# dose

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## dose

1. Med a specific quantity of a therapeutic drug or agent taken at any one time or at specified intervals
2. Physics the total energy of ionizing radiation absorbed by unit mass of material, esp of living tissue; usually measured in grays (SI unit) or rads
3. a small amount of syrup added to wine, esp sparkling wine, when the sediment is removed and the bottle is corked

## Dose

the energy of ionizing radiation absorbed by a unit of mass of irradiated matter (the absorbed dose Da). The absorbed energy is expended in the heating and the chemical and physical transformation of matter. The magnitude of the dose depends on the type of radiation (for example, X-ray or neutron flux), the energy of its particles, the density of their flux, and the composition of the irradiated matter. All other things being equal, the longer the time of irradiation, the greater the dose. Thus, doses accumulate with time. The dose per unit time is called the dose rate.

In addition to the absorbed dose there are the concepts of the exposure dose and the dose equivalent. The exposure dose, a measure of the ionization of air under the action of Xand y-radiation, is measured by the number of charges formed. Coulombs per kg is the unit of exposure dose in the system. An exposure dose of 1 coulomb per kg means that the total charge of all ions of the same sign formed in one kilogram of air is equal to one coulomb. The roentgen is a subsidiary that is widely used for exposure dose; 1 roentgen = 2.57976 x 10-4 coulombs per kg, which corresponds to the formation of 2.08 x 109 pairs of ions in 1 cu cm of air (at 0°C and 760 mm mercury). In order to create that number of ions it is necessary to expend energy equal to 0.114 ergs per cu cm, or 88 ergs per g. Thus, 88 ergs per g is the energy equivalent of the roentgen. The absorbed dose of X-radiation or y radiation in any substance can be calculated from the magnitude of the exposure dose. In order to do this it is necessary to know the composition of the substance and the photon energy.

Thus, the radiation danger to which a human being is subjected under any form of radiation corresponds to the same magnitude of dose equivalent. Natural sources of ionizing radiation (cosmic rays, the natural radioactivity of soil, water, air, and the human body) produce an average equivalent dose rate of 125 millirems per year. A dose equivalent of 400-500 rems received in a short time during irradiation of the whole body may, without special treatment, lead to death. However, the same dose equivalent received evenly during the course of one’s life leads to no perceptible changes. A dose equivalent of 5 rems per year is considered the maximum permissible exposure (MPE) in occupational irradiation.

The minimum dose of γ-radiation that will suppress the reproductive capacity of certain cells after a single irradiation is 5 rems. Inceptive changes in the blood are observed with prolonged daily doses of 0.02-0.05 rems, tumor formation, with 0.11 rems. The long-term consequences of irradiation are judged according to the increase in the frequency of mutation in the offspring. The dosage that will double the frequency of spontaneous mutation in man probably does not exceed 100 rems per generation. With local irradiation—that is, for the purpose of treating malignant tumors—high doses (6,000-10,000 rems in three or four weeks) of X-radiation or γ-radiation are used (carefully shielding the rest of the body).

Radiobiology distinguishes the following doses that lead sooner or later to death in animals: a dose that causes the death of 50 percent of the animals in 30 days (a lethal dose— LD30/50) with single-exposure unilateral X-radiation or γ-radiation is 300 rems for guinea pigs and 1,000 rems for rabbits; the minimum absolute lethal dose (MALD) with general γ-radiation is approximately 600 rems for man. With increases in dosage, the survival time is reduced to 2.8-3.5 days; further increases in dosage do not change that period. Only doses higher than 10,000-20,000 rems shorten the survival time to one day, and with subsequent irradiation, to a few hours. With a dose of 15,000-25,000 rems, cases of “death under the ray” are noted. Particular forms of radiation injury correspond to each dosage range. A number of invertebrate animals, plants, and microorganisms have considerably lower sensitivity.

Dosimeters are used in measuring radiation doses in order to predict radiation effects.

### REFERENCES

GOST 8848-63: Edinitsy radioaktivnosti i ioniziruiushchikh izluchenii. Moscow, 1964.
GOST 12631-67. Koeffitsient kachestva ioniziruiushchikh izluchenii. Moscow, 1967.
Ivanov, V. I. Kurs dozimetrii, 2nd ed. Moscow, 1970.
Golubev, B. P. Dozimetriia i zashchita ot ioniziruiushchikh izluchenii, 2nd ed. Moscow, 1971.

V. I. IVANOV and N. G. DARENSKAIA

## dose

[dōs]
(medicine)
The measure, expressed in number of roentgens, of a property of x-rays at a particular place; used in radiology.
(nucleonics)
References in periodicals archive ?
Our goal was to achieve enrichment of genes and molecular pathways associated with neurological development and disease in order to identify novel gene targets for future investigation into the specific genetic mechanisms underlying developmental Pb toxicity at sublethal doses. Using zebrafish ex utero development, we initiated exposure conditions immediately after fertilization to correspond to the mammalian in utero prenatal developmental period.
In resistant adults, the total protein contents decreased up to 37.59 and 14.04%, at lower and higher sublethal doses of abamectin, respectively, while in the susceptible adults, 11.61% decrease, at lower dose and 81.07% increase, at higher dose was observed.
Some macromolecular abnormalities induced by a sublethal dose of Cymbush 10EC in adult beetles of Tribolium castaneum.
Behavioral and metabolic effects of sublethal doses of two insecticides, chlorpyrifos and methomyl, in the Egyptian cotton leafworm, Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae).
The first group represented the healthy control animals, while the second, third, and fourth groups were given 0.4, 0.8, and 1.2 mg/kg body weight of sublethal doses of lead acetate (Sigma-Aldrich, Ltd., UK), respectively, in their daily supply of drinking water for 12 weeks.
Sublethal doses of the widely used oxidative stress inducer [H.sub.2][O.sub.2] inhibited proliferation and activated the p53-p21 pathway and SA [beta]-gal accumulation in IVD cells, proving the suitability of the system to test potential antisenescence compounds.
(2006) reported a significant reduction in chitin and an increase in total protein of larvae of Tribolium castaneum contaminated by sublethal doses of flufenoxuron.
Previous studies focused on the effect of sanitation procedures and sublethal doses of preservatives on the toxicity of specific microorganism [8]; however, these were conducted on pure cultures.
The regulatory protein Yap1 plays an important role in the hormetic effects caused by low concentrations of either hydrogen peroxide or ethanol, and it is involved in the yeast cross-adaptation to stressful conditions by low sublethal doses of hydrogen peroxide.
[14], conducted in mice, it was demonstrated that intranasal infection with sublethal doses of influenza A virus resulted in lethal infection after further intranasal infection with sublethal doses of group A S.
High doses of the chemical can be lethal to bees, while sublethal doses can either be taken back to the hive.

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