1. Film Image Characteristics Processing
Radiology Chapter 7,8,9
Film
Image Characteristics
Processing

2. Dental X-ray Film What is X-ray Film
Photographic film that has been adapted for dental use
Photographic image – produced when exposed to x-rays

3. Film Composition Film Base – actual film Emphasize contrast of image
Flexible plastic
Withstands: Heat, moisture, chemical exposure
Transparent with blue tint:
Emphasize contrast of image
Enhance image quality
Purpose of film base: provide support for the emulsion

4. Film Composition Cont. Adhesive layer Thin layer of adhesive material
Covers both sides of film base
Attaches the emulsion to the base – allows emulsion to adhere

5. Film Composition Cont. Film emulsion
Coating attached to both sides of film base
Gives film greater sensitivity to x-radiation – shortens exposure time

6. Film emulsion
Made of:
Gelatin
Used to suspend and evenly disperse silver halide crystals over the film base
It absorbs processing solutions and allows the chemicals to react with silver halide crystals
RHS – may ask what type of material is in emulsion – silver halide or silver bromide

7. Film emulsion cont. Made of: Silver halide crystals
Silver bromide and silver iodide
Absorb radiation during x-ray exposure and store energy from the radiation
Small crystals require more radiation (better resolution)
Large crystals require less radiation

8. Film Composition Cont. Protective layer
Thin layer over emulsion to protect film during handling

9. Latent Image Formation
Silver halide crystals absorb x-radiation during exposure and stores energy from radiation
Energy is stored at different levels based on density of objects exposed
Stored energy within silver halide crystals form a pattern & creates an invisible image within emulsion of exposed film – latent image

10. Latent Image Formation Cont.
Denser object – more energy absorbed by object – lighter it appears on film
Film positioned behind amalgam restoration receives almost no radiation
Amalgam is dense & absorbs x-ray energy
Silver halide crystals are not energized – fall off film leaving area opaque
Appear white on film

11. Latent Image Formation Cont.
Less dense objects appear darker on film
Correspond to airspace
Little or no density (tissue, sinus, carious tissue)
Film receives more radiation
Silver halide crystals are highly energized

12. Types of Films Intraoral film Placed INSIDE the mouth
Used to examine teeth & supporting structures
Film packet:
Soft vinyl
Protects film from light and saliva

13. Types of Films Intraoral film Labeled with: Type of film Film speed
Film size
Amount per packet (single or double)
Expiration date

14. Types of Films Intraoral film Black paper Lead foil – behind film
Shields from light
Lead foil – behind film
“herringbone or tire track” effect – may appear lighter
Blocks radiation – helps with fogging
Protects from some scatter radiation

15. Types of Films Intraoral film: Small raised bump
Identification dot
Small raised bump
Raised bump on solid white side of film – faces PID
On one corner of film
Placed in slot of bite block – makes dot go –
Toward the occlusal/incisal surface of teeth

16. Types of Intraoral Exposures
Periapical – PA
Entire tooth
2 – 3 mm around end of root
PDL & Lamina Dura
Bitewing – BWX
Examine interproximal – cavities – usually taken once a year – maybe taken twice depending on Pt
Crowns – Max & Man occl. – bone & gum height

17. Types of Intraoral Exposures
Occlusal - #4 film – usually on children
Film size
0 – children, referred to as Pedo Film
1 – anterior adult – pedo
2 – Standard (most common)
3 – posterior (BW, longer narrower than #2)
4 - occlusal

18. Film Speed Refers to the amount of radiation to produce a radiograph
A speed (slowest) to F speed (fastest)
Only D speed film and E speed film are used for intraoral radiography
E speed requires one-half the exposure time of D speed – has comparable image contrast & resolution (less radiation for patient)
F speed requires one-third the exposure time of E speed film

19. Extraoral Film = 2-4 PA’s Placed outside mouth during exposure
Used to examine large areas of skull or jaws
More sensitive to light/radiation than intraoral film
Films are placed in a cassette with intensifying screens
Intensifying screens step up/accelerate radiation – reducing amount to pt

