(a) As used in the rules in this chapter, the International System of Units (SI) unit of exposure is the coulomb/kilogram (C/kg) of air. The special unit of exposure is the roentgen. One roentgen equals 2.58 x 10-4 coulomb/kilogram of air.
(b) As used in the rules in this chapter, the units of radiation dose are as follows:
  (1) Rad is the special unit of absorbed dose. One rad is equal to an absorbed dose of 100 ergs/gram or 0.01 joule/kilogram (0.01 gray).
  (2) Gray (Gy) is the SI unit of absorbed dose. One gray is equal to an absorbed dose of 1 joule/kilogram (100 rads).
  (3) 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 sievert).
  (4) 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 sievert = 100 rems).
(c) As used in the rules in this chapter, the quality factors for converting absorbed dose to dose equivalent are shown in Table I.
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(d) If it is more convenient to measure the neutron fluence rate than to determine the neutron dose equivalent rate in rem/hour or sievert/hour, as provided in subsection (c) of this section, 1 rem (0.01 sievert) of neutron radiation of unknown energies may, for purposes of the rules in this chapter, be assumed to result from a total fluence of 25 million neutrons/square centimeter incident upon the body. If sufficient information exists to estimate the approximate energy distribution of the neutrons, the licensee may use the fluence rate per unit dose equivalent or the appropriate Q value from Table II to convert a measured tissue dose in rad (gray) to dose equivalent in rem (sievert).
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Source Note: The provisions of this §336.3 adopted to be effective June 5, 1997, 22 TexReg 4588