Radiography in Modern Industry - Kodak

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Figure 116: Characteristic curves of three typical industrial x-ray film.Figure 117: Gradient versus density curves of the typical industrial x-ray films, thecharacteristic curves of which are shown in Figure 116.It is often useful to have a single number, rather than a curve as shown in the figure above, toindicate the contrast property of a film. This need is met by a quantity known as the averagegradient, defined as the slope of a straight line joining two points of specified densities on thecharacteristic curve. In particular, the specified densities between which the straight line is drawnmay be the maximum and minimum useful densities under the conditions of practical use. Theaverage gradient indicates the average contrast properties of the film over this useful range; for agiven film and development technique, the average gradient depends on the density rangechosen. When high-intensity illuminators are available and high densities are used, the averagegradient calculated for the density range 2.0 to 4.0 represents the contrast characteristics of theRadiography in Modern Industry 186
film fairly well. If high densities are for any reason not used, a density range of 0.5 to 2.5 issuitable for evaluation of this quantity. If intermediate densities are used, the average gradientcan be calculated over another range of densities--1.0 to 3.0, for example.Figure 118: Characteristic curve of a typical industrial x-ray film, with the average gradientcalculated over two density ranges.Figure 118shows the characteristic curve of a typical industrial x-ray film. The average gradientsfor this film over both the above density ranges are indicated. The table below gives averagegradients of the typical x-ray films, the characteristic curves of which are shown in Figure 116.Since Film Z does not reach a density of 4.0, its average gradient cannot be given for the higherdensity range.Average GradientFilmDensity Range0.5--2.5Density Range 2.0--4.0X 2.3 5.7Y 2.6 6.3Z 1.7 --Experiments have shown that the shape of the characteristic curve is, for practical purposes,largely independent of the wavelength of x-radiation or gamma radiation. Therefore, acharacteristic curve made with any radiation quality may be applied to exposures made with anyother, to the degree of accuracy usually required in practice, and the same is true of values ofgradient or average gradient derived from the curve.The influence of kilovoltage or gamma-ray quality on contrast in the radiograph, therefore, is theresult primarily of its effect on the subject contrast, and only very slightly, if at all, of any change inthe contrast characteristics of the film. Radiographic contrast can also be modified by choice of afilm of different contrast, or by use of a different density range with the same film. Contrast is alsoaffected by the degree of development, but in industrial radiography, films are developed to theirmaximum, or nearly their maximum, contrast. In the early stages of development, both densityand contrast increase quite rapidly with time of development (See "Effect Of Development TimeRadiography in Modern Industry 187
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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
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instance, the kilovoltage may be fi
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The technique need not be limited t
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Chapter 5: Radiographic ScreensWhen
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Contact between the film and the le
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Figure 29: The number of electrons
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lead foil screens ran be retained w
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Figure 33: The sharpness of the rad
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Figure 34: Low density (right) is a
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such as a wall or floor, on the fil
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from this source. Since scatter als
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A filter reduces excessive subject
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Definite rules as to filter thickne
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0.010-inch front screen of value be
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Example: Suppose that with a given
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If the milliamperage remains consta
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espectively. In other words, a cons
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Any given exposure chart applies to
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Figure 46: Typical gamma-ray exposu
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where the slope of the characterist
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Figure 49: Characteristic curves of
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Figure 51: Characteristic curve of
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Nomogram MethodsIn Figure 54, the s
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Figure 56: Transparent overlay posi
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Figure 58: Overlay positioned so as
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The problem of radiographing a part
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Figure 62: System of lines drawn on
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Chapter 8: Radiographic Image Quali
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Film contrast refers to the slope (
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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
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Figure 70 indicates the direction t
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the lead letters on a radiation-abs
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Therefore, protection requirements
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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
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Figure 77: The roller transport sys
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Rapid Access to Processed Radiograp
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Figure 78: Film-feeding procedures
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Chapter 11: Process ControlUsers of
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3. Age of the developer replenisher
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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
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Figure 83: A schematic diagram of a
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loading-bench activities are carrie
Page 135 and 136: KODAK Quinone-Thiosulfate Intensifi
Page 137 and 138: Methylene-Blue MethodTwo variations
Page 139 and 140: KODAK Hypo Test Solution HT-2Avoird
Page 141 and 142: In summary, use of the test papers
Page 143 and 144: narrow angle would be very thick, e
Page 145 and 146: When radiation passes through a spe
Page 147 and 148: Figure 89: Demonstration of the eff
Page 149 and 150: Figure 90: The amount of gamma radi
Page 151 and 152: The radiograph exposed in the right
Page 153 and 154: To illustrate, let us assume that t
Page 155 and 156: Figure 95: High-speed x-ray picture
Page 157 and 158: Figure 97: Two methods of neutron r
Page 159 and 160: Duplicating RadiographsSimultaneous
Page 161 and 162: Sometimes, as when sets of referenc
Page 163 and 164: PhotofluorographyIn photofluorograp
Page 165 and 166: discontinuities or of segregation i
Page 167 and 168: from the camera or by reaching down
Page 169 and 170: Figure 106: Schematic diagram of th
Page 171 and 172: valuable technique, for instance, i
Page 173 and 174: The position of the spots is determ
Page 175 and 176: Powder Diffraction File, Internatio
Page 177 and 178: 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: Figure 115: Characteristic curve of
Page 189 and 190: 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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