Editing X-ray (section)

==Units of measure and exposure==
The measure of X-rays [[ionization|ionizing]] ability is called the exposure:<ref name="appendix Evaluation of Guidelines for Exposures">{{cite book |title=Evaluation of Guidelines for Exposures to Technologically Enhanced Naturally Occurring Radioactive Materials |date=1999 |publisher=National Academies Press (US) |url=https://www.ncbi.nlm.nih.gov/books/NBK230653/ |chapter=Radiation Quantities and Units, Definitions, Acronyms |isbn=978-0-309-06297-8 }}</ref>
* The [[coulomb]] per kilogram (C/kg) is the [[Systeme International|SI]] unit of [[ionizing radiation]] exposure, and it is the amount of radiation required to create one coulomb of charge of each polarity in one kilogram of matter.
* The [[Roentgen (unit)|roentgen]] (R) is an obsolete traditional unit of exposure, which represented the amount of radiation required to create one [[electrostatic unit]] of charge of each polarity in one cubic centimeter of dry air. 1&nbsp;roentgen&nbsp;=&nbsp;{{val|2.58|e=−4|u=C/kg}}.

However, the effect of ionizing radiation on matter (especially living tissue) is more closely related to the amount of energy deposited into them rather than the [[electric charge|charge]] generated. This measure of energy absorbed is called the [[absorbed dose]]:<ref name="appendix Evaluation of Guidelines for Exposures"/>
* The [[gray (unit)|gray]] (Gy), which has units of (joules/kilogram), is the SI unit of [[absorbed dose]], and it is the amount of radiation required to deposit one [[joule]] of energy in one kilogram of any kind of matter.
* The [[rad (unit)|rad]] is the (obsolete) corresponding traditional unit, equal to 10&nbsp;millijoules of energy deposited per kilogram. 100&nbsp;rad&nbsp;=&nbsp;1&nbsp;gray.

The [[equivalent dose]] is the measure of the biological effect of radiation on human tissue. For X-rays it is equal to the [[absorbed dose]].<ref name="appendix Evaluation of Guidelines for Exposures"/>
* The [[Roentgen equivalent man]] (rem) is the traditional unit of equivalent dose. For X-rays it is equal to the [[Rad (unit)|rad]], or, in other words, 10&nbsp;millijoules of energy deposited per kilogram. 100&nbsp;rem&nbsp;=&nbsp;1&nbsp;Sv.
* The [[sievert]] (Sv) is the SI unit of [[equivalent dose]], and also of [[Effective dose (radiation)|effective dose]]. For X-rays the "equivalent dose" is numerically equal to a [[Gray (unit)|Gray]] (Gy). 1&nbsp;Sv&nbsp;=&nbsp;1&nbsp;Gy. For the "effective dose" of X-rays, it is usually not equal to the Gray (Gy).
{{Radiation related quantities}}