1. Stacy Kopso, M.E.d. RT(R)(M)
Film-Screen
Stacy Kopso, M.E.d. RT(R)(M)

2. Density/Contrast/Patient dose As film speed increases density,
As film speed increases contrast,
As film speed increases patient dose,
decreases
As film speed increases detail,

3. Film Characteristics Emulsion layer Film base
Silver halide crystals suspended in gelatin
Radiation sensitive (silver halide) and light sensitive
Film base
Polyester layer
Gives the film physical stability for handling and processing
Blue tint to decrease eye strain when viewed on illuminator

4. Double emulsion film

5. Screen Film Used with one or two intensifying screens
More sensitive to light and less sensitive to x-rays
Single-emulsion screen film
Emulsion layer on only one side/used with single intensifying screen
Require higher exposure factors/yield greater detail
Used for duplication,subtraction, CT, MRI, sonography, mammography, nuclear medicine and laser printing
Double-emulsion screen film
Emulsion coating on both sides of the base/used with two intensifying screens
Most common x-ray film

6. Latent Image Formation
Image that exists on film after that film has been exposed
Before its is chemically processed
Film processing
Changes the latent image into a manifest image
Manifest image
Image that exists on film after exposure and processing
Radiographic image

7. Latent Image
Latent image centers appear as radiographic density on the manifest image after processing
After enough silver is neutralized, the sensitivity specks in the silver halide crystals are converted to black metallic silver after chemical processing

8. Film Speed
Degree to which the emulsion is sensitive to x-rays or light
↑ speed = ↑ sensitivity = less exposure needed to produce a specific density
Primary factor in speed of film
Silver halide crystals (in emulsion layer)
# of crystals present ( #↑ = speed↑)
Size of crystals (size ↑= speed ↑)
Manufacturers manipulates both of these factors in the production of specific speeds of film
Lower speed film= small crystal size and fewer number of crystals/ low sensitivity, more exposure is needed
High speed(faster) film- large crystal size and increase in number of them/ high sensitivity, less exposure needed

9. Film Contrast
Ability of film to provide a certain level of image contrast
High-contrast= more black and white areas
Low-contrast = shades of gray
Film latitude
Affects the range of radiation exposures that can provide diagnostic optical densities
Higher contrast= narrow exposure latitude
Low contrast= wider exposure latitude

10. Spectral Sensitivity
The color of light to which a particular film is most sensitive
Blue sensitive
Green sensitive
Film and screen need to match
Film will be underexposed if it does not

11. Spectral Emission The color of light produced by a intensifying screen
Blue light
Green light
Spectral matching
Correctly matching the color sensitivity of film to color emission of intensifying screen

12. Intensifying screen

13. Intensifying Screen
A device found in cassettes that contains phosphors that convert x-ray energy into light
This light exposes the radiographic film
Screens purpose is to intensify the action of the x-rays and thus permit much lower x-ray exposures compared with film alone
Generally included two screens (front/back)
Film is exposed to twice as much light
Single screen is used for single emulsion film
Screen is mounted on the backs side of the cassette (opposite side from the xray tube)
Emulsion side of film is placed against the screen

14. Intensifying Screens
Film is much more sensitive to visible light than to x-rays
When screens are used, 90-99% of the total energy to which the film is exposed is light
x-rays account for the remaining 1% to 10% of the energy
Luminescence
Emission of light from the screen when stimulated by radiation
Fluorescence
Ability of phosphors to emit visible light only while exposed to x-rays

15. Intensifying layer Phosphor layer Active layer
Absorbs the x-rays(High absorption coefficiency) and converts them to visible light(High conversion efficiency). Transmits light to the radiographic film (High transmission rate)
Phosphor materials are rare earth elements
Relatively difficult and expensive to extract from earth

