64E-5.501. Definitions

As used in this part, the following definitions apply:

(1) “Accessible surface” means the external surface of any enclosure or housing.

(2) “Added filtration” means any filtration which is in addition to the inherent filtration.

(3) “Aluminum equivalent” means the thickness of type 1100 aluminum alloy affording the same degree of radiation attenuation, under specified conditions, as the material in question. The nominal chemical composition of type 1100 aluminum alloy is 99.00 percent minimum aluminum, 0.12 percent copper.

(4) “Assembler” means any person engaged in the business of assembling, replacing or installing one or more components into an x-ray system or subsystem. The term includes the owner of an x-ray system or his employee or agent who assembles components into an x-ray system that is subsequently used to provide professional or commercial services.

(5) “Attenuation block” means a block or stack, having dimensions 20 centimeters by 20 centimeters by 3.8 centimeters, of type 1100 aluminum alloy or other materials having equivalent attenuation.

(6) “Automatic exposure control” means a device which automatically controls one or more technique factors in order to obtain, at a preselected location, a required quantity of radiation. See also “Phototimer”.

(7) “Barrier”. See “Protective barrier”.

(8) “Beam axis” means a line from the source through the centers of the x-ray field.

(9) “Beam-limiting device” means a device which provides a means to restrict the dimensions of the x-ray field, except for beam-blocking or beam-shaping devices used in radiation therapy.

(10) “Beam monitoring system” means a system designed to detect and measure the radiation present in the useful beam.

(11) “Cephalometric device” means a device intended for the radiographic visualization and measurement of the dimensions of the human head.

(12) “Certified components” means components of x-ray systems which are subject to regulations promulgated under Public Law 90-602, the Radiation Control for Health and Safety Act of 1968.

(13) “Certified system” means any x-ray system which has one or more certified components.

(14) “Changeable filters” means any filter which can be readily removed from the useful beam through any electronic, mechanical or physical process.

(15) “Contact therapy system” means an x-ray system used for therapy with the x-ray tube port placed in contact with or within 5 centimeters of the surface being treated.

(16) “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 and operating modes.

(17) “Cooling curve” means the graphical relationship between the heat units stored and cooling time.

(18) “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.

(19) “Diagnostic source assembly” means the tube housing assembly with a beam-limiting device attached.

(20) “Diagnostic x-ray system” means an x-ray system designed for irradiation of any part of the human body as an aid to diagnosis through visualization of anatomical parts.

(21) “Direct scattered radiation” means that radiation which has been deviated in direction only by materials irradiated by the useful beam. See also “Scattered radiation”.

(22) “Entrance exposure rate” means the roentgens (C per kg) per unit time at the point where the center of the useful beam enters the patient.

(23) “Equipment”. See “X-ray equipment”.

(24) “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.

(25) “Filter” means material placed in the useful beam to preferentially absorb selected radiation.

(26) “Fluoroscopic imaging assembly” means a subsystem in which x-ray photons produce a fluoroscopic image. It includes the image receptors such as the image intensifier and spot film device, equipment housings, electrical interlocks, if any, the primary protective barrier, and structural material providing linkage between the image receptor and the diagnostic source assembly.

(27) “General purpose radiographic x-ray system” means any diagnostic radiographic x-ray system, except computed tomography systems, which, by design, is not limited to radiographic examination of a specific anatomical region.

(28) “Gonad shield” means a primary protective barrier for the testes or ovaries.

(29) “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.

(30) “Healing arts self-referral” means the testing of human beings using x-ray 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 purposes of diagnosis or medical treatment.

(31) “Heat unit” means a unit of energy equal to the product of the peak kilovoltage, milliamperes, and seconds, or kVp × mA × seconds.

(32) “Image intensifier” means a device, when installed in its housing, that instantaneously converts an x-ray pattern into a corresponding light image of higher energy density.

(33) “Image receptor” means any device, such as a 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 electronic or chemical transformations.

(34) “Image receptor support” means that part of a mammographic system designed to support the image receptor in a horizontal plane during the mammographic examination.

(35) “Inherent filtration” means the filtration of the useful beam provided by the permanently installed components of the x-ray tube housing assembly.

(36) “Irradiation” means the exposure of matter to ionizing radiation.

