North Carolina Administrative Code › Title 10A - HEALTH AND HUMAN SERVICES › Chapter 15 - RADIATION PROTECTION › Section .0600 - X RAYS IN THE HEALING ARTS › Section 15 .0602 - DEFINITIONS

Current through Register Vol. 39, No. 2, July 15, 2024
(a) As used in this
				Section, the following definitions shall apply:
(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.
(3)
				"Aluminum equivalent" means the thickness of aluminum, type 1100 alloy,
				affording the same attenuation, under specified conditions, as the material in
				question. The nominal composition of type 1100 aluminum alloy is 99.00 percent
				minimum aluminum and 0.12 percent copper.
(4) "Attenuation block" means a block or
				stack, having dimensions 20 cm by 20 cm by 3.8 cm, of type 1100 aluminum alloy
				or other materials having equivalent attenuation.
(5) "Automatic exposure control" means a
				device which automatically controls one or more technique factors in order to
				obtain, at a preselected location(s), a required quantity of radiation.
				Phototimer is described separately.
(6) "Beam axis" means a line from the source
				of x-rays through the centers of the x-ray fields.
(7) "Beam-limiting device" means a device
				which provides a means to restrict the dimensions of the x-ray field.
(8) "Cephalometric device" means a device
				intended for the radiographic visualization and measurement of the dimensions
				of the human head.
(9) "Changeable
				filters" means any added filter which can be removed from the useful x-ray beam
				through any electronic, mechanical or physical process.
(10) "Contact therapy system" means that the
				x-ray tube target is put within five centimeters of the surface being
				treated.
(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) "Cooling curve" means
				the graphical relationship between heat units stored and cooling
				time.
(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 device attached.
(15) "Diagnostic-type protective tube
				housing" means a tube housing so constructed that the leakage radiation
				measured at a distance of one meter from the source does not exceed 100 mR in
				one hour when the tube is operated at its leakage technique factors.
(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)
				"Direct scattered radiation" means that radiation which has been deviated in
				direction by materials irradiated by the useful beam.(See also scattered
				radiation).
(18) "Entrance exposure
				rate" means the roentgens per unit time at the point where the center of the
				useful beam enters the patient.
(19) "Exposure" means 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 special unit of exposure is the roentgen.
(20) "Field emission equipment" means
				equipment which uses an x-ray tube in which electron emission from the cathode
				is due solely to the action of an electric field.
(21) "Filter" means material placed in the
				useful beam to preferentially attenuate selected radiations.
(22) "Fluoroscopic imaging assembly" means a
				subsystem in which x-ray photons produce a fluoroscopic image. It includes the
				image receptor(s) such as the image intensifier and spot-film device,
				electrical interlocks and structural material providing linkage between the
				image receptor and the diagnostic source assembly.
(23) "General purpose radiographic x-ray
				system" means any radiographic x-ray system which, by design, is not limited to
				radiographic examination of specific anatomical regions.
(24) "Gonad shield" means a protective
				barrier used to reduce exposure to the testes or ovaries.
(25) "Half-value layer (HVL)" means the
				thickness of specified material which attenuates the beam of radiation to an
				extent such that the exposure rate is reduced to one-half of its original
				value. In this definition the contribution of all scattered radiation, other
				than any which might be present initially in the beam concerned, is deemed to
				be excluded.
(26) "Healing arts
				mass screening" means the examination of human beings using x-rays 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 who is legally authorized to prescribe such x-ray tests for the purpose of
				diagnosis or treatment. It does not include the use of x-ray tests as a
				requirement for hospital admission or as a condition of employment.
(27) "Image intensifier" means a device,
				including housing, which converts an x-ray pattern into a corresponding light
				image of higher energy density.
(28) "Image receptor" means any device, such
				as fluorescent screen or radiographic film, which transforms incident x-ray
				photons either into a visible image or into another form which 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) "Installation" means the act of physical
				movement of a radiographic system from one location to another in conjunction
				with a change of ownership.
(31)
				"Lead equivalent" means the thickness of lead affording the same attenuation,
				under specified conditions, as the material in question.
(32) "Leakage radiation" means radiation
				emanating from a diagnostic or therapeutic source assembly except for:
(A) the useful beam and
(B) radiation produced when the exposure
				switch or timer is not activated.
(33) "Leakage technique factors" means the
				technique factors associated with the diagnostic or therapeutic source assembly
				(i.e., tube housing and beam limiting device) which are 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 (mC) 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; and
(C) for all other
				diagnostic or therapeutic source assemblies, the maximum rated peak tube
				potential and the maximum rated continuous tube current for the maximum rated
				peak tube potential.
(34) "Light 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.
(35)
				"Maximum line current" means the rms (root-mean-square) current in the supply
				line of an x-ray machine operating at its maximum rating.
(36) "Mobile equipment" (see x-ray
				equipment).
(37) "Peak tube
				potential" means the maximum value of the potential difference across the x-ray
				tube during an exposure.
