Lesson 2 Flashcards
Foundation for the x-ray film
Base
Material where emulsion is coated
Base
150 to 300 μm thick
Base
History of base:
Glass plate
Cellulose nitrate
Cellulose triacetate
Polyester
Breakable
Glass plate
Flammable
Cellulose nitrate
also called safety base - thick compared to polyester
Cellulose triacetate
modern film base
Polyester
CHARACTERISTICS OF A GOOD BASE MATERIAL
• Dimensional stability
• Optical clarity/uniform lucency
• High tensile strength
• Flexibility
• Inert to processing chemicals
• Chemical memory
• Non-flammable
• Waterproof
• Blue tinted
Thin coat of gelatin
Adhesive layer
Silver halide crystals in gelatin binder
Emulsion
Hardened gelatin
Supercoat or overcoat
the range of frequencies over which
an electromagnetic radiation can b e propagated.
Electromagnetic spectrum
the range of wavelengths of the electromagnetic
spectrum over which an unaided human eye can perceive wavelength changes as an alteration in color.
Visible spectrum
Is the sensitive material use to record the image and is made up of suspension of light sensitive salts (Silver halide crystals) and
gelatin binder.
Emulsion
the principal material used for film emulsion.
Silver halide crystals
2 Silver Halide Crystals used for x-ray type film:
Silver iodide (Agl)
Silver bromide (AgBr)
Is the range of wavelength of the electromagnetic radiation that the film wil respond.
Spectral sensitivity
compatible with calcium tungstate IS which emits blue light
Blue sensitive film
a natural sensitivity that ends at the blue region
of the visible spectrum (480 nm).
AgBr
was adopted to create films with increased
sensitivity.
Spectral Sensitizing (Vogel in 1870’s)
Is the process of extending the sensitivity of
AgBr crystal by coating the surface of the
crystal with one or more layers of dye.
Spectral sensitizing
Types of film according to sensitivity
Monochromatic
Orthochromatic
Panchomatoc
- Blue Sensitive
- Compatible with calcium tungstate screen
- no longer used today
Monochromatic
- Green Sensitive
- Used with gadolinium oxysulfide IS
- currently, the most commonly used type of film
Orthochromatic
- Sensitive to all colors of the visible spectrum
- Not popular
- Has to be processed in total darkness
- no longer used today
Panchromatic
Type of grains
Globular grain
Tabular grain
spherical in shape and has a bigger volume. Use for
blue-sensitive film.
Globular Grain
has a table-top-like structure that provides a bigger
surface are but a smaller volume.
Tabular Grain
first binder use. A mixture of gun-cotton, ether,
and alcohol.
Collodion
from the word “gelata” which means formation in
water. It comes from the collagen fiber in which the primary sources are the cartilage, skin, and the protein matrix (ossein) of the bones of animals. It is the modern binder used.
Gelatin
These are films that have an emulsion layer coated on both sides of the film base.
Duplitized or Double-emulsion.
Films that have emulsion layer coated on only one side of the film base.
Single-emulsion films
