The document describes the structure and processing of radiographic film. It discusses the components of film, including the base, emulsion, and silver halide crystals. It explains the formation of latent images when x-rays strike the film. The stages of film processing are outlined, including development, fixing, washing and drying. Both manual and automated processing techniques are covered. Factors that can affect film processing like temperature are also mentioned.

1. DESCRIBE THE RADIOGRAPHIC
FILM AND FILM PROCESSING
NDANSAW JOSEPH NDIFELAYE
DEPARTMENT OF RADIOLOGY
AMINU KANO TEACHING HOSPITAL, KANO
05-05-2022
5/2/2023 1

2. OUTLINE:
• Introduction
• Structure of a film
• Classification of X-ray films
• Latent image formation
• Conventional Film processing – manual, automatic.
• Factors affecting conventional film processing
• Artifacts
• Film storage
• Digital film processing.
• Summary
• Conclusion
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3. Introduction
• When an X-ray beam reaches the patient, it has no useful medical
information.
• After interaction with the tissues, it has all information that can be
revealed by that particular radiographic examination.
• This information cannot be used unless its transformed in a form that
can be viewed with the eye.
• The photographic film is the material used to decode the information
carried by the attenuated X-ray beam.
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4. Introduction cont
• Radiographic film acquires an image and must be processed before it
is visible.
• The method of transfer of this information might involve a magnetic
tape or disc, a fluoroscopic screen or xenography.
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5. Film Structure
• X – ray film is a photographic film consisting of a photographically
active or radiation sensitive emulsion.
• The emulsion is coated on one or both sides of the base.
• The emulsion is attached to the base by a thin layer of adhesive.
• The delicate emulsion is protected from mechanical damage by layers
known as supercoatings.
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6. Film structure cont
6
Emulsion
Base
Supercoat
Emulsion
Adhesive layer
Double Emulsion Film
Adhesive layer
Supercoat
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7. Film Structure cont – Film Base
• It provides support to the fragile photographic emulsion.
• It must not produce visible pattern or absorb too much light when the
radiographic film is viewed.
• It flexibility, thickness and strength must allow for ease of processing.
• It must have dimensional stability.
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8. Film Structure cont – film base
• Glass plates
• Cellulose nitrate
• Cellulose triacetate
• Polyester: DMT and ethylene glycol.
• Blue tint added to X-ray base or emulsion.
• Polyester are thinner than triacetate.
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9. Film Structure cont- emulsion
• Contains gelatin and silver halide
• The exact composition of the various emulsions is a closely guarded
industrial secret.
• Most conventional X-ray film is made for use with intensifying screens
and has emulsion coated on both sides of the base.
• Emulsion thickness varies with film type but not usually thicker than
0.5mm.
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10. Film Structure cont – emulsion - gelatin
• Made from mostly cattle bone.
• It keeps silver halide grains well dispersed and prevent clumping of
grains.
• Can be penetrated by processing solution rapidly without destroying
its strength.
• Its readily available in large quantity and uniform quality.
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11. Film Structure cont – emulsion – silver halide
• It’s the light sensitive material in the emulsion.
• It consist of 90-95% AgBr and 5-10% AgI.
• The presence of AgI produces an emulsion of much higher sensitivity
than pure AgBr emulsion.
• The silver iodobromide crystals are precipitated under particular
concentration and temperature.
• The silver iodobromide is not a perfect crystal.
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12. Film Structure cont – emulsion – silver halide
• Chemical sensitization of a crystal is by addition of allylthiourea to
emulsion which react with the halide to produce silver sulfide.
• Silver sulfide referred to as the sensitive speck.
• The sensitive speck traps electrons to begin the formation of the
latent image.
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13. Film structure cont - Layers
• Base: cellulose triacetate or polyester for support.
• Substratum: adhesive layer containing gelatin and solvent that bind
emulsion and base.
• Emulsion: silver halide and gelatin with some hardening agents in
main layer where latent images are formed.
• Protective layer: gelatin protects emulsion from damage.
• Total thickness of the film is about 0.25mm.
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14. • TYPES OF X-RAY FILM
• Screen type films Direct exposure type Structure Others
• Conventional dental procedures single emulsion
• Orthochromatic double emulsion
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15. Type of film – single and double emulsion
