| PIXE | particle-induced x-ray emission; proton-induced x-ray emission |
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| SET | Singlephoton Emission Tomography = SPECT |
| SPECT | Single Photon Emission Computed Tomography = SET |
| ECT | electroconvulsive therapy; emission computed tomography; enteric coated tablet; euglobulin clot test... |
| SPECT | single photon emission computed tomography |
| spiral computed tomography | <radiology> Computed tomography in which the X-ray tube continuously revolves around the patient, who is simultaneously moved longitudinally; computer interpolation allows reconstruction of standard transverse scans or images in any preferred plane. Synonym: helical computed tomography, helical CT, spiral CT. (20 Jun 2000) |
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| nuclear magnetic resonance tomography | A special imaging technique used to image internal stuctures of the body, particularly the soft tissues. An MRI image is often superior to a normal X-ray image. It uses the influence of a large magnet to polarize hydrogen atoms in the tissues and then monitors the summation of the spinning energies within living cells. Images are very clear and are particularly good for soft tissue, brain and spinal cord, joints and abdomen. These scans may be used for detecting some cancers or for following their progress. Acronym: MRI (11 Nov 1997) |
| dynamic computed tomography | Computed tomography with rapid injection of contrast medium, usually with sequential scans at only one or a few levels; used to enhance the vascular compartment. Synonym: dynamic CT. (05 Mar 2000) |
| tomography | <procedure, radiology> The recording of internal body images at a predetermined plane by means of the tomograph, also called body section roentgenography. Origin: Gr. Graphein = to write (18 Nov 1997) |
| alpha emission | <physics> Form of nuclear decay where the nucleus emits an alpha particle (see entry below). (09 Oct 1997) |
| beta emission | <radiobiology> Form of nuclear decay where a neutron splits into a proton plus electron plus neutrino set. The proton stays in the nucleus but the electron (beta ray) is ejected. (09 Oct 1997) |
| gamma emission | <physics> Nuclear decay process whereby the nucleus goes from an excited state to a more stable state by emitting a gamma ray. See: gamma ray. (09 Oct 1997) |
| particulate emission | Fine liquid or solid particles discharged with exhaust gases. Usually measured as grains per cubic foot or pounds per million Btu input. (05 Dec 1998) |
| characteristic emission | Monochromatic radiation that is produced when an electron is ejected from an atom and another takes its place by jumping from another shell; the energy of the photon is the difference between that of the two shell positions. Synonym: characteristic emission. (05 Mar 2000) |
| microscope, field emission | <microscopy> An image-forming device in which a strong electrostatic field causes cold emission of electrons from a sharply rounded point or from a specimen that has been placed on that point. The electrons are accelerated to a phosphorescent screen, or photographic film, giving a visible picture of the variation of emission over the specimen surface. (05 Aug 1998) |
| source emission reduction plan | (SERP) A contingency plan developed to reduce emissions during an air quality emergency. (05 Dec 1998) |
| spectrometry, X-ray emission | Identification and measurement of concentration of elements based on the fact that X-rays emitted by an excited element have a wavelength characteristic of that element and an intensity related to its concentration. It includes fluorescence, or secondary-emission, X-ray spectrometry, in which the specimen is irradiated by X-rays. Primary-emission x-ray spectrometry, in which the specimen is bombarded by electrons, is a specific type of X-ray emission spectrometry known as electron probe microanalysis. (12 Dec 1998) |
| spontaneous emission | <radiobiology> Radiation randomly emitted by excited atoms or ions. Contrast with stimulated emission. (09 Oct 1997) |
| stimulated emission | <radiobiology> Radiation coherently emitted by excited ions when driven by a passing light wave and the appropriate transition wavelength. Laser means Light Amplification by Stimulated Emission of Radiation, it occurs when there is a population inversion between the upper and lower energy states of the transition, such that stimulated emission can dominate excitation. Stimulated emission is coherent and codirectional with the stimulating wave, and the rate of stimulated emission is proportional to the intensity of the stimulating wave. (09 Oct 1997) |
| ion cyclotron emission | <radiobiology> As ions gyrate around in a magnetic field (see also larmor radius or cyclotron radius), they radiate radio-frequency electromagnetic waves. This is known as ion cyclotron emission, and can be measured to help diagnose a plasma. (09 Oct 1997) |