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Oral Radiology > Week 5: Film Processing > Flashcards

Week 5: Film Processing Flashcards

1
Q

What is the SLOB rule?

A

Same Lingual Opposite Buccal

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2
Q

What is another name for the SLOB Rule?

A

Clark’s Rule (Tube-shift localization)

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3
Q

Describe the SLOB Rule

A
  • identifies the buccal or lingual location of objects (impacted teeth, root canals etc.) in relatin to a reference object (usually a tooth)
  • two radiographs are taken at different angulations
  • if the tubehead is moved mesially and the image of the object moves medally (in the same direction to which the tubehead was moved) then the objected is located on the** lingual **
  • if the tubve head is moved mesially and the image of the object moves distally (opposite or in a different direction to which the tubehead was moved) then the object is located on the buccal
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4
Q

What must there be a change in for the SLOB rule to work?

A

For the** SLOB Rule to work **there must be a CHANGE in the HORIZONTAL or VERTICAL ANGULATION of the x-ray beam as the tubehead is moved

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5
Q

Describe the SLOB Rule in realtion to Vertical Tube Shift and Intraoral Periapical (IOPA)/ Bitewing (BW) radiogprahs

A
  • The SLOB Rule also works for movement of the tube head in the vertical direction
  • The downward movement of the tubehead requires that the x-ray beam be directed upward
  • When the tubehead is moved upward, the x-ray beam must be directed downward
  • Moving frm the maxillary periapical to the bitewing AND from the bitewing to the mandibular periapical, the tubehead moves DOWN and x-rays BEAM is redirected upward
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6
Q

Is the composite restoration (arrow) located on the buccal or lingual aspect of the tooth?

Also identify the tooth which has the resotration present and ALL the teeth that are seen in the radiograph.

A

Tooth with restoration: 11
Teeth present: 11, 12,13,14 (part of 14)

The composite resotoration on tooth 11 is located on the BUCCAL aspect.

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7
Q

Is the amalgam restoration (arrow) locate on the buccal or lingual aspect of the tooth?

Also identify the tooth which has the resotration present and ALL the teeth that are seen in the radiograph.

A

Tooth with restoration: 26
Teeth present in the IOPA: 22 (part of 22), 23, 24, 25, 26
Teeth present in the BW: 22 (part of 22), 23, 24, 25, 26, 27 (part of 27), 34, 35, 36, 37, 38 (part of 38)

The amalgam resotoration on tooth 26 is located on the lingual aspect.

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8
Q

What is a latent image?

A
  • When radiation interacts with silver halide crystals in the film emulsion, the image on the film is produced
  • There are thousands of silver halide crystals
  • “Latent means “hidden”; the image formed cannot be seen UNTIL the film is processed
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9
Q

Describe the relation of latent image to air/soft tissue, bone, and amalgam/gold

A

The latent image of air/soft tissue: many x-rays pentrate and expose many silver halide crystals therefore these structures are RADIOLUCENT

The latent image of bone: fewer x-rays penetrate and not as many silver halide crystal are exposed

The latent image of amalgam/gold: silver halide crystals are NOT exposed therefore these structures are RADIOOPAQUE

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10
Q

What is another name for latent image?

A

Invisible image

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11
Q

What is dental x-ray film processing?

A

Processing is the general term used to describe the sequence of events required to convert the invisible latent image into the visible, permanent radiographic image. The processing is done using special chemicals.

*special chemicals are the developer and fixer solutions

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12
Q

What are the 5 basic steps of processing?