• Single Emulsion Film e.g. Mammography
• It has the advantage of better image quality/contrast
• Double Emulsion Film e.g. conventional Film
• Its has an advantage of higher efficiency with relative poor contrast
• Laser Films: CT, MRI
• Duplication films
• Subtraction films
• Fluoroscopic spot filming
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16. Type of film - Screen film
• Some films needs to be used in combination with screens.
• Screens uses various types of phosphor layer that emit light photon of
different colors.
• It is important to note that the color of light emitted (wavelength) by
a screen must match the light sensitivity of the film used (spectral
matching).
• Conventional films: sensitive to ultraviolet and blue lights.
• Orthochromatic films: sensitive to ultraviolet, blue and green lights.
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17. Latent image formation
.
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18. Latent Image Formation
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19. Concept of latent image formation
 When x-ray photons or light strike the grains of the sensitive silver
halide in the emulsion, some of the Br- ion electrons are liberated
which are then capture by the Ag+ ions to be converted to metallic
silver at the region of the sensitivity speck.
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20. Concept of latent image formation
• This single atom of silver then acts as electron trap for a second
electron.
• The negative charge causes a second silver ion to migrate to the trap
to form another silver atom and the process continues.
• The negative bromide lost is taken by the gelatin of the emulsion.
• The small clumps of silver can be seen with electron microscope.
• The clumps of silver are termed latent image centers.
• This needs processing to become visible image.
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21. Film processing
• Film processing is a series of chemical processes that converts the
latent image into a visible image
• Processing of conventional radiograph can either be; Manual or
Automatic film processing
• Both share the same principle but differ in the temperature and
concentration of chemicals used
• Automatic film processing use roller transport or track system .
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22. Manual processing
• .
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23. Automatic film processor
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24. Automated Processor Design
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25. Development
• A chemical process that amplifies the latent image to form a visible
image
• The basic reaction is reduction (addition of an electron) of the silver
ion to black metallic silver by the developing agent.
• This causes the crystals to become visible black specks in the
emulsion.
• Development is generally an all-or-none phenomenon because an
entire grain is developed once the process begins.
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26. Development cont
• Development is usually initiated at the site of the latent image.
• The silver in a grain that does not contain a latent image can also be
reduced by the developer but at a much slower rate.
• Development should be discontinued when the difference between
exposed developed grains and unexposed undeveloped grains is at a
maximum .
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27. Constituents of developer solution
• Developing agents
• Activator
• Restrainers
• Preservatives
• Hardener
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28. Developing agents
• They are reducing agents which supply electrons to the silver
ions in the exposed silver halide grains converting them to atoms
of metallic silver.
• The chemical agents used are hydroquinone, phenidone and
metol.
• Hydroquinone is used mainly in combination with metol or
phenidone.
• This leads to synergy.
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29. Developing Agents cont.
• They reduce silver ions to metallic silver causing oxidation and
inactivation of developing agent and the liberation of hydrogen ions.
• The silver thus formed is deposited at the latent image site.
• It gradually enlarge this initially microscopic black spot into a single
visible black speck of silver in the emulsion.
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30. Developing Agent cont
• Activator (Sodium carbonate) – provide alkaline medium, softens and
swells the emulsion so that the reducers can reach the exposed
crystal
• Restrainer (Potassium bromide) – moderates the development by
making them become more selective therefore reduce fogging.
• Preservative (Sodium sulfite) – Helps to protect the reducing agents
from oxidation by atmospheric oxygen
• Hardener (Glutaraldehyde) - retards the swelling of the emulsion.
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31. Developing agents cont
Properties of an ideal developer
Must be selective and distinguish between exposed and unexposed
grains.
Sufficiently high activity.
As resistant as possible to the presence of bromine ions.
No single reducing agent satisfies all these requirements so
combinations are used.
