180 NAC 1-014. UNITS OF EXPOSURE AND DOSE

014. UNITS OF EXPOSURE AND DOSE. As used in Title 180: 014.01 COULOMB 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. 014.02 UNITS OF DOSE. The units of dose are: (A) Gray (Gy);(B) Rad;(C) Rem; and(D) Sievert. 014.03 QUALITY FACTORS. The quality factors for converting absorbed dose to dose equivalent are shown in Table I. TABLE I QUALITY FACTORS AND ABSORBED DOSE EQUIVALENCIES Quality Factor Absorbed Dose Equal to TYPE OF RADIATION (Q) 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. 014.04 NEUTRON 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.