Committed dose equivalent and Committed effective dose equivalent are dose quantities used in the United States system of radiological protection for irradiation due to an internal source.

Committed dose equivalent (CDE)

CDE is defined by the United States

Nuclear Regulatory Commission The Nuclear Regulatory Commission (NRC) is an independent agency of the United States government tasked with protecting public health and safety related to nuclear energy. Established by the Energy Reorganization Act of 1974, the NRC began operat ...

in Title 10, Section 20.1003, of the

Code of Federal Regulations In the law of the United States, the ''Code of Federal Regulations'' (''CFR'') is the codification of the general and permanent regulations promulgated by the executive departments and agencies of the federal government of the United States. ...

(10 CFR 20.1003), such that "The Committed dose equivalent, CDE (H_T,50) is the dose to some specific organ or tissue of reference (T) that will be received from an intake of

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...

material by an individual during the 50-year period following the intake". "The calculation of the committed effective dose equivalent (CEDE) begins with the determination of the equivalent dose, H_T, to a tissue or organ, T. Where D_T,R is the absorbed dose in

rads RAD or Rad may refer to: People * Robert Anthony Rad Dougall (born 1951), South African former racing driver * Rad Hourani, Canadian fashion designer and artist * Nickname of Leonardus Rad Kortenhorst (1886–1963), Dutch politician * Radley Rad ...

(one gray, an SI unit, equals 100 rads) averaged over the tissue or organ, T, due to

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

type, R, and W_R is the radiation weighting factor. The unit of equivalent dose is the

rem Rem or REM may refer to: Music * R.E.M., an American rock band * ''R.E.M.'' (EP), by Green * "R.E.M." (song), by Ariana Grande Organizations * La République En Marche!, a French centrist political party * Reichserziehungsministerium, in Nazi G ...

( sievert, in SI units)."

Committed effective dose equivalent (CEDE)

This is defined in Title 10, Section 20.1003, of the Code of Federal Regulations of the USA the CEDE dose (HE,50) as the sum of the products of the committed dose equivalents for each of the body organs or tissues that are irradiated multiplied by the weighting factors (W_T) applicable to each of those organs or tissues. "The probability of occurrence of a

stochastic Stochastic (, ) refers to the property of being well described by a random probability distribution. Although stochasticity and randomness are distinct in that the former refers to a modeling approach and the latter refers to phenomena themselv ...

effect in a tissue or organ is assumed to be proportional to the equivalent dose in the tissue or organ. The constant of proportionality differs for the various tissues of the body, but in assessing health detriment the total risk is required. This is taken into account using the tissue weighting factors, W_T, which represent the proportion of the stochastic risk resulting from irradiation of the tissue or organ to the total risk when the whole body is irradiated uniformly and H_T is the equivalent dose in the tissue or organ, T, in the equation:" Committed Effective Dose Equivalent (CEDE) refers to the dose resulting from internal radiation exposures. The CEDE is combined with the Deep-Dose Equivalent (DDE), the dose from external whole body exposures, to produce the Total Effective Dose Equivalent (TEDE), the dose resulting from internal and external radiation exposures.

Units

Both quantities can be expressed in rem or sieverts (Sv).

Pathways for Exposure

The intake of radioactive material can occur through four pathways: inhalation of airborne contaminants such as

radon Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colourless, odourless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through ...

, ingestion of contaminated food or liquids, absorption of vapors such as tritium oxide through the skin, and injection of medical radioisotopes such as

technetium-99m Technetium-99m (99mTc) is a metastable nuclear isomer of technetium-99 (itself an isotope of technetium), symbolized as 99mTc, that is used in tens of millions of medical diagnostic procedures annually, making it the most commonly used medical ra ...

. Some artificial radioisotopes such as

iodine-131 Iodine-131 (131I, I-131) is an important radioisotope of iodine discovered by Glenn Seaborg and John Livingood in 1938 at the University of California, Berkeley. It has a radioactive decay half-life of about eight days. It is associated with nuc ...

are chemically identical to natural

isotopes Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) ...

needed by the body, and may be more readily absorbed if the individual has a deficit of that element. For instance, potassium iodide (KI), administered orally immediately after exposure, may be used to protect the

thyroid The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the thyroid isthmus. The thy ...

from ingested radioactive

iodine Iodine is a chemical element with the symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , and boils to a vi ...

in the event of an accident or attack at a

nuclear power plant A nuclear power plant (NPP) is a thermal power station in which the heat source is a nuclear reactor. As is typical of thermal power stations, heat is used to generate steam that drives a steam turbine connected to a electric generator, generato ...

