_______________________________ DCA05DR Dental Radiation Health, Safety, and Protection, 3rd Edition
Dosimetry: Practice of determining the quantity and intensity of ionizing radiation exposure. Effective dose: Sum of the weighted equivalent doses for the radiosensitive tissues and organs of the body; used to estimate risk; expressed in sieverts (Sv). Electromagnetic radiation: Energy propagated by wave motion through oscillation between the electric and magnetic fields. These energies exist over a broad continuum, differ in wavelength and frequency, and include both nonionizing and ionizing forms. X-rays, gamma rays, and ultraviolet light are examples of ionizing electromagnetic radiation. Equivalent dose or dose equivalent: Mean absorbed dose in a tissue or organ modified by the radiation weighting factor; used to compare the biologic effect of different types of radia- tion on tissue; expressed in roentgen equivalent man (rem) or sieverts (Sv). Exposure: Measure of ionization of air by x-radiation or gamma radiation; expressed in roentgens (R) or coulombs per kilogram (C/kg). Filtration: Use of aluminum and other metals to remove low- energy x-rays from the primary beam. Free radical: Uncharged molecule that contains an unpaired electron in its valence shell. Heritable: Capable of being inherited as a genetic trait. Image receptor: Device or recording medium in the form of film, solid-state detectors, or photostimulable phosphor plates used to capture a radiographic image. Indirect effect: Radiation effect that results from the interac- tion of radiation with water and the production of free radicals. Ionization: Removal of orbital electrons from the atom, creat- ing positive and negative ions or ion pairs. Ionizing radiation: Electromagnetic or particulate radiation with sufficient energy to remove an electron from an atom and form an ion pair. Latent image: Pattern of stored energy on an exposed film or plate emulsion made visible by processing. Latent period: Amount of time between exposure to ionizing radiation and the appearance of observable biologic effects. Lead apron: Protective shield made of lead or a lead-equivalent material, used to protect patient reproductive tissues from scat- ter radiation during dental radiographic procedures. Leakage radiation: Form of secondary radiation emitted from the tubehead housing. Linear energy transfer: Measure of the rate at which energy is transferred from ionizing radiation to the irradiated tissue. Maximum permissible dose (MPD): Dose of occupational radiation not expected to produce significant radiation effects
GLOSSARY Absorbed dose: Measure of the radiation energy absorbed per unit mass of matter, regardless of the type of ionizing radia- tion or the type of matter; expressed in Gray (Gy) or radiation absorbed dose (rad) units. ALARA: Radiation safety principle that states that radiation exposure should be kept to a minimum; as low as reasonably achievable. Charge-coupled device (CCD): Solid-state silicon chip detector that converts light or x-ray photons to electrons. Collimation: Restriction of the size and shape of the primary x-ray beam to reduce patient exposure and improve image quality. Complementary metal oxide semiconductor: Solid-state silicon chip detector similar to CCD detectors but differing in pixels read-out and power requirements. Cosmic radiation: Electromagnetic and particulate radiation emitted by the sun and stars; a form of natural radiation. Crookes tube: A glass vacuum tube that lights up when elec- trons strike its inside walls. Cross-linking: Creation of side spurs by radiation exposure and attachment to adjacent macromolecule or portion of the same molecule; the joining of two molecules. Dental radiographer: Qualified dental professional who positions, exposes, and processes dental x-ray image receptors. Dental radiography: Production of radiographic images of the teeth and adjacent structures by the exposure of an image receptor to x-rays. Deterministic effect: Biologic response in which the severity varies with radiation dose; a threshold dose exists. Diagnostic image: High-quality radiographic image that accu- rately records the area of interest, is properly exposed, and has the necessary detail to render a diagnosis. Diagnostic radiation: Human-made radiation used in the heal- ing arts for the diagnosis and treatment of disease; typically associated with low-dose radiation exposures. Digital image: Electronic image composed of pixels. Digital imaging: Filmless, computer-based imaging technol- ogy that utilizes digital receptors for the acquisition, display, storage, and transfer of radiographic images. Dissociation: Process of disjoining, separating, or breaking apart. Dose: Amount of radiation absorbed by an irradiated object. Dose limit: The maximum amount of radiation considered to be safe for an individual to receive. A dose limit can be prescribed for an organ or for the whole body.
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