| acute radiation syndrome | <syndrome> A syndrome caused by exposure of the body to large amounts of radiation, (e.g., from certain forms of therapy, accidents, and nuclear explosions; it is divided into three major forms which are, in ascending order of severity, the haematogic, gastrointestinal, and central nervous system-cardiovascular forms; its clinical manifestations are divided into prodromal, latent, overt, and recovery stages. (05 Mar 2000) |
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| adaptive radiation | <chemistry> The evolution of new speciesor sub-species to fill unoccupied ecological niches. (06 May 1997) |
| alpha radiation | <physics, radiobiology> The most easily absorbable type of radiation, it consists of a stream of alpha particles, doubly ionised helium nuclei which are electrically charged and produce intense ionisation in matter. Alpha radiation can be deflected in electromagnetic fields. (09 Oct 1997) |
| annihilation radiation | The radiation resulting when a positron from beta positive decay comes to rest. It encounters an electron, and they annihilate each other and convert their rest mass into two 0.51-MeV gamma rays emitted in exactly opposite directions. (05 Mar 2000) |
| background radiation | <radiobiology> Level of environmental radation due to background sources. Background sources can be natural, such as cosmic rays and natural radioactive elements (principally radon, but including other elements such as isotopes of potassium (which people get substantial amounts of in foods like bananas)). They can also be man-made, such as from fossil-fuel combustion, everyday leakage from nuclear activities, and leftover from atmospheric nuclear weapons tests. Background radiation is usually distinguished from acute radiation, such as from medical X-rays, nuclear accidents, radioisotope therapy, or other short-term doses. The man-made contribution to background radiation is quite small compared to the natural contribution, medical uses dominate human exposure to acute radiation. (09 Oct 1997) |
| beta radiation | <radiobiology> Radiant energy from a source of beta rays. (05 Mar 2000) |
| radiation | <radiobiology> Propagation of energy through space. In the context of this report, it is electromagnetic radiation (X-rays or gamma rays) or corpuscular radiation (alpha particles, electrons, protons, neutrons) capable of producing ionisation. (16 Dec 1997) |
| radiation anaemia | Hypoplastic anaemia sometimes occurring after high-level acute or low-level chronic exposure to ionizing radiation. (05 Mar 2000) |
| radiation biology | Field of science that studies the biological effects of ionizing radiation. (05 Mar 2000) |
| radiation biophysics | The study of the effects of radiation on cells, tissues, biomolecules, and living organisms. (05 Mar 2000) |
| radiation burn | A burn caused by exposure to radium, X-rays, atomic energy in any form, ultraviolet rays, etc. (05 Mar 2000) |
| radiation caries | Caries of the cervical regions of the teeth, incisal edges, and cusp tips secondary to xerostomia induced by radiation therapy to the head and neck. (05 Mar 2000) |
| radiation cataract | A cataract caused by excessive or prolonged exposure to ultraviolet rays, X-rays, radium, beta rays, gamma rays, heat, or radioactive isotopes. (05 Mar 2000) |
| radiation chemistry | The science concerned with the effects of ionizing or nuclear radiation on chemical reactions or materials. (05 Mar 2000) |
| radiation chimera | An organism whose body contains cell populations of different genotypes as a result of the injection of foreign cells into it after it has received sufficient ionizing radiation to destroy the mature host cells which would otherwise reject the injected cells. (12 Dec 1998) |