(37) “Kilovolts peak (kVp)”. See “Peak tube potential”.

(38) “kV” means kilovolts.

(39) “kWs” means kilowatt second. It is equivalent to kV × mA × seconds × 10-3.

(40) “Lead equivalent” means the thickness of lead affording the same attenuation, under specified conditions, as the material in question.

(41) “Leakage radiation” means radiation emanating from the diagnostic or therapeutic source assembly, except for the useful beam and radiation produced when the exposure switch or timer is not activated.

(42) “Leakage technique factors” means the technique factors associated with the diagnostic or therapeutic source assembly 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 milliampere seconds (10 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.

(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.

(43) “Light field” means that area of the intersection of the light beam from the beam-limiting device and one of the sets 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.

(44) “Line-voltage regulation” means the difference between the no-load and the load line potentials expressed as a percent of the load line potential. It is calculated using the following equation: Percent line-voltage regulation = 100 (Vn - V1)/V1 where Vn = no-load line potential and V1 = load line potential.

(45) “mAs” means milliampere second.

(46) “Maximum line current” means the root-mean-square current in the supply line of an x-ray machine operating at its maximum rating.

(47) “Mobile x-ray equipment”. See “X-ray equipment”.

(48) “Peak tube potential” means the maximum value of the potential difference across the x-ray tube during an exposure.

(49) “Phantom” means a volume of material behaving in a manner similar to tissue with respect to the attenuation and scattering of radiation.

(50) “Photofluorographic” means an x-ray system designed to superimpose a patient’s anatomical x-ray image from a fluoroscopic input phosphor onto a film strip through a system of lenses.

(51) “Phototimer” means a device for controlling radiation exposures to image receptors by the amount of radiation which reaches a radiation monitoring device. The radiation monitoring device is part of an electronic circuit which controls the duration of time the tube is energized. See also “Automatic exposure control”.

(52) “Portable x-ray equipment”. See “X-ray equipment”.

(53) “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.

(54) “Primary dose monitoring system” means a system which will monitor the useful beam during irradiation and which will terminate irradiation when a preselected number of dose monitor units have been delivered.

(55) “Primary protective barrier”. See “Protective barrier”.

(56) “Protective apron” means an apron made of radiation absorbing material used to reduce radiation exposure.

(57) “Protective barrier” means a barrier containing radiation absorbing material used to reduce radiation exposure. The types of protective barriers are as follows:

(a) “Primary protective barrier” means the material, excluding filters, placed in the useful beam to reduce the radiation exposure by a required degree, for protection purposes.

(b) “Secondary protective barrier” means a barrier sufficient to attenuate the stray radiation by a required degree, for protection purposes.

(58) “Protective glove” means a glove made of radiation absorbing material and used to reduce radiation exposure.

(59) “Qualified person” means an individual who has the knowledge and training to measure ionizing radiation, to evaluate safety techniques and to advise regarding radiation protection needs.

(60) “Radiation detector” means a device which, in the presence of radiation, provides a signal or other indication suitable for use in measuring single or multiple quantities of incident radiation.

(61) “Radiation therapy simulation system” means a radiographic or fluoroscopic x-ray system, intended for localizing the volume to be exposed during radiation therapy, and confirming the position and size of the therapeutic irradiation field.

(62) “Radiograph” means an image receptor on which the image is created directly or indirectly by an x-ray pattern and results in a permanent record.

(63) “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.

(64) “Radiological physicist” means an individual who meets one of the following criteria:

(a) Is certified by the American Board of Radiology in therapeutic radiological physics, radiological physics, or x and gamma ray physics; or

(b) Has a bachelor’s degree in a physical science or engineering and 3 years full-time experience working in therapeutic radiological physics under the direction of a physicist certified by the American Board of Radiology. The work duties must include duties involving the calibration and spot checks of a medical accelerator or a sealed source teletherapy unit; or

(c) Has a master’s or a doctor’s degree in physics, biophysics, radiological physics, health physics or engineering; has had 1 year of full-time training in therapeutic radiological physics; and has had 1 year of full-time work experience in a radiotherapy facility where the individual’s duties involved calibration and spot checks of a medical accelerator or a sealed source teletherapy unit; or

(d) Has performed radiation physics work for a period of at least 10 years full time, prior to the effective date of these rules, in the field of therapeutic radiological physics in radiotherapy facilities where the individual’s duties involved calibration and spot checks of a medical accelerator or a sealed source teletherapy unit.

