X-ray films

1. Dr. Pankaj Kaira
JR – I Radiodiagnosis
SRMSIMS,Bareilly.

2. Introduction-
 The X-Ray films, help us to record the information
regarding the object (tissue) through which the x-
rays passes & hence they greatly help in diagnosis,
& treatment of the patient problem.
 Image recorded on film is caused by exposure to
photons.

3. HISTORY-
 The first x-rays were recorded on glass
plates.
 These were coated with emulsion on one side
only.
 The exposure dose was quite high.
 In 1839, the phenomenon of development
was discovered by Louis Daguerre

4.  One year later, it was discovered that treating
exposed silver chloride paper with sodium chloride
would make the image permanent.
 Nitrocelluose based film was used in 1914 for
recording x-rays.
 This film was single-emulsion but was quiet
flammable
 It was later discovered that double-emulsion
responded to x-rays faster.
 In 1924, safety film made of cellulose triacetate
replaced the nitrocellulose based film.

5. X- ray film
AdhesiveBase
Polyester
polyethylene
terephthalate
Emulsion
Silver
halide
grains
Vehicles
matrix

7. BASE -FILM
 It is a transparent supporting material.
 POLYESTER POLYETHYLENE
TEREPHTHALATE RESIN are used.
 Thickness - 0.18 mm
Film
Base
0.18 mm

8. IDEAL PROPERTIES BASE MATERIAL
1. Structural support for fragile emulsion.
2. Low light absorption : Should not produce visible
pattern on the radiograph.
3. Flexible, thick, & strong.
4. Dimensional stability : Maintain size and shape
during processing, handling and storage.
5. Non - Flammable.

9. Triacetate and Polyester are clear and colorless.
Adopted in 1933, blue tint was added to the x-ray
film in an effort to produce a film that was “easier” to
look at.
Causes less eye strain.
Blue tint can be added to either to the base or to the
emulsion.
All present x ray films are blue tinted.
TINTED FLUE FILM

10. FUNCTIONS OF BASE
 Provide support for emulsion layer.
 To transmit light.

11. ADHESIVE LAYER
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 Also called subbing layer or Substratum layer.
 Made of mixture of gelatin solution and solvent of
film base.
 It keeps emulsion layer and base adhered to each
other during coating stage and processing.
 Provides uniform surface over which the emulsion
can be coated uniformly.

12. EMULSION LAYER
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 Has 2 principle components –
I. Silver halide grains
II. Vehicle matrix
 It consists of a homogeneous mixture of gelatin and silver
halide crystals.
 In typical emulsion 90 to 99% is AgBr and about 1 to 10% AgI .
Emulsion
Layers
 The presence of AgI produce an emulsion of much higher
sensitivity than a pure AgBr emulsion.
 It also contains traces of sulfur (ALLYLTHIOUREA).

13.  How silver halide crystals are made … ???
Dissolve Metallic silver in nitric acid.
to form
Silver nitrate
by mixing
silver nitrate + KBr = Ag-Br + potassium
nitrate

14. 14
 Silver halide in a emulsion is in the form of small crystals.
 Silver halide crystals may be tabular, globular,
polyhedral, or irregular in shape.
 Crystal size might vary from
1.0 –1.5 microns in diameter
with about 6.3 x 1010 grains
per centimeter of emulsion.

16. Silver Iodo Bromide Crystals
• An Imperfect crystal
(perfect crystal has
almost no
photographic
sensitivity).
• Several types of
crystal defects
noted.

17.  A Point defect consists
of a Silver Ion that has
moved out of its
normal position in
crystal lattice
(Interstitial Ions).

18.  A dislocation is a line
imperfection in the
crystal.
 Cause a strain in the
wall structure.
 Iodine ion strains the
crystal in this way

19.  Chemical sensitization of the crystals are produced by
adding allythiourea, a sulfur containing compound to the
emulsion , which reacts with silver halide to form silver
sulfide.This Silver Sulphide is usually located on surface of
the crystals and is referred as “sensitivity speck”.It is the
sensitivity speck that traps elctrons to begin formation of the
latesnt image centers.

20. Point defect in
cubic lattice.
Sensitivity
speck by Silver
sulfide
The sensitivity speck traps electron and form Latent image.

21.  Remnant radiation interacts with the silver halide
crystals
 Mainly by the photoelectric interaction
 The energy deposited into the film is in the same
pattern as the subject that was exposed to radiation
 This invisible image is known as the latent image
 A latent image on photographic (radiographic) film
is an invisible image produced by the exposure of
the film to light (radiation).
 By chemically processing the latent image it is made
visible known as the manifest image.

