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Radiation Units and Conversions


International System of Units (SI) Unit and Common Unit Terminology

  SI Units* Common Units
Radioactivity becquerel (Bq) curie (Ci)
Absorbed Dose gray (Gy) rad
Dose Equivalent sievert (Sv) rem
Exposure coulomb/kilogram (C/kg) roentgen (R)

* SI Units: International System of Units

Note: In the table above the common units and SI units in each row are not equivalent in value, i.e., 1 curie does not equal 1 becquerel, but they both measure the same parameter.
See Conversion Equivalence



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Conversion Equivalence

1 curie

=

3.7 x 1010 disintegrations per second

1 becquerel

=

1 disintegration per second

 

1 millicurie (mCi)

=

37 megabecquerels (MBq)

1 rad

=

0.01 gray (Gy)

1 rem

=

0.01 sievert (Sv)

1 roentgen (R)

=

0.000258 coulomb/
kilogram (C/kg)

 

1 megabecquerel (MBq)

=

0.027 millicuries (mCi)

1 gray (Gy)

=

100 rad

1 sievert (Sv)

=

100 rem

1 coulomb/
kilogram (C/kg)

=

3,880 roentgens



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Prefixes Often Used with SI Units

Multiple

Prefix

Symbol

1012

tera

T

109

giga

G

106

mega

M

103

kilo

k

10-2

centi

c

10-3

milli

m

10-6

micro

μ

10-9

nano

n



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Dose Unit Conversion Tool

Insert a number with up to 2 decimal points

Absorbed Dose




Dose Equivalent





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Radioactivity Unit Conversion Tool

Insert a number with up to 2 decimal points
Results are expressed in E-notation*






*E-notation examples:
3.05e+9 = 3.05 x 109
7.26e-3 = 7.26 x 10-3



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Exposure Unit Conversion Tool

Insert a number with up to 2 decimal points
Results are expressed in E-notation*



*E-notation examples:
3.05e+9 = 3.05 x 109
7.26e-3 = 7.26 x 10-3



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Conversion Factors

To convert from

To

Multiply by

Curies (Ci)

becquerels (Bq)

3.7 x 1010

millicuries (mCi)

megabecquerels (MBq)

37

microcuries (μCi)

megabecquerels (MBq)

0.037

millirads (mrad)

milligrays (mGy)

0.01

millirems (mrem)

microsieverts (μSv)

10

milliroentgens (mR)

microcoulombs/kilogram (μC/kg)

0.258

 

To convert from

To

Multiply by

becquerels (Bq)

curies (Ci)

2.7 x 10-11

megabecquerels (MBq)

millicuries (mCi)

0.027

megabecquerels (MBq)

microcuries (μCi)

27

milligrays (mGy)

millirads (mrad)

100

microsieverts (μSv)

millrems (mrem)

0.1

microcoulombs/kilogram (μC/kg)

milliroentgens (mR)

3.88

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References

  1. Radiation Dose Explained (1:07 min) (DOE/ORISE/REAC/TS) Watch video
  2. Differences Between Rad/Gray and Rem/Sievert (1:37 min) (DOE/ORISE/REAC/TS) Watch video
  3. Sievert (Wikipedia)
  4. Radiation Units - brief explanation (Michigan State University)

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US Department of Health & Human Services     
U.S. Department of Health & Human Services Office of the Assistant Secretary for Preparedness and Response National Library of Medicine