The sievert (symbol: Sv) is the SI derived unit of dose equivalent. SI derived units are part of the SI system of measurement units and are derived from the seven SI base units They are derived from SI basic units/defined The equivalent dose ( H T) is a measure of the Radiation dose to tissue where an attempt has been made to allow for the different relative biological It attempts to reflect the biological effects of radiation as opposed to the physical aspects, which are characterised by the absorbed dose, measured in grays. Radiation, as in Physics, is Energy in the form of waves or moving Subatomic particles emitted by an atom or other body as it changes from a higher energy Absorbed dose (also known as total ionizing dose, TID is a measure of the energy deposited in a medium by Ionizing radiation. The gray (symbol Gy is the SI unit of absorbed radiation dose. It is named after Rolf Sievert, a Swedish medical physicist famous for work on radiation dosage measurement and research into the biological effects of radiation. Professor Rolf Maximilian Sievert ( 6 May 1896 &ndash 3 October 1966) was a medical Physicist whose major contribution was in the "Sverige" redirects here For other uses see Sweden (disambiguation and Sverige (disambiguation.

Contents 1 Definition 2 SI multiples and conversions 3 Explanation 4 Q values 5 N values 6 Spelling 7 See also 8 References

Definition

The equivalent dose to a tissue is found by multiplying the absorbed dose, in grays, by a dimensionless "quality factor" Q, dependent upon radiation type, and by another dimensionless factor N, dependent on all other pertinent factors. In Dimensional analysis, a dimensionless quantity (or more precisely a quantity with the dimensions of 1) is a Quantity without any Physical units N depends upon the part of the body irradiated, the time and volume over which the dose was spread, even the species of the subject. Together, Q and N constitute the radiation weighting factor, W_R . Q is the same thing as the Relative Biological Effectiveness [RBE]. Relative Biological Effectiveness (RBE is a Health physics concept introduced in the 1950s after it was noted that different types of radiation might affect living organisms For an organism composed of multiple tissue types a weighted sum or integral is often used. A weight function is a mathematical device used when performing a sum integral or average in order to give some elements more of a "weight" than others The European Space Agency 's INTErnational Gamma-Ray Astrophysics Laboratory ( INTEGRAL) is detecting some of the most energetic radiation that comes from space (In 2002, the CIPM decided that the distinction between Q and N causes too much confusion and therefore deleted the factor N from the definition of absorbed dose in the SI brochure. The International Committee for Weights and Measures is the English name of the Comité international des poids et mesures ( CIPM, sometimes written in English [1]. )

In terms of SI base units:

1 Sv = 1 J/kg = 1 m²/s² = 1 m²·s^–2

Although the sievert has the same dimensions as the gray (i. The International System of Units (SI defines seven dimensionally independent SI base units. The joule (written in lower case ˈdʒuːl or /ˈdʒaʊl/ (symbol J) is the SI unit of Energy measuring heat, Electricity The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International The second ( SI symbol s) sometimes abbreviated sec, is the name of a unit of Time, and is the International System of Units The metre or meter is a unit of Length. It is the basic unit of Length in the Metric system and in the International The second ( SI symbol s) sometimes abbreviated sec, is the name of a unit of Time, and is the International System of Units e. joules per kilogram), it measures a different thing. The joule (written in lower case ˈdʒuːl or /ˈdʒaʊl/ (symbol J) is the SI unit of Energy measuring heat, Electricity To avoid any risk of confusion between the absorbed dose and the equivalent dose, the corresponding special units, namely the gray instead of the joule per kilogram for absorbed dose and the sievert instead of the joule per kilogram for the dose equivalent, should be used. For a given amount of radiation (measured in grays), the biological effect (measured in sieverts) can vary considerably as a result of the radiation weighting factor W_R. This variation in effect is attributed to the Linear Energy Transfer [LET] of the type of radiation, creating a different relative biological effectiveness for each type of radiation under consideration. Linear energy transfer (LET is a measure of the Energy transferred to material as an ionizing particle travels through it Relative Biological Effectiveness (RBE is a Health physics concept introduced in the 1950s after it was noted that different types of radiation might affect living organisms Per most government regulations, the RBE [Q] for electron and photon radiation is 1, for neutron radiation it is 10, and for alpha radiation it is 20. There is some controversy that the Q or RBE for alpha radiation is underestimated due to mistaken assumptions in the original work in the 1950s that developed those values. That original work neglected the component of the nucleus recoil radiation for alpha emitters.

