R 333.5020
R 333.5020 Units of dose.
Cite as Mich. Admin. Code R 333.5020
Rule 20. (1) As used in these rules, the units of dose are the following:
(a) Gray (Gy) is the SI unit of absorbed dose. One gray is equal to an absorbed dose
of 1 joule per kilogram (100 rads).
(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) Sievert (Sv) 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)
(d) 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 rads multiplied by the quality
factor. (1 rem = 0.01 Sv)
(2) As used in these rules, the quality factors for converting absorbed dose to dose
equivalent are shown in table 20-1:
TABLE 20-1
QUALITY FACTORS AND ABSORBED DOSE EQUIVALENCIES
Type of Radiation
Quality Factor
*
Absorbed Dose
Equal to a Unit
Dose Equivalent
X, gamma, or beta radiation and high-
speed electrons
1
1
Alpha
particles,
multiple-charged
particles, fission fragments and heavy
particles of unknown charge
20
0.05
Neutrons of unknown energy
10
0.1
High-energy protons
10
0.1
*Absorbed dose in gray equal to 1 Sv or the absorbed dose in rad equal to 1 rem.
(3) If it is more convenient to measure the neutron fluence rate than to determine the
neutron dose equivalent rate in sievert per hour or rem per hour, as provided in subrule
(2) of this rule, 0.01 Sv (1 rem) of neutron radiation of unknown energies may, for
purposes of these rules, 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 registrant may use the fluence
rate per unit dose equivalent or the appropriate quality factor from table 20-2 to convert a
measured tissue dose in gray or rad to dose equivalent in sievert or rem.
TABLE 20-2
MEAN QUALITY FACTORS AND FLUENCE PER UNIT DOSE
EQUIVALENT FOR MONOENERGETIC NEUTRONS
Neutron
Energy
(MeV)
Quality
Factor*
Fluence per Unit
Dose Equivalent**
(Neutrons cm-2 Sv-
1)
Fluence per
Unit
Dose Equivalent**
(Neutrons cm-2 rem-
1)
(therma
l)
2.5 x 10-8
2.0
9.8 x 1010
9.8 x 108
1.0 x 10-7
2.0
9.8 x 1010
9.8 x 108
1.0 x 10-6
2.0
8.1 x 1010
8.1 x 108
1.0 x 10-5
2.0
8.1 x 1010
8.1 x 108
1.0 x 10-4
2.0
8.4 x 1010
8.4 x 108
1.0 x 10-3
2.0
9.8 x 1010
9.8 x 108
1.0 x 10-2
2.5
1.0 x 1011
1.0 x 109
1.0 x 10-1
7.5
1.7 x 1010
1.7 x 108
5.0 x 10-1
11.0
3.9 x 109
3.9 x 107
1.0
11.0
2.7 x 109
2.7 x 107
2.5
9.0
2.9 x 109
2.9 x 107
5.0
8.0
2.3 x 109
2.3 x 107
7.0
7.0
2.4 x 109
2.4 x 107
1.0 x 101
6.5
2.4 x 109
2.4 x 107
1.4 x 101
7.5
1.7 x 109
1.7 x 107
2.0 x 101
8.0
1.6 x 109
1.6 x 107
4.0 x 101
7.0
1.4 x 109
1.4 x 107
6.0 x 101
5.5
1.6 x 109
1.6 x 107
1.0 x 102
4.0
2.0 x 109
2.0 x 107
2.0 x 102
3.5
1.9 x 109
1.9 x 107
3.0 x 102
3.5
1.6 x 109
1.6 x 107
4.0 x 102
3.5
1.4 x 109
1.4 x 107
*Value of quality factor at the point where the dose equivalent is maximum in a 30-centimeter
diameter cylinder tissue-equivalent phantom.
**Monoenergetic neutrons incident normally on a 30-centimeter diameter cylinder tissue-
equivalent phantom.