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irradiation |
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irradiation /ir·ra·di·a·tion/ (ĭ-ra″de-a´shun)
1. radiotherapy. 2. the dispersion of nervous impulse beyond the normal path of conduction. 3. the application of rays, such as ultraviolet rays, to a substance to increase its vitamin efficiency.
irradiation [irā′dē·ā′shən] Etymology: L, irradiare, to beam upon exposure to any form of radiant energy, such as heat, light, or x-rays. Radioactive sources of radiant energy, such as x-rays or isotopes of iodine or cobalt, are used diagnostically to examine internal body structures. The same or similar sources of radioactivity in larger amounts are used to destroy microorganisms or tissue cells that have become cancerous. Infrared or ultraviolet light may be used to produce heat in body tissues for pain relief or to treat acne, psoriasis, or other skin ailments. Ultraviolet light is also used to identify certain bacteria and toxic molds. See also radiation sickness, radioactivity, ultraviolet. irradiate, v. irradiation [ĭ-ra″de-a´shun] 2. the dispersion of nervous impulse beyond the normal path of conduction. 3. the exposure of a substance to radiation, which consists of any of numerous kinds of rays that travel at the speed of light. Every living thing is subject to some irradiation by cosmic rays, ultraviolet rays in sunlight, and other natural radiation in the environment, all of which is usually slight and harmless. In large amounts, however, certain kinds of radiation cause direct harm to living cells, especially those rays that have a greater frequency and produce more energy. Irradiation of certain foods, including milk, kills harmful bacteria, prevents spoilage, and sometimes increases its vitamin efficiency. X-ray photography is used in industrial research and in diagnosis of disorders within the body. Radiation therapy usually refers to treatment by x-rays and gamma rays. X-rays are produced by bombarding a tungsten target with high-speed electrons in a vacuum tube; gamma rays are emitted during the decay of radioisotopes. X-rays may be employed to kill organisms causing skin diseases, for example, or to destroy the abnormal cells that form tumors. Gonads, blood cells, and cancer cells are especially sensitive to radiation, particularly to x-rays and gamma rays. Other rays are also used medically. Infrared rays produce a radiant heat used for the treatment of sprains and bursitis; tissues such as muscles and joints are relaxed and soothed by the penetration of these rays. Ultraviolet rays are used in sun lamps to treat skin diseases, such as acne and psoriasis. See also discussion of protection against harmful effects of radiation under radiation. extended field irradiation irradiation of an extended field in radiation therapy for malignant lymphoma. external beam irradiation radiation therapy in which the radiation is emitted from a source located at a distance from the body. hemibody irradiation external beam irradiation involving exposure of half the body. interstitial irradiation see radiation therapy. involved field irradiation irradiation of only the involved field in radiation therapy for malignant lymphoma. total body irradiation (whole-body irradiation) TBI; external beam irradiation involving exposure of the entire body.
irradiation (irā´dēā´sh n 1. the exposure of material to roentgen or other radiation. (One speaks of
radiation therapy but not of irradiation of the patient.) 2. the exposure to radiation. irradiation exposure to radiant energy (heat, x-rays, etc.) for therapeutic or diagnostic purposes. See also radiation (3). Irradiation of certain foods, including milk, kills harmful bacteria and prevents spoilage. X-ray photography is used in industrial research and in diagnosis of disorders within the body. irradiation teratogen
irradiation at the time of organogenesis which is capable of causing congenital defects such as ankylosis of limb joints and cleft palate. irradiation 1. Application of electromagnetic radiations to an object. 2. A phenomenon in which a bright area against a black background appears larger than a darker area of equal size against the same background. Syn. Helmholtz illusion.
irradiation 1 Radiation therapy, see there 2 Blood irradiation, see there Want to thank TFD for its existence? Tell a friend about us, add a link to this page, add the site to iGoogle, or visit the webmaster's page for free fun content. |
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