The Metric Conversion Act of 1975 (
PL
94-168 ) urged the increasing awareness and use of
the International System of Units (SI). The generally accepted regulatory
values in the narrative portions of this document are followed by the SI
equivalents in parentheses. Where appropriate, schedules and appendices are
provided with notes concerning conversion factors. The inclusion of the SI
equivalent is for informational purposes only.

(1) The unit of exposure is the coulomb per
kilogram (C/kg). One roentgen is equal to 2.58x10^{-4}
coulomb per kilogram of air.

(2)
The units of

radiation dose are:

(a) Gray
(Gy) is the SI unit of absorbed dose. One gray is equal to an absorbed dose of
one joule per kilogram (100 rad);

(b) Rad is the special unit of absorbed dose.
One rad is equal to an absorbed dose of 100 erg per gram or 0.01 joule per
kilogram (0.01 Gy);

(c) Rem is the
special unit of any of the quantities expressed as dose equivalent. The dose
equivalent in rem is equal to the absorbed dose in rad multiplied by the
quality factor (1 rem = 0.01 Sv).

(d) Sievert is the SI unit of any of the
quantities expressed as dose equivalent. The dose equivalent in sievert is
equal to the absorbed dose in gray multiplied by the quality factor (1 Sv = 100
rem).

(e) As used in these
regulations, the quality factors for converting

absorbed dose to dose
equivalent are shown in 10

CFR 20 Part 20.1004 Table 1004(b).1.

(3) If it is more convenient to
measure the neutron fluence rate than to determine the neutron

dose equivalent
rate in rem per hour or sieverts per hour, as provided in (2)(c) of this rule,
one rem (0.01 Sv) of neutron radiation of unknown energies may, for purposes of
the regulations in this part, be assumed to result from a total fluence of 25
million neutrons per square centimeter incident upon the body. If sufficient
information exists to estimate the approximate energy distribution of the
neutrons, the licensee may use the fluence rate per unit

dose equivalent or the
appropriate Q value from 10

CFR 20 part 20.1004 Table 1004(b).2 (at the end of
this

division) to convert a measured tissue dose in gray or rad to dose
equivalent in sievert rem.

## Notes

Or. Admin. R.
333-100-0070

HD 1-1991, f. & cert.
ef. 1-8-91; HD 15-1994, f. & cert. ef. 5-6-94; PH 3-2003, f. & cert.
ef. 3-27-03; PH 31-2004(Temp), f. & cert. ef. 10-8-04 thru 4-5-05; PH
36-2004, f. & cert. ef. 12-1-04; PH 12-2006, f. & cert. ef. 6-16-06; PH
4-2007, f. & cert. ef. 3-1-07; PH 10-2011, f. 9-30-11, cert. ef.
10-1-11

Tables referenced are available from the
agency.

Stat. Auth.: ORS 453.635

Stats. Implemented: ORS 453.605 -
453.807