A
  1. Development: exposed silver halide crystals converted to black metallic silver
  2. Rinsing: Developer solution is removed from the film before fixing
  3. Fixing: unexposed silver halide crystals are removed from the film
  4. Washing: all chemical are removed from the film
  5. Drying
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13
Q

```

What does the developer soultion contain and what does it do?

A
  • Developer (phenidone and hydroquinone): converts exposed silver halide crystals into black metallic silver
  • **Preservative (sodium sulfite): **helps protect the developer from being oxidized by air
  • Activator (sodium? or potassium hydroxide): makes the solution alkaline (pH of 10-11); and softens the gelatin allowing developer to reach the crystals
  • **Restrainer (potassium bromide): **reduces effects of the developer on unexposed crystals
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14
Q

What does the fixer solution contains and what does it do?

A
  • Clearing agent (ammonium thiosulfate): dissolves and removes unexposed silver halide crystals from emulstion
  • Preservative (ammonium sulfite): inhibits decomposition (oxidation) of the clearing agent
  • Acidifier (acetic acid~pH of 4-5): neutralizes any contaminating alkali from the developer
  • Hardner (aluminum sulfate): hardens emulsion so that the film can be handelded
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15
Q

What are the methods of processing?

A

Methods of processing:
1. Manual method
2. Automatic method
3. Daylight method

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16
Q

Describe the steps of manual processing

A
  1. Turn all the room lights off, turn on the safe light, and unwrap the film
  2. Clip the flim to the hanger (handle with the hanger by the edge of the film to avoid damage)
  3. Develop the film (30 seconds, 68 degrees F) *according to the manufactures instructions if different
  4. Rinse (agitate continously)
  5. Fix (4-6 minutes, agitate inmittently for 5 seconds every 30 seconds)
  6. Wash in clear running water
  7. Hand flims to dry (on the film mount)
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17
Q

What is the clearing time?

A
  • The time taken for unexposed film to become clear
  • Calculated using freshly mized fixer solution at recommended concentration and temperature (20-25 degrees)
  • Fixing time is calculaetd to be twice the clearing time
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18
Q

Describe film mounting

A
  • Only mount dry films
  • Confrim patient details- correct film in the correct chart
  • Check the orientation and mount films appropriately
  • Films may be mounted in special designed film mounts or may be stapled onto clear acetate and labled with patient details
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19
Q

When may a daylight loader be used?

A

A daylight loader may be used if there is not enough room in the dental office for a dark room.

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20
Q

What the mandatory log details?

A

It is **MANDATORY ** that dental x-rays are logged with the following:

  • patients details
  • date
  • type of film and view
  • institution
  • if possible, exposure details
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21
Q

Disscuss film storage

A
  • store films in a cool, dry place away from heat and light
  • **must keep films for 7 years **
  • however this could be a long time
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22
Q

What are the attributes of the darkroom?

A
  • It must be light-tight as the silver halide crystals are sensitive to light
  • It must have hot and cold water available; a mixing valve, which regulates temperature
  • It should have an adequate size and must be kept very clean
  • Have a wet area, dry area and these should be separate
  • Temperature of the dark room- 20-25 degrees C and humidity- 50-70%
23
Q

What is dark room light-tightness?

A
  • Turn off al the lights
  • Note any leaks around doorways in walls etc.
  • Can initially be marked and repaired with duct tape
  • Remember to oraganize permanent repairs
24
Q

Describe safelighting (including filters)

A
  • Safelights are used in used inthe darkroom to provide adequate light so that you can see what you are doing when you unwrap films for processing
  • The safelights have special filters that produce light that does not expose the film
  • There are two filters currently available: an orange one (Morlite) and a red one (GBX-2)
  • The red filter provides more light than the older safelights
  • The safelight should have a 15-watt bulb and be mounted to the wall or ceiling at least 4 feet (120cm) from the working area (where the films are unwrapped)
25
Q

What is quality control?

A

Establish a start-up protocol to be followed every morning

Dailly start up protocol:
* Stir chemicals- use separate rods to avoid contamination of solutions
* Clean and dry the benches
* Check temperatures of chemicals
* Check, clan and load film cassesttes
* Check for light leaks

