Radiography in Modern Industry - Kodak

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Example 3: The types of problems given in Examples 1 and 2 above are often combined inactual practice. Suppose, for example, that a radiograph was made on Film X with an exposure of20 mA-min and that a density of 1.0 was obtained. Then suppose that a radiograph at the samekilovoltage but on Film Y at a density of 2.5 is desired for the sake of the higher contrast and thelower graininess obtainable. The problem can be solved in a single step.Locate the intersection of the original density of 1.0 and the characteristic curve of Film X (Point Ein Figure 53) for the original exposure--20 mA-min--passes through point # and the horizontal linecoincides with the line for the new density of 2.5. The new exposure of 220 mA-min is read frompoint F (See Figure 53), the intersection of the horizontal line and the characteristic curve of FilmY.Figure 53: Characteristic curves of Films X and Y. Transparent overlay positioned for thegraphical solution of Example 3.Figure 54: Typical nomogram for solution of exposure calculations. The uses of thediagram are explained in the next section.Radiography in Modern Industry 76
Nomogram MethodsIn Figure 54, the scales at the far left and far right are relative exposure values. They do notrepresent milliampere-minutes, curie-hours, or any other exposure unit; they are to be consideredmerely as multiplying (or dividing) factors, the use of which is explained below. Note, also, thatthese scales are identical, so that a ruler placed across them at the same value will intersect thevertical lines, in the center of the diagram, at right angles.On the central group of lines, each labeled with the designation of a film whose curve is shown inthe Figure 47, the numbers represent densities.The use of Figure 54 will be demonstrated by a re-solution of the same problems used asillustrations in both of the preceding sections. Note that in the use of the nomogram, thestraightedge must be placed so that it is at right angles to all the lines--that is, so that it cuts theoutermost scales on the left and the right at the same value.Example 1: Suppose a radiograph made on Film Z (See Figure 47) with an exposure of 12 mAminhas a density of 0.8 in the region of maximum interest. It is desired to increase the density to2.0 for the sake of the increased contrast there available.Place the straightedge across Figure 54 so that it cuts the Film Z scale at 0.8. The reading on theoutside scales is then 9.8. Now move the straightedge upward so that it cuts the Film Z scale at2.0; the reading on the outside scales is now 41. The original exposure (12 mA-min) must bemultiplied by the ratio of these two numbers--that is, by 41/9.8 = 4.2. Therefore, the new exposureis 12 x 4.2 mA-min or 50 mA-min.Example 2: Film X has a higher contrast than Film Z at D = 2.0 (See Figure 47) and also lowergraininess. Suppose that, for these reasons, it is desired to make the aforementioned radiographon Film X with a density of 2.0 in the same region of maximum interest.Place the straightedge on Figure 54 so that it cuts the scale for Film Z at 2.0. The reading on theoutside scales is then 41, as in Example 1. When the straightedge is placed across the Film Xscale at 2.0, the reading on the outside scale is 81. In the previous example, the exposure for adensity of 2.0 on Film Z was found to be 50 mA-min. In order to give a density of 2.0 on Film X,this exposure must be multiplied by the ratio of the two scale readings just found--81/41 = 1.97.The new exposure is therefore 50 x 1.97 or 98 mA-min.Example 3: The types of problems given in Examples 1 and 2 are often combined in actualpractice. Suppose, for example, that a radiograph was made on Film X (See Figure 47) with anexposure of 20 mA-min and that a density of 1.0 was obtained. A radiograph at the samekilovoltage on Film Y at a density of 2.5 is desired for the sake of the higher contrast and thelower graininess obtainable. The problem can be solved graphically in a single step.The reading on the outside scale for D = 1.0 on Film X is 38. The corresponding reading for D =2.5 on Film Y is 420. The ratio of these is 420/38 = 11, the factor by which the original exposuremust be multiplied. The new exposure to produce D = 2.5 on Film Y is then 20 x 11 or 220 mAmin.Sliding Scales For Exposure ChartsAn exposure chart is an exceedingly useful radiographic tool. However, as pointed out in"Preparing An Exposure Chart", it has the limitations of applying only to a specific set ofradiographic conditions. These are:1. The x-ray machine usedRadiography in Modern Industry 77
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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
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: Figure 51: Characteristic curve of
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
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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
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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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