(1) "Accessible surface" means the external
surface of the enclosure or housing provided by the manufacturer.
(2) "Added filter" means the filter added to
the inherent filtration.
"Aluminum equivalent" means the thickness of aluminum (Type 1100 alloy)
1 affording the same attenuation, under specified
conditions, as the material in question.
(4) "Analytical x-ray equipment" means any
device that utilizes x-rays for the purpose of examining the microstructure of
(5) "Attenuation block"
means a block or stack, having dimensions 20 cm by 20 cm by 3.8 cm, or type
1100 aluminum alloy1 or other materials having
"Automatic exposure control" means a device that automatically controls one or
more technique factors in order to obtain at a pre-selected location(s) a
required quantity of radiation.
"Beam axis" means a line from the source through the centers of the x-ray
(8) "Beam-limiting device"
means a device that provides a means to restrict the dimensions of the x-ray
means components of diagnostic x-ray systems that are subject to regulations
promulgated under P.L.
(10) "Collimator" means a device or mechanism
by which the x-ray beam is restricted in size.
(11) "Control panel" means that part of the
x-ray control upon which are mounted the switches, knobs, pushbuttons, and
other hardware necessary for manually setting the technique factors.
(12) "Contact therapy apparatus" means x-ray
apparatus designed for therapy at very short treatment distances, 5 centimeters
or less, usually employing tube potentials in the range of 20 to 50
(13) "Dead-man switch" means a
switch so constructed that a circuit closing contact can be maintained only by
continuous pressure on the switch by the operator.
(14) "Diagnostic source assembly" means the
tube housing assembly with a beam limiting device attached.
(15) "Diagnostic type tube housing" means
X-ray tube housing so constructed that at a distance of 1 meter from the
target, the leakage cannot exceed 100 milliroentgens in 1 hour when the tube is
operated at its maximum continuous rated current for the maximum rated tube
potential. An acceptable method for the determination of the maximum leakage
from an x-ray tube is to take measurements at 8 compass points in each of the 3
planes at right angles to each other at 1 meter from the target with the useful
beam blocked with ten half-value layers (HVL) of attenuating
(16) "Diagnostic x-ray
system" means an x-ray system designed for irradiation of any part of the human
body for the purpose of diagnosis or visualization.
(17) "Diaphragm" means a device or mechanism
by which the x-ray beam is restricted in size.
(18) "Entrance exposure rate" means the
roentgens per minute at the point where the center of the useful beam enters
(19) "Equipment" means
design" means one in which all failures of indicator of safety components that
can reasonably be anticipated cause the equipment to fail in a mode such that
personnel are safe from exposure to radiation. For example:
(a) if a light indicating X-RAY ON fails, the
production of x-rays shall be prevented, and
(b) if a shutter status indicator fails, the
shutter shall close.
"Field emission equipment" means equipment that uses an x-ray tube in which
electron emission from the cathode is due solely to the action of an electric
(22) "Filter" means material
placed in the useful beam to absorb preferentially the less penetrating
imaging assembly" means a component that comprises a reception system in which
x-ray photons produce a fluoroscopic image. It includes equipment housing,
electrical interlocks if any, the primary protective barrier, and structural
material providing linkage between the image receptor and the diagnostic source
(24) "General purpose
radiographic x-ray system" means any radiographic x-ray system that, by design,
is not limited to radiographic examination of specific anatomical
(25) "Gonadal shield"
means a protective barrier for the gonads.
(26) "Half-value layer" (HVL) means thickness
of an absorber required to reduce a beam of radiation to one-half its incident
(27) "Image intensifier" means a device that
converts instantaneously by means of photo-emissive surfaces and electronic
circuitry an x-ray pattern into a light pattern of greater intensity than would
have been produced by the original x-ray pattern.
(28) "Image receptor" means 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.
(29) "Inherent filtration" means the
filtration permanently in the useful beam; it includes the window of the x-ray
tube and any permanent tube or source enclosure.
(30) "Kilovolts peak" (kVp) means the crest
value in kilovolts of the potential difference of a pulsating potential
generator. When only one-half of the wave is used, the value refers to the
useful half of the wave.
means kilowatt second which is equal to the product of kilovolts, amperes, and
seconds or 103 kVp.mA.sec.
(32) "Lead equivalent" means the thickness of
lead affording the same attenuation, under specified conditions, as the
material in question.
radiation" means radiation emanating from the diagnostic source assembly except
(a) The useful beam and
(b) Radiation produced when the exposure
switch or timer is not activated.
"Leakage technique factors" means the
technique factors associated with the tube housing assembly that are used in
measuring leakage radiation. They are defined as follows:
(a) For capacitor energy storage equipment,
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 (mAs) or the minimum obtainable from the unit, whichever is
(b) For field emission
equipment rated for pulsed operation, the maximum rated number of x-ray pulses
in an hour for operation at the maximum rated peak tube potential.
(c) For all other equipment, the maximum
rated continuous tube current for the maximum rated peak tube
field" means that area of the intersection of the light beam from the
beam-limiting device and 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 illumination is one-fourth of the maximum in the intersection.
