Varian Linatron High-Energy X-ray Applications 2007

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LINEAR ATTENUATION COEFFICIENT Constant used to describe the degree of x-ray attenuation per unit path length in a specified material. It is a function of x-ray energy and is usually expressed in units of reciprocal inch or centimeter. MAGNIFICATION Degree of projection and enlargement of regions of the object being radiographed in the developed film that result from the choice of distances between the source, object, and film in the radiography setup. NARROW BEAM (See BROAD BEAM) NDT An acronym of NONDESTRUCTIVE TESTING, and the name given to a test, inspection, or examination of materials to determine specific properties or characteristics, or to locate defects without causing damage to the object under test. PENETRAMETER Same as IQI. PAIR PRODUCTION An absorption process for photons of energies greater than 1.02 MeV, in which the photon transforms into a pair of particles (an electron and a positron). PHOTOELECTRIC ABSORPTION An absorption process for photons of energies under 1 MeV in which the photon loses all of its energy to an atomic electron. The electron leaves its atomic orbit and continues to move though the material. RAD Unit of radiation dose; 1 rad equals the absorption of 100 ergs of (any form of) radiation per gram of absorbing material. RADIOGRAPHIC COVERAGE That section and area of the object that is radiographed, exposed and imaged on the x-ray film. The RADIOGRAPHIC COVERAGE is usually stated as part of the specifications for the radiography work. page 62 REAL-TIME IMAGING X-ray radiography that produces instantaneous and continuous images on a TV monitor. The images obtained can be electronically processed to enhance their quality, and can be recorded (e.g., on videotape) for later playback. ROENTGEN Unit of radiation exposure (the ability of an x-ray beam to ionize air) corresponding to producing 1.610 x 1012 ion pairs per gram air. SCATTER mRADIATION Secondary x-rays and electrons produced whenever a primary x-ray beam irradiates an object. Also includes objects not being examined such as the floor, walls, tables, etc. Secondary radiations are emitted in all directions, and are of lower energy than the primary rays. SENSlTIVITY Refers to the degree to which images of wires (Wire Sensitivity), drilled holes in plaques (Plaque Sensitivity), steps (Contrast or Thickness Sensitivity), and actual defects in materials (Radiographic Sensitivity) are displayed and capable of being discerned in an x-ray film or other imaging device. Sensitivity is usually expressed as a percentage of the thickness of the object being examined. SOURCE-TO-FILM DISTANCE The actual distance between the focal spot of the x-ray source and the plane of the x-ray film in the specific exposure. This distance affects the amount of exposure used in every application of radiography. 22˚ PYRAMID Refers to the size and shape of the collimator used in the Linatron Model 200A, 400 and 1000. The collimator provides a cone (four-sided pyramid) of radiation with the focal spot as apex, the base a square, and with the sides forming a 22˚ interior angle. Varian Linatron applications
UNSHARPNESS Degree of loss in image fidelity (in the x-ray film) of edges and other features of the object being examined. Appears as regions of fuzziness or of indefinite location in the image of the edge. Major contributor to unsharpness are the geometry of the setup (Geometric Unsharpness), and the inherent effect of the screens and film used (Film-Screen Unsharpness). WHITE RADIATION The presence and distribution of x-ray photons at all energies up to the maximum emitted by an x-ray source. X-RAY LEAKAGE Refers to x-ray radiation that originates within an x-ray machine, and which penetrates the materials of the x-ray head in directions other than the opening provided by the collimator. X-RAY OUTPUT The intensity of the useful x-ray beam, usually expressed as rads per minute at l-meter from the x-ray source on the beam CENTRAL ray. page 63 Varian Linatron applications
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Varian Linatron High-Energy X-ray A
Page 5:
Preface This manual presents theory
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FIGURE 1-3. Linatron M System Diagr
Page 10 and 11:
Linatron targets are specially desi
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FIGURE 2-3. Half-value layer for pr
Page 14 and 15:
Beaming and Field Flatness. Electro
Page 16 and 17: FIGURE 3-2. Linatron x-ray intensit
Page 18 and 19: It is most convenient to have expos
Page 20 and 21: Vacuum cassettes are recommended wh
Page 22 and 23: Table 4-3 lists some relative speed
Page 24 and 25: Manufacturers publish density versu
Page 26 and 27: FIGURE 4-5. Plot of density versus
Page 28 and 29: The total unsharpness is reduced to
Page 30 and 31: This wedge block is then radiograph
Page 32 and 33: Increasing Latitude With Multiple F
Page 34 and 35: FIGURE 4-12. Linatron 2 MeV typical
Page 38 and 39: FIGURE 4-16. Linatron typical expos
Page 44 and 45: Radiographic Procedures General Con
Page 46 and 47: When radiographing curved sections,
Page 48 and 49: Radiography of Welds Radiography is
Page 50 and 51: The width of separation required fo
Page 52 and 53: The propellant in large motors is o
Page 54 and 55: Grain Radiography Coverage Requirem
Page 56 and 57: Bibliography Books Practical Radiog
Page 58 and 59: Normally, the light generated in th
Page 60 and 61: FIGURE 6-3. Real-time automated ins
Page 62 and 63: Real-time image acquisition display
Page 64 and 65: D/T RATIO Ratio of the distance bet
Page 68: Security & Inspection Products 6883
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