Code of Maine Rules › 10 - DEPARTMENT OF HEALTH AND HUMAN SERVICES › 144 - DEPARTMENT OF HEALTH AND HUMAN SERVICES - GENERAL › Chapter 220 - Rules Relating to Radiation Protection › Part F - X-RAYS IN THE HEALING ARTS › Section 144-220-F-2 - Definitions

Current through 2024-29, July 17, 2024
As used in this part, the following definitions
					 apply:
Accessible surface
means the external surface
					 of the enclosure or housing provided by the manufacturer.
Added filtration
means any filtration that is
					 in addition to the inherent filtration.
Aluminum equivalent
means the thickness of
					 type 1100 aluminum alloy1 affording the same
					 attenuation, under specified conditions, as the material in question.
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 or her employee or agent who assembles components into an x-ray system that
					 is subsequently used to provide professional or commercial services.
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.
Automatic exposure
control means a device that
					 automatically controls one or more technique, factors in order to obtain at a
					 preselected location(s) a required quantity of radiation (Includes devices such
					 as photo timers and ion chambers).
Barrier
(See Protective barrier.)
Beam axis
means a line from the source through
					 the centers of the x-ray fields.
Beam-limiting device
means a device that
					 provides a means to restrict the dimensions of the x-ray field.
Beam monitoring system
means a system designed
					 to detect and measure the radiation present in the useful beam.
C-arm x-ray system
means an x-ray system in
					 which the image receptor and x-ray tube housing assembly are connected by a
					 common mechanical support system in order to maintain a desired spatial
					 relationship. This system is designed to allow a change in the projection of
					 the beam through the patient without a change in the position of the patient.
					 This definition does not refer to a conventional fluoroscopic system or to a
					 dental cephalametric x-ray machine.
Cephalometric device
means a device intended
					 for the radiographic visualization and measurement of the dimensions of the
					 human head.
Certified components
mean components of x-ray
					 systems, which components are subject to the X-ray Equipment Performance
					 Standards promulgated under Public Law 90-602, the Radiation
					 Control for Health and Safety Act of 1968.
Certified system
means any x-ray system that
					 has one or more certified component(s).
Changeable filters
means any filter, exclusive
					 of inherent filtration, which filter can be removed from the useful beam
					 through any electronic, mechanical or physical process.
Coefficient of variation or "C"
means the
					 ratio of the standard deviation to the mean value of a population of
					 observations. It is estimated using the following equation:
Click
					 to view image
where
[SIGMA] = Estimated standard deviation of the
					 population.
[PI] = Mean value of observations in sample.
[OMEGA]1 = with observation in
					 sample.
[RETROFLEX HOOK] = Number of observations in sample
Computed tomography
means the production of a
					 tomogram by the acquisition and computer processing of x-ray transmission
					 data.
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.
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.
Cooling curve
means the graphical relationship
					 between heat units stored and cooling time.
CT
(see Computed tomography.)
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.
Diagnostic source assembly
means the tube
					 housing assembly with a beam-limiting device attached.
Diagnostic x-ray imaging system
means an
					 assemblage of components for the generation, emission, and reception of x-rays
					 and the transformation, storage, and visual display of the resultant x-ray
					 image.
Diagnostic x-ray system
means an x-ray system
					 designed for irradiation of any part of the human or animal body for the
					 purpose of diagnosis or visualization.
Direct scattered radiation
means that
					 scattered radiation, which has been deviated in direction only by materials,
					 irradiated by the useful beam (See Scattered radiation.)
Direct supervision
means that during use of
					 the radiation producing sources and devices, the supervisor is present to
					 observe and correct, as needed, the performance of the individual being
					 supervised who is using the radiation producing sources and devices.
Entrance exposure rate
means the exposure free
					 in air per unit time at the point where the center of the useful beam enters
					 the patient.
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.
Filter
means material placed in the useful
					 beam to absorb preferentially selected radiations.
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, if any, and structural material providing linkage
					 between the image receptor and diagnostic source assembly.
Focal spot (actual)
means 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.
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.
Gonad shield
means a protective barrier for
					 the testes or ovaries.
Healing arts screening
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 purpose of diagnosis or treatment.
Heat unit
means a unit of energy equal to the
					 product of the peak kilovoltage, milliamperes, and seconds, i.e., kVp x mA x
					 second.
Image intensifier
means a device, installed in
					 its housing, which instantaneously converts an x-ray pattern into a
					 corresponding light image of higher energy density.
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 transformations.
Image receptor support
means, for mammographic
					 systems, that part of the system designed to support the image receptor during
					 a mammography.
Inherent filtration
means the filtration of
					 the useful beam provided by the permanently installed components of the tube
					 housing assembly.
Irradiation
means the exposure of matter to
					 ionizing radiation.
Kilovolts peak
(See. Peak tube
					 potential.)
kV
means kilovolts. kVp (See Peak tube
					 potential.)
kWs
means kilowatt second.
Leakage radiation
means radiation emanating
					 from the diagnostic or therapeutic source assembly except for:
(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 diagnostic or therapeutic 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
				  being10 millicoulombs, i.e., 10 milliampere seconds, 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.
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.
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.
mA
means milliampere.
mAs
means milliampere second.
Mammographic facility
means a facility that
					 has an x-ray machine that is used, exclusively or not, for taking breast
					 radiographs. Some facilities, such as hospitals, may have mammographic x-ray
					 machines. These x-ray machines shall comply with the requirements, which apply
					 to mammographic facilities.
