Radiography in Modern Industry - Kodak

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Table VI: Approximate Corrections for Reciprocity Law FailureDistanceIncreased by(Direct and Lead Screen Exposures) (Fluorescent Screen Exposures)Exposure Time Multiplied by 1 Exposure Time Multiplied by 125% 1.6 about 250% 2.3 about 4100% 4.0 about 8DistanceDecreased by20% 0.62 about 0.533% 0.43 about 0.250% 0.25 about 0.11 Column 2 shows the changes necessitated by the inverse square law only. Column 3 shows thecombined effects of the inverse square law and failure of the reciprocity law.Logarithms consist of two parts: A decimal which is always positive, called the mantissa; and aninteger which may be positive or negative, called the characteristic. In the case of log 316 = 2.50,.50 is the mantissa and 2 is the characteristic. The mantissa may be found by reference to a tableof logarithms, by the use of a slide rule (D and L scales), or by reference to the figure below.Regardless of the location of the decimal point, the logarithms of all numbers having the samefigures in the same order will have the same mantissa.Figure 43: Scale for determining logarithms.The characteristic of the logarithm is determined by the location of the decimal point in thenumber. If the number is greater than one, the characteristic is positive and its numerical value isone less than the number of digits to the left of the decimal point. If the number is less than one(for example, a decimal fraction), the characteristic is negative and has a numerical value of onegreater than the number of zeros between the decimal paint and the first integer. A negativecharacteristic of 3 is written either as 3...to indicate that only the characteristic is negative, or as7...-10.From Figure 43, we see that the mantissa of the logarithm of 20 is 0.30. The characteristic is 1.The preceding table illustrates a very important property of logarithms. Note that when a series ofnumbers increases by a constant factor, for example, the series 20, 40, 80, 160 or the series 20,200, 2,000, 20,000, the logarithms have a constant difference, in these cases 0.30 and 1.00,Radiography in Modern Industry 64
espectively. In other words, a constant increase in the logarithm of a number means a constantpercentage increase in the number itself.Photographic DensityPhotographic density refers to the quantitative measure of film blackening. When no danger ofconfusion exists, photographic density is usually spoken of merely as density. Density is definedby the equation:where D is density, I o is the light intensity incident on the film and It is the light intensitytransmitted.The tabulation below illustrates some relations between transmittance, percent transmittance,opacity, and density.This table shows that an increase in density of 0.3 reduces the light transmitted to one-half itsformer value. In general, since density is a logarithm, a certain increase in density alwayscorresponds to the same percentage decrease in transmittance.1.0 100 1 00.50 50 2 0.30.25 25 4 0.60.10 10 10 1.00.01 1 100 2.00.001 0.1 1,000 3.00.0001 0.01 10,000 4.0DensitometersA densitometer is an instrument for measuring photographic densities. A number of differenttypes, both visual and photoelectric, are available commercially. For purposes of practicalindustrial radiography, there is no great premium on high accuracy of a densitometer. A muchmore important property is reliability, that is, the densitometer should reproduce readings fromday to day.X-Ray Exposure ChartsAn exposure chart is a graph showing the relation between material thickness, kilovoltage, andexposure. In its must common form, an exposure chart resembles Figure 44. These graphs areadequate for determining exposures in the radiography of uniform plates, but they serve only asrough guides for objects, such as complicated castings, having wide variations of thickness.Radiography in Modern Industry 65
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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
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 and 62: Example: Suppose that with a given
Page 63: If the milliamperage remains consta
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
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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
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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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