Canis ISSN: 2398-2942

Radiography: X-ray film

Radiographic film properties and storage



Film speed
  • The term "speed" can be applied to films as well as screens Radiography: cassette and intensifying screen.
  • Afastfilm will become blacker for a given exposure than aslowfilm.
  • The speed of films is determined by the size and number of halide grains.
  • Larger grains give faster speedbut reduced resolution.
  • Speed is a relative value and cannot be compared across different manufacturers.
  • Speed is often used to describe a film-screen combination rather than one or the other in isolation.
Storage of x-ray films
  • Radiographic film is a delicate material and requires careful handling.
  • Ideal storage facilities:
    • Cool conditions (10-18°C).
    • Dry conditions (no more than 50% humidity).
    • Away from sudden changes in temperature and humidity.
    • Protected from light.
    • Protected from processing chemicals and their fumes.
    • Protected from ionizing radiation.
    • Film stored on edge (not stacked on top of one another as this may ’ pressure marks.
      Even when stored in ideal conditions film gradually deteriorates with age so stock should be rotated

Film Identification

  • It is essential that radiographs beclearly,correctlyandindeliblylabeled.
  • Information on each film should include:
    • Owner and patient's name or identification number.
    • Date radiograph taken.
    • Hospital or practice name.
    • Anatomical marking, ie left or right.
  • Methods of marking film:
    • "X-Rite" tape:
      • Self-adhesive, lead-impregnated tape on which information is written and then stuck to cassette before exposure.
      • Can be difficult to see on finished radiograph, especially if exposure has been high.
        This problem can be overcome by the use of special holders for the tape.
    • Lead numbers and letters:
      • Commonly used for anatomical marking but can also be used for identification.
      • Words formed from required combinations of letters and stuck to cassette before exposure.
      • Metal holders, into which the letters slide, are also available and can be stamped with practice name.
    • Light marker:
      • Photograph the identification information, written on a special piece of paper, onto a corner of the film which has been shielded from the main exposure by a lead blocker.
      • This marking can be done by manual marking of the film in the dark room or if cassette is inserted into machine before film is removed the identification window in the cassette automatically slides back and exposure is made..
    • Writingon the film after exposure (not ideal but better than nothing).

      For the BVA Hip Dysplasia scheme information must be put on film at point of exposure and therefore only X-rite tape or lead characters are acceptable.

Types of Radiographic film

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Sensitometry

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