Tenn. Comp. R. & Regs. 0400-20-06-.03 - DEFINITIONS

(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) 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 materials.
(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 equivalent attenuation.
(6) "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.
(7) "Beam axis" means a line from the source through the centers of the x-ray fields.
(8) "Beam-limiting device" means a device that provides a means to restrict the dimensions of the x-ray field.
(9) "Certified components" means components of diagnostic x-ray systems that are subject to regulations promulgated under P.L. 90-602.
(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 kVp.
(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 material.
(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 the patient.
(19) "Equipment" means X-ray equipment.
(20) "Fail-safe 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.
(21) "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 field.
(22) "Filter" means material placed in the useful beam to absorb preferentially the less penetrating radiations.
(23) "Fluoroscopic 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 assembly.
(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 regions.
(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 exposure rate.
(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.
(31) "kWs" 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.
(33) "Leakage radiation" means radiation emanating from the diagnostic source assembly except for:
(a) The useful beam and
(b) Radiation produced when the exposure switch or timer is not activated.
(34) "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 larger.
(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 potential.
(35) "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.
(36) "Misadministration" means an event that meets the criteria in Rule 0400-20-05-.145.
(37) "Mobile equipment". See "X-ray equipment".
(38) "Multipurpose 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 operation.
(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 receptors.
(42) "Primary beam". See "Useful beam" as defined in Rule 0400-20-04-.04.
(43) "Peak tube potential" means the maximum value of the potential difference across the x-ray tube during an exposure.
(44) "Portable 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.
(47) "Protective glove" means a glove made of radiation absorbing materials equivalent to at least 0.25 millimeters of lead used to reduce radiation exposure.
(48) "Qualified 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 protection needs.
(49) "Radiograph" 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 tape).
(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 useful beam.
(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 image receptor.
(56) "Stationary equipment". See "X-ray equipment".
(57) "Stray radiation" means the sum of leakage and scattered radiation.
(58) "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.
(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 mAs.
(59) "Total filter" means the sum of the inherent and added filters.
(60) "Tube" means an x-ray tube, unless otherwise specified.
(61) "Tube 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 tube housing.
(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.
(65) "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.
(67) "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.
(68) "X-ray equipment" means an x-ray system, subsystem, or component thereof.
(a) Mobile 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.
(c) Stationary 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 vehicle.
(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 (FDA).
(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 elements.
(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 interface location.
(72) "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 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.
(74) "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).


Tenn. Comp. R. & Regs. 0400-20-06-.03
Original rule filed February 22, 2012; effective May 22, 2012. Amendments filed September 10, 2019; effective 12/9/2019.

Authority: T.C.A. ยงยง 4-5-201, et seq.; 68-202-101, et seq.; and 68-202-201, et seq.

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