Intensifying Screens

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Intensifying Screens
2012-04-29 21:28:00

AHA. i suck at this one.
Show Answers:

  1. What does intensifying screens do?
    - They emit light when x-ray hits the phosphore in it.
  2. What does intensifying screens do to patient dose and detail?
    It lowers the dose but decreases detail
  3. How many % of latent image is formed by the light? How much of the latent image is formed by the actrual x-ray photons hitting the film?
    • 99% of latent image is formed by light.
    • 1% of it is made from the actual x-ray photons.
  4. What is the intensifying screens composed of? ( Parts of it and in order from the part closest to the film and back )

    Whats a good way to remember it ( The awesome way, and no this person does not really exist )
    • Protective Coating
    • Phosphor Layer
    • Reflective Layer
    • Base

    • Pria
    • Patel
    • Really
    • Blows
  5. What is the base made of? What does it have to be chemically in order to be used as a base?
    The base is made of polyester plastic and it has to be INERT so that it wont react with the phosphors nor will it interefere with the conversion of x-ray photosn to light.
  6. What is the reflective layert composed of?
    Magnesium oxide or Titanium dioixde
  7. What does the reflective layer do to patient dose? How does it do that?
    It reduces patient dose by reflecting twice as much light to the film than you would without a reflective layer.

    Because of this, you can use less technique and be able to get a good image.
  8. What does the phosphor layers do?
    Its able to absorb energy of x-ray photons and emit light photons.
  9. What does the protective coat do?
    Protects the phosphors from abrasions and stains.
  10. What characterstics does the phopshor layer have?
    High atomic number - to increase probablity of an incident x-ray photon interaction

    High conversion efficiency -to emit as much light photons PER x-ray interaction.

    Appropriate spectral matching - to ensure maximum latent image formation

    Minimal phosphoresence
  11. What is luminescence?
    Ability to emit light in response to excitation.
  12. How is fluoresence and phospheresence different?
    • Fluorosecne = instanteous emission
    • Phosphoresence = delayed emmision
  13. What is the average lifespan on intesnifying screens?
    The average life span is 5-7 years.
  14. Why are rare earths prefered?
    Rareearths have great absorption ability, high conversion efficiencdy and high intensification.
  15. What are rare earths conversion efficiency?
  16. What material was used prior to rare earths? What was it's Conversion Effiency percntage?
    Calcium tungstate at 5%
  17. Why are rare earths beter than calcium tungsgtate?
    Better speed while maintaining resolution.
  18. What light does gadolinium emit?
  19. What is resolution?
    Ability to accurately see an image.
  20. How much resolution can the naked eye see?
    10-20 lp/mm
  21. What is the most common screen problem? How does it affect density?
    Poor film/screen contact increasing density.
  22. What test is used to see poor film screen contact?
    Wire mesh test
  23. What is intesnification factor?
    measurement of amplification when converting xray into light
  24. What is emission spectra
    The color intensifying screens emit.
  25. Why should rare earths be matched with both green and blue lights?
    Conversion efficiency will be greatly reduced otherwise.
  26. How is latitude described?
    Narrow latitude exhibit high contrast and high speed but lower resolution.

    Vice versa.