20. Extraoral Film Panoramic Film aka Pano aka Panorex
Shows wide view of Max & Man – teeth 15% larger
Radiation level for a pano equivalent approx 4 PA’s
Used for TMJ or wisdom teeth

21. Extraoral Film Cephalometric Film aka Ceph
Shows bony & soft tissue areas of facial profile
Side profile – TMJ, spine, neck, skull,
Used for ortho to measure growth

22. Duplicating Film Makes identical copy of a film
Used for insurance claims or transferring patients

23. Chapter 8 DIAGNOSTIC Ideal radiograph is neither too light or too dark
A diagnostic radiograph is:
Clear – crisp, clear image, like analog TV vs. HD TV
Undistorted
Low Contrast – many varying shades of gray

24. HIGH QUALITY FILMS
To fully understand why things appear dark or light on film we need to examine the characteristics of the objects
RHS – KNOWING WHETHER YOU ARE DESCRIBING THE OBJECT OR
OBJECT AS IT APPEARS ON THE FILM IS CRUCIAL TO YOUR UNDERSTANDING QUESTIONS ON RHS EXAM

25. TRANSLUCENT Objects that allow light to pass through easily
Windows / glass
Air
When related to dentistry and radiographic film it would be termed radiolucent

26. RADIOLUCENT Dark allows more x-rays to pass through
Portion of processed film that is dark or black
Silver Halide Crystals are energized
Structure that lacks density & allows x-ray to pass with little or no resistance
Structures do not appear or if they do they are quite dark, even black, ex.: air space, gingiva, mucosa, tongue, cheek

27. OPAQUE Objects that do not allow light to pass through them easily
Wall
Rocks
Metals
When related to dentistry and radiographic film it would be termed Radiopaque

28. RADIOPAQUE Portion of a processed film that is light or white
Silver Halide Crystals have NOT been energized
Structures are dense & absorb or resist the passage of the x-ray
The more dense or thick the structure the lighter it appears, ex.: enamel, bone, amalgam, restorative metals

29. GEOMETRIC CHARACTERISTICS
Problems that can occur on film
Deals with size & shape of the image (tooth) as it appears on the film
Includes three characteristics:
Sharpness
Magnification
Distortion

30. SHARPNESS Refers to the clarity of the image
Detail, resolution, & definition
How crisp and sharp a picture
Seen by the amount of silver halide crystals
Small crystals but lots of them = better resolution yet requires more radiation to the patient

31. SHARPNESS
Penumbra
When image on the radiograph looks fuzzy or blurry
Caused by movement of patient or PID
Clarity is not as good in F speed films but are good enough to diagnose
FYI – sharpness is one factor that is usually outside the control of the DA

32. MAGNIFICATION When image of the object appears larger than actual size
Very important in Endodontics
Influencing factors include:
Target to film distance – Source of x-rays to film
16” PID = less image magnification
8” PID = more image magnification

33. MAGNIFICATION Influencing factors include cont.:
Object to film distance – tooth to film
Closer the film is to the tooth the less image enlargement there will be on the film
One area where bisecting the angle is better – will have more magnification w/paralleling technique

34. DISTORTION Shape & Size of object
Any variation in the shape of an image on film
Caused by improper angulation of the PID or improper film alignment

35. IMPROPER ANGULATION Improper Horizontal Angulation
Can result in “fat images”
The angle of x-ray beam (left to right)
Causes overlapping
Mesial of one tooth on the distal of another
PID should be at a 90 degree angle to film

36. IMPROPER ANGULATION Improper Vertical angulation
Results in either (short) Foreshortening or (long) Elongation
Foreshortening
Angulation is to steep
Too positive
Excessive vertical angulation
Image produced is shorter than its actual size

37. IMPROPER ANGULATION Elongation Angulation is to low Too negative
Insufficient vertical angulation
Image produced is longer that it’s actual size

38. STEPWEDGE Stepwedge: Aluminum of varied thickness
Used to check short and long scale contrast
Placed on top of film – Expose
Absorbs varying amounts of x-rays
Different densities & contrasts will appear – Ch.10

