Radiography in Modern Industry - Kodak

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2. A certain source-film distance3. A particular type of film4. Processing conditions used5. The film density on which the chart is based6. The type of screens (if any) that are usedOnly if the conditions used in practice agree in every particular with those used in the productionof the exposure chart can exposures be read directly from the chart. If one or more of theconditions are changed, a correction factor must be applied to the exposure as determined fromthe chart. Correction factors to allow for differences between one x-ray machine and another, orbetween one type of screen and another, are best determined by experiment--often a newexposure chart must be made. Changes in the other four conditions, however, can in many casesbe calculated, making use of the characteristic curve of the films involved or of the inverse squarelaw.Numerical work involved in these corrections can often be avoided by the use of sliding scalesaffixed to the exposure chart. The preparation of these sliding scales will be facilitated (1) if theexposure chart has a logarithm of exposure (or of relative exposure) scale along one verticalboundary and (2) if the horizontal (exposure) lines are available on a transparent overlay (SeeFigure 55), on which the spacing of the lines corresponds to those in Figure 44. These overlayscan be made by tracing from the exposure chart involved onto exposed, fixed-out, x-ray film orany stiff transparent plastic material.Note that arrowheads are printed on the Figures 55 and 56. When these coincide, the exposuresread from the chart are those corresponding to the conditions under which the chart was made.The material that follows describes the technique of modifying the exposure chart in the earlierfigure, to allow for changes in radiographic conditions 2 through 5 above. The sections below arenumbered to correspond to the list in "Preparing An Exposure Chart".Figure 55: Pattern of transparent overlay for exposure chart of Figure 44.Radiography in Modern Industry 78
Figure 56: Transparent overlay positioned over the exposure chart in such a way as toduplicate that in an earlier figure. Thus, it applies to Film X a density of 1.5 and a sourcefilmdistance of 40 inches.2. Source-film distance. Since the intensity of the radiation varies inversely with the square of thesource-film distance, the exposure must vary directly with the square of the distance if a constantdensity on the radiograph is to be maintained. If source-film distance is to be changed, therefore,the exposure scale on the chart must be shifted vertically a distance that is in accord with the law.The chart of Figure 44 was made using a 40-inch source-film distance. Assume that it is desiredto make the chart applicable to distances of 30 and 60 inches as well. Note that column 2 of thetable below is calculated from the inverse square law and that the ratio is taken so that it isalways greater than 1. (This is done merely for convenience, it being easier to work withlogarithms of numbers greater than 1 than with logarithms of decimal fractions.) The logarithms incolumn 3 can be found in Figure 43, with a slide rule, or in a table of logarithms.Distance Intensity Ratio (relative to 40 in.) Logarithm of Intensity Ratio30 in. 1.78 1 0.2560 in. 2.25 2 0.351 Intensity greater than that at 40 inches by this factor.2 Intensity less than that at 40 inches by this factor.A mark is put on the margin of the exposure chart a log E interval of 0.25 above the printed arrow.When the transparent overlay is displaced upward to this position, exposures for a 30-inch focusfilmdistance can be read directly. Similarly, a mark is put a log E interval of 0.35 below theprinted arrow. The overlay, in this position, gives the exposures required at a source-film distanceof 60 inches. In the figure below, the exposure chart and overlay are shown in this position.Radiography in Modern Industry 79
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RadiographyinModernIndustry
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RadiographyinModernIndustryFOURTH E
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ContentsIntroduction...............
