Code of Massachusetts Regulations › 105 CMR - DEPARTMENT OF PUBLIC HEALTH › Title 105 CMR 120.000 - The Control of Radiation › RECORDKEEPING REQUIREMENTS › Section 120.402 - Definitions

Current through Register 1525, July 5, 2024
As used in
				  105 CMR
				  120.400, the following definitions
				  apply:
Accessible Surface
means the
				  external surface of the enclosure or housing provided by the
				  manufacturer.
Accessory Component
means:
(1) A component used with diagnostic X-ray systems, such as a
				  cradle or film changer, that is not necessary for the compliance of the system
				  with applicable provisions of
				  105 CMR
				  120.400 but which requires an initial
				  determination of compatibility with the system; or
(2) A component necessary for compliance of the system with
				  applicable provisions of
				  105 CMR
				  120.400 but which may be interchanged with
				  similar compatible components without affecting the system's compliance, such
				  as one of a set of interchangeable beam-limiting devices; or
(3) A component compatible with all X-ray systems with which
				  it may be used and that does not require compatibility or installation
				  instructions, such as a tabletop cassette holder.
Added Filtration
means any
				  filtration which is in addition to the inherent filtration.
Air Kerma
means kerma in air
				  (
see
definition of Kerma)
Air Kerma Rate (AKR)
means the air
				  kerma per unit time.
Aluminum Equivalent
means the
				  thickness of type 1100 aluminum alloy1 affording the
				  same attenuation, under specified conditions, as the material in
				  question.
Approved Provider
means a
				  post-secondary institution of higher learning, a provider approved by the
				  American Society of Radiologic Technologists (ASRT), a provider of Category I
				  CME approved by the American Academy of Physician Assistants (AAPA), a provider
				  accredited by the Accreditation Council for Continuing Medical Education
				  (ACCME) or ACCME-recognized state medical society (SMS), a provider of Category
				  1 CME approved by the American Medical Association (AMA), or other recognized
				  national continuing medical education approval body approved by the
				  Agency.
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 alloy1 or other materials
				  having equivalent attenuation.
Automatic Exposure Control (AEC)
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
				  (Includes devices such as phototimers and ion chambers).
Automatic Exposure Rate Control
				  (AERC)
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 per unit time.
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
				  which provides a means to restrict the dimensions of the x-ray field.
Bone Densitometry System
means a
				  medical device which uses electronically-produced ionizing radiation to
				  determine the density of bone structures of human patients.
C-arm Fluoroscope
means a
				  fluoroscopic x-ray system in which the image receptor and x-ray tube housing
				  assembly are connected or coordinated. Such a system allows a change in the
				  direction of the beam axis with respect to the patient without moving the
				  patient.
Cantilevered Tabletop
means a
				  tabletop designed such that the unsupported portion can be extended at least
				  100 cm beyond the support.
Cassette Holder
means a device,
				  other than a spot-film device, that supports and/or fixes the position of an
				  x-ray film [imaging] cassette during an x-ray exposure.
Cephalometric Device
means a device
				  intended for the radiographic visualization and measurement of the dimensions
				  of the human head.
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.
Certified System
means any x-ray
				  system which has one or more certified component(s).
Changeable Filters
means any filter,
				  exclusive of inherent filtration, which 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 here to view
				  image
where
s = Estimated standard deviation of the population.
X = Mean value of observations in sample.
X = ith observation in
				  sample.
n = 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 five 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.
Contrast Scale
(CS) means the change
				  in the linear attenuation coefficient per CTN relative to water; that
				  is:
Click here to view
				  image
where:
µx = linear attenuation
				  coefficient of the material of interest
µw = linear attenuation
				  coefficient of water
(CTN)x = CTN of the material of
				  interest
(CTN)w = CTN of water
Cooling Curve
means the graphical
				  relationship between heat units stored and cooling time.
CR
means: Computed Radiography, an
				  indirect type of imaging system. The receptor used within a CR cassette is
				  called a photostimulable imaging plate and it absorbs the radiation exiting the
				  patient. The exposed plate is processed in a CR reader, where the absorbed
				  energy is extracted. The resultant latent image data is converted from an
				  analog to a digital signal and a digital image is created.
