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The absorbed dose can be a poor indicator of the biological effect of radiation, as the biological effect can depend on many other factors, including the type of radiation, energy, and type of tissue. The relative biological effectiveness can help give a better measure of the biological effect of radiation.
Effective dose is a dose quantity in the International Commission on Radiological Protection (ICRP) system of radiological protection. [1]It is the tissue-weighted sum of the equivalent doses in all specified tissues and organs of the human body and represents the stochastic health risk to the whole body, which is the probability of cancer induction and genetic effects, of low levels of ...
The NRC's definition of dose equivalent is "the product of the absorbed dose in tissue, quality factor, and all other necessary modifying factors at the location of interest." However, it is apparent from their definition of effective dose equivalent that "all other necessary modifying factors" excludes the tissue weighting factor. [17]
The median effective dose is the dose that produces a quantal effect (all or nothing) in 50% of the population that takes it (median referring to the 50% population base). [6] It is also sometimes abbreviated as the ED 50, meaning "effective dose for 50% of the population". The ED50 is commonly used as a measure of the reasonable expectancy of ...
"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 (one gray, an SI unit, equals 100 rads) averaged over the tissue or organ, T, due to radiation type, R, and W R is the radiation weighting factor.
The deterministic effects that can lead to acute radiation syndrome only occur in the case of high doses (> ~10 rad or > 0.1 Gy) and high dose rates (> ~10 rad/h or > 0.1 Gy/h). A model of deterministic risk would require different weighting factors (not yet established) than are used in the calculation of equivalent and effective dose.
To measure the biological effects of radiation on human tissues, effective dose or dose equivalent is used. [4] The dose equivalent measures the effective radiation dosage in a specific organ or tissue. [4] The dose equivalent is calculated by the following equation: [4] Dose equivalent = Absorbed dosage x Tissue weighting factor
Organs that are remote from the site of irradiation will only receive a small equivalent dose (mainly due to scattering) and therefore contribute little to the effective dose, even if the weighting factor for that organ is high. Effective dose is used to estimate stochastic risks for a ‘reference’ person, which is an average of the population.