INTERNATIONAL
UNITS for X-RAY DOSE
The
metric system of weights and measures is now officially known by the
French name Le Système International d'Unités (abbreviation
SI), or in English as the International System of Units.
SI units
for x-ray dose are now gradually replacing the units of rad and
rem which have previously been used in radiology
literature.
We have used the term rad to measure x-ray
dose at a specified part.
 |
The Gray (Gy) is now used for this
purpose.
|
We have used the term rem to measure the
ionizing capacity of other forms of ionizing radiation other than
x-ray; for example, isotope dose for nuclear medicine procedures.
|
The Sievert (Sv) is now used for this
purpose.
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1 rad of
x-ray dose has the same biologic effect as 1 rem of isotope dose.
Likewise,
1 Gy of x-ray dose has the same biologic effect as 1Sv of isotope dose.
In literature regarding x-ray dose it is common
to use rem (in the past) or Sievert (currently) as inclusive terms that
refer to all radiation, whether it is x-ray or some other form of
ionizing radiation.
The
typical metric names for units smaller than the named unit are utilized.
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deci
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0.1 (1/10)
|
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centi
|
0.01
(1/100)
|
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milli
|
0.001
(1/1000)
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Therefore,
it is common in contemporary radiology literature to read about
radiation doses measured in milliSieverts (mSv).
CONVERSIONS
|
1 Gy
|
=
|
100 rads
|
|
1Sv
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=
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100 rems
|
|
1 rad
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=
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0.01 Gy
(1/100)
|
|
1rem
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=
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0.01 Sv
|
|
100 mr
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=
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1mGy
(0.001 Gy)
|
|
100 mrem
|
=
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1mSv
(0.001 Sv)
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1 mSv = 1/10 rem
1 mGy = 1/10 rad
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