| (1) Except where otherwise specified, all communications and reports concerning this chapter and applications filed under them should be addressed to the Radiation Control Program, Department of State Health Services, P.O. Box 149347, Mail Code 1987, Austin, Texas, 78714-9347. Communications, reports, and applications may be delivered in person to the agency's office located at 8407 Wall Street, Austin, Texas. (2) Documents transmitted to the agency will be deemed submitted on the date of the postmark, telegram, telefacsimile, or electronic media transmission. (j) Interpretations. Except as specifically authorized by the agency in writing, no interpretation of the meaning of this chapter by any officer or employee of the agency other than a written legal interpretation by the agency, will be considered binding upon the agency. (k) Mean quality factors and absorbed dose equivalencies. (1) As used in this chapter, the quality factors for converting absorbed dose to DE are shown in the following table: Attached Graphic (2) 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 paragraph (1) of this subsection, 1 rem (0.01 Sv) of neutron radiation of unknown energies may, for purposes of this section, 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 DE or the appropriate Q value from the following table to convert a measured tissue dose in rad (gray) to DE in rem (Sv). Attached Graphic (l) As low as reasonably achievable (ALARA). The registrant shall use, to the extent practical, procedures and engineering controls based upon sound radiation protection principles to achieve occupational doses and public doses that are ALARA. (m) Occupational dose limits. (1) The registrant shall control the occupational dose to individuals to the following dose limits. (A) An annual limit shall be the TEDE being equal to 5 rems (0.05 Sv). (B) The annual limits to the lens of the eye, to the skin of the whole body, and to the skin of the extremities shall be: (i) an LDE of 15 rems (0.15 Sv); and (ii) an SDE of 50 rems (0.5 Sv) to the skin of the whole body, or to the skin of any extremity. (C) The annual limits for a minor shall be 10% of the annual occupational dose limits specified in subparagraphs (A) and (B) of this paragraph. (D) If a woman declares her pregnancy, the registrant shall ensure that the DE to an embryo/fetus during the entire pregnancy, due to occupational exposure of a declared pregnant woman, does not exceed 0.5 rem (5 mSv). If a woman chooses not to declare pregnancy, the occupational dose limits specified in paragraph (1)(A) and (B) of this subsection are applicable to the woman. (i) The registrant shall make efforts to avoid substantial variation above a uniform monthly exposure rate (air kerma rate) to a declared pregnant woman so as to satisfy the limit in paragraph (1) of this subsection. The National Council on Radiation Protection and Measurements recommended in NCRP Report No. 91 "Recommendations on Limits for Exposure to Ionizing Radiation" (June 1, 1987) that no more than 0.05 rem (0.5 mSv) to the embryo/fetus be received in any 1 month. (ii) If by the time the woman declares pregnancy to the registrant, the DE to the embryo/fetus has exceeded 0.45 rem (4.5 mSv), the registrant shall be deemed to be in compliance with paragraph (1) of this subsection, if the additional DE to the embryo/fetus does not exceed 0.05 rem (0.5 mSv) during the remainder of the pregnancy. (iii) The DE to an embryo/fetus shall be taken as the DE that is most representative of the DE to the embryo/fetus from external radiation, that is, in the mother's lower torso region. (iv) If multiple measurements have been made, assignment of the DDE for the declared pregnant woman from the individual monitoring device that is most representative of the DE to the embryo/fetus shall be the DE to the embryo/fetus. Assignment of the highest DDE for the declared pregnant woman to the embryo/fetus is not required unless that dose is also the most representative DDE for the region of the embryo/fetus. (v) If multiple measurements have not been made, assignment of the highest DDE for the declared pregnant woman shall be the DE to the embryo/fetus. (2) The assigned DDE shall be for the portion of the body receiving the highest exposure. The assigned SDE shall be the dose averaged over the contiguous 10 square centimeters of skin receiving the highest exposure. (3) When a protective apron is worn while working with fluoroscopic equipment used for clinical diagnostic or research purposes, the effective dose equivalent (EDE) for external radiation shall be determined as follows. (A) When only 1 individual monitoring device is used and it is located at the neck (collar) outside the protective apron, the reported DDE shall be the EDE for external radiation; or (B) When only 1 individual monitoring device is used and it is located at the neck (collar) outside the protective apron, and the reported dose exceeds 25% of the limit specified in paragraph (1) of this subsection, the reported DDE value multiplied by 0.3 shall be the EDE for external radiation; or (C) When individual monitoring devices are worn, both under the protective apron at the waist and outside the protective apron at the neck (collar), the EDE for external radiation shall be assigned the value of the sum of the DDE reported for the individual monitoring device located at the waist under the protective apron multiplied by 1.5 and the DDE reported for the individual monitoring device located at the neck (collar) outside the protective apron multiplied by 0.04. (4) The EDE determined by paragraph (3) of this subsection shall be recorded as part of an individual's dose record and will contribute to that individual's annual TEDE. (5) The DDE, LDE, and SDE may be assessed from surveys or radiation measurements for the purpose of demonstrating compliance with the occupational dose limits, if the individual monitoring device was not in the region of highest potential exposure, or the results of individual monitoring are unavailable. (6) The registrant shall reduce the dose that an individual may be allowed to receive in the current year by the amount of occupational dose received from radiation machines or radioactive materials while employed by any other person. See subsection (r)(4) of this section. (n) Conditions requiring individual monitoring of occupational dose. (1) Each registrant shall monitor exposures from radiation machines at levels sufficient to demonstrate compliance with the occupational dose limits of this section. As a minimum, each registrant shall monitor occupational exposure to radiation from radiation machines and shall supply and require the use of individual monitoring devices by: (A) adults likely to receive, in 1 year from sources external to the body, a dose in excess of 10% of the limits in subsection (m)(1) of this section; (B) minors likely to receive, in 1 year from sources of radiation external to the body, a DDE in excess of 0.1 rem (1 mSv), an LDE in excess of 0.15 rem (1.5 mSv), or an SDE to the skin or to the extremities in excess of 0.5 rem (5 mSv); (C) declared pregnant women likely to receive during the entire pregnancy, from sources of radiation external to the body, a DDE in excess of 0.1 rem (1 mSv); and (D) individuals entering a high or very high radiation area. (2) Notwithstanding the requirements of paragraph (1)(A) of this subsection, no personnel monitoring shall be required for personnel operating only minimal threat radiation machines as specified in subsection (ll)(3) of this section. (o) Dose limits for individual members of the public. (1) Each registrant shall conduct operations so that: (A) the TEDE to individual members of the public from exposure to radiation from radiation machines does not exceed 0.5 rem (5 mSv) in a year, exclusive of the dose contribution from background radiation, exposure of patients to radiation for the purpose of medical diagnosis or therapy, or to voluntary participation in medical research programs; and (B) the dose in any unrestricted area from registered external sources does not exceed 0.002 rem (0.02 mSv) in any 1 hour. (2) If the registrant permits members of the public to have access to restricted areas, the limits for members of the public continue to apply to those individuals. (3) The agency may impose additional restrictions on radiation levels in unrestricted areas in order to restrict the collective dose. Cont'd... |
