1

Dental X-ray Film Processing

2

Film Processing

• Refers to a series of steps that produce a visible permanent image on a dental radiograph

• The process consists of two major steps that transform the latent image into a visible image and preserves that image permanently.

3

Manual Film Processing

4

From Latent Image to Visible Image:

• During the manual development process, the film undergoes a series of reactions with chemical solutions.

• Developer– rinsed

• Fixer– Rinsed– Dried

5

Manual Tank Processing

6

Selective Reduction

• Selective reduction refers to – the reduction of the energized, exposed silver

halide crystals into black metallic silver.– This happens in the developer– Unenergized, unexposed silver halide crystals

are removed from the film.– This happens in the fixer

7

From Latent image to Visible Image

8

Processing Procedures

• The film is first placed in a chemical called the developing solution . – This chemical can distinguish between the

exposed and unexposed silver halide crystals.

• The silver halide crystals that are exposed will become black or gray metallic silver, while the unexposed silver halide crystals will remain unaffected.

9

Processing Procedures

• Next, the film is placed in a solution called fixer for a specific amount of time. This solution removes the unexposed silver halide crystals

• This process creates the clear or white areas on the film

• Most importantly, the black metallic silver remains on the film

10

The resultant image

• The image is made up of black, white and gray areas.

• These are formed from the types of structures exposed on the film.

11

Blacks, Whites & Shades of Gray

12

RADIOLUCENT

• A radiolucent structure is one that readily permits the passage of the x-ray beam and allows more x-rays to reach the film.

• If more x-rays reach the film, more silver halide crystals within the film emulsion are exposed and energized.

• This results in increased deposits of black metallic silver.

• A radiograph with large deposits of black metallic silver appears black, or radiolucent.

13

RADIOPAQUE

• A radiopaque structure is one that resists the passage of x-rays and therefore limits the amount of radiation that reaches the film.

• These unexposed halide crystals are removed from the film during processing. No black metallic silver deposits will show on the film.

• Therefore, a radiopaque film appears white or clear.

14

Processing Chemistry

• Necessary to have the proper solutions for adequate processing

• These chemicals can come in ready use liquid, liquid concentrate, or in a powder form

• Chemicals should be fresh for proper results, and changed on a 3-4 week basis depending on frequency of use

15

Developer Solution

• The developing solution is also known as the reducing solution. Why?

• The purpose of the developer is to reduce the exposed halide crystals chemically into black metallic silver.

• The developer also softens the film emulsion.

16

Developer Chemicals

• Hydroquinone– its purpose is to slowly generate black tones and

contrast. – To be effective, the temperature should be 68

degrees or higher• Elon

– quickly generates the many gray tones on a radiograph

• See page 89, Table 9-1 of your text for all of the chemical components of the developing solution

17

The Fixer Solution

• The purpose of the fixing agent is to remove or “clear” all unexposed and undeveloped silver halide crystals from the film emulsion

• By doing this, the black image produced by the developer becomes readily distinguishable.

18

The Fixer Chemicals

• Sodium thiosulfate– The clearing agent

• Potassium alum– The hardening agent – hardens the film emulsion

• Acidifier– This neutralizes the alkaline developer, and

stops the developing process

• Preservative

19

Manual Processing

• This is a much more technique sensitive process

• Temperature effects duration of films in baths• Process: Developer, rinse, Fixer, rinse, dry• A thermometer is kept in the chemical baths

to accurately estimate the time needed to process the films

• A timer is needed to identify when to move the films into the next bath

• Film hangers are also necessary to dry the films thoroughly after development

20

Manual Film Processing

Processing Tanks Film Hangers

21

The Darkroom

22

The Darkroom• Provides an environment in which x-ray

films can be handled and processed.• Room lighting with incandescent lighting is

acceptable for performing tasks such as stocking and cleaning or replenishing solutions

• Some important considerations for the darkroom:– Size of the room itself– Location in the building– Proper lighting equipment– Temperature and humidity control

23

Lighting in the Darkroom:

• To be a “darkroom” the room cannot emit any white light

• The darkroom should be – light-tight, with no light leaks– this could cause film fog – an overall dull graying of the film which makes

interpretation difficult

24

Safe lighting

• Safe lighting is necessary for illumination during the development process.

• A safelight consists of a low wattage bulb (7 or 15 watts) with a safelight filter

25

Safe lighting

• The filter removes the blue green portion of visible light, and allows only light from the red-orange portion of the light spectrum through which does not harm the film.

• A working distance of at least four feet must be kept to prevent exposure of the dental films being processed

26

Darkroom Safe lighting

27

Automatic Processing

28

Automatic Film Processor

29

Automatic Processor

30

Automatic Processing

• An auto processor simplifies the development process:

• It uses racks to move the films in and out of the developer, fixer, and water bath in just the right amount of time needed.

• It also dries the films when complete, allowing them to be handled right away

• Sequence is: develop, fix, rinse. NO RINSING takes place in between the developer and the fixer with automatic processing.

31

The Auto Processor:

• This allows for a more controlled method of processing films.

• The major advantage is the time saved in developing – on the average, 4-6 minutes, as opposed to an hour for manual!

• Other advantages include:– Less space is needed (no darkroom required)– Less equipment also (no tanks, plumbing

requirements, etc.)

32

Replenishing Solutionsand Maintenance

33

Chemical Maintenance:

• Evaporation occurs with both the fixer and developer from use and exposure to air

• This can decrease the strength and volume

• A replenisher (a super concentrated chemical solution) can be added to replace what has been lost.

• Replenishers can be added on a daily basis to maintain chemical freshness

34

Replenisher Solutions