Current through Reg. 49, No. 38; September 20, 2024
(d)
Definitions. The following words and terms when used in this section shall have
the following meaning, unless the context clearly indicates otherwise.
(1) Absorbed dose--The energy imparted by
ionizing radiation per unit mass of irradiated material. The units of absorbed
dose are the gray (Gy) and the rad.
(2) Accessible surface--The external surface
of the enclosure or housing provided by the manufacturer.
(3) Act--Texas Radiation Control Act, Texas
Health and Safety Code, Chapter 401.
(4) Adult--An individual who is 18 years or
older.
(5) Agency--The Department
of State Health Services.
(6)
Agreement state--Any state with which the United States Nuclear Regulatory
Commission (NRC) has entered into an effective agreement under Section 274b of
the Atomic Energy Act of 1954, as amended (73 Stat. 689).
(7) Air kerma--The kinetic energy released in
air by ionizing radiation. Kerma is the quotient of dE by dM, where dE is the
sum of the initial kinetic energies of all the charged ionizing particles
liberated by uncharged ionizing particles in air of mass dM. The SI unit of air
kerma is joule per kilogram and the special name for the unit of kerma is Gy.
For purposes of this section, when exposure in air measured in roentgen (R) is
to be converted to dose in air measured in Gy, a nationally recognized standard
air conversion factor shall be used.
(8) Applicant--A person seeking a certificate
of registration issued in accordance with the provisions of the Act and the
requirements in this section.
(9)
As low as is reasonably achievable (ALARA)--Making every reasonable effort to
maintain exposures to radiation as far below the dose limits in this section as
is practical, consistent with the purpose for which the registered activity is
undertaken, taking into account the state of technology, the economics of
improvements in relation to the state of technology, the economics of
improvements in relation to benefits to the public health and safety, and other
societal and socioeconomic considerations, and in relation to utilization of
ionizing radiation and radiation machines in the public interest.
(10) Attenuate--To reduce the air kerma rate
upon passage of radiation through matter.
(11) Attenuation block--A block or stack,
having dimensions 20 centimeters (cm) by 20 cm by 3.8 cm, of type 1100 aluminum
alloy or other materials having equivalent attenuation. The nominal chemical
composition of type 1100 aluminum alloy is 99 percent minimum aluminum, 0.12
percent copper.
(12) Automatic
exposure control--A device that automatically controls one or more technique
factors in order to obtain a required quantity of radiation at preselected
locations (See definition for phototimer).
(13) Background radiation--Radiation from
cosmic sources; non'technologically enhanced naturally occurring radioactive
material, including radon, except as a decay product of source or special
nuclear material, and including global fallout as it exists in the environment
from the testing of nuclear explosive devices or from past nuclear accidents,
such as Chernobyl, that contribute to background radiation and are not under
the control of the registrant. "Background radiation" does not include
radiation from radiation machines regulated by the agency.
(14) Barrier--See definition for protective
barrier.
(15) Beam axis--A line
from the source through the centers of the x-ray fields.
(16) Beam-limiting device--A device that
provides a means to restrict the dimensions of the x-ray field.
(17) Beam quality (diagnostic x-ray)--A term
that describes the penetrating power of the x-ray beam. This is identified
numerically by half-value layer and is influenced by kilovolt peak (kVp) and
filtration.
(18) Central axis of
the beam--A line passing through the virtual source and the center of the plane
figure formed by the edge of the first beam'limiting device.
(19) Certificate of registration--A form of
permission given by the agency to an applicant who has met the requirements for
registration set out in the Act and this chapter.
(20) Collective dose--The sum of the
individual doses received in a given period of time by a specified population
from exposure to a specified source of radiation.
(21) Commissioner--The Commissioner of the
Department of State Health Services.
(22) Committed Effective Dose Equivalent
(HE,50)--The sum of the products of the weighting
factors applicable to each of the body organs or tissues that are irradiated
and the committed dose equivalent to these organs or tissues
(HE,50 =
ΣWTHT.50).
(23) Computed tomography (CT)--The
production of a tomogram by the acquisition and computer processing of x-ray
transmission data.
(24) Control
panel--The part of the radiation machine control upon which are mounted the
switches, knobs, push buttons, and other hardware necessary for manually
setting the technique factors.