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Chapter 1: The Radiographic Process
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Intensifying ScreensX-ray and other
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makes it a very suitable material f
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Figure 6: Typical voltage waveforms
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Table I - Typical X-ray Machines an
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The wavelengths (or energies of rad
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Table III - Industrial Gamma-Ray So
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1. The source of light should be sm
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B and H in the Figure 13 show the e
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Figure 14: Geometric construction f
Page 27 and 28: Figure 17: Pinhole pictures of the
Page 29 and 30: The kilovoltage applied to the x-ra
Page 31 and 32: Figure 21: Schematic diagram of som
Page 33 and 34: kind of material radiographed, the
Page 35 and 36: instance, the kilovoltage may be fi
Page 37 and 38: The technique need not be limited t
Page 39 and 40: Chapter 5: Radiographic ScreensWhen
Page 41 and 42: Contact between the film and the le
Page 43 and 44: Figure 29: The number of electrons
Page 45 and 46: lead foil screens ran be retained w
Page 47 and 48: Figure 33: The sharpness of the rad
Page 49 and 50: Figure 34: Low density (right) is a
Page 51 and 52: such as a wall or floor, on the fil
Page 53 and 54: from this source. Since scatter als
Page 55 and 56: A filter reduces excessive subject
Page 57 and 58: Definite rules as to filter thickne
Page 59 and 60: 0.010-inch front screen of value be
Page 61 and 62: Example: Suppose that with a given
Page 63 and 64: If the milliamperage remains consta
Page 65 and 66: espectively. In other words, a cons
Page 67 and 68: Any given exposure chart applies to
Page 69 and 70: Figure 46: Typical gamma-ray exposu
Page 71 and 72: where the slope of the characterist
Page 73 and 74: Figure 49: Characteristic curves of
Page 75 and 76: Figure 51: Characteristic curve of
Page 77: Nomogram MethodsIn Figure 54, the s
Page 81 and 82: Figure 58: Overlay positioned so as
Page 83 and 84: The problem of radiographing a part
Page 85 and 86: Figure 62: System of lines drawn on
Page 87 and 88: Chapter 8: Radiographic Image Quali
Page 89 and 90: Film contrast refers to the slope (
Page 91 and 92: Hole Type PenetrametersThe common p
Page 93 and 94: of the same thickness as the specim
Page 95 and 96: Chapter 9: Industrial X-ray FilmsMo
Page 97 and 98: Figure 70 indicates the direction t
Page 99 and 100: the lead letters on a radiation-abs
Page 101 and 102: Therefore, protection requirements
Page 103 and 104: 5. Avoid pressure damage caused by
Page 105 and 106: Paddles or plunger-type agitators a
Page 107 and 108: slow, and the development time reco
Page 109 and 110: ubbles make their way to the surfac
Page 111 and 112: When development is complete, the f
Page 113 and 114: soften considerably with prolonged
Page 115 and 116: Figure 77: The roller transport sys
Page 117 and 118: Rapid Access to Processed Radiograp
Page 119 and 120: Figure 78: Film-feeding procedures
Page 121 and 122: Chapter 11: Process ControlUsers of
Page 123 and 124: 3. Age of the developer replenisher
Page 125 and 126: Figure 80: Control chart below for
Page 127 and 128: DiscussionDensitometric data and pr
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Figure 82: Plan of a manual x-ray p
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Figure 83: A schematic diagram of a
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loading-bench activities are carrie
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KODAK Quinone-Thiosulfate Intensifi
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Methylene-Blue MethodTwo variations
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KODAK Hypo Test Solution HT-2Avoird
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In summary, use of the test papers
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narrow angle would be very thick, e
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When radiation passes through a spe
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Figure 89: Demonstration of the eff
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Figure 90: The amount of gamma radi
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The radiograph exposed in the right
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To illustrate, let us assume that t
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Figure 95: High-speed x-ray picture
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Figure 97: Two methods of neutron r
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Duplicating RadiographsSimultaneous
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Sometimes, as when sets of referenc
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PhotofluorographyIn photofluorograp
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discontinuities or of segregation i
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from the camera or by reaching down
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Figure 106: Schematic diagram of th
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valuable technique, for instance, i
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The position of the spots is determ
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Powder Diffraction File, Internatio
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Processing TechniquesRadiographs on
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Since this formula applies only to
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such that it does not distort the i
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Figure 113: A: Representation of a
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Figure 115: Characteristic curve of
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film fairly well. If high densities
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Density = 1.5 Density = 2.5Film Rel
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In most industrial radiography, the
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e noted here. Although the average
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Chapter 17: Film Graininess; Signal
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The ratio of signal to noise has a
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Chapter 18: The Photographic Latent
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Thus, the change that makes an expo
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Figure 130: Stages in the developme
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electrons by successive Compton int
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Development is essentially a chemic
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Chapter 19: ProtectionOne of the mo
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duct is brought into the x-ray room
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Radiography in Modern Industry - Kodak

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