180 Neb. Admin. Code, ch. 1, § 014

Current through September 17, 2024

Section 180-1-014 - UNITS OF EXPOSURE AND DOSE

As used in Title 180:

014.01COULOMB PER KILOGRAM. The unit of exposure is the coulomb per kilogram (C/kg) of air. One roentgen is equal to 2.58E-4 coulomb per kilogram of air.

014.02UNITS OF DOSE. The units of dose are:

(A) Gray (Gy);

(B) Rad;

(C) Rem; and

(D) Sievert.

014.03QUALITY FACTORS. The quality factors for converting absorbed dose to dose equivalent are shown in Table I.

TABLE I

QUALITY FACTORS AND ABSORBED DOSE EQUIVALENCIES

TYPE OF RADIATION	Quality Factor (Q)	Absorbed Dose Equal to a Unit Dose Equivalent
X, gamma, or beta radiation and high-energy 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 is equal to 1 Sv or the absorbed dose in rad equal to 1 rem.

014.04NEUTRON FLUENCE RATE. If it is more convenient to measure the neutron fluence rate than to determine the neutron dose equivalent rate in rems per hour or sieverts per hour, as provided in 180 NAC 1-014.03, 0.01 Sv (1 rem) of neutron radiation of unknown energies may, for purposes of Title 180, 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 or registrant may use the fluence rate per unit dose equivalent or the appropriate Q value from Table II to convert a measured tissue dose in gray or rad to dose equivalent in sievert or rem.

TABLE II

MEAN QUALITY FACT0RS, Q, AND FLUENCE PER UNIT DOSE EQUIVALENT FOR MONOENERGETIC NEUTRONS

	Neutron Energy (MeV)	Quality Factor (Q)	Fluence per Unit Dose Equivalent (neutrons cm-2 rem-1)	Fluence per Unit Dose Equivalent (neutrons cm-2 sievert-1)
(thermal)	2.5E-8	2	980E+6	980E+8
	1E-7	2	980E+6	980E+8
	1E-6	2	810E+6	810E+8
	1E-5	2	810E+6	810E+8
	1E-4	2	840E+6	840E+8
	1E-3	2	980E+6	980E+8
	1E-2	2.5	1010E+6	1010E+8
	1E-1	7.5	170E+6	170E+8
	5E-1	11	39E+6	39E+8
	1	11	27E+6	27E+8
	2.5	9	29E+6	29E+8
	5	8	23E+6	23E+8
	7	7	24E+6	24E+8
	10	6.5	24E+6	24E+8
	14	7.5	17E+6	17E+8
	20	8	16E+6	16Ex8
	40	7	14E+6	14E+8
	60	5.5	16E+6	16E+8
	1E+2	4	20E+6	20E+8
	2E+2	3.5	19E+6	19E+8
	3E+2	3.5	16E+6	16E+8
	4E+2	3.5	14E+6	14E+8

The value of quality factor (Q) at the point where the dose equivalent is maximum in a 30-centimeter diameter cylinder tissue-equivalent phantom.

The fluence per unit dose equivalent is monoenergetic neutrons incident normally on a 30-centimeter diameter cylinder tissue-equivalent phantom.

180 Neb. Admin. Code, ch. 1, § 014

Amended effective 3/13/2018

Amended effective 6/15/2021