39. Chapter 9 DENTAL X-RAY PROCESSING
Film Processing – converting a latent image (invisible) on the film into a visible image and preserving it permanently
Latent Image – Invisible pattern
Silver halide crystals absorb x-ray
Energy is stored & forms an invisible image
Pattern not seen until developed

40. REDUCTION
Reduction: During processing a chemical reaction occurs and halide portion of exposed silver halide crystal are removed
Selective Reduction
Exposed or energized Silver Halide Crystals become black metallic silver– stay on film
(behind radiolucent structures)
Unexposed or un-energized Silver Halide Crystals are removed from film – fall off film
(behind radiopaque structures)

41. DEVELOPER Developer – Black bottle, Black lid, Black label
First solution to touch dental radiograph
Temperate determines total time it takes to complete x-ray
Creates the dark or black areas
Softens emulsion – so picture will appear

42. DEVELOPER CONTAINS Hydroquinone Elon
Creates the black tones & sharp contrast
Temperature sensitive
Inactive below 60 degrees
Very active above 80 degrees
Elon
Acts quickly to produce visible image

43. DEVELOPER CONTAINS Preservatives Accelerators Restrainer
Prevent solution from oxidizing in the -
Accelerators
Activates solution
Soften
Restrainer
Potassium bromide
Stops development of both exposed & unexposed silver halide crystals

44. FIXER Red bottle, red lid, red label
Removes the unexposed silver halide crystals
Silver stays in fixer making it TOXIC
Creates the white or light areas on dental radiograph
Black metallic silver is not removed & remains on film
Films can be left in the fixer for an indefinite time without any effect on film

45. FIXER Films cannot be left in developer or water
Approximately 2 minutes in fixer the film may be viewed in light
Ingredients include:
Fixing agent – removes or clears all unexposed & undeveloped silver halide crystals from emulsions

46. FIXER Cont. Ingredients include:
Preservative – prevents chemical deterioration of the fixing agent
Hardening agent – harden & shrink the gelatin in the film emulsion after it has been softened by accelerator in the developing solution.
Acidifier – stops the developing process

47. 5 STEPS TO MANUAL PROCESSING
Develop
Rinse
Fixer
Water Wash
Drying

48. 5 STEPS TO MANUAL PROCESSING
Developer
First step in film processing
Temp. of developer determines time
68 degrees is optimum temp. for 4 ½ to 5 mins
Range 68 – 74 optimun – Check temp. daily
Below 60 – react slow & film appears light
Above 80 – react fast & film appears dark
Warmer solution – shorter time
Cooler solution – longer time

49. 5 STEPS TO MANUAL PROCESSING
Rinse
To remove the developer from the film and stop the development process
Usually about 30 seconds
Fixer
Usually double the time to spend in Fixer
If 5 minutes in developer then 10 mins in fix

50. 5 STEPS TO MANUAL PROCESSING
Water wash
Always for 20 – 30 minutes
Removes all excess chemicals from emulsion
Drying
Hang films on film hanger to Dry

51. AUTOMATIC PROCESSING Special machine – works through rollers
Developer – still the first solution to touch film & optimum temp 80 degrees
Fixer – second solution to touch film
Rinse – rinses films
Dryer – dries films quickly
Replenisher pump – automatically replenishes chemicals – maintain adequate freshness, strength & solution levels

52. Darkroom
Provides a completely dark environment where x-ray film can be handled and processed
Location & Size
Large enough for all equipment and a person
Should be at least square ft (4x4,4x5)
Ventilation system
Temperature – approx. 70 degrees – if exceeds 90 film fogging may occur

53. Darkroom Lighting Should be completely dark – light tight
Any visible white light will be bad for film & cause film fogging
Safelight
Red – orange spectrum
Low intensity light (15 watt) or regular white bulb w/light filter
GBX2 best with extra-oral film
Must be placed a minimum of 4 ft away from working area

54. Film Storage Film is adversely affected by: To prevent film fog: Heat
Humidity
Radiation
To prevent film fog:
Keep film in cool dry place
Temp ranges from 50 – 70 degrees
Shield from radiation sources
Watch expiration date

55. We Made it to the end of 7,8,9