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32. Developer Replenishment
• During use, developer solution is consumed but acquire hydrogen
ions and bromide.
• Replenishment must compensate for these agents by being free from
bromide, by containing alkali agents and buffers and restoring
preservative and developing agent.
• Each time a film is processed, a small portion of the developing
solution is removed and replaced with a replenishment solution.
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33. Developer Replenishment cont
• Almost all conventional radiographs are now processed with
automatic film processor with automatic developer replenishment.
• Traditional replenishment was developed for high volume operations
were many films are processed in a day.
• Many automatic processors operate in small installations making
oxidation of the developer more important than the consequences of
the development process.
• Replenishment is either for high volume of low volume.
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34. Developer Replenishment – high volume
• During use, developer solution is consumed but acquire hydrogen
ions and bromide.
• Replenishment must compensate for these agents by being free from
bromide, by containing alkali agents and buffers and restoring
preservative and developing agent.
• Lifetime of a tank of developer will last about 2-3months in a busy
department.
• Replenishment rate is 60ml of developer for each 14x17 inch film
processed.
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35. Developer Replenishment – low volume
• Many automatic processors operate in small installations making
oxidation of the developer more important than the consequences of
the development process.
• Here, pH increases, no bromide produced and replenishment is
infrequent.
• Standard replenisher has high pH with no bromide.
• Decrease bromide concentration has adverse effect on the film
sensitometry.
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36. Developer Replenishment – low volume
• A developer with low pH and higher sulfite concentration retard
oxidation
• High buffering capacity to minimize pH effect of oxidation.
• Replenisher has low pH than developer and contains bromide.
• Replenisher rate is usually higher, 90ml per 14x17 inch film to
increase developer turnover rate.
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37. Rinsing
• Rinsing or Stop bath: The film is next rinsed to remove the developer
solution before proceding to the fixing solution
• Rinsing time – 30secs.
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38. Fixing
• Only part of the silver halide in the emulsion is reduced to silver
during development.
• The remaining silver impairs both the immediate and permanence
usefulness of the developed radiograph.
• The fixing solution must remove silver halide without damaging the
image formed by the metallic silver.
• Ag+ x Br- = constant
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39. Fixing
• The fixing agents used are cyanides and thiosulfates.
• The thiosulfates in the form of sodium and ammonium salts are
commonly used.
• The ammonium thiosulfate is more active and is used in fixer supplied
in liquid form.
• Fixing solution also contains a chromium or aluminum compound.
• It also contains an acid, stabilizers and a buffer to maintain the acidic
pH level.
• Fixing time: 15mins.
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40. Washing
• The film is washed with water to remove all the fixing-bath chemicals
• Retained thiosulfate in the emulsion will react with silver image to
form brown silver sulfide.
• The amount of thiosulfate retained determines the useful lifetime of
processed film
• The less the amount of retained thiosulfate the longer the life span
• Duration: 20mins.
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41. Drying
• The film is finally dried for viewing
• It is passed through a chamber in which hot air is circulating
• Duration: 30mins.
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42. Summary of events in processing a Radiograph
Step Purpose Manual Automatic
Development Production of manifest image from the latent image 5 min 22s
Rinsing to remove the developer solution before proceeding to the fixing
solution.
30s -
Fixing Arrest the chemical activity of the residual developer,removes
remaining silver halides and hardening of gelatin.
15 min 22s
Washing Removal of Excess/residual chemicals. 20 mins 20s
Drying Removal of water and preparation of Radiograph for viewing 30mins 26s
>1Hour 90s
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43. Darkroom procedure
• A light tight room in the vicinity of a radiography cubicle.
• Two sources of light, white light(ceiling) for regular illuminations for
mixing solutions &cleaning the room.
• Safelight which contains 10-15watts bulb with special filters. located
4feets from the work surface.
• Safe handling time – should be 30 – 40 seconds.
• Development temperature – usually 20oC(manual) 33-
33.8’C(automatic)
• Development time – 3 – 10 minutes.
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44. Processing Techniques
• Manual
• 1 hour
• Automatic
• 90 seconds
• Less variation (standardized)