SI multiples and conversions

Frequently used SI multiples are the millisievert (1 mSv = 10^–3 Sv) and microsievert (1 μSv = 10^–6 Sv). An SI prefix (also known as a metric prefix) is a name or associated symbol that precedes a unit of measure (or its symbol to form a Decimal multiple or

An older unit of the equivalent dose is the rem (Röntgen equivalent man); 1 Sv is equal to 100 rem, for a quality factor Q=1. The Röntgen ( roentgen) equivalent in man or rem (symbol rem) In some fields and countries, rem and mrem continue to be used along with Sv and mSv, causing confusion.

Explanation

Various terms are used with this unit:

• Dose equivalent
• Ambient dose equivalent
• Directional dose equivalent
• Personal dose equivalent
• Organ equivalent dose

The millisievert (mSv) is commonly used to measure the effective dose in diagnostic medical procedures (e. g. , X-rays, nuclear medicine, positron emission tomography, and computed tomography). X-radiation (composed of X-rays) is a form of Electromagnetic radiation. Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy Positron emission tomography ( PET) is a Nuclear medicine imaging technique which produces a three-dimensional image or map of functional processes in the Computed tomography (CT is a Medical imaging method employing Tomography. The natural background effective dose varies considerably from place to place, but typically is around 2. Background radiation is the Ionizing radiation emitted from a variety of natural and artificial Radiation sources 4 mSv/year [2] (pdf).

For acute full body equivalent dose, 1 Sv causes nausea, 2-5 Sv causes hair loss, hemorrhage and will cause death in many cases. Nausea ( Latin: Nausea, Greek:, " Sea-sickness " also called wamble) is the sensation of unease and discomfort Baldness involves the state of lacking hair where it often grows especially on the head Bleeding, technically known as hemorrhaging / haemorrhaging (see American and British spelling differences) is the loss of Blood from More than 3 Sv will lead to death in 50% of cases within 30 days, and over 6 Sv survival is unlikely. See radiation poisoning for a more complete analysis of effects of various dosage levels. Radiation poisoning, also called " radiation sickness " or a " creeping dose " is a form of damage to organ tissue due to excessive exposure to

Given the linear no-threshold model of radiation response , the collective dose that a population is exposed to is measured in "man-sieverts" (man. The linear no-threshold model ( LNT) is a model of the damage caused by Ionizing radiation which presupposes that the response is Linear (i Sv).

Q values

Here are some quality factor values:

• Photons, all energies : Q = 1
• Electrons and muons, all energies : Q = 1
• Neutrons,
  • energy < 10 keV : Q = 5
  • 10 keV < energy < 100 keV : Q = 10
  • 100 keV < energy < 2 MeV : Q = 20
  • 2 MeV < energy < 20 MeV : Q = 10
  • energy > 20 MeV : Q = 5
• Protons, energy > 2 MeV : Q = 5
• Alpha particles and other atomic nuclei : Q = 20

N values

Here are some N values for organs and tissues:

• Gonads: N = 0. In Physics, the photon is the Elementary particle responsible for electromagnetic phenomena The electron is a fundamental Subatomic particle that was identified and assigned the negative charge in 1897 by J The muon (from the letter mu (μ--used to represent it is an Elementary particle with negative Electric charge and a spin of 1/2 This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive Alpha particles (named after and denoted by the first letter in the Greek alphabet, α consist of two Protons and two Neutrons bound together into a The gonad is the organ that makes Gametes The gonads in males are the Testes and the gonads in Females are the Ovaries. 20
• Bone marrow, colon, lung, stomach: N = 0. Bone marrow is the flexible tissue found in the hollow interior of Bones In adults marrow in large bones produces new Blood cells It constitutes 4% of The colon is a storage tube for solid wastes The main function of the colon appears to be extraction of Water and salts from Feces. lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive In Human anatomy, the stomach is a J-shaped hollow muscular organ of the Gastrointestinal tract involved in the second phase of Digestion, following 12
• Bladder, brain, breast, kidney, liver, muscles, oesophagus, pancreas, small intestine, spleen, thyroid, uterus: N = 0. In Anatomy, the urinary bladder is a hollow muscular, and distensible (or elastic organ that sits on the Pelvic floor in Mammals It is the The brain is the center of the Nervous system in animals All Vertebrates and the majority of Invertebrates have a brain The breast is the upper Ventral region of an animal’s Torso, particularly that of Mammals including Human beings. The kidneys are complicated organs that have numerous biological roles The liver is a vital organ in the human body and is present in Vertebrates and some other animals Muscle (from Latin musculus, diminutive of mus "mouse" is contractile tissue of the body and is derived from the The esophagus or oesophagus (see American and British English spelling differences) sometimes known as the gullet, is an organ in The pancreas is a Gland organ in the digestive and Endocrine system of Vertebrates. In Biology the small Intestine is the part of the Gastrointestinal tract (gut between the Stomach and the Large intestine, and comprises The spleen is an organ found in all Vertebrate animals In humans the spleen is located in the abdomen of the body where it functions in the destruction of redundant Red The thyroid is one of the largest Endocrine glands in the body The uterus (from the Latin word for womb) is the major Female reproductive organ of most Mammals including Humans One end the 05
• Bone surface, skin: N = 0. Bones are rigid organs that form part of the Endoskeleton of Vertebrates They function to move support and protect the various organs of the body produce The skin is the outer covering of living tissue of an animal (or plant 01

