Nebraska Administrative Code › Topic - HEALTH AND HUMAN SERVICES SYSTEM › Title 180 - CONTROL OF RADIATION › Chapter 20 - THERAPEUTIC RADIATION MACHINES FOR HUMAN USE › Section 180-20-002 - DEFINITIONS

Current through June 17, 2024
The following definitions apply to this chapter.
002.01
ABSORBED DOSE
  RATE.
Absorbed dose rate is the absorbed dose per unit time, for
  machines with timers, or dose monitor unit per unit time for linear
  accelerators.
002.02
AIR KERMA (K).
Air kerma (K) is the kinetic energy
  released in air by ionizing radiation. Kerma is determined as the quotient of
  dE, where dE is the sum of the initial kinetic energies of all ionizing
  particles liberated by uncharged ionizing particles in air of mass dM. The
  International System of Units (SI) unit of air kerma is joule per kilogram and
  the special name for the unit of kerma is the gray (Gy).
002.03
BARRIER.
Barrier has the same meaning as stated in protective barrier.
002.04
BEAM AXIS.
Beam axis is the axis of rotation of the beam limiting device.
002.05
BEAM-LIMITING
  DEVICE.
Beam-limiting device is a field defining collimator,
  integral to the therapeutic radiation machine, which provides a means to
  restrict the dimension of the useful beam.
002.06
BEAM MONITORING
  SYSTEM.
Beam monitoring system is a system designed and installed
  in the radiation head to detect and measure the radiation present in the useful
  beam.
002.07
BEAM
  SCATTERING FOIL.
Beam scattering foil is a thin piece of material,
  usually metallic, placed in the beam to scatter a beam of electrons in order to
  provide a more uniform electron distribution in the useful beam.
002.08
BENT BEAM LINEAR
  ACCELERATOR.
Bent beam linear accelerator is a linear accelerator
  geometry in which the accelerated electron beam must change direction by
  passing through a bending magnet.
002.09
CHANGEABLE
  FILTERS.
Changeable filters are any filter, exclusive of inherent
  filtration, which can be removed from the useful beam through any electronic,
  mechanical, or physical process.
002.10
CONTACT THERAPY
  SYSTEM.
Contact therapy system is a therapeutic machine with a
  short target to skin distance (TSD), usually less than 5 centimeters.
002.11
CONVENTIONAL
  SIMULATOR.
Conventional simulator is any x-ray system designed to
  reproduce the geometric conditions of the radiation therapy
  equipment.
002.12
DETECTOR.
Detector has the same meaning as radiation
  detector.
002.13
DOSE
  MONITOR UNIT (DMU).
Dose monitor unit (DMU) means the unit
  response from the beam monitoring system from which the absorbed dose can be
  calculated.
002.14
ELECTRONIC BRACHYTHERAPY.
Electronic brachytherapy is
  the method of radiation therapy where an electrically generated source of
  ionizing radiation is placed in or near the tumor or target tissue to deliver
  therapeutic radiation dosage.
002.15
ELECTRONIC BRACHYTHERAPY
  DEVICE.
Electronic brachytherapy device is a system used to
  produce and deliver therapeutic radiation including the x-ray tube, the control
  mechanism, the cooling system, and the power source.
002.16
ELECTRONIC BRACHYTHERAPY
  SOURCE.
Electronic brachytherapy source is an x-ray tube component
  used in an electronic brachytherapy device.
002.17
EXTERNAL BEAM RADIATION
  THERAPY.
External beam radiation therapy is a therapeutic
  irradiation in which the source of radiation is at a distance from the
  body.
002.18
FIELD-FLATTENING FILTER.
Field-flattening filter is a
  filter used to homogenize the absorbed dose rate over the radiation
  field.
002.19
FILTER.
Filter is material placed in the useful beam
  to change beam quality in therapeutic radiation machines subject to 180 NAC
  20-006.
002.20
GANTRY.
Gantry is part of a radiation therapy system supporting and allowing movements
  of the radiation head about a center of rotation.
002.21
HALF-VALUE LAYER
  (HVL).
Half-value layer (HVL) is the thickness of a specified
  material which attenuates x-radiation or gamma radiation to an extent such that
  the air kerma rate, exposure rate or absorbed dose rate is reduced to one-half
  of the value measured without the material at the same point.
002.22
INTERLOCK.
Interlock is a device preventing the start or continued operation of equipment
  unless certain predetermined conditions prevail.
002.23
INTERRUPTION OF
  IRRADIATION.
Interruption of irradiation is the stopping of
  irradiation with the possibility of continuing irradiation without resetting of
  operating conditions at the control panel.
002.24
IRRADIATION.
Irradiation is the exposure of a living being or matter to ionizing
  radiation.
002.25
ISOCENTER.
Isocenter is the center of the sphere
  through which the useful beam axis passes while the gantry moves through its
  full range of motions.
002.26
KILOVOLT (kV) OR KILO ELECTRON VOLT (keV).
Kilovolt
  (kV) or kiloelectron volt (keV) is the energy equal to that acquired by a
  particle with one electron charge in passing through a potential difference of
  one thousand volts in a vacuum. The current convention is to use kilovolts (kV)
  for photons and kiloelectron volt (keV) for electrons.
002.27
LEAD
  EQUIVALENT.
Lead equivalent is the thickness of the material in
  question affording the same attenuation, under specified conditions, as
  lead.
002.28
LEAKAGE
  RADIATION.
Leakage radiation is radiation emanating from the
  radiation therapy system except for the useful beam.
002.29
LIGHT FIELD.
Light field is the area illuminated by light, simulating the radiation
  field.
002.30
MA.
The term mA is milliampere (mA).
002.31
MEGAVOLT (MV) OR
  MEGAELECTRON VOLT (MEV).
Megavolt (MV) or megaelectron volt (MeV)
  is the energy equal to that acquired by a particle with one electron charge in
  passing through a potential difference of one million volts in a vacuum. The
  current convention is to use megavolt (MV) for photons and megaelectron volt
  (MeV) for electrons.
002.32
MISADMINISTRATION.
Misadministration is an event that
  meets the criteria in 180 NAC 20-005.02.
002.33
MOBILE ELECTRONIC
  BRACHYTHERAPY SERVICE.
Mobile electronic brachytherapy service is
  the transportation of an electronic brachytherapy device to provide electronic
  brachytherapy at an address that is not the address of record.
002.34
MONITOR UNIT
  (MU).
Monitor unit (MU) has the same meaning as dose monitor
  unit.
002.35
MOVING
  BEAM RADIATION THERAPY.
Moving beam radiation therapy is radiation
  therapy with any planned displacement of radiation field or patient relative to
  each other, or with any planned change of absorbed dose distribution. Includes
  arc, skip, conformal, intensity modulation, and rotational therapy.
002.36
NOMINAL TREATMENT
  DISTANCE.
Nominal treatment distance is:
(A) For electron irradiation, the distance
  from the scattering foil, virtual source, or exit window of the electron beam
  to the entrance surface of the irradiated object along the central axis of the
  useful beam; or
(B) For x-ray
  irradiation, the virtual source or target to isocenter distance along the
  central axis of the useful beam. For non-isocentric equipment, this distance
  must be that specified by the manufacturer.