"Misadministration" means an event that
meets the criteria in Rule
(37) "Mobile equipment". See "X-ray
radiographic equipment" means an x-ray machine designed or used for
radiographic examinations of more than one part of the body, or one designed or
used for both diagnosis and therapy.
(39) "Normal operation" means operation under
conditions suitable for collecting data as recommended by a manufacturer of the
x-ray system. Recommended shielding and barriers shall be in place.
(40) "Open beam x-ray equipment" means an
analytical x-ray producing device designed in such a way that the primary beam
is not completely enclosed by the tube housing-apparatus complex during normal
(41) "Phototimer" means
a method for timing radiation exposures to image receptors by the amount of
radiation that reaches a sensitive photo tube behind the receptor and that
provides a means for precisely reproducing densities on these
"Primary beam". See
"Useful beam" as defined in Rule
(43) "Peak tube potential" means the maximum
value of the potential difference across the x-ray tube during an
equipment". See "X-ray equipment".
(45) "Position indicating device" (PID) means
a device on dental x-ray equipment used to indicate the beam position and to
establish a definite source-surface (skin) distance. It may or may not
incorporate or serve as a beam-limiting device.
(46) "Protective apron" means an apron made
of radiation absorbing materials equivalent to at least 0.25 millimeters of
lead used to reduce radiation.
"Protective glove" means a glove made of radiation absorbing materials
equivalent to at least 0.25 millimeters of lead used to reduce radiation
individual" means an individual who has demonstrated to the satisfaction of the
Division that he possesses the knowledge and training to measure ionizing
radiation, to evaluate safety techniques and to advise regarding radiation
means a permanent picture or image produced on a sensitive surface by a form of
radiation other than visible light.
(50) "Rating" means the operating limits as
specified by the original component manufacturer.
(51) "Recording" means producing a permanent
form of an image resulting from x-ray photons (e.g., film, video
(52) "Scattered radiation"
means radiation that, during passage through matter, has been deviated in
direction. It may also have been modified by a decrease in energy.
(53) "Shutter" means an adjustable device,
generally of lead, fixed to an x-ray tube housing to intercept or collimate the
(54) "Source" means
the focal spot of the x-ray tube.
(55) "Source-image receptor distance" (SID)
means the distance from the source to the center of the input surface of the
equipment". See "X-ray equipment".
(57) "Stray radiation" means the sum of
leakage and scattered radiation.
"Technique factors" means the conditions
of operation. They 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
(c) For all other
equipment, peak tube potential in kV and either tube current in mA and exposure
time in seconds, or the product of the tube current and exposure time in
(59) "Total filter"
means the sum of the inherent and added filters.
(60) "Tube" means an x-ray tube, unless
housing-apparatus complex" means those parts of an analytical x-ray device in
which x-rays are produced and utilized.
(62) "Tube housing assembly" means the tube
housing with tube installed. It includes high-voltage and/or filament
transformers and other appropriate elements when they are contained within the
(63) "Tube rating
chart" means the set of curves that specify the rated limits of operation of
the tube in terms of the technique factors.
(64) "Variable-aperture beam-limiting device"
means a beam limiting device that has capacity for stepless adjustment of the
x-ray field size at given SID.
"Visible area" means that portion of the input surface of the image receptor
over which incident x-ray photons are producing a visible image.
(66) "X-ray apparatus" means any device for
the production of x-rays.
"X-ray control" means a device that controls input power to the x-ray
high-voltage generator and/or the x-ray tube. It includes equipment that
controls the technique factors of the x-ray exposure.
"X-ray equipment" means an x-ray system,
subsystem, or component thereof.
means x-ray equipment mounted on a permanent base with wheels and/or casters
for moving while completely assembled.
(b) Portable means x-ray equipment designed
to be hand-carried.
means x-ray equipment that is installed in a fixed location.
(d) Transportable means x-ray equipment to be
installed in a vehicle or that may be readily disassembled for transport in a
(e) "Hand-held" means
portable X-ray equipment that is specifically designed to operate when held in
a person's hand and is approved by the U.S. Food and Drug Administration
(69) "X-ray field"
means 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 exposure
rate is one-fourth of the maximum in the intersection.
(70) "X-ray high-voltage generator" means a
device that transforms electrical energy from the potential supplied by the
x-ray control to the tube operating potential. The device may also include
direct current, filament transformers for the x-ray tube(s), high-voltage
switches, electrical protective devices, and other appropriate
(71) "X-ray gauge" means
an x-ray producing device designed and manufactured for the purpose of
detecting, measuring, gauging, or controlling thickness, density, level, or
system" means 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.
(73) "X-ray subsystem" means any combination
of two or more components of an x-ray system for which there are requirements
specified in this Chapter.
"X-ray tube" means any electron tube that is designed for the conversion of
electrical energy into x-ray energy.
1 The nominal chemical composition
of type 1100 aluminum alloy is 99.00 percent minimum aluminum, 0.12 percent
copper. "Aluminum - Standards and Data," The Aluminum Association, New York,
New York. (1969).