| CR | calculation rate; calculus removed; calorie-restricted; cardiac rehabilitation; cardiac resuscitatio... |
|---|---|
| CRO | cathode ray oscilloscope; centric relation occlusion |
| CRT | cadaveric renal transplant; cardiac resuscitation team; cathode-ray tube; certified; Certified Recor... |
| CWXSP | Coal Workers' X-ray Surveillance Program |
| CX | cervix; chest x-ray; connexin; critical experiment |
| quitch grass | <botany> A perennial grass (Agropyrum repens) having long running rootstalks, by which it spreads rapidly and pertinaciously, and so becomes a troublesome weed. Also called couch grass, quick grass, quick grass, twitch grass. Origin: Properly quick grass, being probably so called from its vigorous growth, or from its tenacity of life. See Quick, and cf. Couch grass. Source: Websters Dictionary (01 Mar 1998) |
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| oil of lemon grass | Volatile oil from Cymbopogon citratus and of C. Flexuosus (family Gramineae). Used in perfumery and as a source of citral for the synthesis of vitamin A. (05 Mar 2000) |
| timothy grass | <botany> A kind of grass (Phleum pratense) with long cylindrical spikes; called also herd's grass, in England, cat's-tail grass, and meadow cat's-tail grass. It is much prized for fodder. Origin: From Timothy Hanson, who carried the seed from New England to Maryland about 1720. Source: Websters Dictionary (01 Mar 1998) |
| twitch grass | <botany> See Quitch grass. Source: Websters Dictionary (01 Mar 1998) |
| johnson grass | <botany> A tall perennial grass (Sorghum Halepense), valuable in the Southern and Western States for pasture and hay. The rootstocks are large and juicy and are eagerly sought by swine. Synonym: Cuba grass, Means grass, Evergreen millet, and Arabian millet. Origin: Named after W. Johnson of Alabama, who planted it about 1840-1845. Source: Websters Dictionary (01 Mar 1998) |
| lyme grass | <botany> A coarse perennial grass of several species of Elymus, especially. E. Canadensis, and the European E. Arenarius. Source: Websters Dictionary (01 Mar 1998) |
| actinic ray | A light ray toward and beyond the violet end of the spectrum that acts upon a photographic plate and produces other chemical effects. Synonym: chemical ray. (05 Mar 2000) |
| alpha ray | <physics> A radioactive particle made up of two protons and two neutrons, these particles are created by the decay of a radioactive material or by nuclear bombardment, and they are the same as the nucleus of a helium-4 atom. (09 Oct 1997) |
| ap, X-ray | An X-ray picture in which the beams pass from front-to-back (anteroposterior). As opposed to a PA (posteroanterior) film in which the rays pass through the body from back-to-front. (12 Dec 1998) |
| beta ray | 1. <radiobiology> Original term used for electrons (and positrons) ejected from decaying nuclei via beta emission. (Label derives from the old days when we had various kinds of radiation emission, and they were labelled alpha, beta, and gamma (the first letters of the Greek Alphabet) because no one really knew what any of them were.) 2. A stream of positive or negative electrons ejected with high energy from a disintegrating atomic nucleus; most biomedically used isotopes emit negative particles (electrons or negatrons, rather than positrons). Cathode rays are low-energy negative electrons produced in cathode ray tubes, also called television tubes or oscilloscopes. (12 Sep 2000) |
| gamma ray | <radiobiology> Electromagnetic radiation (photons) with energies greater than (roughly) 100 keV (that is, 100,000 electron volts). Gamma radiation frequently accompanies alpha and beta decays, and always accompanies fission. Gamma rays are highly penetrating and are best shielded against using dense materials, such as lead or depleted uranium. (Gamma rays are similar to X-rays, but are generally higher in energy and nuclear in origin.) Gamma rays have wavelengths of 1 nanometre or shorter. These are highly energised, deeply penetrating photons which can be emitted from an atomic nucleus during nuclear fission (the splitting of an atom) and during regular atomic decay (radioactivity). (13 Oct 1997) |
| gamma ray knife | A beam of high energy X-rays. See: radiosurgery. (05 Mar 2000) |
| panoramic X-ray | <dentistry> An X-ray taken by a machine that rotates around your head to give the orthodontist a picture of your teeth, jaws and other important information. (08 Jan 1998) |
| panoramic X-ray film | In dentistry, a radiograph taken to give a panoramic view of the entire upper and lower dental arch as well as the temporomandibular joints. (05 Mar 2000) |
| ray | <botany> A zygomorphic flower in the family Asteraceae, a radial band of cells traversing the conducting elements in woody stems. Of a compound umbel, one of the first (lower) series of branches of the inflorescence main stem. (09 Oct 1997) |