(25) CT conditions of operation--All
selectable parameters governing the operation of a CT system including, nominal
tomographic section thickness, filtration, and the technique factors as defined
in this subsection.
(26) CT
gantry--The tube housing assemblies, beam-limiting devices, detectors, and the
supporting structures and frames that hold these components.
(27) Declared pregnant woman--A woman who has
voluntarily informed the registrant, in writing, of her pregnancy and the
estimated date of conception. The declaration remains in effect until the
declared pregnant woman voluntarily withdraws the declaration in writing or is
no longer pregnant.
(28) Deep dose
equivalent (Hd) that applies to external whole-body
exposure--The dose equivalent at a tissue depth of 1 cm (1,000 milligrams per
square centimeter (mg/cm2)).
(29) Diagnostic source assembly--The tube
housing assembly with a beam-limiting device attached.
(30) Dose--A generic term that means absorbed
dose, dose equivalent, or total effective dose equivalent. For purposes of this
section, "radiation dose" is an equivalent term.
(31) Dose equivalent
(Ht)--The product of the absorbed dose in tissue,
quality factor, and all other necessary modifying factors at the location of
interest. The units of dose equivalent are the sievert (Sv) and rem.
(32) Dose limits--The permissible upper
bounds of radiation doses established in accordance with this chapter. For
purposes of this section, "limits" is an equivalent term.
(33) Effective dose equivalent
(HE)--The sum of the products of the dose equivalent to
the organ or tissue (HT) and the weighting factors
(WT) applicable to each of the body organs or tissues
that are irradiated (HE =
ΣWTHT).
(34) Embryo/fetus--The developing human
organism from conception until the time of birth.
(35) Entrance exposure (Entrance air
kerma)--The exposure in air expressed in roentgens (R) or the dose in air (air
kerma) expressed in Gy, measured at the point where the center of the useful
beam enters the animal.
(36)
Equipment performance evaluations (EPE)--Required testing performed by a
registered service provider at a specified interval to ensure radiation
machines operate in compliance with this chapter.
(37) Exposure--The quotient of dQ by dm where
"dQ" is the absolute value of the total charge of the ions of one sign produced
in air when all the electrons (negatrons and positrons) liberated by photons in
a volume element of air having mass "dm" are completely stopped in air. The SI
unit of exposure is the coulomb per kilogram (C/kg). The roentgen is the
special unit of exposure. For purposes of this section, this term is used as a
noun.
(38) Exposure rate (air
kerma rate)--The exposure per unit of time. For purposes of this section "air
kerma rate" is an equivalent term.
(39) External dose--That portion of the dose
equivalent received from any source of radiation outside the body.
(40) Extremity--Hand, elbow, arm below the
elbow, foot, knee, and leg below the knee. The arm above the elbow and the leg
above the knee are considered part of the whole body.
(41) Field emission equipment--Equipment that
uses an x-ray tube in which electron emission from the cathode is due solely to
the action of an electric field.
(42) Field size--The dimensions along the
major axes of an area in a plane perpendicular to the central axis of the beam
at the normal treatment or examination source to image distance and defined by
the intersection of the major axes and the 50 percent isodose line.
(43) Filter--Material placed in the useful
beam to preferentially absorb selected radiation.
(44) Fluoroscopic imaging assembly--A
subsystem in which x-ray photons produce a fluoroscopic image. It includes the
image receptors, such as the image intensifier and spot-film device, electrical
interlocks, if any, and structural material providing linkage between the image
receptor and diagnostic source assembly.
(45) Focal spot--The area projected on the
anode of the x-ray tube bombarded by the electrons accelerated from the cathode
and from which the useful beam originates.
(46) Gray (Gy)--The SI unit of absorbed dose.
One Gy is equal to an absorbed dose of 1 joule per kilogram (J/kg) or 100 rad.
(47) Half-value layer--The
thickness of a specified material that attenuates the beam of radiation to an
extent such that the air kerma rate is reduced to one-half of its original
value.
(48) High radiation
area--An area, accessible to individuals, in which radiation levels external to
the body could result in an individual receiving a dose equivalent in excess of
0.1 rem (1 millisievert (mSv)) in one hour at 30 cm from any source of
radiation or from any surface that the radiation penetrates.