16. Screen Speed The capability of a screen to produce visible light
Purpose
Decrease the radiation dose to the patient
Intensity the action of the x-rays by converting them to visible light
Allows radiographer to use lower mAs
Disadvantage
Reduction in recorded detail
Faster screen produces more light than a slower screen given the same exposure
Faster screen reduces pt exposure but it degrades image resolution and increases quantum noise (too few photons reaching image receptor to form the image/ grainy appearance) find a balance
Slower screen speed produces less light so more technique is needed/ better detail

17. Factors that affect Screen Speed
Absorption efficiency
Screens ability to absorb the incident xray photons
Rare earth phosphor screen absorbs 60% of incident photons
Conversion efficiency
How well the screen phosphor takes these xray photons and converts them to visible light
Thickness of phosphor layer
Thicker layer contains more phosphor material(more light is produced/intensifying the screen speed)
Size of phosphor crystals
Larger crystals produce more light= faster screen
Increased absorption and conversion efficiency mean that rare earth have increased speed compared to previous used phosphor calcium tungstate

18. Factors that affect Screen Speed (cont’d)
Reflective layer
Increases screen speed by reflecting light back toward the film
Absorbing layer or dye in phosphor layer
Decreases screen speed by absorbing light that would otherwise reach and expose the film
Fast sppeds (400) is a good balance of decrease dosage while still maintaining detail
Slower speed (100) labeled detail or extremity (tabletop exams only/low technique)

19. Screen Speed
Par speed screen is given a numerical speed value equal to 100.
A screen that requires one half the amount of radiation to produce a desired density is considered to have twice the speed of the par speed screen and would have a numerical value of 200.
New mAs/Old mAs= Old screen speed/New screen speed

20. An acceptable radiographic image is obtained using exposure factors of 75kVp and 25 mAs with a 200 speed inmaging system. If the imaging system speed is increased to 400, what new mAs is required to produce an image of similar density?
12.5 mAs

21. Reflective layer
increases screen speed by reflecting light back towards film
Protective layer is above the phosphor layer

22. Screen Maintenance Daily cleaning of screen Film screen contact test
Wire mesh tool/ placed on screen and exposed
Screen B shows poor film-screen contact/local area of unsharpness (poor recorded detail)

23. Film Processing

24. Manifest Image
The image that exists on the film after processing/radiographic image
Exposure of the silver bromide crystal in the film emulsion by light or x-ray photons initiates the conversion
Chemical processing of the exposed film completes the conversion of latent to manifest

25. Automatic Film Processor
Chemical tanks, roller transport system, dryer system

26. Stages in Processing of a Radiograph
Developing
Fixing
Washing
Drying
90 second process
Temperature of processor must be between 90-95°F

27. Developing Reducing agents Purpose Chemicals used (work together)
Reduce exposed silver halide to metallic silver and to add electrons to exposed silver halide
Chemicals used (work together)
Phenidone
Fast reducer, producing gray(lower) densities
Hydroquinone
Slow reducer, producing black(higher) densities
Alkaline pH environment
Needs an alkaline PH environment

28. Fixing Remove unexposed silver halide from the film
Makes the remaining image permanent
Secondary functions
Stop the development process
Further harden emulsions
Fixing agent
Ammonium thiosulfate
Acidic pH environment
Silver recovery unit

29. Washing Remove fixing solution from the surface of film
If not properly washed, film shows a brown staining of the image
fixing agent thiossulfate remained
Process of washing
Diffusion- exposes the film to water that contains less thiosulfate than film
Wash water must be replaced frequently

30. Drying Remove 85 to 90% of the moisture from the film
If films are dried excessively, the emulsion layers can crack (10-15% of water must be retained)

31. Systems Automatic processor Vertical transport system of rollers
The film enters the feed tray
Transport and crossover rollers ensure the film is moved into and through the tanks at a constant speed
Electric motor/ on off power and standby control (shuts off when processor is not in use for awhile/reactivates when button is pushed)