Cradle
means:
(1) A removable device which supports and may restrain a
				  patient above an x-ray table; or
(2) A device;
(a) Whose patient support structure is interposed between the
				  patient and the image receptor during normal use;
(b) Which is equipped with means for patient restraint;
				  and
(c) Which is capable of rotation about its long
				  (longitudinal) axis.
CT
means computed tomography; the
				  production of a tomogram by the acquisition and computer processing of x-ray
				  transmission data.
CT Condition of Operation
means all
				  selectable parameters governing the operation of a CT x-ray system including,
				  but not limited to, nominal tomographic section thickness, filtration, and the
				  technique factors as defined in
				  105 CMR
				  120.400.
CT Gantry
means the tube housing
				  assemblies, beam-limiting devices, detectors, and the supporting structures and
				  frames which hold these components.
CT Number
(CTN) means the number
				  used to represent the x-ray attenuation associated with each elemental area of
				  the CT image, that is:
Click here to view
				  image
where:
k = contrast (a value of 1,000 is assigned when the
				  Hounsefield scale of CTN is used)
µx = linear attenuation
				  coefficient of the material of interest
µw = linear attenuation of water
				  w
Cumulative Air Kerma
means the total
				  air kerma accrued from the beginning of an examination or procedure and
				  includes all contributions from fluoroscopic and radiographic
				  irradiation.
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.
Detector
(
See
Radiation Detector
).
Diagnostic Source Assembly
means the
				  tube housing assembly with a beam-limiting device attached.
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.
Diagnostic X-ray Imaging System
means an assemblage of components for the generation, emission, and reception
				  of x-ray and the transformation, storage, and visual display of the resultant
				  x-ray image.
Direct Scattered Radiation
means
				  that scattered radiation which has been deviated in direction only by materials
				  irradiated by the useful beam (
See
Scattered
				  Radiation
).
Dose
means the absorbed dose as
				  defined by the International Commission on Radiation Units and Measurements.
				  The absorbed dose, D, is the quotient of de by dm, where de is the mean energy
				  imparted to matter of mass dm; thus D=de/dm, in units of J/kg, where the
				  special name of the unit of absorbed dose is gray (Gy).
DR
means Direct Radiography or
				  Digital Radiography, is a form of x-ray imaging where digital x-ray sensors are
				  used instead of traditional photographic film.
Elemental Area
means the smallest
				  area within a tomogram for which the x-ray attenuation properties of a body are
				  depicted.
Entrance Exposure Rate
means the
Exposure
per unit time at the point where the center
				  of the useful beam enters the patient.
Equipment
(
See
X-ray Equipment
).
Exposure (X)
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 and positrons liberated or created
				  by photons in air of mass dm are completely stopped in air; thus X=dQ/dm, in
				  units of C/kg. A second meaning of exposure is the process or condition during
				  which the x-ray tube produces x-ray radiation.
Facility
means the location within
				  one building or vehicle and under the same administrative control at which one
				  or more x-ray equipment systems are installed or located for the purpose of
				  diagnosis or treatment.
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 Air Kerma Display
				  Devices
means separate devices, subsystems, or components that
				  provide the display of AKR and cumulative air kerma, respectively. They include
				  radiation detectors, if any, electronic and computer components, associated
				  software, and data displays.
Fluoroscopic Imaging Assembly
means
				  a subsystem in which x-ray photons produce a fluoroscopic images or
				  radiographic images recorded from the fluoroscopic image receptor. 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.
Fluoroscopic Irradiation Time
means
				  the cumulative duration during an examination or procedure of operator-applied
				  continuous pressure to the device, enabling x-ray tube activation in any
				  fluoroscopic mode of operation.
Fluoroscopic Procedure
means the
				  production and display of serial x-ray images for the purpose of observing
				  real-time motion of anatomical structures.
Fluoroscopy
means a technique for
				  generating x-ray images and presenting them simultaneously and continuously as
				  visible images. This term has the same meaning as the term "radioscopy" in the
				  standards of the International Electrotechnical Commission.
Focal Spot (Actual)
means the area
				  projected on the anode of the x-ray tube 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.
