| (60) Non-certified x-ray systems--X-ray systems manufactured
and assembled prior to certification requirements of Title 21, CFR,
effective as specified in Title 21, CFR, Part 1020.30(a).
(61) Patient--An individual subjected to healing arts
examination, diagnosis, or treatment.
(62) Peak tube potential--The maximum value of the
potential difference in kilovolts across the x-ray tube during an
exposure.
(63) Phantom--A volume of material behaving in a manner
that can be related to tissue with respect to the attenuation and
scattering of radiation.
(64) 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).
(65) Physician--An individual licensed by the Texas
Medical Board.
(66) Portable x-ray systems--X-ray systems that are
mounted on a permanent base with wheels and/or casters for moving
while completely assembled. Portable x-ray systems may also include
x-ray systems designed to be hand-carried.
(67) Practitioner of the healing arts (practitioner)--A
person licensed to practice healing arts by either the Texas Medical
Board as a physician, the Texas Board of Chiropractic Examiners, or
the Texas State Board of Podiatric Medical Examiners.
(68) Primary protective barrier--(See definition for
protective barrier).
(69) Protective apron--An apron made of radiation attenuating
materials used to reduce radiation exposure.
(70) 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--A barrier sufficient
to attenuate the useful beam to the required degree.
(B) secondary protective barrier--A barrier sufficient
to attenuate the stray radiation to the required degree.
(71) Protective glove--A glove made of radiation attenuating
materials used to reduce radiation exposure.
(72) Radiation machine--Any device capable of producing
ionizing radiation except those devices with radioactive material
as the only source of radiation.
(73) Radiation oncologist--A physician with a specialty
in radiation therapy.
(74) Radiograph--An image receptor on which the image
is created directly or indirectly by an x-ray exposure and results
in a permanent record.
(75) Radiologist--A physician with a specialty in using
ionizing and non-ionizing radiation for medical imaging and interpretation
for diagnostic and treatment purposes.
(76) Reference level--The suggested levels at which
a facility should review its methods and determine if acceptable image
quality can be achieved at a lower radiation output level as determined
by measurements taken from a selected phantom. The specific purpose
of the reference level is to provide a benchmark for comparison of
imaging equipment performance under prescribed conditions and is not
intended to define a maximum or minimum exposure limit for any patient.
(77) Reference plane--A plane that is displaced from
and parallel to the tomographic plane.
(78) Roentgen (R)--The special unit of exposure. One
roentgen (R) equals 2.58 x 10-4 C/kg
of air.
(79) 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.
(80) Scan increment--The amount of relative displacement
of the patient with respect to the CT system between successive scans
measured along the direction of such displacement.
(81) Scan sequence--A preselected set of 2 or more
scans performed consecutively under preselected CT conditions of operation.
(82) Scan time--The period of time between the beginning
and end of x-ray transmission data accumulation for a single scan.
(83) Scattered radiation--Radiation that has been deviated
in direction during passage through matter.
(84) Secondary protective barrier (See definition for
protective barrier).
(85) 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.
(86) Single tomogram system--CT system that obtains
x-ray transmission data during a scan to produce a single tomogram.
(87) Source--The focal spot of the x-ray tube.
(88) Source-to-image receptor distance--The distance
from the source to the center of the input surface of the image receptor.
(89) Source-to-skin distance (SSD)--The distance from
the source to the skin of the patient.
(90) Special purpose x-ray system--Any x-ray system
that is limited by design to radiographic examinations of specific
anatomical regions. Special purpose x-ray systems include, but are
not limited to, dedicated chest units, cystography units, and head
and skull units.
(91) Special procedures--The application of special
x-ray systems and specialized techniques to obtain required diagnostic
information. Special procedures include, but are not limited to, angiography,
cardiac catheterization, myelography, and surgery.
(92) Spot film--A radiograph that is made during a
fluoroscopic examination to permanently record conditions that exist
during that fluoroscopic procedure.
(93) Spot film device--A device intended to transport
and/or position a radiographic image receptor between the x-ray source
and fluoroscopic image receptor. It includes a device intended to
hold a cassette over the input end of an image intensifier for the
purpose of making a radiograph.
(94) Stationary x-ray system--A stationary x-ray system
that is installed in a fixed location.
(95) Stray radiation--The sum of leakage and scattered
radiation.
(96) Supervision--The delegating, by the practitioner,
of the task of applying radiation to persons who perform tasks under
the practitioner's control and who are certified under the Medical
Radiologic Technologist Act, Texas Occupations Code, Chapter 601.
The practitioner assumes full responsibility for these tasks and shall
assure that the tasks will be administered correctly.
(97) Target--The part of a radiation machine head that
by design intercepts a beam of accelerated particles with subsequent
emission of other radiation.
(98) Technique chart--A chart that provides technical
factors, anatomical examination, patient thickness for examination
being performed, and source-to-image distance needed to make clinical
radiographs when the radiographic system is in manual mode.
(99) 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.
(100) Tomogram--The depiction of the x-ray attenuation
properties of a section through the body.
(101) Tomographic plane--The geometric plane that is
identified as corresponding to the output.
(102) Tomographic section--The volume of an object
whose x-ray attenuation properties are imaged in a tomogram.
(103) 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.
(104) Tube--An x-ray tube, unless otherwise specified.
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