Equis ISSN 2398-2977

Radiography: cassettes and intensifying screens

Contributor(s): Tim Donovan, Patricia Rose, Jeffrey Watkins, Jonie Watkins

Cassette

  • A radiographic image may be recorded in a number of ways
  • X-ray film.
  • Digitally.
  • Camera.
  • Cine or video film.
  • The radiographic image is formed when x-rays passing through a patient are selectively absorbed by structures within the patient.
  • The x-rays that pass through the patient to the film, creating a latent image, that can be seen after developing.
  • The image can be considered a shadowgram  Radiation physics: image production - shadowgram  .
  • The film is usually held in a cassette which contains, in addition, a pair of intensifying screens.
  • Standard sizes
  • 18 x 24 cm.
  • 24 x 30 cm.
  • 30 x 40 cm.
  • 35 x 35 cm.
  • 35 x 43 cm.

Cassettes are usually very strong but can be damaged by being dropped or mishandled

  • Cassette construction
  • See diagram   Radiation physics: cassette construction  .

  • Box
  • A conventional cassette is a light-proof box, hinged at one side.
  • Usually steel frame but some are made of sturdy plastic. .
  • Fastenings secure but easy to use in the dark room.
  • The front is radiolucent made of
  • Aluminum.
  • Plastic.
  • Carbon fiber.
  • Steel with a lead foil lining.

  • Pressure pad
  • A soft foam pad.
  • Keeps screen in close contact with film once loaded into cassette.
    If cassette is bent or dented close contact between the screens and the film is lost resulting in image unsharpness   Radiography: image quality 

  • Intensifying screen
  • Pressure pad keeps screen tight against film.
  • If double emulsion x-ray film is being used two screens will be present and the film is sandwiched between them.

Intensifying Screen

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Care of Intensifying Screens

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