Half-value Layer
means the thickness
				  of specified material which attenuate the beam of radiation to an extent such
				  that the exposure rate is reduced to one-half of its original value. In 105 CMR
				  120.402:
Half-value Layer
, the contribution of all
				  scattered radiation, other than any which might be present initially in the
				  beam concerned, is deemed to be excluded.
Hand-held X-ray Equipment
means
				  x-ray equipment that is designed to be hand-held during operation.
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 by
				  the Commonwealth of Massachusetts to prescribe such x-ray tests for the purpose
				  of diagnosis or treatment. 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.
HVL
(
See
Half-value Layer
).
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, radiographic film, x-ray image intensifier tube,
				  solid-state detector, or gaseous detector 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. In those cases where means are
				  provided to preselect a portion of the image receptor, the term "image
				  receptor" shall mean the preselected portion of the device.
Inherent Filtration
means the
				  filtration of the useful beam provided by the permanently installed components
				  of the tube housing assembly.
Interventional Procedures
means
				  procedures that utilize imaging for guidance. Imaging includes, but is not
				  limited to, fluoroscopy and CT.
Irradiation
means the exposure of
				  matter to ionizing radiation.
Isocenter
means the center of the
				  smallest sphere through which the beam axis passes when the equipment moves
				  through a full range of rotations about its common center.
Kerma
means the quantity defined by
				  the International Commission on Radiation Units and Measurements. The kerma, K,
				  is the quotient of dEtr by dm, where dEtr is the sum of the initial kinetic
				  energies of all the charged participles liberated by uncharged particles in a
				  mass dm of material; thus K=dEtr/dm, in units of J/kg, where the special name
				  for the unit of kerma is gray (Gy). When the material is air, the quantity is
				  referred to as "air kerma."
Kilovolts Peak
(
See
Peak Tube Potential
).
kV
means kilovolts.
kVp
(
See
Peak Tube Potential
).
kWs
means kilowatt second.
Last Image Hold (LIH)
radiograph
				  means an image obtained either by retaining one or more fluoroscopic images,
				  which maybe temporarily integrated, at the end of a fluoroscopic exposure or by
				  initiating a separate and distinct radiographic exposure automatically and
				  immediately in conjunction with termination of the fluoroscopic
				  exposure.
Lateral Fluoroscope
means the x-ray
				  tube and image receptor combination in a biplane system dedicated to the
				  lateral projection. It consists of the lateral x-ray tube housing assembly and
				  the lateral image receptor that are fixed in position relative to the table
				  with the x-ray beam axis parallel to the plane of the table.
Lead Equivalent
means the thickness
				  of lead affording the same attenuation, under specified conditions, as the
				  material in question.
Leakage Radiation
means radiation
				  emanating from the diagnostic or therapeutic source assembly except for:
(1) The useful beam; and,
(2) Radiation produced when the exposure switch or timer is
				  not activated.
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:
(1) 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 ten
				  millicoulombs,
i.e.
, ten milliampere seconds, or the minimum
				  obtainable from the unit, whichever is larger.
(2) 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.
(3) 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.
Linear Attenuation Coefficient
(µ) means the quotient of dN/N by d1 when dN/N is the fraction of
				  uncharged ionizing radiation that experience interactions in traveling a
				  distance d1 in a specific material.
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-Vl)/Vl
where
Vn = No-load line potential
				  and
Vl = Load line potential.
mA
means milliampere.
mAs
means milliampere second.
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
).
Mode of Operation
means, for
				  fluoroscopic systems, a distinct method of fluoroscopy or radiography provided
				  by the manufacturer and selected with a set of several technique factors or
				  other control settings uniquely associated with the mode. The set of distinct
				  technique factors and control settings for the mode may be selected by the
				  operation of a single control. Examples of distinct modes of operation include
				  normal fluoroscopy (analog or digital), high-level control fluoroscopy,
				  cineradiography (analog and digital), digital subtraction angiography,
				  electronic radiography using the fluoroscopic image receptor, and photospot
				  recording. In a specific mode of operation, certain system variables affecting
				  kerma, AKR, or image quality, such as image magnification, x-ray field size,
				  pulse rate, pulse duration, number of pulses, source-image receptor distance
				  (SID), or optical aperture, may be adjustable or may vary; their variation per
				  se does not comprise a mode of operation different from the one that has been
				  selected.
