Oxygen enhancement ratio

src: slideplayer.com

The Oxygen Enhancement Ratio (OER) or the effect of increased oxygen in radiobiology refers to the increased therapeutic or adverse effects of ionizing radiation due to the presence of oxygen. This is called the most important oxygen effect when cells are exposed to ionizing radiation doses.

OER is traditionally defined as the ratio of radiation doses during oxygen deprivation compared with no lack of oxygen for the same biological effect. It may provide numerical values ​​that vary depending on the biological effect chosen. In addition, OER can be presented in terms of hyperoxic environment and/or with an altered oxygen baseline, complicating the significance of this value.

${\ displaystyle OER = {\ frac {Radiation \, dose \, in \, hypoxia} {Radiation \, dose \, in \, air}}}$

The maximum OER depends mainly on ionizing density or LET of radiation. Higher LET radiation and higher relative biological effectiveness (RBE) have lower OER in mammalian cell tissue. The maximum OER value varies from about 1-4. Maximum OERs range from about 2-4 to low-LET radiation such as X-rays, beta particles and gamma rays, whereas OER is a union for high-LET radiation such as low energy alpha particles.

Video Oxygen enhancement ratio

Use in medicine

The effect is used in medical physics to improve the effects of radiation therapy in oncology treatments. Additional oxygen abundance creates additional free radicals and increases damage to the target tissue.

In inner solid tumors become less oxygen than normal tissue and up to three times higher doses are required to achieve the same probability of tumor control as in tissues with normal oxygenation.

Maps Oxygen enhancement ratio

Description of Oxygen Effect

The most famous explanation of the effects of oxygen is the oxygen fixation hypothesis that postulates that oxygen permanently corrects radical-induced DNA damage to become permanent. Recently, it has been argued that the effects of oxygen involve exposure to the radiation of cells that cause their mitochondria to produce larger quantities of reactive oxygen species.

src: rsta.royalsocietypublishing.org

See also

• Radiation therapy
• Radiobiology
• Health physics
• Hypoxia

src: rsos.royalsocietypublishing.org

References

Eric J. Hall and Amato J. Giaccia: Radiobiology for radiologists, Lippincott Williams & amp; Wilkins, 6th Ed., 2006

Source of the article : Wikipedia