Statutes, codes, and regulations
Michigan Administrative Code
Department - Labor and Economic OpportunityMIOSHAX-Ray Machine RegistrationIonizing Radiation Rules Governing the Use of Radiation MachinesPart 1 - GENERAL PROVISIONS FOR THE USE OF RADIATION MACHINES
GENERAL REQUIREMENTS
Section R. 333.5020 - Units of dose

Mich. Admin. Code R. 333.5020

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Section R. 333.5020 - Units of dose

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 highspeed 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)

(thermal)

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.

Mich. Admin. Code R. 333.5020

2016 MR 10, Eff. 5/25/2016