Radiography in Modern Industry - Kodak

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Chapter 10: Fundamentals of ProcessingIn the processing procedure, the invisible image produced in the film by exposure to x-rays,gamma rays, or light is made visible and permanent. Processing is carried out under subduedlight of a color to which the film is relatively insensitive. The film is first immersed in a developersolution, which causes the areas exposed to radiation to become dark, the amount of darkeningfor a given degree of development depending on the degree of exposure. After development, andsometimes after a treatment designed to halt the developer reaction abruptly, the film passes intoa fixing bath. The function of the fixer is to dissolve the darkened portions of the sensitive salt.The film is then washed to remove the fixing chemicals and solubilized salts, and finally is dried.Processing techniques can be divided into two general classes--"Manual Processing" and"Automated Film Processing".If the volume of work is small, or if time is of relatively little importance, radiographs may beprocessed by hand. The most common method of manual processing of industrial radiographs isknown as the tank method. In this system, the processing solutions and wash water arecontained in tanks deep enough for the film to be hung vertically. Thus, the processing solutionshave free access to both sides of the film, and both emulsion surfaces are uniformly processed tothe same degree. The all-important factor of temperature can be controlled by regulating thetemperature of the water in which the processing tanks are immersed.Where the volume of work is large or the holding time is important, automated processors areused. These reduce the darkroom manpower required, drastically shorten the interval betweencompletion of the exposure and the availability of a dry radiograph ready for interpretation, andrelease the material being inspected much faster. Automated processors move films through thevarious solutions according to a predetermined schedule. Manual work is limited to putting theunprocessed film into the processor or into the film feeder, and removing the processedradiographs from the receiving bin.General ConsiderationsCleanlinessIn handling x-ray films, cleanliness is a prime essential. The processing room, as w ell as theaccessories and equipment, must be kept scrupulously clean and used only for the purposes forwhich they are intended. Any solutions that are spilled should be wiped up at once; otherwise, onevaporation, the chemicals may get into the air and later settle on film surfaces, causing spots.The thermometer and such accessories as film hangers should be thoroughly washed in cleanwater immediately after being used, so that processing solutions will not dry on them and possiblycause contamination of solutions or streaked radiographs when used again.All tanks should be cleaned thoroughly before putting fresh solutions into them.Mixing Processing SolutionsProcessing solutions should be mixed according to the directions on the labels; the instructionsas to water temperature and order of addition of chemicals should be followed carefully, asshould the safe-handling precautions for chemicals given on labels or instruction sheets.The necessary vessels or pails should be made of AISI Type 316 stainless steel with 2 to 3percent molybdenum, or of enamelware, glass, plastic, hard rubber, or glazed earthenware.(Metals such as aluminum, galvanized iron, tin, copper, and zinc cause contamination and resultin fog in the radiograph.)
Paddles or plunger-type agitators are practical for stirring solutions. They should be made of hardrubber, stainless steel, or some other material that does not absorb or react with processingsolutions.Separate paddles or agitators should be provided for the developer and fixer. If the paddles arewashed thoroughly and hung up to dry immediately after use, the danger of contamination whenthey are employed again will be virtually nil. A motor-driven stirrer with a stainless steel propelleris a convenient aid in mixing solutions. In any event, the agitation used in mixing processingsolutions should be vigorous and complete, but not violent.Manual ProcessingWhen tank processing is used, the routine is, first, to mount the exposed film on a hangerimmediately after it is taken from the cassette or film holder, or removed from the factory-sealedenvelope. (See Figure 71) Then the film can be conveniently immersed in the developer solution,stop bath, fixer solution, and wash water for the predetermined intervals, and it is held securelyand kept taut throughout the course of the procedure.At frequent intervals during processing, radiographic films must be agitated. Otherwise, thesolution in contact with the emulsion becomes exhausted locally, affecting the rate and evennessof development or fixation.Another precaution must be observed: The level of the developer solution must be kept constantby adding replenisher. This addition is necessary to replace the solution carried out of thedeveloper tank by the films and hangers, and to keep the activity of the developer constant.Special precautions are needed in the manual processing of industrial x-ray films in roll form.These are usually processed on the commercially available spiral stainless-steel reels. The spacebetween the turns of film on such a reel is small, and loading must be done carefully lest the turnsof film touch one another. The loaded reel should be placed in the developer so that the film isvertical--that is, the plane of the reel itself is horizontal. Agitation in the developer should not beso vigorous as to pull the edges of the film out of the spiral recesses in the reel. The reel must becarefully cleaned with a brush to remove any emulsion or dried chemicals that may collect withinthe film-retaining grooves.Radiography in Modern Industry 105
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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
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: 5. Avoid pressure damage caused by
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
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
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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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