| (94) Scattered radiation--Radiation that has been deviated
in direction during passage through matter.
(95) Secondary protective barrier--See definition for
protective barrier.
(96) Shallow dose equivalent (Hs )
(that applies to the external exposure of the skin of the whole body
or the skin of an extremity)--The dose equivalent at a tissue depth
of 0.007 cm (7 milligrams per square centimeter).
(97) Shutter--A device attached to the tube housing
assembly that can totally intercept the useful beam and that has a
lead equivalency not less than that of the tube housing assembly.
(98) SI--The abbreviation for the International System
of Units.
(99) Sievert (Sv)--The SI unit of any of the quantities
expressed as dose equivalent. The dose equivalent in Sv is equal to
the absorbed dose in Gy multiplied by the quality factor (1 Sv = 100
rem.)
(100) Source-to-image receptor distance (SID)--The
distance from the source to the center of the input surface of the
image receptor.
(101) Source-to-skin distance (SSD)--The distance from
the source to the skin of the animal.
(102) Special units--The conventional units historically
used by registrants, i.e. rad (absorbed dose), and rem (dose equivalent).
(103) Spot film--A radiograph that is made during a
fluoroscopic examination to permanently record conditions that exist
during that fluoroscopic procedure.
(104) Stray radiation--The sum of leakage and scattered
radiation.
(105) Supervision--The delegating of the task of applying
radiation in accordance with this section to persons not licensed
in veterinary medicine, who perform tasks under the veterinarian's
control. The veterinarian assumes full responsibility for these tasks
and shall assure that the tasks will be administered correctly.
(106) Survey--An evaluation of the radiological conditions
and potential hazards incident to the production, use, transfer, disposal,
and presence of radiation machines. When appropriate, such survey
includes, tests, physical examination of location of radiation machines,
measurements of levels of radiation present, and evaluation of administrative
and engineered controls.
(107) Technique chart--A chart that provides technical
factors, anatomical examination, and animal size for examination being
performed needed to make clinical radiographs when the radiation machine
is in manual mode.
(108) Technique factors--The conditions of operation
that are specified as follows:
(A) for capacitor energy storage equipment, peak tube
potential in kV and quantity of charge in mAs;
(B) for field emission equipment rated for pulsed operation,
peak tube potential in kV and number of x-ray pulses;
(C) for CT systems designed for pulsed operations,
peak tube potential in kV, scan time in seconds, and either tube current
in mA, x-ray pulse width in seconds, and the number of x-ray pulses
per scan or the product of tube current, x-ray pulse width, and the
number of x-ray pulses in mAs;
(D) for CT systems not designed for pulsed operation,
peak tube potential in kV, and either tube current in mA and scan
time in seconds or the product of tube current and exposure time in
mAs when the scan time and exposure time are equivalent; and
(E) for all other x-ray systems, peak tube potential
in kV and either tube current in mA and exposure time in seconds or
the product of tube current and exposure time in mAs.
(109) Termination--A release by the agency of the obligations
and authorizations of the registrant under the terms of the certificate
of registration. It does not relieve a person of duties and responsibilities
imposed by law or rule.
(110) Texas Regulations for Control of Radiation--All
sections of Chapter 289 of this title.
(111) Total effective dose equivalent--The sum of the
effective dose equivalent (for external exposures) and the committed
effective dose equivalent (for internal exposures).
(112) Traceable to a national standard--This indicates
that a quantity or a measurement has been compared to a national standard,
for example, the National Institute of Standards and Technology, directly
or indirectly through one or more intermediate steps and that all
comparisons have been documented.
(113) Tube--An x-ray tube, unless otherwise specified.
(114) Tube housing assembly--The tube housing with
tube installed. It includes high-voltage and filament transformers
and other appropriate elements when such are contained within the
tube housing.
(115) Unrestricted area--An area, access to which is
neither limited nor controlled by the registrant. For purposes of
this section, "uncontrolled area" is an equivalent term.
(116) Useful beam--Radiation that passes through the
window, aperture, cone, or other collimating device of the source
housing. Also referred to as the primary x-ray beam.
(117) Veterinarian--An individual licensed by the Texas
Board of Veterinary Medical Examiners.
(118) Veterinary medicine--The term when used in this
chapter has the same meaning as found in Texas Occupations Code, Chapter
801.
(119) Very high radiation area--An area, accessible
to individuals, in which radiation levels from radiation machines
external to the body could result in an individual receiving an absorbed
dose in excess of 500 rads (5 grays) in one hour at 1 meter from a
radiation machine or from any surface that the radiation penetrates.
At very high doses received at high dose rates, units of absorbed
dose, Gy and rad, are appropriate, rather than units of dose equivalent,
Sv and rem.
(120) Violation--An infringement of any rule, license
or registration condition, order of the agency, or any provision of
the Act.
(121) Whole body--For purposes of external exposure,
head and trunk, including male gonads, arms above the elbow, or legs
above the knee.
(122) Worker--An individual engaged in work under a
certificate of registration issued by the agency and controlled by
a registrant but does not include the registrant.
(123) X-ray control panel--A device that controls input
power to the x-ray high-voltage generator or the x-ray tube. It includes
equipment, such as timers, phototimers, automatic brightness stabilizers,
and similar devices that control the technique factors of an x-ray
exposure.
(124) X-ray field--That area of the intersection of
the useful beam and any one of the set of planes parallel to and including
the plane of the image receptor, whose perimeter is the locus of points
at which the air kerma rate is one-fourth of the maximum in the intersection.
(125) X-ray system--An assemblage of components for
the controlled production of x-rays. It includes minimally an x-ray
high-voltage generator, an x-ray control, a tube housing assembly,
a beam-limiting device, and the necessary supporting structures. Additional
components that function with the system are considered integral parts
of the system.
(126) X-ray tube--Any electron tube that is designed
to be used primarily for the production of x-rays.
(127) Year--The period of time beginning in January
used to determine compliance with the provisions of this chapter.
The registrant may change the starting date of the year used to determine
compliance by the registrant provided that the change is made at the
beginning of the year and that no day is omitted or duplicated in
consecutive years.
(e) Exemptions.
(1) The agency may, upon application or upon its own
initiative, exempt a source of radiation or a kind of use or user
from the requirements of this section if the agency determines that
the law does not prohibit the exemption and it will not result in
a significant risk to public health or safety or the environment.
In determining such exemptions, the agency will consider:
(A) state of technology;
(B) economic considerations in relation to benefits
to the public health and safety; and
(C) other societal, socioeconomic, or public health
and safety considerations.
(2) Electronic equipment that produces radiation incidental
to its operation for other purposes is exempt from the registration
and notification requirements of this section, if the dose equivalent
rate averaged over an area of 10 square cm does not exceed 0.5 millirem
(5 microsieverts) per hour at 5 cm from any accessible surface of
such equipment. The production, testing, or factory servicing of such
equipment shall not be exempt.
(3) Radiation machines in transit or in storage incident
to transit are exempt from the requirements of this section. This
exemption does not apply to the providers of radiation machines for
mobile services.
Cont'd... |