Maximum line current
means the
					 root-mean-square current in the supply line of an x-ray machine operating at
					 its maximum rating.
Mobile x-ray equipment
(See x-ray
					 equipment.)
Mobile van
means an x-ray facility housed
					 within a vehicle, which facility is moved, or capable of being moved to
					 different locations for the purpose of performing x-ray examinations.
PBL
(positive beam limitation) means the
					 automatic or semi-automatic adjustment of an x-ray beam to the size of the
					 selected image receptor, whereby exposures cannot be made without such
					 adjustment.
Peak tube potential
means the maximum value of
					 the potential difference across the x-ray tube during an exposure.
Phantom
means a volume of material behaving in
					 a manner similar to tissue with respect to the attenuation and scattering of
					 radiation.
Phototimer
means a method for controlling
					 radiation
exposures
to image receptors by measuring
					 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 "Automatic
exposure
control").
PID
(See position indicating device.)
Portable C-arm x-ray system
means an x-ray
					 system in which the image receptor and x-ray tube housing assembly are
					 connected by a common mechanical support system in order to maintain a desired
					 spatial relationship.
Portable x-ray equipment
(See x-ray
					 equipment.)
Position indicating
device means a device on
					 dental x-ray equipment used to indicate the beam position and to establish a
					 definite source-surface (skew) distance. It may or may not incorporate or serve
					 as a beam-limiting device.
Primary dose monitoring system
means a system
					 that will monitor the useful beam during irradiation and which will terminate
					 irradiation when a pre-selected number of dose monitor units have been
					 acquired.
Primary protective barrier
(See Protective
					 barrier.)
Protective apron
means an apron made of
					 radiation absorbing materials used to reduce radiation exposure.
Protective barrier
means a barrier of
					 radiation absorbing material(s) 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.
(b)
Secondary protective barrier
means the material which
				  attenuates stray radiation.
Protective glove
means a glove made of
					 radiation absorbing materials used to reduce radiation exposure.
Quality assurance program (QA)
means a
					 program, including quality control, which program extends to administrative,
					 educational, and preventive maintenance methods. For purposes of these rules, a
					 QA program is directed at radiographic facilities and includes a continuing
					 evaluation of the adequacy and effectiveness of the overall imaging
					 program.
Quality control (QC)
means a series of
					 distinct technical procedures with the aim to provide high quality images while
					 emitting as low a dose as necessary. QC includes, but is not limited to, the
					 frequent evaluations of film processing, cassettes and intensifying screens,
					 the film and the x-ray equipment.
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.
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.
Radiographic imaging system
means any system
					 whereby a permanent or temporary image is recorded on an image receptor by the
					 action of ionizing radiation.
Rating
means the operating limits as specified
					 by the component manufacturer.
Recording
means producing a permanent form of
					 an image resulting from x-ray photons.
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.
Scattered radiation
means radiation that,
					 during passage through matter, has been deviated in direction (See direct
					 scattered radiation).
Secondary dose monitoring system
means a
					 system that will terminate irradiation in the event of failure of the primary
					 system.
Secondary protective barrier
(See Protective
					 barrier.)
Shutter
means a device attached to the tube
					 housing assembly which can intercept the entire cross sectional area of the
					 useful beam and which has a lead equivalency not less than that of the tube
					 housing assembly.
SID
(See "Source-image receptor
					 distance").
Source
means the focal spot of the x-ray
					 tube.
Source-image receptor distance
means the
					 distance from the source to the center of the input surface of the image
					 receptor.
Spot check
means a procedure that is performed
					 to assure that a previous calibration, continues to be valid.
Spot film
means a radiograph that is made
					 during a fluoroscopic examination to permanently record conditions, which exist
					 during that fluoroscopic procedure.
Spot-film device
means a device intended to
					 transport and/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.
SSD
means the distance between the source and
					 the skin entrance plane of the patient.
Stationary x-ray equipment
(See "x-ray
					 equipment.)
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 pulses;
				  and
(c) For all other equipment,
				  peak tube potential in kV and either tube current in mA and exposure time in
				  seconds, on the product of tube current and exposure time in mAs.
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.
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.
Tube
means an x-ray tube, unless otherwise
					 specified.
Tube housing assembly
means the tube housing
					 with tube installed. It includes high-voltage and/or filament transformers and
					 other appropriate elements when such are contained within the tube
					 housing.
Tube rating chart
means the set of curves that
					 specify the rated limits of operation of the tube in terms of the technique
					 factors.
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.
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.
Visible area
means that portion of the input
					 surface of the image receptor over which incident x-ray photons are producing a
					 visible image.
Wedge filter
means an added filter effecting
					 continuous progressive attenuation on all or part of the useful beam.
X-ray exposure control
means a device, switch,
					 button or other similar means by which an operator initiates and/or terminates
					 the radiation exposure. The x-ray exposure control may include such associated
					 equipment as timers and back-up timers.
X-ray equipment
means an x-ray system,
					 subsystem, or component thereof. Types of x-ray equipment are as
					 follows:
Mobile x-ray equipment
means x-ray equipment
					 mounted on a permanent base with wheels and/or casters for moving while
					 completely assembled.
Portable x-ray equipment
means x-ray equipment
					 designed to be hand-carried.
Stationary x-ray equipment
means x-ray
					 equipment which is installed in a fixed location.
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.
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 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.
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.
X-ray tube
means any electron tube that is
					 designed to be used primarily for the production of x-rays.
1 The nominal chemical
					 composition of type 1100 aluminum alloy is 99.00 percent minimum aluminum, 0.12
					 percent copper.