Radiography in Modern Industry - Kodak

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Figure 20: Schematic diagram illustrating the inverse square law.Since x-rays conform to the laws of light, they diverge when they are emitted from the anode andcover an increasingly larger area with lessened intensity as they travel from their source. Thisprinciple is illustrated in the figure above. In this example, it is assumed that the intensity of the x-rays emitted at the anode A remains constant and that the x-rays passing through the aperture Bcover an area of 4 square inches on reaching the recording surface C 1 , which is 12 inches (D)from the anode. Then, when the recording surface is moved 12 inches farther from the anode, toC 2 , so that the distance from the anode is 24 inches (2D), or twice its earlier value, the x-rays willcover 16 square inches--an area four times as great as that at C 1 . It follows, therefore, that theradiation per square inch on the surface at C 2 is only one-quarter of that at the level C 1 . Thus, theexposure that would be adequate at C 1 must be increased four times in order to produce at C 2 aradiograph of equal density. In practice, this can be done by increasing the time or by increasingthe milliamperage.Radiography in Modern Industry 30
Figure 21: Schematic diagram of some of the ways x- or gamma-ray energy is dissipatedon passing through matter. Electrons from specimens are usually unimportantradiographically; those from lead foil screens are very important.This inverse square law can be expressed algebraically as follows:where I 1 and I 2 are the intensities at the distances D 1 and D 2 respectively.Radiation Absorption In The SpecimenWhen x-rays or gamma rays strike an absorber (See Figure 21), some of the radiation isabsorbed and another portion passes through undeviated. It is the intensity variation of theundeviated radiation from area to area in the specimen that forms the useful image in aradiograph. However, not all the radiation is either completely removed from the beam ortransmitted. Some is deviated within the specimen from its original direction--that is, it is scatteredand is nonimage-forming. This nonimage-forming scattered radiation, if not carefully controlled,will expose the film and thus tend to obscure the useful radiographic image. Scattered radiationand the means for reducing its effects are discussed in detail in "Scattered Radiation". Anotherportion of the energy in the original beam is spent in liberating electrons from the absorber. Theelectrons from the specimen are unimportant radiographically; those from lead screens,discussed in detail in "Radiographic Screens", are very important.X-ray EquivalencyIf industrial radiography were done with monoenergetic radiation, that is, with an x-ray beamcontaining but a single wavelength, and if there were no scattering, the laws of absorption of x-rays by matter could be stated mathematically with great exactness. However, since a broadband of wavelengths is used and since considerable scattered radiation reaches the film, the lawscan be given only in a general way.The x-ray absorption of a specimen depends on its thickness, on its density and, most importantof all, on the atomic nature of the material. It is obvious that of two specimens of similarcomposition, the thicker or the more dense will absorb the more radiation, necessitating anRadiography in Modern Industry 31
Page 1 and 2: RadiographyinModernIndustry
Page 3 and 4: RadiographyinModernIndustryFOURTH E
Page 5 and 6: ContentsIntroduction...............
Page 7 and 8: Chapter 1: The Radiographic Process
Page 9 and 10: Intensifying ScreensX-ray and other
Page 11 and 12: makes it a very suitable material f
Page 13 and 14: Figure 6: Typical voltage waveforms
Page 15 and 16: Table I - Typical X-ray Machines an
Page 17 and 18: The wavelengths (or energies of rad
Page 19 and 20: Table III - Industrial Gamma-Ray So
Page 21 and 22: 1. The source of light should be sm
Page 23 and 24: B and H in the Figure 13 show the e
Page 25 and 26: Figure 14: Geometric construction f
Page 27 and 28: Figure 17: Pinhole pictures of the
Page 29: The kilovoltage applied to the x-ra
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 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
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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
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Film contrast refers to the slope (
Page 91 and 92:
Hole Type PenetrametersThe common p
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of the same thickness as the specim
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Chapter 9: Industrial X-ray FilmsMo
Page 97 and 98:
Figure 70 indicates the direction t
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the lead letters on a radiation-abs
Page 101 and 102:
Therefore, protection requirements
Page 103 and 104:
5. Avoid pressure damage caused by
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Paddles or plunger-type agitators a
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slow, and the development time reco
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ubbles make their way to the surfac
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When development is complete, the f
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soften considerably with prolonged
Page 115 and 116:
Figure 77: The roller transport sys
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Rapid Access to Processed Radiograp
Page 119 and 120:
Figure 78: Film-feeding procedures
Page 121 and 122:
Chapter 11: Process ControlUsers of
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3. Age of the developer replenisher
Page 125 and 126:
Figure 80: Control chart below for
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DiscussionDensitometric data and pr
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Figure 82: Plan of a manual x-ray p
Page 131 and 132:
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
Page 145 and 146:
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
Page 155 and 156:
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
Page 163 and 164:
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
Page 179 and 180:
Since this formula applies only to
Page 181 and 182:
such that it does not distort the i
Page 183 and 184:
Figure 113: A: Representation of a
Page 185 and 186:
Figure 115: Characteristic curve of
Page 187 and 188:
film fairly well. If high densities
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Density = 1.5 Density = 2.5Film Rel
Page 191 and 192:
In most industrial radiography, the
Page 193 and 194:
e noted here. Although the average
Page 195 and 196:
Chapter 17: Film Graininess; Signal
Page 197 and 198:
The ratio of signal to noise has a
Page 199 and 200:
Chapter 18: The Photographic Latent
Page 201 and 202:
Thus, the change that makes an expo
Page 203 and 204:
Figure 130: Stages in the developme
Page 205 and 206:
electrons by successive Compton int
Page 207 and 208:
Development is essentially a chemic
Page 209 and 210:
Chapter 19: ProtectionOne of the mo
Page 211 and 212:
duct is brought into the x-ray room
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Radiography in Modern Industry - Kodak

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