(49) Image intensifier--A device, installed
in its housing, that instantaneously converts an x-ray pattern into a
corresponding light image of higher energy density.
(50) Image receptor--Any device, such as a
fluorescent screen, radiographic film, or digital sensor that transforms
incident x-ray photons either into a visible image or into another form that
can be made into a visible image by further transformations.
(51) Individual--A human being.
(52) Individual monitoring--The assessment of
dose equivalent to an individual by the use of:
(A) individual monitoring devices; or
(B) survey data.
(53) Individual monitoring
devices--Devices designed to be worn by a single individual for the assessment
of dose equivalent. For purposes of this section, "personnel dosimeter,"
"dosimeter," and "personnel monitoring equipment" are equivalent terms.
Examples of individual monitoring devices include film badges,
thermoluminescence dosimeters, optically stimulated luminescence dosimeters,
pocket ionization chambers (pocket dosimeters), and electronic personal
dosimeters.
(54) Inspection--An
examination or observation, including records, tests, surveys, and monitoring
to determine compliance with the Act and requirements of this section, orders,
and conditions of the agency.
(55)
Ionizing radiation--Any electromagnetic or particulate radiation capable of
producing ions, directly or indirectly, in its passage through matter. Ionizing
radiation includes gamma rays and x-rays, alpha and beta particles, high speed
electrons, neutrons, and other nuclear particles.
(56) Irradiation--The exposure of matter to
ionizingradiation.
(57)
kV--Kilovolt.
(58) kVp--Kilovolt
peak (See definition for peak tube potential).
(59) Lead equivalent--The thickness of lead
affording the same attenuation, under specified conditions, as the material in
question.
(60) Lens dose
equivalent--The external dose equivalent to the lens of the eye at a tissue
depth of 0.3 cm (300 mg/cm2).
(61) Licensing state--Any state with rules
equivalent to the Suggested State Regulations for Control of Radiation relating
to, and having an effective program for, the regulatory control of naturally
occurring or accelerator-produced radioactive material.
(62) mA--Milliampere.
(63) mAs--Milliampere-second.
(64) Medical research--The investigation of
various health risks and diseases as it pertains to veterinary practices.
(65) Member of the public--Any
individual, except when that individual is receiving an occupational dose.
(66) Minor--An individual who is
under 18 years of age.
(67) Mobile
service operation--The provision of radiation machines and personnel at
temporary sites for limited time periods. The radiation machines may be fixed
inside a motorized vehicle or may be a portable radiation machine that may be
removed from the vehicle and taken into a facility for use.
(68) Monitoring--The measurement of radiation
and the use of the results of these measurements to evaluate potential
exposures and doses. For purposes of this section, "radiation monitoring" and
"radiation protection monitoring" are equivalent terms.
(69) Occupational dose--The dose received by
an individual during the course of employment in which the individual's
assigned duties involve exposure to sources of radiation from
licensed/registered and unlicensed/unregistered sources of radiation, whether
in the possession of the licensee/registrant or other person. Occupational dose
does not include dose received from background radiation, from any medical
administration the individual has received, from exposure to individuals
administered radioactive material and released in accordance with this section,
from voluntary participation in medical research programs, or as a member of
the public.
(70) Peak tube
potential--The maximum value of the potential difference in kilovolts across
the x-ray tube during an exposure.
(71) Person--Any individual, corporation,
partnership, firm, association, trust, estate, public or private institution,
group, agency, local government, any other state or political subdivision or
agency thereof, or any other legal entity, and any legal successor,
representative, agent, or agency of the foregoing, other than the NRC and other
federal government agencies licensed or exempted by the NRC.
(72) Personnel monitoring equipment--See
definition for individual monitoring devices.
(73) Phototimer--A method for controlling
exposures to image receptors by the amount of radiation that reaches a
radiation detection device. The radiation detection device is part of an
electronic circuit that controls the duration of time the tube is activated
(See definition for automatic exposure control).
(74) Primary protective barrier--See
definition for protective barrier.
(75) Protective apron--An apron made of
radiation absorbing materials used to reduce radiation exposure.
