MEDICAL XRAY FILM

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MEDICAL X-RAY FILM

• Prof. Susan A. Olavidez

Last revised June 2004
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CONSTRUCTION OF A MEDICAL X-RAY FILM

• BASE
• Brief History
• Glass plate
• Cellulose acetate
• Cellulose triacetate
• 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

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CONSTRUCTION OF A MEDICAL X-RAY FILM

• ADHESIVE (Substratum) LAYER
• Thin coat of gelatin
• EMULSION
• Silver halide crystal in gelatin
  binder
• SUPERCOAT
• Hardened gelatin

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ELECTROMAGNETIC SPECTRUM

• Electromagnetic Spectrum is the range of
  frequencies over which an electromagnetic
  radiation can be propagated.

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VISIBLE SPECTRUM

• Visible spectrum is the range of wavelength of
  the electromagnetic spectrum over which an
  unaided human eye can perceive wavelength changes
  as an alteration in color.

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EMULSION

• Emulsion is the sensitive material use to record
  the image and is made up of suspension of light
  sensitive salts (silver halide crystal) and
  gelatin binder.
• Silver halide crystal is the principal material
  used for film emulsion.
• 2 halides used for x-ray type film
• iodine
• bromine

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SPECTRAL SENSITIVITY

• Spectral sensitivity is the range of wavelength
  of the electromagnetic radiation that the film
  will respond.
• PEAK SENSITIVITY is the range of wavelength in
  which the film will exhibit its highest response
• CUT-OFF SENSITIVITY is the range of wavelength
  beyond which the film is no longer sensitive.

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SPECTRAL SENSITIZING

• AgBr has a natural sensitivity that ends at the
  blue region of the visible spectrum (480 nm).
• The addition of 2-4 of silver iodide marginally
  improved the films sensitivity (530 nm).
• The blue sensitive film is compatible with
  calcium tungstate IS which emits blue light.
• In 1970 another IS was introduced, the rare
  earth screen which primarily emits green light.
  But no film was compatible.
• A process introduced by Vogel in 1870s known as
  spectral sensitizing was adopted to create films
  with increased sensitivity.

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SPECTRAL SENSITIZING

• Spectral sensitizing is the process of extending
  the sensitivity of silver bromide crystal by
  coating the surface of the crystal with one or
  more layers of dye.
• The green light is absorb at the surface of the
  crystal and transfer its energy to the crystal
  itself

AgBr Crystal
AgBr Crystal w/ dye
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TYPES OF FILM ACCORDING TO SENSITIVITY

• MONOCHROMATIC - blue sensitive films

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TYPES OF FILM ACCORDING TO SENSITIVITY

• ORTHOCHROMATIC - green sensitive film

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TYPES OF FILM ACCORDING TO SENSITIVITY

• PANCHROMATIC - sensitive to all colors of the
  visible spectrum

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GRAIN TECHNOLOGY

• TWO TYPES OF GRAIN
• Globular Grain - spherical in shape and has a
  bigger volume. Use for blue sensitive film.
• Tabular grain - has a table-top like structure
  that provides bigger surface are but smaller
  volume.

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ADVANTAGES OF TABULAR GRAIN

• Increased resolution due to reduction in
  cross-over

• Reduction in silver coating weight
• Suitable for 45 s processing

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GRAIN SIZE AND DISTRIBUTION

• 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 sizes 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 of
  the film.

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BINDER

• BINDER binds the silver halide crystal.
• HISTORY
• Collodion - first binder use. A mixture of
  gun-cotton, ether and alcohol.
• Gelatin- 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 bone of animals. It is the modern binder use.

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BASIC FILM TYPES ACCORDING TO CONSTRUCTION

• DUPLITIZED. These are films that have emulsion
  layer coated on both sides of the film base.
• Screen type film - use with IS
• Contrast (standard) type
• Half-speed
• Latitude
• Non-screen type film (Direct Exposure film)
• Has thicker emulsion layer
• higher resolution
• requires higher exposure factor

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BASIC FILM TYPES ACCORDING TO CONSTRUCTION

• SINGLE-COATED FILM. Films that have emulsion
  layer coated on only one side of the film base.
• USES
• Ultrasound
• Nuclear medicine
• CT Scan
• Magnetic Resonance Imaging (MRI)
• Digital Subtraction Angiography (DSA)
• Mammography
• Cardiovascular Angiography
• Photofluorography

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FILM FORMATS AND PACKAGING

• Standard Sizes
• 8x10 in.
• 10x12
• 11x14
• 14x14
• 14x17

• Other Sizes
• 8x12 in.
• 12x14
• 4x4
• 70 mm roll/sheet film
• 35 mm roll film w/ perforation

• Packaging
• Available in 25 50, 100, and 500 sheets
• AFW (Alternate folded wrapped)
• NIF ( non-interleaved films)

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STORAGE AND HANDLING CONDITION

• Films should be stored vertically not
  horizontally.
• Try to maintain an even temperature on the
  storage area. The swing should be relatively
  low, about 1oC to 2oC. The ideal temperature is
  10oC if the films are to be stored for longer
  than 3 months. If not, films can be stored at
  21oC temperature.
• Make sure that the storage are is not damp. A
  value of 50 relative humidity should be aimed
  for.
• Avoid storing photographic chemicals in the same
  area as the film.
• Fumes (carbon monoxide, formalin, formaldehyde)
  and certain types of paint can fog the film.
• Mercury vapor can fog film. Do not use mercury
  thermometer in processing room.
• Films should be stored away from the source of
  radiation.
• Use the first in, first out principle.

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THANK YOU ?