Radiography in Modern Industry - Kodak

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Radiographic ShadowsThe basic principles of shadow formation must be given primary consideration in order to assuresatisfactory sharpness in the radiographic image and essential freedom from distortion. A certaindegree of distortion naturally will exist in every radiograph because some parts will always befarther from the film than others, the greatest magnification being evident in the images of thoseparts at the greatest distance from the recording surface (See Figure 11).Note, also, that there is no distortion of shape in Figure 11E above--a circular object having beenrendered as a circular shadow. However, under circumstances similar to those shown, it ispossible that spatial relations can be distorted. In Figure 12 the two circular objects can berendered either as two circles (See Figure 12A) or as a figure-eight-shaped shadow (See Figure12B). It should be observed that both lobes of the figure eight have circular outlines.Figure 12: Two circular objects can be rendered as two separate circles (A) or as twooverlapping circles (B), depending on the direction of the radiation.Distortion cannot be eliminated entirely, but by the use of an appropriate source-film distance, itcan be lessened to a point where it will not be objectionable in the radiographic image.Application To RadiographyThe application of the geometric principles of shadow formation to radiography leads to fivegeneral rules. Although these rules are stated in terms of radiography with x-rays, they also applyto gamma-ray radiography.1. The focal spot should be as small as other considerations will allow, for there is a definiterelation between the size of the focal spot of the x-ray tube and the definition in theradiograph. A large-focus tube, although capable of withstanding large loads, does notpermit the delineation of as much detail as a small-focus tube. Long source-film distanceswill aid in showing detail when a large-focus tube is employed, but it is advantageous touse the smallest focal spot permissible for the exposures required.Radiography in Modern Industry 22
B and H in the Figure 13 show the effect of focal spot size on image quality. As the focalspot size is increased from 1.5 mm (B) to 4.0 mm (H), the definition of the radiographstarts to degrade. This is especially evident at the edges of the chambers, which are nolonger sharp.2. The distance between the anode and the material examined should always be as greatas is practical. Comparatively long-source distances should be used in the radiography ofthick materials to minimize the fact that structures farthest from the film are less sharplyrecorded than those nearer to it. At long distances, radiographic definition is improvedand the image is more nearly the actual size of the object.3. A to D in the Figure 13 show the effects of source-film distance on image quality. As thesource-film distance is decreased from 68 inches (A) to 12 inches (D) the imagebecomes more distorted until at 12 inches it is no longer a true representation of thecasting. This is particularly evident at the edges of the casing where the distortion isgreatest.4. The film should be as close as possible to the object being radiographed. In practice, thefilm--in its cassette or exposure holder--is placed in contact with the object.In B and E of Figure 13, the effects of object-film distance are evident. As the object-filmdistance is increased from zero (B) to 4 inches (E), the image becomes larger and thedefinition begins to degrade. Again, this is especially evident at the edges of thechambers that are no longer sharp.5. The central ray should be as nearly perpendicular to the film as possible to preservespatial relations.As far as the shape of the specimen will allow, the plane of maximum interest should beparallel to the plane of the film.Finally, in F and G of the Figure 13, the effects of object-film-source orientation areshown. When compared to B, image F is extremely distorted because although the film isperpendicular to the central ray, the casting is at a 45° angle to the film and spatialrelationships are lost. As the film is rotated to be parallel with the casting (G), the spatialrelationships are maintained and the distortion is lessened.Radiography in Modern Industry 23
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: 1. The source of light should be sm
Page 25 and 26: 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 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 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
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
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KODAK Quinone-Thiosulfate Intensifi
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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
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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 and 186:
Figure 115: Characteristic curve of
Page 187 and 188:
film fairly well. If high densities
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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