| and in relation to utilization
of ionizing radiation and radiation machines in the public interest.
(12) Attenuate--To reduce the exposure rate (air kerma
rate) upon passage of radiation through matter.
(13) 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).
(14) 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 sources of radiation regulated by
the agency.
(15) Barrier--(See definition for protective barrier.)
(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) 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.
(19) Certified radiation machines--Radiation machines
that have been certified in accordance with Title 21, Code of Federal
Regulations (CFR).
(20) Coefficient of variation or C--The ratio of the
standard deviation to the mean value of a population of observations.
It is estimated using the following equation:
Attached Graphic
(21) Collective dose--The sum of the individual doses
received in a given period by a specified population from exposure
to a specified source of radiation.
(22) Commissioner--The Commissioner of the Department
of State Health Services.
(23) 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 = ΣWT HT.50 ).
(24) Contested case--A proceeding in which the agency
determines the legal rights, duties, or privileges of a party after
an opportunity for adjudicative hearing.
(25) Continuous pressure type switch--A switch so constructed
that a circuit closing contact can be maintained only by continuous
pressure on the switch by the operator.
(26) Consultant--An individual who is not routinely
engaged in work under the registrant who provides advice related to
compliance with this chapter.
(27) Control panel--The part of the radiation machine
where the switches, knobs, push buttons, and other hardware necessary
for manually setting the technique factors are located.
(28) 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.
(29) Deep dose equivalent (Hd ),
that applies to external whole body exposure--The dose equivalent
at a tissue depth of 1 centimeter (1000 milligrams per square centimeter).
(30) Dentist--An individual licensed to practice dentistry
by the Texas State Board of Dental Examiners.
(31) Diagnostic source assembly--The tube housing assembly
with a beam-limiting device attached.
(32) Director--The director of the radiation control
program under the agency's jurisdiction.
(33) 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.
(34) 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.
(35) 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.
(36) 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 = ΣWT HT ).
(37) Embryo/fetus--The developing human organism from
conception until the time of birth.
(38) Entrance exposure (Entrance air kerma)--The entrance
exposure in air expressed in roentgens or the entrance dose in air
(air kerma) expressed in gray, measured at the point where the center
of the useful beam enters the patient.
(39) 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.
(40) 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 International System of Units (SI) unit of exposure
is the coulomb per kilogram. The roentgen is the special unit of exposure.
For purposes of this section, this term is used as a noun.
(41) Exposure rate (air kerma rate)--The exposure per
unit of time. For purposes of this section, "air kerma rate" is an
equivalent term.
(42) External dose--That portion of the dose equivalent
received from any source of radiation outside the body.
(43) 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.
(44) 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.
(45) Filter--Material placed in the useful beam to
absorb selected radiations preferentially.
(46) Gray (Gy)--The SI unit of absorbed dose. One gray
is equal to an absorbed dose of one joule per kilogram or 100 rad.
(47) Half-value layer (HVL)--The thickness of a specified
material that attenuates the beam of radiation to an extent such that
the exposure rate (air kerma rate) is reduced to one-half of its original
value.
(48) Healing arts--Any system, treatment, operation,
diagnosis, prescription, or practice for the ascertainment, cure,
relief, palliation, adjustment, or correction of any human disease,
ailment, deformity, injury, or unhealthy or abnormal physical or mental
condition.
(49) Hearing--A proceeding to examine an application
or other matter before the agency in order to adjudicate rights, duties,
or privileges.
(50) Human use--For exposure to x-ray radiation from
radiation machines, the external administration of radiation to human
beings for healing arts purposes or research or development specifically
authorized by the agency.
(51) 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.
(52) Individual--Any human being.
(53) Individual monitoring--The assessment of dose
equivalent to an individual by the use of:
(A) individual monitoring devices; or
(B) survey data.
(54) 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, but are not limited to,
film badges, thermoluminescence dosimeters, optically stimulated luminescence
dosimeters, pocket ionization chambers (pocket dosimeters), and electronic
personal dosimeters.
(55) Informal conference--A meeting held by the agency
with a person to discuss the following:
(A) safety, safeguards, or environmental problems;
(B) compliance with regulatory or registration condition
requirements;
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