A mechanistic investigation of the oxygen fixation hypothesis and oxygen enhancement ratio

Open-access modeling paper on the physical basis of the oxygen effect. Its introduction summarizes the oxygen enhancement ratio: relative to anoxia, well-oxygenated tumors respond better by a factor of 2.5–3; half-maximum radiosensitivity occurs around an oxygen partial pressure of 3 mmHg, with maximum OER typically reached above 20 mmHg; and oxygen must be present before irradiation or within microseconds of it. It explains the oxygen fixation hypothesis — that DNA radical damage can usually be repaired, but repair is more difficult or impossible when the radical has reacted with oxygen. Full text read in Europe PMC (PMC4765087). (The journal classes it as a research paper; DoseLab uses it for its introductory summary.)

A concise introduction to the oxygen enhancement ratio and the oxygen fixation hypothesis — the usual explanation of why oxygen makes radiation more effective.