22.  Metallic silver is black, so it is this metallic
silver that produces black areas on a
developed films.
 Exposure of silver-iodo-bromide grains to
light photons emitted by screen / direct x-ray
exposure initiates the formation of atomic
silver to form a visible pattern.

23.  Energy absorbed from Light
photon ejects Br electron
 Electron trapped at sensitivity
speck where it is trapped and
temporarily fixed .
 Negative electron attracts
interstitialAg+ ion
 Ag+ and e- combine to form
neutral (black) Ag
 If >6-10Ag0 accumulate at
speck, it becomes a latent
image center: ie, it is
developable.

24. This process repeats.

25. GRAIN SIZE AND DISTRIBUTION
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GRAIN SIZE and DISTRIBUTION affects the following:
 SPEED: The bigger the average grain size, the higher the
speed of the film.
 CONTRAST: Affected by size distribution.The more
available in the film, the lower the contrast.
 GRAININESS: Graininess is the apparent clumping of the
crystal as seen on the radiograph.The bigger the crystal,
the higher the graininess o f the film.

26. GELATIN
 Gelatin is used as the suspending medium and
binding agent for the silver halide particles.
 It comes collagen fiber in which primary source are
the cartilage, skin and the protein matrix (ossein) of
bone of animals.

27. WHY WE USE GELATIN AS BINDER…?
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 It is a medium in which SILVER NITRATE and SODIUM
BROMIDE can react and the resulting AgBr get finely and
evenly dispersed and remain suspended.
 In warm state it can be easily spread on the film base.
 On cooling, it sets firmly on the base as gel.
 It is flexible and does not crack easily on bending.
 It is optically transparent .
 Gelatin does not react chemically with the silver halide .
 It is porous so the processing chemicals can penetrate to the
silver halide crystals.
 Some of the constituents in gelatin enhances the activity of
Silver bromide and some act as antifoggant.

28. SUPERCOAT (OVERCOAT)
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Protective layer of gelatin
 Provides sturdiness to unexposed radiographic film.
 Antistatic
 Reduces damage from scratches, pressure, or
contamination during storage, handling and
processing.
Supercoating

29. FEW ADDITIVES
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 Preservative – Phenol as bacteriocide
 Silver iodide – To extend sensitivity towards blue
range.
 Some dyes may extend Colour sensitivity further
 Glycerin to make the emulsion pliable
 Saponin – To make the emulsion receptive to the
processing chemicals
 Alcohol –To prevent frothing during coating

30. 1. According to their USES –
 Intraoral films
Periapical films
No. 0 – children
No. 1 – anterior adult
No.2 – standard adult
Occlusal films
Bitewing films
 Extraoral films

31.  2. According to SPEED –
 Slow film
 SpeedA
 Speed B
 SpeedC
 Fast film
 D – ultra speed
 E – ekta speed
 F – ultra ekta speed
 Hyper speed G

32.  3. According to emulsion layer -
 Single coated
 Double coated
 4. According to packaging –
 Single film packet
 Double film packet

33. 1) Screen Films :
 Most commonly used
 Sensitive to blue light emitted by intensifying
screens and direct actions of x-rays.
 Used in cassettes with intensifying screens
 High speed.

34. 2) Non-screen / Direct exposure films:
 Has thicker coat of emulsion used without
intensifying screen.
 Depends mainly on action of x-ray.
 Four times faster than that of screen films so
requires 1/4th exposure only.
 Must be manually processed because of thick
emulsion.

35. Uses :
 A)In limb radiography.
 B)To detect intra-ocular foreign body.
 C)In dental with intra-oral cardboard.

36. 3) Mammography film:
 Single coated
 Fine grain
 Slow speed
 High contrast
 Designed to be used with single intensifying
screen
 Combination must be fast to deliver
minimum dose to the glandular tissue.

37. 4) Duplicating Film :
 Used to copy radiograph.
 Original cassette to be copied is inserted into
a cassette whose opaque front has been
replaced by pane of clear glass.
 Special duplicating film is placed with
emulsion side down onto radiograph and lid
closed.
 Exposure made.

38.  What is speed of X-RAY FILM …???
 It is defined as the amount of the radiation
required to produce the radiograph of adequate
density.
 Slow film – Require more exposure & vice versa.
 Factors affecting film speed –
 Size of crystals
 Shape of grains
 Thickness of emulsions

39. Differenceb/wSingleCoatedandDoubleCoated
X-rayFilm
Characteristic Single coated Double coated
Emulsion layer One side Both side
Patient Radiation dose More Less
Radiographic detail More Less
Average gradient (G) Very less more
Parallax effect No yes
Contrast Less more

40. THANKYOU