| (22) 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.
(23) CT conditions of operation--All selectable parameters
governing the operation of a CT system including, but not limited
to, nominal tomographic section thickness, filtration, and the technique
factors as defined in this subsection.
(24) CT gantry--The tube housing assemblies, beam-limiting
devices, detectors, and the supporting structures and frames that
hold these components.
(25) Cumulative air kerma (CAK)--The air kerma accumulated
at a specific point in space relative to the fluoroscopic gantry during
a procedure. CAK does not include tissue backscatter and is measured
in Gy. Some manufacturers identify CAK as cumulative dose (CD).
(26) Diagnostic source assembly--The tube housing assembly
with a beam-limiting device attached.
(27) Diagnostic x-ray system--An x-ray system designed
for irradiation of any part of the human body for the purpose of diagnosis
or visualization.
(28) Dose-area product (DAP)--Dose-area product is
the integral of air kerma (absorbed dose to air) across the entire
x-ray beam emitted from the x-ray tube. DAP is a surrogate measurement
for the entire amount of energy delivered to the patient by the beam.
DAP is measured in R x cm2 (cGy x cm2 ).
(29) Dose-length product (DLP)--DLP is the CTDIvol multiplied by the scan length (slice thickness
x number of slices) in centimeters. It reflects the total energy absorbed
attributable to the complete scan acquisition but is independent of
what is actually scanned.
(30) Entrance exposure (Entrance air kerma)--The entrance
exposure in air expressed in roentgens (R) or the entrance dose in
air (air kerma) expressed in gray (Gy), measured at the point where
the center of the useful beam enters the patient.
(31) Entrance exposure rate (air kerma rate)--The exposure
(air kerma) per unit time at the point where the center of the useful
beam enters the patient.
(32) 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.
(33) 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% isodose
line.
(34) Filter--Material placed in the useful beam to
preferentially absorb selected radiations.
(35) Fluoroscopic system--A system 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.
(36) Fluoroscopically-Guided Interventional (FGI) Procedures--An
interventional diagnostic or therapeutic procedure performed via percutaneous
or other access routes, usually with local anesthesia or intravenous
sedation, which uses external ionizing radiation in the form of fluoroscopy
to localize or characterize a lesion, diagnostic site, or treatment
site, to monitor the procedure, and to control and document therapy.
FGI procedures may include but not be limited to:
(A) TIPS creation (transjugular intrahepatic portosystemic
shunt);
(B) Embolization (any location, any lesion);
(C) Stroke therapy;
(D) Biliary drainage;
(E) Angioplasty with or without stent placement;
(F) Stent-graft placement;
(G) Chemoembolization;
(H) Angiography and intervention for gastrointestinal
hemorrhage;
(I) Carotid stent placement;
(J) RF (radiofrequency) cardiac ablation;
(K) Complex placement of cardiac EP (electrophysiology)
devices; and
(L) PCI (percutaneous coronary intervention) (single
or multiple vessel).
(37) 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.
(38) General purpose x-ray system--Any x-ray system
that is not limited by design to radiographic examinations of specific
anatomical regions.
(39) Gonadal shield--A protective barrier for the testes
or ovaries.
(40) 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.
(41) 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.
(42) Healing arts screening--The testing of asymptomatic
human beings using radiation machines for the detection or evaluation
of health indications when such tests are not specifically and individually
ordered by a licensed practitioner of the healing arts legally authorized
to prescribe such x-ray tests for the purpose of diagnosis or treatment.
(43) High level control for fluoroscopy--Any selected
mode having an entrance exposure rate (air kerma rate) above 10 roentgens
per minute (R/min) or (100 mGy/min). This mode shall meet the high
level requirements in subsection (m)(3)(A)(i)(II), (ii)(II), or (iii)(II)
of this section.
(44) Image intensifier--A device, installed in its
housing that instantaneously converts an x-ray pattern into a corresponding
light or digital image.
(45) Image receptor--Any device, such as a fluorescent
screen or radiographic film 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.
(46) Irradiation--The exposure of matter to ionizing
radiation.
(47) kV--Kilovolt.
(48) kVp--Kilovolt peak (See definition for peak tube
potential).
(49) kWs--Kilowatt-second. It is equivalent to 10 E
3 watt-second, where 1 watt-second = 1 kV x 1 milliampere (mA) x 1
second.
(50) Lead equivalent--The thickness of lead affording
the same attenuation, under specified conditions, as the material
in question.
(51) Leakage radiation--Radiation emanating from the
diagnostic source assembly except for the useful beam and radiation
produced when the exposure switch or timer is not activated.
(52) Leakage technique factors--The technique factors
associated with the diagnostic source assembly that is used in measuring
leakage radiation. They are defined as follows:
(A) for diagnostic source assemblies intended for capacitor
energy storage equipment, the maximum-rated peak tube potential and
the maximum-rated number of exposures in an hour for operation at
the maximum-rated peak tube potential with the quantity of charge
per exposure being 10 millicoulombs (10 milliampere-second (mAs))
or the minimum obtainable from the unit, whichever is larger;
(B) for diagnostic source assemblies intended for field
emission equipment rated for pulsed operation, the maximum-rated peak
tube potential and the maximum-rated number of x-ray pulses in an
hour for operation at the maximum-rated peak tube potential; or
(C) for all other diagnostic source assemblies, the
maximum-rated peak tube potential and the continuous tube current
for the maximum-rated peak tube potential.
(53) Licensed medical physicist--An individual holding
a current Texas license under the Medical Physics Practice Act, Texas
Occupations Code, Chapter 602, with a specialty in diagnostic medical
physics.
(54) mA--Milliampere.
(55) mAs--Milliampere-second.
(56) Medical research--The investigation of various
health risks and diseases.
(57) Mobile service operation--The provision of x-ray
systems and personnel at temporary sites for limited time periods.
The x-ray systems may be fixed inside a motorized vehicle or may be
a radiation machine that may be removed from the vehicle and taken
into a facility for use.
(58) Multiple slice tomogram system--A computed tomography
x-ray system that obtain x-ray transmission data simultaneously during
a single scan to produce more than one tomogram.
(59) Nominal tomographic section thickness--The full-width
at half-maximum of the sensitivity profile taken at the center of
the cross sectional volume over which x-ray transmission data are
collected.
Cont'd... |
