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.
|
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.
|
deci
|
0.1
(1/10)
|
|
centi
|
0.01
(1/100)
|
|
milli
|
0.001
(1/1000)
|
Therefore,
it is common in contemporary radiology literature to read about radiation
doses measured in milliSieverts (mSv).
CONVERSIONS
|
1
Gy
|
=
|
100
rads
|
|
1Sv
|
=
|
100
rems
|
|
1
rad
|
=
|
0.01
Gy (1/100)
|
|
1rem
|
=
|
0.01
Sv
|
|
100
mr
|
=
|
1mGy
(0.001 Gy)
|
|
100
mrem
|
=
|
1mSv
(0.001 Sv)
|
1
mSv = 1/10 rem
1
mGy = 1/10 rad
|
