erythema dose

Acute radiodermatitis occurs when an "erythema dose" of ionizing radiation is given to the skin, after which visible erythema appears up to 24hrs after.

According to Dr. J. E. Jelinek, a clinical professor of dermatology at New York University Medical Center, the amount of exposure to sunlight needed to produce redness in the skin - the minimum erythema dose or M.E.D. - varies from person to person.