Environmental, Health and Safety Services

X-Ray Safety Definitions

Access panel - A panel that is designed to be opened for maintenance purposes to permit access to the interior of the cabinet.

Aluminum equivalent - The thickness of type 1100 aluminum alloy affording the same attenuation as the material in question.

Analytical X-ray equipment - Equipment used for X-ray diffraction and fluorescence analysis, (excludes cabinet X-ray systems, electron microscopes and diagnostic X-ray equipment).

Automatic exposure control - A device that automatically controls one or more technique factors in order to obtain a required quantity of radiation.

Beam-limiting device - A device that provides a means to restrict the dimensions of the X-ray field.

Cabinet X-ray system - X-ray system with the X-ray tube installed in an enclosure, which is intended to contain the object being irradiated, provide radiation attenuation, and exclude personnel from its interior during X-ray generation.

Certified components - Parts of X-ray systems that are subject to regulations adopted under the Radiation Control for Health & Safety act of 1968.

Cooling curve - The graphical relationship between heat units stored and cooling time.

Dead-man switch - A switch that can only be kept ON by continuous pressure.

Diagnostic X-ray system - An X-ray system designed for irradiation of a human or animal for the purpose of diagnosis or visualization.

Diffracted beam - A beam composed of mutually reinforcing scattered X-rays.

Direct scattered radiation - Scattered radiation that has been deviated in direction only by the object exposed to the useful beam.

Enclosed beam configuration - An analytical X-ray system in which all possible X-ray paths are fully enclosed.

Fail-Safe design - A design feature that guarantees that the beam port shutters close or prevent appearance of the primary beam in the event of failure of a safety or warning device.

Gonad shield - A protective barrier for the testes or ovaries.

Half-value layer - The thickness of a material that attenuates the beam of radiation to one-half of its original value.

Healing arts screening - The testing of humans using X-ray equipment for the detection or evaluation of health problems, when such tests are not specifically and individually ordered by a medical doctor.

Heat unit - A unit of energy equal to the product of the peak voltage, current, and seconds.

Image intensifier - A device that converts an X-ray pattern into a corresponding light image of higher energy density.

Image receptor - A device, such as a fluorescent screen or radiographic film, which transforms incident X-ray photons into a visible image.

Inherent filtration - Filtration of the useful beam provided by the permanently installed parts of the tube housing.

Miscellaneous (equipment) - Equipment that produces X-rays secondary to its primary function.

Kilovolt peak (kVp) - The maximum value of the potential difference across the X-ray tube during an exposure.

Lead equivalent - The thickness of lead affording the same attenuation as the material in question.

Leakage radiation - Radiation, except the useful beam, emanating from the tube housing.

Local components - Includes areas that are struck by X-rays, such as radiation source housings, port and shutter assemblies, collimators, sample holders, cameras, goniometers, detectors and shielding; but not including power supplies, transformers, amplifiers, readout devices and control panels.

Milliampere second (mAs) - The product of tube current and exposure time.

Mobile equipment - X-ray equipment mounted on a permanent base with wheels.

Open-beam configuration - An analytical X-ray system in which some part of the body could accidentally be placed in the primary or diffracted beam path.

Primary beam - X-rays that pass through an aperture of the source housing by a direct path from the X-ray tube.

Protective apron - An apron made of radiation-attenuating materials.

Protective barrier - A barrier of radiation-attenuating materials used to reduce radiation exposure. The types of protective barriers are:

  • Primary - material placed in the useful beam, excluding filters, to reduce radiation exposure.
  • Secondary - barrier that attenuates leakage and scattered radiation.

Qualified expert - An individual, who has demonstrated by training and experience to the satisfaction of the State, that he possesses the knowledge and training to measure ionizing radiation, to evaluate safety techniques, and to advise others regarding radiation safety needs.

Safety interlock - Device that is intended to prevent the generation of X-rays when a door or access panel is opened.

Scattered radiation - Radiation that has been deviated in its direction during passage through an object.

Stationary equipment - X-ray equipment that is installed in a fixed position.

Technique factors - The condition of operation that is the peak tube potential in kV and either the tube current in mA and exposure time in seconds, or the product of the tube current and exposure time in mAs.

Tube rating chart - The set of curves that specify the rated limits of operation of the tube in terms of the technique factors.

Useful beam - Radiation that passes through the tube housing port and the aperture of the beam-limiting device when the exposure switch is activated.

Variable aperture - A beam-limiting device that allows for stepless adjustment of the X-ray field.

X-ray source housing - That portion of an analytical X-ray system that contains the X-ray tube.