ED50

absorbed dose that amount of energy from ionizing radiations absorbed per unit mass of matter, expressed in rads.

air dose the intensity of an x-ray or gamma-ray beam in air, expressed in roentgens.

booster dose an amount of immunogen (vaccine, toxoid, or other antigen preparation), usually smaller than the original amount, injected at an appropriate interval after primary immunization to sustain the immune response to that immunogen.

curative dose (CD) a dose that is sufficient to restore normal health. See also median curative dose.

divided dose fractionated dose.

effective dose (ED) that quantity of a drug that will produce the effects for which it is administered. See also median effective dose.

erythema dose that amount of radiation that, when applied to the skin, causes erythema (temporary reddening).

fatal dose lethal dose.

fractionated dose a fraction of the total dose prescribed, as of chemotherapy or radiation therapy, to be given at intervals, usually during a 24-hour period.

infective dose (ID) that amount of a pathogenic agent that will cause infection in susceptible subjects. See also median infective dose and tissue culture infective dose.

lethal dose (LD) that quantity of an agent that will or may be sufficient to cause death. See also median lethal dose and minimum lethal dose.

loading dose a dose of medication, often larger than subsequent doses, administered for the purpose of establishing a therapeutic level of the medication.

maintenance dose the amount of a medication administered to maintain a desired level of the medication in the blood.

maximum tolerated dose tolerance dose.

maximum permissible dose the largest amount of ionizing radiation that one may safely receive within a specified period according to recommended limits in current radiation protection guides. The specific amounts vary with age and circumstance.

median curative dose (CD₅₀) a dose that abolishes symptoms in 50 per cent of test subjects.

median effective dose (ED₅₀) a dose that produces the desired effect in 50 per cent of a population.

median infective dose (ID₅₀) that amount of pathogenic microorganisms that will produce demonstrable infection in 50 per cent of the test subjects.

median lethal dose (LD₅₀) the quantity of an agent that will kill 50 per cent of the test subjects; in radiology, the amount of radiation that will kill, within a specified period, 50 per cent of individuals in a large group or population.

median tissue culture infective dose (TCID₅₀) that amount of a pathogenic agent that will produce infection in 50 per cent of cell cultures inoculated.

minimum lethal dose

reference dose an estimate of the daily exposure to a substance for humans that is assumed to be without appreciable risk; it is calculated using the no observed adverse effect level and is more conservative than the older margin of safety.

skin dose (SD)

threshold dose the minimum dose of ionizing radiation, a chemical, or a drug that will produce a detectable degree of any given effect.

threshold erythema dose (TED) the single skin dose that will produce, in 80 per cent of those tested, a faint but definite erythema within 30 days, and in the other 20 per cent, no visible reaction.

tissue culture infective dose (TCID) that amount of a pathogenic agent that will produce infection when inoculated on tissue cultures; used with a numeric qualifier.

tolerance dose the largest quantity of an agent that may be administered without harm. Called also maximum tolerated dose.