Movable Tabletop
means a tabletop
				  which, when assembled for use, is capable of movement with respect to its
				  supporting structure within the plane of the tabletop.
Multiple Tomogram System
means a
				  computed tomography x-ray system which obtains x-ray transmission data
				  simultaneously during a single scan to produce more than one tomogram.
Nominal Tomographic Section
				  Thickness
means the full-width at half-maximum of the sensitivity
				  profile taken at the center of the cross sectional volume over which x-ray
				  transmission data are collected.
Nurse Practitioner
means a person
				  licensed as a Registered Nurse by the Massachusetts Board in Nursing pursuant
				  to M.G.L. c. 112, § 74, who is authorized by such Board to practice in an
				  advanced practice nursing role as a nurse practitioner pursuant to M.G.L. c.
				  112, § 80B, and
				  244 CMR 4.00:
The
				  Practice of Nursing in the Expanded Role
.
NVLAP
means National Voluntary
				  Laboratory Accreditation Program.
Patient
means an individual
				  subjected to healing arts examination, diagnosis, or treatment.
PBL
See
105 CMR
				  120.402:
Positive Beam Limitation
.
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. This requires that both the atomic number (Z) and the
				  density of the material be similar to that of tissue.
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
Automatic Exposure
				  Control
).
Physician Assistant
means a person
				  licensed as a physician assistant by the Massachusetts Board of Registration in
				  Physician Assistants pursuant to M.G.L. c. 112, § 9I.
PID
(
See
"Position
				  indicating device").
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 (skin) distance. It may or may not
				  incorporate or serve as a bean-limiting device.
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.
Post-secondary Institution of Higher
				  Education
means a degree granting institution duly accredited by
				  an accrediting agency recognized by the United States Department of
				  Education.
Practitioner of the Healing Arts
means an individual licensed to practice healing arts by the Commonwealth of
				  Massachusetts.
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:
(1) "Primary protective barrier" means the material,
				  excluding filters, placed in the useful beam;
(2) "Secondary protective barrier" means a barrier sufficient
				  to attenuate the stray radiation.
Protective Glove
means a glove made
				  of radiation absorbing materials used to reduce radiation exposure.
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 ½
				  second.
Qualified Medical Physicist
means an
				  individual is:
(1) Registered with the Agency, under the provisions of
				  105 CMR
				  120.026, as a provider of radiation services
				  in the area of calibration and compliance surveys and,
(2) Is certified by the American Board of Radiology
				  in:
(a) Therapeutic medical physics; or
(b) Diagnostic medical physics; or
(c) Nuclear medical physics; or
(3) Is certified by the American Board of Medical Physics;
				  or
(4) Is certified by the Canadian College of Medical Physics;
				  or
(5) Hold a master's or doctor's degree in physics,
				  biophysics, radiological physics, Radiological Science, Nuclear Physics, health
				  physics, or other catagory approved by the Agency.
Radiation Detector
means a device
				  which in the presence of radiation provides a signal or other indication
				  suitable for use in measuring one or more quantities of incident
				  radiation.
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.
Radiography
means a technique for
				  generating and recording an x-ray pattern for the purpose of providing the user
				  with an image(s) after termination of the exposure.
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.
Rated Line Voltage
means the range
				  of potentials, in volts, of the supply line specified by the manufacturer at
				  which the x-ray machine is designed to operate.
Rated Output Current
means the
				  maximum allowable load current of the x-ray high-voltage generator.
Rating
means the operating limits as
				  specified by the component manufacturer.
Recording
means producing a
				  retrievable form of an image resulting from x-ray photons.
Reference Plane
means a plane which
				  is displaced from and parallel to the tomographic plane.
Routine
means diagnostic procedures
				  utilizing x-ray equipment that are performed at least weekly.
Scan
means the complete process of
				  collecting x-ray transmission data for the production of a tomogram. Data can
				  be collected simultaneously during a single scan for the production of one or
				  more tomogram.
Scan Increment
means the amount of
				  relative displacement of the patient with respect to the CT x-ray system
				  between successive scans measured along the direction of such
				  displacement.
