Editing Equivalent dose (section)

==Calculation==
[[File:SI Radiation dose units.png|400px|thumb|right|Relationships of SI external "protection" dose quantities]]
Equivalent dose ''H''<sub>T</sub> is calculated using the mean [[absorbed dose]] deposited in body tissue or organ T, multiplied by the radiation weighting factor ''W''<sub>R</sub> which is dependent on the type and energy of the radiation R.

The radiation weighting factor represents the [[relative biological effectiveness]] of the radiation and modifies the absorbed dose to take account of the different biological effects of various types and [[Electronvolt|energies]] of radiation.

The ICRP has assigned radiation weighting factors to specified radiation types dependent on their [[relative biological effectiveness]], which are shown in accompanying table.<ref>ICRP publication 103, glossary</ref>

Calculating equivalent dose from absorbed dose;

:<math>H_T = \sum_R W_R \cdot D_{T,R} </math>
where
:''H<sub>T</sub>''&nbsp; is the equivalent dose in sieverts (Sv) absorbed by tissue T,
:''D<sub>T,R</sub>''&nbsp; is the absorbed dose in grays (Gy) in tissue T by radiation type R and
:''W<sub>R</sub>''&nbsp; is the radiation weighting factor defined by regulation.
Thus for example, an absorbed dose of 1 Gy by alpha particles will lead to an equivalent dose of 20 Sv, and an equivalent dose of radiation is estimated to have the same biological effect as an equal amount of absorbed dose of gamma rays, which is given a weighting factor of 1.

To obtain the equivalent dose for a mix of radiation types and energies, a sum is taken over all types of radiation energy doses.<ref name="ICRP103" /> This takes into account the contributions of the varying biological effect of different radiation types.

{| class="wikitable" style="float:right;"
|+Radiation weighting factors W<sub>R</sub> (formerly termed Q factor)<br/> used to represent [[relative biological effectiveness]]<br/> according to ICRP report 103<ref name="ICRP103">{{cite journal |title=The 2007 Recommendations of the International Commission on Radiological Protection |journal=Annals of the ICRP |year=2007 |volume=37 |series=ICRP publication 103 |issue=2–4 |url=http://www.icrp.org/publication.asp?id=ICRP%20Publication%20103 |access-date=17 May 2012 |isbn=978-0-7020-3048-2 |url-status=dead |archive-url=https://web.archive.org/web/20121116084754/http://www.icrp.org/publication.asp?id=ICRP%20Publication%20103 |archive-date=16 November 2012 }}</ref>
|-
! Radiation !! Energy !! W<sub>R</sub> (formerly Q)
|-
| [[x-ray]]s, [[gamma ray]]s,<br>[[beta particle]]s, [[muon]]s ||&nbsp; || {{0}}1
|-
| rowspan=3 |[[neutron]]s || < 1 MeV         || 2.5 + 18.2·e<sup>−[ln(E)]²/6</sup>
|-
| 1...50 MeV  || 5.0 + 17.0·e<sup>−[ln(2·E)]²/6</sup>
|-
| > 50 MeV  || 2.5 + 3.25·e<sup>−[ln(0.04·E)]²/6</sup>
|-
| [[proton]]s, charged [[pion]]s  || &nbsp;        || {{0}}2
|-
| [[alpha particle]]s, [[Nuclear fission product|fission<br>products]], heavy [[atomic nucleus|nuclei]] || &nbsp; || 20
|}