(65) “Rating” means the operating limits of a component as specified by the component manufacturer.

(66) “Recording” means producing a permanent form of an image resulting from x-ray photons, such as film or video tape.

(67) “Registrant”, as used in this part and in Parts IV, VI and VIII, means any person who possesses and administratively controls an x-ray system or other radiation producing machine and is required by the provisions in Part I to register with this Department.

(68) “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 midscale reading.

(69) “Scattered radiation” means radiation that, during passage through matter, has been deviated in direction. See “Direct scattered radiation”.

(70) “Secondary dose monitoring system” means a system which will terminate irradiation in the event of failure of the primary system.

(71) “Secondary protective barrier”. See “Protective barrier”.

(72) “Shutter” means a device attached to the tube housing assembly which can totally intercept the useful beam and which has a lead equivalency not less than that of the tube housing assembly.

(73) “Source” means the focal spot of the x-ray tube.

(74) “Source-image receptor distance (SID)” means the distance from the source to the center of the input surface of the image receptor.

(75) “Spot check” means a procedure which is performed to assure that a previous calibration continues to be valid.

(76) “Spot film” means a radiograph which is made during a fluoroscopic examination to permanently record conditions which exist during that fluoroscopic procedure.

(77) “Spot-film device” means a device intended to transport 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.

(78) “SSD” means the distance between the source and the skin of the patient.

(79) “Stationary x-ray equipment”. See “X-ray equipment”.

(80) “Stray radiation” means the sum of leakage and scattered radiation.

(81) “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.

(82) “Termination of irradiation” means the stopping of irradiation in a fashion which will not permit continuance of irradiation without the resetting of operating conditions at the control panel.

(83) “Traceable to a national standard” means that a quantity or a measurement has been compared to a national standard directly or indirectly through one or more intermediate steps and that all comparisons have been documented.

(84) “Tube” means an x-ray tube, unless otherwise specified. See “X-ray tube”.

(85) “Tube housing assembly” means the tube housing with tube installed. It includes high voltage or filament transformers and other appropriate elements when such are contained within the tube housing.

(86) “Tube rating chart” means the set of curves provided by the manufacturer which specify the rated limits of operation of the tube in terms of the technique factors.

(87) “Useful beam” means the radiation emanating from the tube housing port or the radiation head and passing through the aperture of the beam-limiting device when the exposure controls are in a mode to cause the system to produce radiation.

(88) “Variable-aperture beam-limiting device” means a beam-limiting device which has capacity for stepless adjustment of the x-ray field size at a given SID.

(89) “Visible area” means that portion of the input surface of the image receptor over which incident x-ray photons are producing a visible image.

(90) “Wedge filter” means an added filter effecting continuous progressive attenuation on all or part of the useful beam.

(91) “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.

(92) “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 or casters for moving while completely assembled.

(b) “Portable” means x-ray equipment designed to be hand carried.

(c) “Stationary” means x-ray equipment which is installed in a fixed location.

(d) “Special purpose” means x-ray equipment or a system designed for radiographic examinations of a specific anatomical area of the human body utilizing image receptors of more than one size; for example, the head or the spinal column.

(93) “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.

(94) “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, high-voltage switches, electrical protective devices and other appropriate elements.

(95) “X-ray system” means an assemblage of components for the controlled production of x-rays. It minimally includes 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.

(96) “X-ray subsystem” means any combination of two or more components of an x-ray system.

(97) “X-ray tube” means any electron tube which is designed for the conversion of electrical energy into x-ray energy.

(98) “Medical physicist” means a person who practices the branch of physics that is associated with the practice of medicine.

(99) “Clinical image” means a radiograph.

(100) “Pulsed mode” means operation of the x-ray system such that the x-ray tube current is pulsed by the x-ray control to produce one or more exposure intervals of duration less than one-half second.

Rulemaking Authority 404.051 FS. Law Implemented 404.022, 404.031, 404.051(1), (4) FS. History–New 7-17-85, Amended 4-4-89, 11-20-94, 1-5-95, 5-15-96, Formerly 10D-91.602.