by Sushmitha Annamalai

1. SEMINAR ON
RADIOGRAPHIC FILM
-SUBMITTED BY
A SUSHMITHA.
2015245024

2. •Construction
•Characteristics
•Storage and Handling
CONTENT

3. Film Construction
• It has two basic parts,
• Base: Originally glass - too fragile.
Cellulose-based - too flammable
1920-60,Polyester - 1960’s-present
• emulsion
• Most of the film has two layers of
emulsion.
• So they are referred as Double
emulsion film.

4. ,

5. Film contruction
Emulsion-
• Gelatin that is made from cattle byproducts.
• Silver halide -
95-98% silver bromide, Silver iodide and Silver chloride.
Protective layer- it works as “super-coat” which protects emulsio
from physical damage ,hard gelatin.

6. Types of films
• Construction based:
Single emulsion (screen)
Double emulsion (screen)
Non-screen film
Duplication “copy” film.
• Applications based:
Radiography
Photofluorography
Dental
Duplication (copies) – CRT/Video/
Electronic imaging.

7. LATENT IMAGE FORMATION
How the film works!
• Latent-Hidden – as the silver halide crystals are exposed to electromagnetic
radiation, they are ionized and a conversion to metallic silver is begun. This is
completed in the processor.
• Sensitization speck– Impurities/imperfections intentionally introduced to
crystals during manufacturing. Found on surface of crystal ,Acts as electron
trap, trapping electrons released during ionization of crystals. Essential for
development of black metallic silver.
The latent image is theorized as being formed in the following manner: – Radiant
energy (x-ray photon or light photon from screen) strikes the crystal & liberates an
electron from the valence shell of a bromide ion.

9. • When a positive silver ion comes within the negative field of the
speck, it may be attracted to the speck & take on an electron & form
an atom of metallic silver.
• Occurs many times within the same crystal when struck by radiant
energy.
• Once the film has been exposed to radiant energy & a latent image
has been formed, the film is capable of developing a radiographic
image.
• Chemicals in the processor greatly enhance this chemical reaction
converting a latent image to a visible image.

10. film characteristics
Speed - Sensitivity, indicated by location of characteristic curve along log relative exp. (x) axis.
–
• The film requiring the least exposure to produce a given density is the fastest.
• Function of silver halide crystal size, number of sensitivity specks, & emulsion layer
thickness.
• influences amount of density or blackening from a given exposure.
• Application - select according to part/procedure.
Latitude - inherent ability of emulsion to record a long range of density levels .Ability of a
film to record a gray scale.
Influences –
• wide latitude - uses broad range of exposures to produce densities within diagnostically-
useful range (low contrast / gray film).

11. • narrow latitude - uses limited range of exposures
to produce densities within diagnostically-useful
range (high contrast / black and white film) .
Application – indirectly indicates our margin for
error in technique selection.
Density – the degree of blackening of an area of film .
Base + Fog – the inherent film density, before exposure
and after processing.
• Blue die added to base to reduce glare.
• Background exposure (chemical fumes, cosmic
radiation etc.)
Recorded detail
– our ability to see small structures in an image. – Function
of crystal size (smaller crystals have better resolution)..
Application - Select according to part/procedure.

12. H & D CURVE
GRAPHICAL RELATIONSHIP BETWEEN AMOUNT OF EXPOSURE & RESULTANT DENSITY ON FILM, ALSO
KNOWN AS A CHARACTERISTIC CURVE.

13. The characteristic curves of two or more different films can
be plotted on the same chart for comparison.

14. • FILM STORAGE AND HANDLING:
• Temperature –
• Store film at 40 – 70 degrees F.
• Exceeding recommendations generally causes overall
increase in film density.
• Film stored at cold temperatures not permitted to reach
room temperature prior to use frequently exhibit a
blotchy appearance.
• Humidity –
• Store film at 50 – 65% humidity
• Low humidity promotes static electricity .
• High humidity causes emulsion to swell & soften,
making it prone to scratches & sticking.

15. Light:
• Exposed film is especially sensitive to light exposure
(even the safelight).
• Causes increased density of exposed portions of film.
• Normal room light is not a problem with unopened
boxes of film.
• Will cause increased density with opened or damaged
boxes
Radiation:
• Exposed film is especially sensitive to even small
exposures of radiation .
• Causes increased density.
• Film must be shielded from all radiation exposure (both
exposed and unexposed)

16. Pressure:
• Boxes should be stored on end.
• Do not lay flat & stack. Do not cram boxes on shelf or pressure artifacts
may result.

17. THANK YOU