| MR | Maddox rods; magnetic resistance; magnetic resonance; mandibular reflex; mannose-resistant; may repe... |
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| MRA | magnetic resonance angiography; main renal artery; marrow repopulation activity; medical record anal... |
| MRCP | magnetic resonance cholangiopancreatography |
| MRI | machine-readable identifier; magnetic resonance imaging; medical records information; Medical Resear... |
| MRM | magnetic resonance mammography; modified radical mastectomy |
| radiation myelopathy | Damage to the spinal cord from exposure to X-rays or other high energy radiation; usually radiation myelitis. Synonym: radiation myelitis. (05 Mar 2000) |
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| 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 of corpus callosum | The spreading out of the fibres of the corpus callosum in the centrum semiovale of each cerebral hemisphere. Synonym: radiatio corporis callosi. (05 Mar 2000) |
| radiation oncologist | A physician specifically trained in the use of high energy X-rays to treat cancer. (09 Oct 1997) |
| radiation oncology | <study> The medical study of the use of radiation (X-rays, gamma rays or electrons) to destroy cancers. (09 Oct 1997) |
| radiation physicist | A nonmedically qualified person who specialises in the application of physics to plan and deliver irradiation, assisting the radiotherapist in planning and treatment. (16 Dec 1997) |
| radiation pneumonitis | Injurious effects of radiotherapy on the lungs. There are three phases in the reaction of the lungs to radiation injury: an acute phase occurring 1 to 2 months after exposure, a subacute phase 2 to 9 months after exposure, and a chronic or fibrotic phase more than 9 months after exposure. In the acute phase there is vascular damage, congestion, oedema, and mononuclear cell infiltration; in the subacute phase the alveolar walls are infiltrated with mononuclear inflammatory cells and fibroblasts; in the chronic phase, alveolar fibrosis and capillary sclerosis take place. (cecil textbook of medicine, 19th ed, p2343) (12 Dec 1998) |
| radiation poisoning | 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-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 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) |
| radiation-sensitizing agents | Drugs used to potentiate the effectiveness of radiation therapy in destroying unwanted cells. (12 Dec 1998) |
| 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) |