Changes

<blockquote>In radiation biology, clinical radiology, and radiological protection the absorbed dose, D, is the basic physical dose quantity, and it is used for all types of ionising radiation and any irradiation geometry. It is defined as ... the mean energy imparted to matter ... [divided by the mass]

When using the quantity absorbed dose in practical protection applications, doses are averaged over tissue volumes. It is assumed that, for low doses, the mean value of absorbed dose averaged over a specific organ or tissue can be correlated with radiation detriment for stochastic effects in that tissue with an accuracy sufficient for the purposes of radiological protection.</blockquote>

<blockquote>The protection quantities are used to specify exposure limits to ensure that the occurrence of stochastic health effects is kept below unacceptable levels and that tissue reactions are avoided. The definition of the protection quantities is based on the average absorbed dose, D_T,R in the volume of a specified organ or tissue T (see Table 3), due to radiation of type R (see Table 2). The radiation R is given by the type and energy of radiation either incident on the body or emitted by radionuclides residing within it. The protection quantity equivalent dose in an organ or tissue, H_T, is then defined by

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where wR is the radiation weighting factor for radiation R. The sum is performed over all types of radiations involved. The unit of equivalent dose is J kg^-1 and has the special name sievert (Sv).</blockquote>

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<blockquote> ... The development of ... effective dose has made a significant contribution to radiological protection as it has enabled doses to be summed from whole and partial body exposure from external radiation of various types and from intakes of radionuclides.</blockquote>

<blockquote>The effective dose, E, ... is defined by a weighted sum of tissue equivalent doses as:

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