techniques.
Purpose of the Study:
- To investigate the role of transient oxygen depletion in the skin sparing effect of FLASH irradiation.
- To determine the impact of varying oxygen concentrations on FLASH and conventional dose-rate (CDR) irradiation effects on skin.
- To assess the relationship between tissue oxygen levels and FLASH radiobiological effects.
Main Methods:
- FVB/N mice underwent irradiation with 27 Gy protons at either FLASH (~120 Gy/s) or CDR (0.5 Gy/s) dose rates.
- Mice were exposed to varying oxygen concentrations (5%, 7%, 20.9%, 100%) prior to and during irradiation.
- Skin contraction, epidermal thickening, and fibrosis were assessed, alongside non-invasive measurement of skin oxygenation using phosphorescence quenching.
Main Results:
- FLASH irradiation significantly reduced skin contraction, epidermal thickening, and fibrosis compared to CDR in air-breathing mice.
- The FLASH sparing effect diminished with decreasing oxygen levels, becoming negligible under 5% oxygen.
- CDR irradiation showed increased skin contraction with 100% oxygen and decreased contraction with 7% or 5% oxygen.
Conclusions:
- Transient oxygen depletion is a key factor in the skin sparing effect of FLASH irradiation.
- The absence of oxygen eliminates the FLASH sparing effect on late normal tissue effects like skin contraction.
- Mean tissue oxygen partial pressure (pO2) alone may not fully capture the cellular susceptibility to FLASH-induced radiobiological hypoxia.
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