Scan Sequence
means a preselected
				  set of two or more scans performed consecutively under preselected CT
				  conditions of operation.
Scan Time
means the period of time
				  between the beginning and end of x-ray transmission data accumulation for a
				  single scan.
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 which 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 totally intercept the useful beam and which
				  has a lead equivalency not less than that of the tube housing assembly.
SID
(
See
Source-image Receptor Distance
).
Single Tomogram System
means a CT
				  x-ray system which obtains x-ray transmission data during a scan to produce a
				  single tomogram.
Solid State X-ray Imaging Device
means an assembly, typically in a rectangular panel configuration, that
				  intercepts x-ray photons and converts the photon energy into a modulated
				  electronic signal representative of the x-ray intensity over the area of the
				  imaging device. The electronic signal is then used to create an image for
				  display and/or storage.
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.
Source-skin Distance (SSD)
means the
				  distance from the source to the center of the entrant x-ray field in the plane
				  tangent to the patient skin surface.
Spot Film
means a radiograph which
				  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 the fluoroscopic image receptor for the
				  purpose of producing a radiograph.
SSD
means the distance from the
				  source to the center of the entrant x-ray field in the plan tangent to the
				  patient skin surface.
Stationary Tabletop
means a tabletop
				  which, when assembled for use, is incapable of movement with respect to its
				  supporting structure within the plane of the tabletop.
Stationary X-ray Equipment
(
See
X-ray Equipment
).
Stray Radiation
means the sum of
				  leakage and scattered radiation.
Supervising Physician
means a
				  physician who holds a full license issued by the Board of Registration in
				  Medicine and who supervises all professional activities of a physician
				  assistant in accordance with
				  243 CMR 2.08
				  and
				  263 CMR 5.00. For the purposes
				  of
				  105 CMR
				  120.405, a supervising physician shall meet
				  the requirements of 120.405(K)(1)(a) or (b).
Technique Factors
means the
				  conditions of operation. They are specified as follows:
(1) For capacitor energy storage equipment, peak tube
				  potential in kV and quantity of charge in mAs;
(2) For field emission equipment rated for pulsed operation,
				  peak tube potential in kV and number of x-ray pulses;
(3) For CT equipment designed for pulsed operations, peaktube
				  potential in kV, scan time in seconds, and either tube current in milliamperes
				  (mA), x-ray pulse width in seconds, and the number of x-ray pulses per scan or
				  the product of tube current, x-ray pulse width, and the number of x-ray pulses
				  in mAs;
(4) For CT equipment not designed for pulsed operation, peak
				  tube potential in kV, and either tube current in mA and scan time in seconds or
				  the product of tube current and exposure time in mAs and the scan time when the
				  scan time and exposure time are equivalent; and,
(5) 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.
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.
Tomogram
means the depiction of the
				  x-ray attenuation properties of a section through the body.
Tomographic Plane
means that
				  geometric plane which is identified as corresponding to the output
				  tomogram.
Tomographic Section
means the volume
				  of an object whose attenuation properties are imaged in a tomogram.
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 which 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.
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 Control
means a device which
				  controls input power to the x-ray high-voltage generator and/or the x-ray tube.
				  It includes equipment such as timers, phototimer, automatic brightness
				  stabilizers, and similar devices, which control the technique factors of an
				  x-ray exposure.
X-ray Equipment
means an x-ray
				  system, subsystem, or component thereof. Types of x-ray equipment are as
				  follows:
(1) "Mobile X-ray Equipment" means x-ray equipment mounted on
				  a permanent base with wheels and/or casters for moving while completely
				  assembled.
(2) "Portable X-ray Equipment" means x-ray equipment designed
				  to be hand-carried.
(3) "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 AKR is ¼ of the maximum in the intersection.
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.
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 Table
means a patient support
				  device with its patient support structure (tabletop) interposed between the
				  patient and the image receptor during radiography and/or fluoroscopy. This
				  includes, but is not limited to, any stretcher equipped with a radiolucent
				  panel and any table equipped with a cassette tray (or buckey), cassette tunnel,
				  image intensifier, or spot-film device beneath the tabletop.
X-ray Tube
means any electron tube
				  which 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% minimum aluminum, 0.12% copper.