45. Manual Processing
• Prep
• Proper temp.
• Stirred
• Don’t share between tanks
• Turn on the safelight

46. Manual Processing Cont.
• Tension clip hanger
• Stationary clips first
• Movable clips second
• Stretch film
• Channel hanger
• Hold with one hand and slide the film into the channel with the other

47. Manual Processing Cont.
• Developing
• Agitate film while in developer to remove air bubbles from film surface
• 5 minutes
• While processing, refill the cassette
• Carfeul to have dry hands when reloaded
• Water spots can cause an artifact

48. Manual Processing Cont.
• Rinse
• Tilt film so chemical carryover goes into the rinse bath
• This places more of the exhausted developer into rinse
• Agitated in rinse for 30 seconds
• Fix
• Agitate film for about 15 seconds to remove air bubbles from film
surface
• Fix twice the time of developing example 10 minutes
• Can view in normal room light after 1 minute but need to place back
into fixer

49. Manual Processing Cont.
• Wash for 20-30 minutes
• Drying
• Dust free environment
• Don’t allow films to touch
• Cut off sharp points on corners where tension clip hangers put holes in
corners
• Store in envelope

50. Automatic Processing
• Highly standardized
• Produces dry film in short period
• Costly machine
• Pays for itself in a short period of time

51. Automatic Processing Cont.
• Same routine as manual processing
• Higher temps and special chemicals
• Film transported through the machine with rollers at controlled
speed
• Rinse between developer and fixer eliminated
• Carryover removed by compression of rollers on film

52. Automatic Processing Cont.
• Chemicals in peak condition because they are replenished on regular basis
• Tubs under processor
• Maintain temp and mix chemicals
• Maintenance
• Solution level check
• Replenishment rate check
• Temp check
• Roller operation check
• Rinsing and wiping of rollers and racks
• Regular cleaning of tanks

53. Factors Affecting Film Processing
• The thermostat is set to maintain the developer
temperature in the range between 33°C and 33.8°C in
90-second automatic processors.
• Developer temperatures below this range result in
slower chemical reactions and an underdeveloped
film with decreased density and low contrast.
• Temperatures above this range result in rapid
chemical reactions, overdeveloped film, increased
image density, and a high-contrast, narrow-latitude
image.
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54. Artifacts
• It can be described as an undesirable optical density on radiograph
• They are produced due to fault in exposure, processing, handling or
storage of films.
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55. Types of artifacts
• Exposure artifacts
• Processing artifacts
• Handling/storage artifacts
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56. Exposure artifacts
• Motion
• Improper positioning
• Poor film screen contact
• Foreign Objects
• Back-scatter
• Improper use of grid
• Dirt on the screen
• Over/under exposures
• Light leakage into the cassette
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57. Processing artifacts
• Hypo retention
• Roller mark
• Static electricity
• Finger mark
• Water stain
• Milky/cloudy unexposed areas
• Image underdevelopment
• Image over development/fogging
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58. Handling/storage artifacts
• Light Fog
• Radiation fog
• Static
• Scratches
• Hypo retention
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59. 5/2/2023 59

60. Pressure artifact from fingernails
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61. Hypo retention
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62. Conventional film storage and handling
• Fresh film should be stored in a cool, dry place with a temperature
<70°C and with 40-60% relative humidity.
• Storage under heat conditions above 70°C will increase the fog and
decrease the image contrast.
• Storage under conditions of low humidity, less than about 40%, will
increase static artifacts.
• Film must be shielded from radiation exposure, heat and chemical
fumes.
• The stocks should be rotated, on the first in/first out principle (FIFO)
the oldest should be used first.
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63. Digital film processing
• It replaces the traditional film/screen systems with special detectors.
• They are either cassette based or cassette-less.
• Regardless of the system, the process of image acquisition is basically
the same.
• After the primary x-ray radiation beam passes through the patient,
the exit radiation is detected, and signal data are processed, displayed
and stored.
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64. Basic components of digital imaging system
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65. 5/2/2023 65

