Radiography in Modern Industry - Kodak

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Although the lines of an exposure chart are normally straight, they should in most cases becurved--concave downward. The straight lines are convenient approximations, suitable for mostpractical work, but it should be recognized that in most cases they are only approximations. Thedegree to which the conventionally drawn straight line approximates the true curve will vary,depending on the radiographic conditions, the quality of the exposing radiation, the materialradiographed, and the amount of scattered radiation reaching the film.In addition, time, temperature, degree of activity, and agitation of the developer are all variablesthat affect the shape of the characteristic curve and should therefore be standardized. When, inhand processing, the temperature or the activity of the developer does not correspond to theoriginal conditions, proper compensation can be made by changing the time according tomethods described in "Control of Temperature and Time". Automated processors should becarefully maintained and cleaned to achieve the most consistent results. In any event, thegreatest of care should always be taken to follow the recommended processing procedures.Radiography in Modern Industry 86
Chapter 8: Radiographic Image Quality and DetailVisibilityBecause the purpose of most radiographic inspections is to examine a specimen forinhomogeneity, a knowledge of the factors affecting the visibility of detail in the finishedradiograph is essential. The summary chart below shows the relations of the various factorsinfluencing image quality and radiographic sensitivity, together with page references to thediscussion of individual topics. For convenience, a few important definitions will be repeated.Factors Affecting Image QualityRadiographic Image QualityRadiographic ContrastDefinitionSubjectContrastFilm ContrastGeometricFactorsFilmGraininess,ScreenMottleFactorsAffected by:A -Absorptiondifferencesin specimen(thickness,composition,density)B - RadiationwavelengthC -ScatteredradiationReducedby:1 - Masksanddiaphragms2 - Filters3 - Leadscreens4 - Potter-BuckydiaphragmAffected by:A - Type of FilmB - Degree of development (type of developer, time andtemperature of development, activity of developer, degree ofagitation)C - DensityD - Type of screens (fluorescent vs lead or none)Affected by:A - FocalspotsizeB - SourcefilmdistanceC -SpecimenfilmdistanceD -Abruptnessof thicknesschanges inspecimenE - ScreenfilmcontactF - Motion ofspecimenAffected by:A - Type ofFilmB - Type ofscreenC - RadiationwavelengthD -DevelopmentRadiographic sensitivity is a general or qualitative term referring to the size of the smallest detailthat can be seen in a radiograph, or to the ease with which the images of small details can bedetected. Phrased differently, it is a reference to the amount of information in the radiograph.Note that radiographic sensitivity depends on the combined effects of two independent sets offactors. One is radiographic contrast (the density difference between a small detail and itssurroundings) and the other is definition (the abruptness and the "smoothness" of the densitytransition). See Figure 63.
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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
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Figure 17: Pinhole pictures of the
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The kilovoltage applied to the x-ra
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Figure 21: Schematic diagram of som
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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 and 78: Nomogram MethodsIn Figure 54, the s
Page 79 and 80: Figure 56: Transparent overlay posi
Page 81 and 82: Figure 58: Overlay positioned so as
Page 83 and 84: The problem of radiographing a part
Page 85: Figure 62: System of lines drawn on
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
Page 129 and 130: Figure 82: Plan of a manual x-ray p
Page 131 and 132: Figure 83: A schematic diagram of a
Page 133 and 134: loading-bench activities are carrie
Page 135 and 136: 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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