Radioactive Material - Conversion Tables

(Bq to Ci, Sv to mrem...)

The International System of units (Système International (SI)) is commonly used when referencing measurements. The application of these terms assists researchers in clearly communicating their findings with colleagues around the world. Unfortunately not all countries have adopted this international standard. In terms of radiation use, at the University of Ottawa, the commonly reference measurements are that of radioactivity and radiation dose. These units are often referred to in both their SI units (becquerel and sievert) and the traditional units (curie and rem). To assist you in converting between the two systems the following tables have been created.

Common Prefixes for SI Units

Submultiples Multiples    
10-3 milli
103 kilo k
10-6 micro micro symbol 106 mega M
10-9 nano
109 giga G
10-12 pico
1012 tera T


The activity of a radioactive substance is the measurement of the number of disintegration of the atom noted per second. The working SI unit is bequerel (Bq), while the traditional unit is a curie (Ci).

1Bq = 1 disintegration per second
1 Ci = 3.7 x 1010 Bq

Radiation Table

Radiation Tables

Other Useful Conversions

20MBq = 0.54mCi
50MBq = 1.35mCi
200MBq = 5.41mCi
5GBq = 135mCi
10GBq = 270mCi

2mCi = 74MBq
5mCi = 185MBq
10mCi = 370MBq
50mCi = 1.85GBq
250mCi = 9.25GBq

Contamination Criteria (Loose)

Class A radionuclides 0.3 Bq/cm2 = 8.1 pCi/cm2
Class B radionuclides 3 Bq/cm2 = 81 pCi/cm2
Class C radionuclides 30 Bq/cm2 = 810 pCi/cm2

Radiation Dose

Absorbed Dose:

Absorbed dose is the amount of energy absorbed into matter. The working SI unit is rad (rad), while the traditional unit is a gray (Gy).

1 rad = 62.4 x 106 MeV per gram
1 gray = 100 erg per gram

1 rad = 0.01 gray
1 gray (Gy) = 100 rad

Dose Equivalent:

Dose equivalent is the absorbed dose into biological matter taking into account the interaction of the type of radiation and its associated linear energy transfer through specific tissues. The working SI unit is the sievert (Sv), while the traditional unit is roentgen equivalent man (rem).

1Sv = 1 rads x quality factor x any other modifying factors
1rem = 1 gray x quality factor x any other modifying factors

1 Sv =100 roentgen equivalent man (rem)
1 rem = 0.01Sv = 10mSv

Dose qequivalent table

Dose equivalent tables

Other Useful Conversions:

Dose rate criteria (outside storage area):

2.5 Sv/hr = 0.25mrem/hr

CNSC Dose Limits (non-Nuclear Energy Worker):

Whole body = 1mSv/yr = 100 mrem/yr
Skin, Hands, Feet = 50 mSv/yr = 5 rem/yr


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Last updated: 2010.10.22