'Electron' p7 Searchterm 'Electron' found in 14 terms [ • ] and 63 definitions [• ]Result Pages : •
Binding energy is equal to the amount of energy which is used to free electrons or disintegrate nuclides from their atomic bond. The electron binding energy of a hydrogen atom is with 13.6 eV very low. The nuclear binding energy of an alpha-particle, energy equivalent of the sum of the individual masses of nuclides minus the mass of the whole nucleus, is 28.3 MeV. See also Alpha Decay, Beta Decay and Gamma Quantum. Further Reading: Basics:
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A computed tomography (CT) scanner is used to create cross-sectional
slices of different objects. The medical version of CT system scans the human body for tumors or other abnormalities, other versions are used for non-destructive testing in the industry. The CT imaging system includes the moveable gantry and patient table or couch. The gantry is a frame that contains the x-ray source, collimators, filters, detectors, a data acquisition system (DAS), rotational components including slip ring systems and all associated electronics. The x-ray tube and detector system are mounted opposite each other, allowing a rapid and synchronous rotation around the patient table. In older CT scanners a small generator supplied power to the x-ray tube and the rotational components via cables for operation. Up to the 4th generation the CT tube and detectors rotate together around the patient for each slice. CT systems with slip ring technology (the x-ray tube rotates around a stationary ring of detectors) operate without cables and provides continuous rotation of the gantry components without interference of cables. Spiral CT scanners work with a continuous table movement while the x-ray tube is rotating around the patient. Overview about CT scanner generations:
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1st generation has a pencil beam and one detector;
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2nd generation has a narrow fan beam and multiple detectors;
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3rd generation has a wide fan beam;;
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4th generation is equipped with a detector ring;
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6th generation is the helical (or spiral) CT scanner;
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7th generation is the multi-detector row CT.
See also Contrast Media Injector, Dual-Head CT Power Injector, Syringeless CT Power Injector. Further Reading: News & More:
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The continuum of energies transferred to electrons by Compton scattering is called the Compton continuum. It reflects also the maximum energy which a photon can give to the Compton electron depending on a maximum scattering angle and it's initially energy.
See also Compton Effect. •
The filament is the source of electrons (cathode) in x-ray tubes. A thin wire (0.1- 0.5 mm, usually tungsten) emits electrons due to thermionic emission, operating in a vacuum and energized with electric current. A CT tube utilizes a larger filament with larger size of the effective focal spot than a conventional x-ray tube. •
An imaging plate is used in computed radiography (CR) instead of a conventional film cassette. The imaging plate is coated with photostimulable phosphors. The phosphor layer is doped with special substances to alter the crystalline structure and physical properties. After radiation, the enhanced phosphor material absorbs and stores x-ray energy in gaps of the crystal structure, building a latent image. Usually, the storage phosphors are stimulated with a low-energy laser to release visible light at each point of x-ray absorption. To read-out the image, the plate is inserted into a computed radiography scanner. The scanning laser beam causes the electrons to relax to lower energy levels, emitting light that is captured by a photo-multiplier tube and converted into an electrical signal. The electronic signal is then converted to digital data and can be displayed on laser-printed films, workstations, transmitted to remote systems, and stored digitally. The CR units automatically erase the image plate after the complete scan. Phosphor imaging plates, like film, are stored in cassette format and can be re-used very often if they are handled carefully. Existing conventional x-ray equipment, from generators to x-ray tubes and examination systems, can be used with imaging plates. Further Reading: Basics:
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