(76) Protective barrier--A barrier of
radiation absorbing materials used to reduce radiation exposure. The types of
protective barriers are as follows:
(A)
primary protective barrier, which is a barrier sufficient to attenuate the
useful beam to the required degree; or
(B) secondary protective barrier, which is a
barrier sufficient to attenuate the stray radiation to the required degree.
(77) Public dose--The
dose received by a member of the public from exposure to radiation from
licensed/registered and unlicensed/unregistered sources of radiation, whether
in the possession of the licensee/registrant or other person. It does not
include occupational dose or doses received from background radiation, from any
medical administration the individual has received, from exposure to
individuals administered radioactive material and released in accordance with
this section, or from voluntary participation in medical research programs, or
as a member of the public.
(78)
Rad--The special unit of absorbed dose. One rad is equal to an absorbed dose of
100 ergs per gram (erg/g) or 0.01 J/kg (0.01 Gy).
(79) Radiation (ionizing radiation)--Any
alpha particles, beta particles, gamma rays, x-rays, neutrons, high-speed
electrons, high-speed protons, and other particles capable of producing ions.
Radiation, as used in this part, does not include non-ionizing radiation, such
as radio- or microwaves, or visible, infrared, or ultraviolet light.
(80) Radiation area--Any area, accessible to
individuals, in which radiation levels could result in an individual receiving
a dose equivalent in excess of 0.005 rem (0.05 mSv) in 1 hour at 30 cm from the
radiation machine or from any surface that the radiation penetrates.
(81) Radiation machine--An x-ray system,
subsystem, or component capable of producing ionizing radiation except those
devices with radioactive material as the only source of radiation. For purposes
of this section, "radiation machine," "x-ray equipment," "x-ray system," and
"x-ray unit" are equivalent terms. Types of radiation machines include:
(A) A stationary radiation machine, which is
a radiation machine that is installed in a fixed location.
(B) A hand-held radiation machine, which is a
radiation machine that is designed to be hand-held during operation.
(C) A portable radiation machine, which is a
radiation machine that is mounted on a permanent base with wheels or casters
for moving while completely assembled, including a hand-carried radiation
machine that is designed to be mounted on a support while operating.
(D) A mobile radiation machine, which is a
radiation machine that is transported in a vehicle to be used at various
temporary locations.
(82) Radiation safety officer (RSO)--An
individual who has a knowledge of and the authority and responsibility to apply
appropriate radiation protection rules, standards, and practices, who shall be
specifically authorized on a certificate of registration, and who is the
primary contact with the agency.
(83) Radiograph--An image receptor on which
the image is created directly or indirectly by an x-ray exposure and results in
a permanent record.
(84)
Registrant--Any person issued a certificate of registration by the agency in
accordance with the Act and this chapter.
(85) Regulation--See definition for rule.
(86) Rem--The special unit of any
of the quantities expressed as dose equivalent. The dose equivalent in rem Sv
is equal to the absorbed dose in rad or Gy multiplied by the quality factor (1
rem = 0.01 Sv).
(87) Remote
inspection--An examination by the agency of information submitted by the
registrant on a form provided by the agency.
(88) Research and development--Research and
development is defined as:
(A) theoretical
analysis, exploration, or experimentation; or
(B) the extension of investigative findings
and theories of a scientific or technical nature into practical application for
experimental and demonstration purposes, including the experimental production
and testing of models, devices, radiation machines, equipment, materials, and
processes.
(89)
Restricted area--An area, access to which is limited by the registrant for the
purpose of protecting individuals against undue risks from exposure to
radiation. Restricted area does not include areas used as residential quarters,
but separate rooms in a residential building may be set apart as a restricted
area.
(90) Roentgen (R)--The
special unit of exposure. One R equals 2.58 x 10'4
C/kg of air (See definition for exposure).
(91) Rule--Any agency statement of general
applicability that implements, interprets, or prescribes law or policy, or
describes the procedure or practice requirements of an agency. The term
includes the amendment or repeal of a prior section but does not include
statements concerning only the internal management or organization of any
agency and not affecting private rights or procedures. The word "rule" was
formerly referred to as "regulation."
(92) Scan--The complete process of collecting
x-ray transmission data for the production of a tomogram. Data can be collected
simultaneously during a single scan for the production of one or more
tomograms.
(93) Scan time--The
period of time between the beginning and end of x-ray transmission data
accumulation for a single scan.
(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.