64E-5.106. Units of Exposure and Dose

(1) As used in these regulations, the unit of exposure is the coulomb per kilogram (C/kg). One roentgen is equal to 2.58 × 10-4 coulomb per kilogram of air. (2) As used in these regulations, the units of dose are: (a) Gray (Gy) is the SI unit of absorbed dose. One gray is equal to an absorbed dose of 1 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). (3) As used in these regulations, the quality factors for converting absorbed dose to dose equivalent are shown below: QUALITY FACTORS AND ABSORBED DOSE EQUIVALENCIES Absorbed Dose Equal Quality Factor to a Unit Dose TYPE OF RADIATION (Q) Equivalenta X, gamma, or beta radiation and 1 1 high-speed electrons Alpha particles, multiple-charged 20 0.05 particles, fission fragments and heavy particles of unknown charge Neutrons of unknown energy 10 0.1 High-energy protons 10 0.1 a Absorbed dose in rad equal to 1 rem or the absorbed dose in gray equal to 1 Sv. (4) 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 Rule 64E-5.106, F.A.C., above, 0.01 Sv (1 rem) of neutron radiation of unknown energies can, for purposes of these regulations, 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 can use the fluence rate per unit dose equivalent or the appropriate Q value from the table below to convert a measured tissue dose in gray or rad to dose equivalent in sievert or rem. MEAN QUALITY FACTORS, Q, AND FLUENCE PER UNIT DOSE EQUIVALENT FOR MONOENERGETIC NEUTRONS Fluence per Unit Fluence per Unit Neutron Quality Dose Equivalentb Dose Equivalentb Energy Factora (neutrons (neutrons (MeV) (Q) cm-2 rem-1) cm-2 Sv-1) (thermal) 2.5 × 10-8 2 980 × 106 980 × 108 1 × 10-7 2 980 × 106 980 × 108 1 × 10-6 2 810 × 106 810 × 108 1 × 10-5 2 810 × 106 810 × 108 1 × 10-4 2 840 × 106 840 × 108 1 × 10-3 2 980 × 106 980 × 108 1 × 10-2 2.5 1010 × 106 1010 × 108 1 × 10-1 7.5 170 × 106 170 × 108 5 × 10-1 11 39 × 106 39 × 108 1 11 27 × 106 27 × 108 2.5 9 29 × 106 29 × 108 5 8 23 × 106 23 × 108 7 7 24 × 106 24 × 108 10 6.5 24 × 106 24 × 108 14 7.5 17 × 106 17 × 108 20 8 16 × 106 16 × 108 40 7 14 × 106 14 × 108 60 5.5 16 × 106 16 × 108 1 × 102 4 20 × 106 20 × 108 2 × 102 3.5 19 × 106 19 × 108 3 × 102 3.5 16 × 106 16 × 108 4 × 102 3.5 14 × 106 14 × 108 aValue of quality factor at the point where the dose equivalent is maximum in a 30-cm diameter cylinder tissue-equivalent phantom. bMonoenergetic neutrons incident normally on a 30-cm diameter cylinder tissue-equivalent phantom.