26
Q

What is the processing error in this radiograph?

A

The film is too dark

27
Q

What is the processing error in this radiograph?

A

The film is too light

28
Q

True or false: this film is of incorrect density

A

FALSE

*the film is of CORRECT density

29
Q

How can an overall darkening of the film result?

A
  • Overexposure
    1. Excessive mA, peak, kvp, time
    2. SHORT film-source distance
  • Processing errors
    1. Overdevelopment
    2. Hot developer solution,
    3. High developer concentration,
    4. Inadequate fixaton,
    5. Accidental light exposure
30
Q

The following films were processed at 68° F (constant temperature), which type and what was the error that occured?

A

Processing error: too much time in the developer solution (overdevelopment)

31
Q

The following films were all developed for 5 minutes, which type and what error has occured?

A

Processing error: hot developer solution

32
Q

What is the processing error in this radiograph?

A

Inadequate fixation

33
Q

What is the processing error in this radiograph?

A

Accidental exposure to light
* The completely black area on the right side of the film bewlo is caused by light exposing the film when the darkroom light (not the safelight) was turned on before the film was completely in the automatic proessor
* Light leaks or faulty safelightining would result in an overall darkening of rhe film, similar to too hight of a temperature

34
Q

What are the causes of a light film?

A

A light film can result from any of the following:
* Underexposure
1. Insufficent mA, peak, kvp, time
2. Large film-source distance
3. Film packet reversed in the mouth

  • Underexposure
    1. Underdevelopment
    2. Depleted developer solution
    3. Diulted or contaminated developer
    4. Excessive fixation
35
Q

What is the error in this radiograph?

A

Film fog

36
Q

What are the causes of film fog?

A

Film fog:

  • increase film density resulting from scattered radiation, improper safelighting, improper film storage, and use of expired film
  • darkens the whole film and makes it harder to see the density differences (contrast) making the film of less diagnostic quality
37
Q

What are the cause of dark areas in a radiograph?

A
  • Developer spots
  • Yellow/brown staining
  • Dark lines
  • Finger and nail print
  • Tire track appearance
  • Thin balck tree branching lines
  • Films overlapped during processing
  • Film bending
38
Q

What is the error in this radiograph?

A

**Dark spots- developer contamination **
* If drops of developer accidentally contact the film prior to processing

39
Q

What are the TWO errors in the radiograph?

A

1. Yellow/brown stain- depleted fixer
If the film is not adequately fixed, the underdeveloped crystals will not be removed from the film, resulting in a yellowish-brown stain

2. Cone-cut

40
Q

What is the error in this radiograph?

A

**Dark lines **
* if the automatic processor is not cleaned properly the rollers may become dirty. This results in black lines on the film

41
Q

What is the error in this radiograph and what may it be mistaken or confused with?

A

**Finger nail print **
* appears as a black crescent shape mark
* occurs due to mishandling of film emulsion
* may be mistaken or confused with a root fracture

42
Q

What is the error in this radiograph?

A

Finger print
* Developer solution on fingertips will produce black markings on the final radiograph

43
Q

What is the error in this radiograph?

A

**Finger Print **
* Fixer solution on finger tips will produce white markings on the final radiograph

44
Q

What is the error in this radiograph?

A

**Tire track appearance **
* A reversed film appeart light with a tire-track pattern

45
Q

What causes the tire track appearance?

A

Lead foil

46
Q

True or false: in a digital film the metal dot should face the teeth/phosphorplate ring?

A

FALSE

47
Q

What is the error in this radiograph?

A

A reversed digital film

48
Q

What is the error in these radiographs?

A

**Thin black tree branching lines **
* If the film it removed too quickly from the packet (intraoral) or from the film box/cassette (extraoral) friction may be created, resulting in static discharge. This may create black dots, lines or tree-branch patterns

49
Q

What is the error in these radiographs?

A

**Films overlapped during processing **
* if the films are fed into the automatic processor too quickly the films may overlap each other

50
Q

What is the error in this radiograph?

A

Film bending (black lines)

51
Q

What are the causes of light areas on radiographs?

A
  • Fixer spots
  • Air bubble artifact
52
Q

What is the error in these radiographs?

A

**Light spots- fixer contamination **
* occurs if the fixer accidentally contacrs the film prior to processing

53
Q

What is the error in this radiograph?

A

**Air bubble artifact **
* occurs due to failure to agitate the film as it is placed in the develper
* an air pocket occurs and the developing agent cannot reach the emulsion

Oral Radiology (5 decks)

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