66. Analog-To-Digital Converter
• All direct digital systems initially convert the analog signal from the
detector to a digital signal using ADC.
• The digital data are available for processing, display and storage.
• Imaging detectors produce continuously varying signals called analog
signals, these signals make up the latent image.
• Digital systems represent the signal by a series of discrete values
which makes up the intensity of the pixels.
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67. Sources of digital images
• 1.Directly from MR, CT
• 2. Digitized fluoroscopic images
• 3. Computed radiographic plates
• 4. Direct Digital Radiography
• 5. Digitized conventional film images
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68. Computed Radiography
• CR is a “cassette-based” system that uses a special solid-state
detector plate instead of a film inside a cassette.
• The exterior dimensions and appearance of the CR cassette are the
same as those of a conventional film cassette.
• The CR cassette is placed in the Bucky tray or for portable
examinations and exposed in the same manner as a conventional film
cassette.
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69. Computed Radiography
• Most CR systems are set up to have the same response as a 200-
speed film per screen system, although this can be changed.
• The resolution of CR systems depends on the pixel size but is not as
good as that of conventional film/screen systems.
• The contrast resolution of CR is superior to that of conventional
film/screen systems.
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70. Computed Radiography
• The CR cassette contains a solid-state plate called a photostimulable
storage phosphor imaging plate (PSP) that responds to radiation by
trapping energy in the locations where the x-rays strike.
• The CR detector plate is made of a thin, plastic material and is
extremely fragile.
• CR plates and cassettes can be reused many thousands of times, but
will break if dropped.
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71. CR Plate
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72. Layers of Imaging plate
● Protective layer: This is a very thin, tough, clear plastic that protects
the phosphor layer from handling trauma.
● Phosphor layer: This is the active layer. This is the layer of
photostimulable phosphor that traps electrons during exposure. It is
typically made of barium fluorohalide phosphors.
● Conductive layer: This layer grounds the plate to reduce static
electricity problems and to absorb light to increase sharpness
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73. Layers of Imaging plate
● Support layer: This is a semi-rigid material that provides the imaging
sheet with strength and is a base for coating the other layers.
● Light shield layer: This prevents light from erasing data on the
imaging plate or striking through the backing layer.
● Backing layer: This is a soft polymer that protects the back of the
cassette.
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74. PSP
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75. Computed Radiography
• The radiation dose from a CR exposure is usually set to correspond to
a comparable film/screen exposure.
• The incident x-ray beam interacts with the photostimulable
phosphors that are in the active layer of the imaging plate.
• The interaction stimulates the electrons in the phosphors allowing
the electrons to enter the conductive layer, where they are trapped in
an area of the phosphor known as the phosphor center.
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76. Computed Radiography
• This is the latent image that will create the digital image for the
computer to record and display.
• The trapped signal will remain for hours or days; however,
deterioration of the signal begins almost immediately.
• So it is vitally important to process the imaging plate immediately
after exposure
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77. Forming and developing CR image
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78. Reading the image plate
• After the exposure, the CR cassette is placed in the processing reader
to produce a visible image.
• The processing reader opens the CR cassette and removes and scans
the detector plate with a laser beam or solid state laser diodes.
• As the plate is fed through the processing reader, a laser beam scans
the plate with red light in a raster pattern and gives energy to the
trapped electrons.
• The red laser light is emitted using 2 eV, which is needed to energize
the trapped electrons.
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79. Reading the image plate
• The trapped electrons are now able to leave the active layer where
they emit blue light photons as they return to a lower energy state.
• As the laser beam scans, the imaging plate lines of light intensity
information will be detected by a photomultiplier tube.
• The photomultiplier tube converts the visible light into an electronic
signal which is in analog form.
• The analog signal must be converted to a digital signal for the
computer to apply algorithmic formulas to the information
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80. Reading the image plate
• When the laser beam scans the plate each line of the imaging plate
correlates to one pixel dimension.
• The analog signal emitted for each pixel has an infinite range of values
which the ADC must convert into discrete values which can be stored
as digital code.
• This digital code will determine the gray scale for each individual
pixel.
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81. Reading the image plate
• All the pixel densities will be combined to represent the many
density values in the image which affects the density and contrast of
the image.
• Once the conversion is complete, the light intensity and the position
of the laser beam are stored as digital data for each pixel.
• At this point, the manifest image is now visible on the computer
monitor.
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82. Reading the image plate
• After the entire plate has been scanned, a high-intensity light source
releases any remaining trapped energy to prepare the plate for reuse.
• The cassette is then closed and returned to the ready bin for reuse.
• The entire processing cycle requires about 60 seconds (s).
• It is never necessary to open the CR cassette or to handle the
detector plate.
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83. Advantages of CR
• It utilizing your existing equipment.
• The images are stored on computer with a back-up system in place.
• One are able to transmit images to remote sites.
• The radiologist has quick access to previous CR images for
comparison.
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84. 5/2/2023 84

