1. Image Receptor Systems
Film/Screen Imaging
Computed Radiography
Digital Radiography

3. Image Capture
Image Receptor

4. Image Receptor Types Film/Screen Systems Computed Radiography Systems
Direct Digital Systems

5. Image Receptor Types

6. Film/Screen, CR, DR systems

7. Terminology Image receptor Image capture Beam absorption Attenuation
Primary radiation
Secondary radiation
Scatter radiation
Remnant radiation
Exit radiation
Latitude
Latent image
Manifest image

8. Film/Screen Imaging Film construction Cassette construction
Film capture
Film developing
Film Interpretation/Storing

9. FIRST “FILM” Early Years: Developments: Glass plates Cellulose acetate
Break easily
Difficulty in storage
Expensive
Developments:
Cellulose acetate
Highly flammable
Easily torn
Polyester Base
Cellulose acetate is a base that was highly flammable.

10. Today’s Modern Film

11. Film Sizes Metric: Standard: 18cm x 24cm 8” x 10” 24cm x 30cm
There are problems with film and cassettes. If you have a metric film and a standard cassette, they are not compatible.
IF you user a smaller film inside a larger cassette, it can be used but often times people will clip.

12. X-ray Film
Two basic parts:
1. Base
2. Emulsion and Topcoat

13. Film Construction

14. Film Construction - BASE
Made of a polyester plastic
Must be clear, strong, consistent thickness
Tinted pale blue or blue-gray (reduces eye strain)
Uniform lucency
COATED ON 1 OR 2 SIDES WITH EMULSION
Single emulsion you can get better detail but you must use more radiation.
Double emulsion you use less radiation but you get less detail
With single emulsion you place the active layer closest to the intensifying screen.
There is protective coat on top of the emulsion to protect the emulsion.

15. Film Construction - EMULSION
Film emulsion can be on one side or both sides of base (single emulsion / double emulsion)
Protective overcoat layered on top of emulsion-topcoat, supercoat
Emulsion is a gelatin containing the film crystals---THE HEART OF THE FILM
There is a protective coat on the emulsion to protect from handling damage
Gelatin is filled with silver halide crystals.

16. Film Emulsion Made of mixture of gelatin & silver halide crystals
Silver halide crystals made of silver bromide (90%) and silver iodide (10%)
Photographically active layer – activated by light & radiation to create image
They used to be round but now they are more flat.

17. Latent Image Imaged Formed by:
Direct x-ray interaction with film
Indirect interaction with light from cassette
Image is not seen until developed chemically developed by processor.

18. Film Storage Clean, dry location 40 – 60 % Humidity 70 º Fahrenheit
Away from chemical fumes
Safe from radiation exposure
Standing on edge
Expiration date clearly visible
You have to store it upright because they will warp.

19. Cassettes function Protect film from exposure to light
Protect film from bending and scratching during use.
May contain intensifying screens, keeps film in close contact to screen during exposure.

20. FILM CASSETTE or FILM HOLDER
The CASSETTE is used to hold the film during examinations.
It consist of front and back intensifying screens, and has a lead (Pb) backing.
The cassette is light tight

21. Cardboard Cassettes Direct x-ray exposure to film:
Requires 25 to 400 times more radiation to create an image on the film
Better detail than film screen (no blurring of image from light)
All exposure made from x-ray photons
Very large dose to the patient
These do not have screens, we get great detail. But it takes 25 to 400 times the radiation.
200 mas with 50 kvp.
2 mas with intensifying screens.

22. CASSETTE CONSTRUCTION
CASSETTE FRONT
CASSETTE BACK
Exposure side of cassette is the “front”.
Has the ID blocker (patient identification)
Made of radiolucent material
Intensifying screen mounted to inside of front
Back made of metal or plastic
Inside back is a layer of lead foil – prevents backscatter that could fog the film
Inside foil layer is a layer of padding – maintains good film/screen contact
Back intensifying screen mounted on padding

23. Cassette Construction

24. Screen Construction Polyester plastic base – support layer
Phosphor layer – active layer
Reflective layer – increases screen efficiency by redirecting light headed in other directions
Protective coating

25. Intensifying Screens Phosphors
RARE EARTH – (emits green light)
Developed in 1980’s
Most efficient
Most common in use today
CALCIUM TUNGSTATE (blue light)
Not as efficient
Not used as often
Calcium tungstate was a slower film.

26. Reduce patient exposure Increase x-ray tube life
INTENSIFYING SCREENS
DISADVANTAGES:
less detail than direct exposure
ADVANTAGES:
Reduce patient exposure
Increase x-ray tube life

27. The light photons are emitted by phosphor crystals.
These crystals are significantly larger than the silver halide crystals in the film
Screen reduces image sharpness
Exams requiring extremely fine detail use screens with small crystals.
The light photons generated in the intensifying screen are emitted by phosphor crystals.
These crystals are significantly larger than the silver halide crystals in the film
use of a screen reduces image sharpness somewhat
Some examinations requiring extremely fine detail use screens with small crystals

31. Image creation Latent Image
1% of x-ray photons that leave patient
Interact with phosphors of intensifying screens
100’s of light photons created to make image on film
Light photons expose silver halide crystals in the film emulsion –
Turn black metallic silver after procession

32. Film Development

33. Process of X-ray Image FILM LATENT IMAGE MANIFEST IMAGE X-RAY
PROCESSOR

34. Developing Chemicals
Developing is the stage where the latent image is converted to the manifest (visible)
Image.
Phenidone Developing Agent
Hydroquinone Developing Agent
Sodium Carbonate Activator
Potassium Bromide Restrainer
Developing Agents help change ionic silver to metallic silver (black). Silver ion is
said to be reduced. Only crystals that contain the latent image are reduce to
metallic silver.

35. Fixer Chemicals
The stage of processing where the film gets treated so that the image will not fade
but will remain permanently is called fixing.
Acetic acid activator
Ammonium thiosulfate(hypo) clearing agent
Potassium alum hardener
Sodium sulfite preservative
Water solvent
Fixing the film CLEARS the film of all undeveloped silver halides.
It is important to stop the developing process because with time, all the ionic silver
will be reduced to metallic silver, thus ruining our image. Our latent image must
be processed in a timely fashion or we will have image degradation.

36. Wash Cycle
The function of the wash cycle is to remove ANY residual chemicals
from the film. Water is used as the washing agent. Failure to completely
wash the residual chemicals could result in film fog, hypo retention,
yellowing of films, fading of films,
Dry Cycle
The final step of the processing is to dry the film before it leaves the
processer. Failure to do so occasionally results in sticky films which
eventually cause artifacts.

37. Extras…..
Replenishment : As chemistry is used up by the processing of
image, the proper chemical balance is needed to be maintained.
As a film enters the first stages of processing, the replenishment
system turns on and the chemistry in both developer and the fixer
are added to as needed according to prescribed rates.
Silver Recovery: As the latent image is developed into the manifest
image, the unaffected silver halide crystals will be washed off. Each
processor will have a silver recovery system in place. This is economically sound
and environmentally helpful. It also helps prevent the processor from breaking
down due to clogging of the system by metallic silver. $

38. Film Storage

39. YOUR XRAY IMAGE
You will need to bring to class an object or objects to image during week 12 and week 13. Each student will produce one image.

40. Any Questions ??????