(38)
				"Phototimer" means a method for controlling radiation exposures to image
				receptors by the amount of radiation which reaches a radiation monitoring
				device(s). The radiation monitoring device(s) is part of an electronic circuit
				which controls the duration of time the tube is activated (see also "Automatic
				exposure control").
(39) "Portable
				equipment" (see x-ray equipment).
(40) "Position indicating device (PID)" means
				a device on dental x-ray equipment used to indicate the beam position and to
				establish a definite source-skin distance. It may or may not incorporate or
				serve as a beam-limiting device.
(41) "Primary protective barrier" means the
				material, excluding filters, placed in the useful beam, for radiation
				protection purposes, to reduce the radiation exposure.
(42) "Protective apron" means an apron made
				of radiation attenuating materials used to reduce radiation exposure.
(43) "Protective barrier" means a barrier of
				radiation attenuating material(s) used to reduce radiation exposure. Types of
				protective barriers are defined in other items of this Rule.
(44) "Protective glove" means a glove made of
				radiation attenuating materials used to reduce radiation exposure.
(45) "Qualified expert" means an individual
				who is registered pursuant to Rule.0205 of this Chapter.
(46) "Radiograph" means an image receptor on
				which the image has been created directly or indirectly by an x-ray pattern and
				results in a permanent record.
(47)
				"Radiographic imaging system" means any system whereby a permanent or
				semi-permanent image is recorded on an image receptor by the action of ionizing
				radiation.
(48) "Rating" means the
				operating limits as specified by the component manufacturer.
(49) "Recording" means producing a permanent
				form of an image resulting from x-ray photons such as film and video
				tape.
(50) "Registrant", as used in
				this Section, means any person who owns or possesses and administratively
				controls an x-ray system which is used to deliberately expose humans or animals
				to the useful beam of the system and is required by the provisions contained in
				Sections.0100 and.0200 of this Chapter to register with the agency.
(51) "Response time" means the time required
				for an instrument system to reach 90 percent of its final reading when the
				radiation-sensitive volume of the instrument system is exposed to a step change
				in radiation flux from zero sufficient to provide a steady state mid-scale
				reading.
(52) "Scattered radiation"
				means radiation that, during passage through matter, has been deviated in
				direction. (See also "direct scattered radiation".)
(53) "Secondary protective barrier" means a
				barrier sufficient to attenuate the stray radiation to the required
				degree.
(54) "SID" means
				source-image receptor distance.
(55) "Source" means the focal spot of the
				x-ray tube.
(56) "Source-image
				receptor distance (SID)" means the distance from the source to the center of
				the input surface of the image receptor.
(57) "Spot film" means a radiograph which is
				made during a fluoroscopic examination to permanently record conditions which
				exist during that fluoroscopic procedure.
(58) "Stationary equipment" (see x-ray
				equipment).
(59) "Stray radiation"
				means the sum of leakage and scattered radiation.
(60) "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 pulses;
				and
(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 tube current and exposure time in mAs.
(61) "Therapeutic-type protective
				tube housing" means the tube housing with tube installed, and it includes high
				voltage and filament transformers and other appropriate elements when they are
				contained within that housing.
(62)
				"Transportation equipment" means x-ray equipment which is installed in a
				vehicle or trailer.
(63) "Tube"
				means an x-ray tube, unless otherwise specified.
(64) "Tube housing assembly" means the tube
				housing with tube installed. It includes high-voltage and filament transformers
				and other appropriate elements when they are contained within the tube
				housing.
(65) "Tube rating chart"
				means the set of curves which specify the rated limits of operation of the tube
				in terms of the technique factors.
(66) "Useful beam" means the radiation which
				passes through the tube housing port and the aperture of the beam-limiting
				device when the exposure switch or timer is activated.
(67) "Variable-aperture beam-limiting device"
				means a beam-limiting device which has capacity for stepless adjustment of the
				x-ray field size at the given SID.
(68) "Visible area" means that portion of the
				input surface of the image receptor over which incident x-ray photons produce a
				visible image.
(69) "X-ray control"
				means a device which 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 which control the technique factors
				of an x-ray exposure.
(70) "X-ray
				equipment" means an x-ray system, subsystem or component thereof.
(A) "Mobile equipment" means x-ray equipment
				mounted on a permanent base with wheels or casters for moving while completely
				assembled.
(B) "Portable equipment"
				means x-ray equipment designed to be hand-carried.
(C) "Stationary equipment" means x-ray
				equipment which is installed in a fixed location.
(71) "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.
(72) "X-ray
				high-voltage generator" means a device which transforms electrical energy from
				the potential supplied by the x-ray control to the tube operating potential.
				The device may also include means for transforming alternating current to
				direct current, filament transformers for the x-ray tube(s), high-voltage
				switches, electrical protective devices and other appropriate
				elements.
(73) "X-ray 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 which function with the system are considered
				integral parts of the system.
(74)
				"X-ray subsystem" means any combination of two or more components of an x-ray
				system for which there are requirements specified in this Section.
(75) "X-ray tube" means an electron tube
				which is designed for the conversion of electrical energy into x-ray
				energy.