ray (ra) [Fr. rai, raie, fr L. radius, ray]
1. Any of several lines diverging from a common center.
2. A line of propagation of any form of radiant energy, esp. light or heat; loosely, any narrow beam of light.
A solar ray capable of producing chemical changes. Synonym: chemical ray
A ray composed of positively charged helium particles derived from atomic disintegration of radioactive elements. Its velocity is one tenth the speed of light. Alpha rays are completely absorbed by a thin sheet of paper and possess powerful fluorescent, photographic, and ionizing properties. They penetrate tissues less than beta rays.
A ray composed of negatively charged electrons expelled from atoms of disintegrating radioactive elements. Synonym: beta particle
border rayGrenz ray.
A ray composed of negatively charged electrons discharged by a cathode through a vacuum, moving in a straight line and producing x-ray photons upon hitting solid matter.
The theoretical center of an x-ray beam. The term designates the direction of the x-ray photons as projected from the focal spot of the x-ray tube to the radiographical film.
A secondary photon produced by an electron giving up energy as it changes location from an outer to an inner shell in an atom. The wavelengths are characteristic of the difference in binding energies.
chemical rayActinic ray.
cosmic raysCosmic radiation.
Highly penetrative waves emitted by radioactive substances.
Ultraviolet radiation (wavelengths between 2050 and 3100 A.U.) capable of reddening skin.
Short wavelength, high-energy electromagnetic radiation emitted by disintegrating atomic nuclei.
A low-energy x-ray photon with an average wavelength of 2 A.U. (range from 1 to 3 A.U.); obtained with peak voltage of less than 10 kV. Grenz rays lie between ultraviolet and x-rays. Synonym: border ray
An x-ray photon of short wavelength and great penetrative power.
Radiation whose wavelength is between 3,900 and 14,000 A.U. Shorter wavelength heat sources penetrate tissues better than longer (infrared) sources. See: heat
An invisible heat ray from beyond the red end of the spectrum. Infrared wavelengths range from 7700 angstrom units (A.U.) to 1 mm. Long-wave infrared rays (15,000 to 150,000 A.U.) are emitted by all heated bodies and exclusively by bodies of low temperature such as hot water bottles and electric heating pads; short-wave infrared rays (7,200 to 15,000 A.U.) are emitted by all incandescent heaters. The sun, electric arcs, incandescent globes, and so-called infrared burners are sources of infrared rays.
Infrared ray energy is transformed into heat in a superficial layer of the tissues. It is used therapeutically to stimulate local and general circulation and to relieve pain. The infrared thermograph is useful in studying the heat of tissues. See: radiation; thermography
One of the visible rays of the spectrum.
In the kidney, one of many slender processes composed of one or two collecting ducts and other straight tubules that project into the cortex from the bases of renal pyramids.
Single wavelength electromagnetic radiation.
A ray between 2540 and 3100 A.U. that is most effective in stimulating pigment production in the skin. This is due to a local response to irritation of cutaneous prickle cells.
A ray composed of positively charged ions that in a discharge tube moves from the anode toward the cathode.
In radiographic imaging, the x-ray beam that originates at the source of radiation. It is usually used to differentiate those rays from the additional scatter radiation that constitutes the majority of the beam used to create images.
roentgen rayX-ray photon.
scattered ray See: radiation
X-ray photons produced after the incoming, primary x-ray photons remove an inner-shell electron from the atom. Secondary rays can also be primary x-rays that have been diverted through scatter interactions with other atoms. Secondary rays are of lower energy than primary rays and are usually absorbed in matter, an interaction that produces x-ray photons via a cascade effect.
An invisible ray of the spectrum beyond the violet rays. The wavelengths of ultraviolet rays vary. They may be refracted, reflected, and polarized, but will not traverse many substances impervious to the rays of the visible spectrum. They rapidly destroy the vitality of bacteria, and are able to produce photochemical and photographic effects.