| radiation risks | The risks to health posed by exposure to radiation. Exposure comes from both natural sources and from man-made ones (medical and occupational). See: background radiation.Because any amount of radiation may cause cellular mutations, considerable effort has been made by government and independent researchers to establish exposure guidelines. In most cases, natural sources account for the bulk of received radiation, with artificial sources adding only a small percentage to the average annual dose. Public perception of the hazards of radiation is often at odds with scientific positions on the matter. In part, equivocal research results (as in attempts to assess the added cancer risk posed by mammograms) contribute to public fears. Some psychological studies have concluded that whether or not public fears of nuclear power plants and other radiation sources are justified, the added stress caused by such fears in itself constitutes a threat to health that should be addressed. (05 Mar 2000) |
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| radiation sickness | A systemic condition caused by substantial whole-body irradiation, seen after nuclear explosions or accidents, rarely after radiotherapy. Manifestations depend on dose, ranging from anorexia, nausea, vomiting, and mild leukopenia, to thrombocytopenia with haemorrhage, severe leukopenia with infection, anaemia, central nervous system damage, and death. Synonym: radiation poisoning. (05 Mar 2000) |
| radiation therapy | <radiobiology> Treatment with high energy radiation from X-rays or other sources of radiation. (16 Dec 1997) |
| radiation tolerance | The ability of some cells or tissues to withstand ionizing radiation without serious injury. Tolerance depends on the species, cell type, and physical and chemical variables, including radiation-protective agents and radiation-sensitizing agents. (12 Dec 1998) |
| radiation weighting factor | In radiation protection, a factor weighting the absorbed dose of radiation of a specific type and energy for its effect on tissue. See: equivalent dose. (05 Mar 2000) |
| radiation, ionizing | Electromagnetic or corpuscular radiation capable of producing ions, directly or indirectly, in its passage through matter. The wavelengths are equal to or smaller than those of short (far) ultraviolet radiation and include gamma and X-rays and high-energy elementary particles. (12 Dec 1998) |
| radiation, nonionizing | Electromagnetic radiation which does not produce ions in matter through which it passes. Its wavelengths are generally greater than those of far ultraviolet radiation and range through the longest radio waves. (12 Dec 1998) |
| radiation-protective agents | Drugs used to protect against ionizing radiation. They are usually of interest for use in radiation therapy but have been considered for other, e.g. Military, purposes. (12 Dec 1998) |
| radiation-sensitizing agents | Drugs used to potentiate the effectiveness of radiation therapy in destroying unwanted cells. (12 Dec 1998) |
| radiative | Capable of radiating; acting by radiation. Source: Websters Dictionary (01 Mar 1998) |
| radiator | That which radiates or emits rays, whether of light or heat; especially, that part of a heating apparatus from which the heat is radiated or diffused; as, a stream radiator. Source: Websters Dictionary (01 Mar 1998) |
| radical | 1. <chemistry> An atom or or electrically neutral group that has one or more unpaired electrons. 2. <botany> Of leaves, clustered at the base of the stem. (09 Oct 1997) |
| radical cystectomy | Surgery to remove the bladder as well as nearby tissues and organs. (12 Dec 1998) |
| radical hysterectomy | Complete removal of the uterus, upper vagina, and parametrium. (05 Mar 2000) |
| radical mastectomy | <procedure, surgery> The surgical removal of the breast, part of the underlying pectoralmuscle and some or all of the lymph nodes under the armpit. (09 Oct 1997) |