85. Direct Radiography
• DR is yet another way to record the x-ray exposure after it has passed
through the patient.
• DR is used to describe images which are recorded on an electronically
readable device that is hard-wired directly to the computer
processing system.
• The detectors and sensors of a DR system are contained inside a rigid
protective housing.
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86. Direct Radiography
• DR uses an array of small solid state detectors to convert incident x-
ray photons to directly form the digital image.
• The major advantage of the DR system is that no handling of a
cassette is required as this is a “cassette-less” system
• The image data are transferred directly to the computer for
processing.
• There are two forms of DR systems: one uses a linear array of
detectors, which sweeps across the area to be imaged, the other has
an array of detectors formed into a matrix.
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87. Direct Radiography
• The linear array records the position of the array and the signal from
each detector to form the image.
• In the matrix system, each detector provides data for one pixel.
• The linear array requires fewer detectors but a longer time to form
each image. This increases the tube heat load and the possibility of
patient motion artifacts.
• A matrix array system requires many more detectors than a linear
array system to achieve the same spatial resolution.
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88. Direct Radiography
• Digital radiography is similar to CR because it is filmless and the image
is stored on the computer.
• The image is displayed for the technologist to check prior to the next
exposure. The images are then sent to a storage system.
• This storage system allows for long term storage or the image can be
printed out on a laser printer to film.
• It has the same benefit as CR.
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89. Direct Radiography
• When using CR or digital radiography imaging, both images are placed
on computer.
• Once transferred, the images can be transferred electronically to
“Picture Archiving and Communication System” (PACS).
• The images can then be sent to the radiologist and ordering physician.
• The images are then archived
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90. Film Digitization
• Any image recorded using a conventional film/screen cassette can be
converted into a digital image by a film digitizer.
• A film digitizer measures the light transmitted at each location on the
film.
• It converts the light intensity to a digital value, and records the
location and intensity values as an image pixel
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91. Film Digitization
• The film is introduced into the feed tray and transported through the
digitizer while the image is scanned for digitization.
• After digitization, the image can be processed, displayed, or
transmitted just like any other digital image.
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92. Film/Printer Combination
• Hard copies are produced on multiformat cameras or laser printers.
• A multiformat camera takes a picture of the display screen.
• A laser printer scans a laser beam across a sheet of film to expose the
image.
• The intensity of the laser beam, and hence the density of the image,
is controlled by the digital data.
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93. Film/Printer Combination
• The laser printer can also produce multiple images on the same film.
• Both the laser printer and the multiformat camera are connected to
an automatic film processor.
• Their images are ready for immediate interpretation after the film is
printed.
• The digital image data are stored in a computer and can be retrieved
whenever required to produce additional hard copies or replace lost
films.
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94. Summary
• X-ray film is a photographic film coated with emulsion on both sides
of the film base.
• Impurities in the silver halide crystal structure increase the light
sensitivity of the film emulsion.
• Exposure causes the grains in the emulsion to develop an invisible
latent image.
• The developing process magnifies the latent image to produce a
visible pattern of black metallic silver.
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95. Summary
• A digital image is formed by a matrix of numbers called pixels.
• Each pixel specifies a unique location and contains information about
the image intensity at that location.
• Digital imaging systems include CR, DR, MR, CT, and fluoroscopic
units.
• Detectors used in digital imaging include fluoroscopic image
intensifiers and scintillation crystals.
• Images on film can be digitized and then processed and transmitted in
PACS.
• An ADC changes analog signals into digital signals.
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96. Conclusion
• If a film is not processed properly, the whole effort made in the X-ray
room or in the ward to obtain a good radiograph will be lost.
• It is essential to pay similar attention to film processing as we do in
the X-ray room or in the ward when taking X-rays.
• Most centers use digital imaging modalities.
• The use of manual/automatic image processing is rapidly being
replaced by digital radiography.
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97. •THANK YOU.
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