And for other organisms, relative to humans:

• Viruses, bacteria, protozoans: N ≈ 0. A virus (from the Latin virus meaning Toxin or Poison) is a sub-microscopic infectious agent that is unable The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Protozoa (in Greek πρῶτον proton "first" and ζῷα zoia "animals" are unicellular Eukaryotes (singular 03 – 0. 0003
• Insects: N ≈ 0. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described 1 – 0. 002
• Molluscs: N ≈ 0. Molluscs are animals belonging to the phylum Mollusca. There are around 250000 extant Species within the phylum with an estimated 70000 06 – 0. 006
• Plants: N ≈ 2 – 0. Plants are living Organisms belonging to the kingdom Plantae. 02
• Fish: N ≈ 0. Fish are aquatic Vertebrate animals that are typically ectothermic (previously Cold-blooded) covered with scales, and equipped with two 75 – 0. 03
• Amphibians: N ≈ 0. Prehistoric amphibian Amphibians (class Amphibia such as Frogs Toads Salamanders Newts Gymnophiona, Sirens and 4 – 0. 14
• Reptiles: N ≈ 1 – 0. Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers 075
• Birds: N ≈ 0. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. 6 – 0. 15
• Humans: N = 1

Spelling

This SI unit is named after Rolf Maximilian Sievert. Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus Professor Rolf Maximilian Sievert ( 6 May 1896 &ndash 3 October 1966) was a medical Physicist whose major contribution was in the As with every SI unit whose name is derived from the proper name of a person, the first letter of its symbol is uppercase (Sv). The musical instrument is spelled Cymbal. A symbol is something --- such as an object, Picture, written word a sound a piece Capital letters or majuscules pronunciation /məˈdʒʌskyuls ˈmædʒəˌskyuls/ in the Roman alphabet A, B, C, D, When an SI unit is spelled out in English, it should always begin with a lowercase letter (sievert), except where any word would be capitalized, such as at the beginning of a sentence or in capitalized material such as a title. Lower case (also lower-case or lowercase) minuscule, or small letters are the smaller form of letters as opposed to upper Note that "degree Celsius" conforms to this rule because the "d" is lowercase. The Celsius Temperature scale was previously known as the centigrade scale. — Based on The International System of Units, section 5. 2.

See also

• Counts per minute
• curie (unit)
• gray (unit)
• rad (unit)
• rem (unit)
• röntgen (unit)
• rutherford (unit)
• Sverdrup (unit) (a unit of volume transport with the same symbol Sv as Sievert)

• Background radiation
• Radiation weighting factor
• Relative Biological Effectiveness
• Linear Energy Transfer

References

Counts per minute (cpm is a measure of Radioactivity. It is the number of Atoms in a given quantity of radioactive material that are detected to have A CURIE (short for Compact URI) is an abbreviated URI expressed in CURIE syntax and may be found in both XML and non-XML grammars The gray (symbol Gy is the SI unit of absorbed radiation dose. The rad is a largely obsolete unit of absorbed Radiation dose with symbol rad. The Röntgen ( roentgen) equivalent in man or rem (symbol rem) For other uses of röntgen or roentgen, see Roentgen The röntgen or roentgen (symbol R) is a unit The rutherford (symbol rd) is an obsolete unit of Radioactivity, defined as the activity of a quantity of radioactive material in which one million The sverdrup, named in honour of the pioneering oceanographer Harald Sverdrup, is a Unit of measure of Volume transport Background radiation is the Ionizing radiation emitted from a variety of natural and artificial Radiation sources The sievert (symbol Sv is the SI derived unit of dose equivalent. Relative Biological Effectiveness (RBE is a Health physics concept introduced in the 1950s after it was noted that different types of radiation might affect living organisms Linear energy transfer (LET is a measure of the Energy transferred to material as an ionizing particle travels through it The International Committee for Weights and Measures is the English name of the Comité international des poids et mesures ( CIPM, sometimes written in English Year 1984 ( MCMLXXXIV) was a Leap year starting on Sunday (link displays the 1984 Gregorian calendar) Year 1985 ( MCMLXXXV) was a Common year starting on Tuesday (link displays 1985 Gregorian calendar) The National Physical Laboratory (NPL is the national Measurement standards laboratory for the United Kingdom, based at Bushy Park in Teddington

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