Radiography in Modern Industry - Kodak

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CassetteOne cassette or film holder for each exposing unit in the operation should be reserved forexclusive use in exposing control film in that unit.Intensifying ScreensIf lead intensifying screens are used in the normal production operation, one set should bereserved for exclusive use in exposing control film.Electronic Thermometer with Submersible Stainless Steel ProbeThis is an essential item if two or more automatic processors are operated at a common densityaim that has close tolerances. It is also helpful in reducing variations in density attributable toprocessing in an automatic processor.General AspectsThe information that follows pertains to the central system as a whole. Specific details ofexposing, processing, use of data accumulated, and the like are presented later.ProcedureEstablish a specific exposure technique for each x-ray unit in the control system. A separatetechnique for each unit is essential because of variability in units of the same design andvariations among units of different designs. Each time control film is exposed in a unit, thetechnique established for that particular unit must be followed exactly.Routinely check the accuracy and the precision of the densitometer using the calibrated film stripor a control strip on which previous readings has been recorded.Maintain a separate process control chart for each exposing unit in the control system.Maintain a separate process control chart for each processor in the control system unless two ormore processors are kept operating at a common level.Expose control film each day in a designated unit. The exposed film is cut into enough strips toprovide a minimum of two strips for each processor in the operation. More than the minimumnumber of strips are cut if possible.Identify each strip.Place half of the strips in an airtight, light tight container; put the container in a moisture proof bag(a bag made of polyethylene, for example); and place the package in the refrigerator to minimizefading of the latent image. The strips are kept in the refrigerator for processing with freshlyexposed strips the following day. (A freshly exposed control strip is always processed with arefrigerated control strip exposed in the same unit the previous day.)Tape the control strips to a leader if they are to be processed in an automated processor. This willprovide better transport. If they are to receive rack-and-tank processing, it may be necessary tomake a special strip hanger or to adapt a standard film hanger in order to hold the strips securely.The control strips should always be processed with the high-density end down.Maintain an accurate, up-to-date log containing all information that could affect process control.The following should be included in the log:1. Maintenance data and changes resulting from readjustment of an exposing unit, includingthe supply of electrical current to the unit and any significant changes in line voltage.2. Maintenance data and changes resulting from readjustment of a processor.Radiography in Modern Industry 122
3. Age of the developer replenisher.4. Replenishment rate of the developer.5. Age of the developer.6. Temperature of the developer at the time control strips are being processed.7. Comments on fixer and wash and their replenishment rates. (Although the condition ofthe fixer and the wash does not noticeably affect the variability of film densities, thecondition of each does have an effect on the physical quality of processed film.)Process Control ChartsTwo steps on the control strip are selected for measurement. One step should have a density of0.6 to 1.0; the other, 2.0 or higher. A specific area of the step is selected for measurement, andthat same area on each of the two steps is measured to obtain a high-density value and a lowdensityvalue. From the first day on, four values are obtained--the value of the high-density stepand the value of the low density step on the fresh control strip and the values of thecorresponding steps an the control strip exposed the preceding day--always in the same area oneach step.The upper and the lower control limits for the process density aim can be assigned arbitrarily onthe basis of acceptable tolerances in the process operation (2.0 ± 0.2, for example). Sometimes itis desirable to calculate more precise control limits, however, and a statistical method, such asthe standard deviation of density values with three sigma control limits, can be used to determinethe limits. If the standard deviation with three sigma control limits is used, 95 percent of all datacollected should be within the limits. (The method of calculating the standard deviation with threesigma control limits, which is given in most books on statistical quality control, has beendescribed in relatively simple terms by Mason -- Mason, R. D.: Statistical Techniques in Businessand Economics. Monograph in Irwin Series in Quantitative Analysis for Business. Published byRichard D. Irwin, Inc., Homewood, Illinois, 1970, pp. 116-123, 314-329.)When a new box of control film is introduced into the operation, control exposures are made onboth the old and the new stock for four days and a temporary process density aim is computed onthe basis of the average densities obtained during the four-day period. After 10 days, the processdensity aim, or the mean density, is recomputed on the 10-day average.The process density aim is reestablished whenever changes are made within the operation. Suchchanges as the introduction of a new control film and alterations to the exposing unit, forexample, make it necessary to reestablish the aim.Control limits for variables of the exposing unit and the film processing are wider than if eitherwere monitored individually.The densitometric data obtained from the control strips can be utilized in several ways. The tablebelow shows densitometric readings for a 10-day period. Some of the data in Figure 78 areplotted on one process control chart (See Figure 80) to show variations in exposure andprocessing; some are plotted on another process control chart (See Figure 81) to indicatechanges in contrast.Radiography in Modern Industry 123
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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
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: Chapter 11: Process ControlUsers of
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
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
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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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