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.

Rulemaking Authority 404.042, 404.051, 404.061 FS. Law Implemented 404.022(2) FS. History–New 1-1-94, Formerly 10D-91.113.