Radiography in Modern Industry - Kodak

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Thus, M 1 T 1 = M 2 T 2 = M 3 T 3 = C, a constant.This is commonly referred to as the reciprocity law. (Important exceptions are discussed below.)To solve for either a new time (T 2 ) or a new milliamperage (M 2 ), simply follow the steps shown inthe example in "Milliamperage-Distance Relation".Table V: Milliamperage-Time and Distance RelationsOld Dist./New Dist.25° 30° 35° 40° 45° 50° 55° 60° 65° 70° 75° 80°25 min. 1.0 1.4 2.0 2.6 3.2 4.0 4.8 5.6 6.8 7.8 9.0 10.030 min. 0.70 1.0 1.4 1.8 2.3 2.8 3.4 4.0 4.8 5.4 6.3 7.135 min. 0.51 0.74 1.0 1.3 1.6 2.0 2.5 3.0 3.4 4.0 4. 5.240 min. 0.39 0.56 0.77 1.0 1.3 1.6 1.9 2.2 2.6 3.1 3.5 4.045 min. 0.31 0.45 0.60 0.79 1.0 1.2 1.5 1.8 2.1 2.4 2.8 3.250 min. 0.25 0.36 0.49 0.64 0.81 1.0 1.2 1.4 1.7 2.0 2.2 2.655 min. 0.21 0.30 0.40 0.53 0.67 0.83 1.0 1.2 1.4 1.6 1.9 2.160 min. 0.17 0.25 0.34 0.44 0.56 0.69 0.84 1.0 1.2 1.4 1.6 1.865 min. 0.15 0.21 0.29 0.38 0.48 0.59 0.72 0.85 1.0 1.2 1.3 1.570 min. 0.13 0.18 0.25 0.33 0.41 0.51 0.62 0.74 0.86 1.0 1.1 1.375 min. 0.11 0.16 0.22 0.28 0.36 0.45 0.54 0.64 0.75 0.87 1.0 1.180 min. 0.10 0.14 0.19 0.25 0.32 0.39 0.47 0.56 0.66 0.77 0.88 1.0The Reciprocity LawIn the sections immediately preceding, it has been assumed that exact compensation for adecrease in the time of exposure can be made by increasing the milliamperage according to therelation M 1 T 1 = M 2 T 2 . This may be written MT = C and is an example of the generalphotochemical law that the same effect is produced for IT = constant, where I is intensity of theradiation and T is the time of exposure. It is called the reciprocity law and is true for direct x-rayand lead screen exposures. For exposures to light, it is not quite accurate and, since someradiographic exposures are made with the light from fluorescent intensifying screens, the lawcannot be strictly applied.Errors as the result of assuming the validity of the reciprocity law are usually so small that theyare not noticeable in examples of the types given in the preceding sections. Departures may beapparent, however, if the intensity is changed by a factor of 4 or more. Since intensity may bechanged by changing the source-film distance, failure of the reciprocity law may appear to be aviolation of the inverse square law. Applications of the reciprocity law over a wide intensity rangesometimes arise, and the relation between results and calculations may be misleading unless thepossibility of failure of the reciprocity law is kept in mind. Failure of the reciprocity law means thatthe efficiency of a light-sensitive emulsion in utilizing the light energy depends on the lightintensity. Under the usual conditions of industrial radiography, the number of milliampere-minutesrequired for a properly exposed radiograph made with fluorescent intensifying screens increasesas the x-ray intensity decreases, because of reciprocity failure.Radiography in Modern Industry 62
If the milliamperage remains constant and the x-ray intensity is varied by changing the focus-filmdistance, the compensating changes shown in Table VI should be made in the exposure time.Table VI gives a rough estimate of the deviations from the rules given in the foregoing sectionthat are necessitated by failure of the reciprocity law for exposures with fluorescent intensifyingscreens. It must be emphasized that the figures in column 3 are only approximate. The exactvalues of the factors vary widely with the intensity of the fluorescent light and with the density ofthe radiograph.When distance is held constant, the milliamperage may be increased or decreased by a factor of2, and the new exposure time may be calculated by the method shown in "Time-DistanceRelation", without introducing errors caused by failure of the reciprocity law, which are serious inpractice.LogarithmsSince logarithms are used a great deal in the following section, a brief discussion of them isincluded here. Some handbooks and intermediate algebra texts give a more detailed treatment.Before discussing logarithms, it is necessary to define the term "power". The power of a numberis the product obtained when the number is multiplied by itself a given number of times. Thus, 10= 10 x 10 = 1000; 5 = 5 2 x 5 = 25. In the first example, 1000 is the third power of 10; in thesecond, 25 is the second power of 5, or 5 raised to the second power. The superscript figure 2 isknown as the exponent. Fractional exponents are used to denote roots.The common logarithm of a number is the exponent of the power to which 10 must be raised togive the number in question. For example, the logarithm of 100 is 2. The logarithm of 316 equals2.50, or log 316 = 250; the logarithm of 1000 equals 3, or log 1000 = 3. It is also said that 1000 isthe antilogarithm of 3 or antilog 3 = 1000.Radiography in Modern Industry 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
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 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: Example: Suppose that with a given
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
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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
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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
Page 185 and 186:
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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