# Oxygen enhancement ratio

Source: https://onco.cc/terms/oxygen-enhancement-ratio/  
OnCo record `oxygen-enhancement-ratio` (Term). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

How many times more radiation a cell without oxygen needs to be killed compared with the same cell with oxygen: about 2.5 to 3 for X-rays, close to 1 for the heaviest particle beams.

## Summary

Oxygen reacts with the free radicals radiation creates in DNA and makes the damage permanent, so oxygenated cells die at lower doses. The oxygen enhancement ratio is near 3 for photons and protons and falls toward 1 for high-LET radiation such as carbon ions and neutrons, which is one argument for particle therapy in hypoxic tumours and for boron neutron capture therapy.

## Fields

- Kind: Term
- Last checked: 2026-09-16
- Tags: radiation-wave1

## Sources

- Wikipedia: https://en.wikipedia.org/wiki/Oxygen_enhancement_ratio
- Wikipedia: https://en.wikipedia.org/wiki/Oxygen_enhancement_ratio

## Connected records

- technologies: [Boron neutron capture therapy](https://onco.cc/technologies/bnct/), [Carbon-ion therapy](https://onco.cc/technologies/carbon-ion/), [Tumour hypoxia: imaging and modification](https://onco.cc/technologies/tumour-hypoxia-modification/)

---
JSON: https://onco.cc/api/v1/entities/oxygen-enhancement-ratio.json