32. Systems Replenishment Developer Fixer
Replacement of fresh chemicals after the loss of chemicals during processing (developer/fixer)
Developer
Use and exposure to air, reducing chemical strength
Fixer
Silver halide removed as it is used during fixing process
Developer solution remains in the film, decreases strength and activity of fixer
Chemicals eventually become exhausted or inactive and their ability to perform their functions decrease
Replenishment is preset in the processor/ bases on size of film or timed intervals

33. Systems Recirculation system Advantages Dryer
Circulates the solutions in the developer and fixer In developer and fixer tanks
Keeps the chemicals mixed
Advantages
Facilitates fast processing
Helps to maintain proper temperature of developer solution
90 sec processor (93-95 degree)
Immersion heater at the bottom of developer & fixer tan
Dryer
by pumping solution out of one portion of the tank and returning it to a different location within the same tank
Temperature
an increase or decrease in developer temp can adversely affect the quality of the radiographic image
Most processors are controlled to heat the solution to its proper temp an maintain that temp for as long as the processor is turned on

34. Radiographic Appearance
Processing Problem
Decrease in density
Developer exhausted
Developer under replenishment
Processor running too fast
Low developer temp
Developer improperly mixed
Increase in density
Developer over replenishment
High developer temp
Light leak in processor
Pinkish stain
Contamination of developer by fixer
Developer or fixer under replenishment
Brown stain
Inadequate washing
Emulsion removed by developer
Insufficient hardener in developer
Milky appearance
Fixer exhausted
Streaks
Dirty processor rollers
Inadequate drying
Water spots
Minus-density scratches
Scratches from guide plates caused by roller or plate misalignment

35. Stacy Kopso, M.Ed., RT(R)(M)
Quality Control
Stacy Kopso, M.Ed., RT(R)(M)

36. Quality Control Film storage Vertically/ prevent pressure artifacts
Away from white light, heat sources and radiation
Shelf life of 18months
Stored at 55-75° temperature
Humidity of 30-60%
Safelight that use filters for the type of film(blue or green light) and wattage matched with film (7.5-15W)
Heat and radiation casue silver halide in film emulsion to break down/ results in fogged film
Low humidity(no moisture)
static charges can expose film
Countertops and feed tray should be clean
Film bin and walls lined with lead if wall backs up to xray room

37. Bending or kinking the film( plus density)
Scratching with fingernails (plus density)

38. C- static discharge from sliding the film over a flat surface if there is to low humidity(plus density)
D- moisture on techs finger (minus density)
E- dirty screen (minus density)

39. Silver Recovery Fixer solution
Used to remove unexposed silver halide from film
Used fixer solution contains high concentration of accumulated silver
Silver recovery(large volume facilities)
Removal of silver from used fixer solution
Connected to drain system of fixer tank
Two methods
Metallic replacement
Steel wool
Silver-extraction filter
Electrolytic method
Electrically charge drum or disk that attracts silver
Steel wool
silver replaces iron in steel wool and can them be removed easily after accumulation in a canister or replacement cartridge occurs
Silver extraction
foam filter that contains steel wool/ does the same as above
Electrolytic
once the drum is full/ remove it
Silver is toxic to environment (follow local and stage agency rules for disposal)

40. Sensitometric Curve OD can range from 0-4
Useful range of optical density is
Straight line region is a properly exposed radiograph
The radiation exposure to the film screen receptor determines the amount of OD created on the film after processing
The intensity of the radiation exposure is a measurement of the amount and energy of the xrays reaching an area of the film
When all other factors remain the same , increasing the exposure intensity, increases the optical density

41. Speed Point Closer to the y axis
Determines the speed of the radiographic film

42. Slope and Film Contrast
The steeper the slope, the higher the film contrast
An increase in contrast= decrease in latitude

43. Exposure Latitude
The range of exposures that produce optical densities within the straight-line region of the sensitometric curve
Exposure latitude and Film contrast have an inverse relationship
Wide-latitude film is a lower contrast film(cxr)
Narrow-latitude film is a higher contrast film(skeletal)