, or the detonation of a nuclear explosive which would release radioactive iodine. Other radioisotopes have an affinity for particular tissues, such as

plutonium Plutonium is a radioactive chemical element with the symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized. The element normally exhibi ...

into bone, and may be retained there for years in spite of their foreign nature. Not all radiation is harmful. The radiation can be absorbed through multiple pathways, varying due to the circumstances of the situation. If the radioactive material is necessary, it can be ingested orally via stable isotopes of specific elements. This is only suggested to those that have a lack of these elements however, because radioactive material can go from healthy to harmful with very small amounts. The most harmful way to absorb radiation is that of ingestion absorption because it is almost impossible to control how much will enter the body.

Committed dose equivalent in the practice of radiological protection

In the case of internal exposure, the dose is not received at the moment of exposure, as happens with external exposure, since the incorporated radionuclide irradiates the various organs and tissues during the time it is present in the body. By definition, the committed dose equivalent corresponds to the received dose integrated over 50 years from the date of intake. In order to calculate it, one has to know the intake activity and the value of the committed dose equivalent per unit of intake activity. The uncertainties of the first parameter are such that the committed dose equivalent can only be regarded as an order of magnitude and not as a very accurate quantity. The use of it is justified, however, for, like the dose equivalent for external exposure, it expresses the risk of stochastic effects for the individual concerned since these effects, should they appear, would do so only after a latent period which is generally longer than the dose integration time. Moreover, the use of the committed dose equivalent offers certain advantages for dosimetric management, especially when it is simplified. A practical problem which may arise is that the annual dose limit is apparently exceeded by virtue of the fact that one is taking account, in the first year, of doses which will actually be received only in the following years. These problems are rare enough in practice to be dealt with individually in each case.

Cigarette smoke measured with SSNTD and corresponding committed equivalent dose

Uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

and

Thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high me ...

contents were measured inside various tobacco samples by using a method based on determining detection efficiencies of the CR-39 and LR-115 II solid state nuclear track detectors (SSNTD) for the emitted

alpha particles Alpha particles, also called alpha rays or alpha radiation, consist of two protons and two neutrons bound together into a particle identical to a helium-4 nucleus. They are generally produced in the process of alpha decay, but may also be prod ...

. Alpha and beta activities per unit volume, due to radon, thoron and their decay products, were evaluated inside cigarette smokes of tobacco samples studied. Annual committed equivalent doses due to short-lived radon decay products from the inhalation of various cigarette smokes were determined in the thoracic and extrathoracic regions of the respiratory tract. Three types of cigarettes made in Morocco of black tobacco show higher annual committed equivalent doses in the extrathoracic and thoracic regions of the respiratory tract than the other studied cigarettes (except one type of cigarettes made in France of yellow tobacco); their corresponding annual committed equivalent dose ratios are larger than 1.8. Measured annual committed equivalent doses ranged from 1.8×10⁻⁹ Sv/yr to in the extrathoracic region and from 1.3×10⁻¹⁰ Sv/yr to in the thoracic region of the respiratory tract for a smoker consuming 20 cigarettes a day."Radon and daughters in cigarette smoke measured with SSNTD and corresponding committed equivalent dose to respiratory tract
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References

US nuclear regulatory commission glossaryRadon and daughters in cigarette smoke measured with SSNTD and corresponding committed equivalent dose to respiratory tract
*SCHLENKER R, A. "Comparison of Intake and Committed Dose Equivalent Permitted by Radiation Protection Systems Based on Annual Dose Equivalent and Committed Dose Equivalent for a Nuclide of Intermediate Effective Half-life." Health Physics, 51.2 (1986): 207-214.

External links

- "The confusing world of radiation dosimetry" - M.A. Boyd, U.S. Environmental Protection Agency. An account of chronological differences between USA and ICRP dosimetry systems. {{Radiation Radioactivity Radiation health effects Equivalent units