RT 180 Test 1

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fongpay03
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110961
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RT 180 Test 1
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2011-10-26 00:19:47
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RT 180 Test
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RT 180 Test 1
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  1. What are 2 factors that effect insufficient density? (film screen)
    • wrong exposure factors
    • underdevelopment
  2. What are 3 things that could effect wrong exposure factors/underexposure for insufficient density? (film screen)
    • insufficient mAs or kVp
    • Too long source image receptor distance (SID)
    • Incorrect centering of patient to photocell or incorrect photocell selection (phototiming/AEC(automatic exposurecontrol)
  3. What are 4 things that could effect wrong exposure underdevelopment for insufficient density? (film screen)
    • Developer temp too low – optimum = 92‐95F/31‐33C
    • Incoming water temp too low – optimum 70‐75F/21‐24C
    • Developer time too short – optimum 20‐25 sec
    • Exhausted, oxidized developer‐ note color change fromclear/transparent to non transparent and dark ice tea to coffeebrown color. Check replenisher pump.
  4. What are 2 factors that effect excessive density? (film screen)
    • wrong exposure factors
    • underdevelopment
  5. What are 3 things that could effect wrong exposure factors/overexposure for excessive density? (film screen)
    • excessive mAs or kVp
    • Too short source image receptor distance (SID)
    • Incorrect centering of patient to photocell or incorrect photocell selection (phototiming/AEC(automatic exposurecontrol)
  6. What are 3 things that could effect wrong exposure overdevelopment for excessive density? (film screen)
    • Developer temp too high
    • Incoming water temp too hot
    • Developer time too long
  7. What is the definition for fog? (film screen)
    increased or unwanted image darkening (density) that does not contribute to the overall diagnostic quality. It is undesirable.
  8. What are 4 things that causes fog? (film screen)
    • light-Incorrect darkroom safelight and light leaks into darkroom
    • radiation
    • chemical fogging
    • improper film storage
  9. What are the different color stains on radiographs? (film screen)
    • Yellow – exhausted , oxidized developer
    • Brown – inadequate washing/fixing
    • Green‐ inadequate/prolong fixing. Also will cause image to fade over time. Mammography requires hypo (fixing) retention testingto ensure that fixing is done correctly‐ federal regulation
    • Metallic – oxidized or contaminated developer
  10. What is the definition of image artifacts? (film screen)
    • any unwanted defect or image on the processed radiograph that does not aid in the formation of the image
    • Key point: exposed radiographic film is 2 to 5x more sensitive toartifact formation than unexposed film.
  11. What are the common causes for image artifacts? (film screen)
    • Rough handling-Scratches, fingernails(crescent shaped), bending(linear marks), static(tree branching), fingerprints
    • Processing‐ usually caused by the rollers-Guide shoes, hesitation lines, pi lines, scratches, detection marks, reticulation,
  12. How do radiographs looks like from dirty intensifying screens? (film screen)
    Small white spots caused by dust/dirt – periodic cleaning, use screen cleaner
  13. What are the 2 essential components of film?
    • base
    • emulsion
  14. Emulsion in film is made out of?
    microscopic crystals of silver bromide (halide) suspended in a gelatin (extracted from cattle skins) that is coated on both sides of the base
  15. What is best used with rare earth screens and requires a special orthochromatic safelight?
    • orthochromatic film
    • sensitive to yellow-green light
  16. What are the characteristics of film emulsion?
    • swells during developing step so the electrochemical change can occur to the exposed crystals -> latent image to visible image
    • shrinks and hardens during fixing step -> permanent image
  17. What are the types of films?
    • by construction:Screen type (the standard) particularly sensitive to the fluorescent light of the intensifying screen
    • by sensitivity or spectral ( color) matching: orthochromatic or panchromatic
  18. Orthochromatic film is sensitive to what color light?
    Sensitive to yellow-green light - most compatible with rare earth screens
  19. Panchromatic film is sensitive to what color light?
    sensitive to red light -- most compatible for laser imaging. Now used for: CT, MRI, digital imaging. Note: manufactured only as single emulsion film
  20. For what procedure are films specially designed for?
    Mammography
  21. What are the 4 major characteristics of film when purchasing?
    • speed or sensitivity
    • image receptor contrast
    • resolution or sharpness of detail
    • latitude
    • **note: way too many notes to type out so please read about each on lecture notes!
  22. What is the definition of speed or sensitivity?
    amount of exposure necessary for the film's emulsion to react to the radiation exposure
  23. Numerical rating scale (notes only)
    • 50 - 100 = slow, detail
    • 200 - 400 = medium
    • 400 - 600 = fast
    • 600 - 800 = ultra fast
    • Key concept: 400 speed image receptor systems are the most common used today. Exception is tabletop extremities that used 100 -200 speed systems
  24. Speed of film is determined by:
    • phosphor material: orthochromatic sensitive film is usually faster = less patient dose
    • crystal size: the larger the crystal size = faster the speed = less dose to patient = decreased image resolution
    • thickness of phosphor layer: thicker the layer = faster the speed = decreased image resolution but less dose to patient (good ALARA)
  25. What is the definition of contrast?
    the visible percentage differences (variations) in the amount of black metallic silver seen in the image. Film manufactures can make film that will demonstrate images with different contrast visualization
  26. high(er) contrast or (lower latitude):
    More “black/white type” image or greater visible differences between the density variations (think anatomy) with less number of visible density variations. Good for extremity imaging.
  27. low(er) scale or (higher latitude):
    gives an image with more visible shades of density variations. “Less black/white type” image with less visible differences between the density variations (think anatomy) with more number of density variations. Good for chest imaging
  28. Radiographic contrast is manipulated what exposure factor?
    kVp
  29. What is the definition for resolution or sharpness of detail?
    ability of the film emulsion to visibly produce a sharp image. Determined by the speed of the film
  30. What is the rule for resolution or sharpness of detail?
    Rule: the slower the speed of the film or intensifying screen or the imaging receptor system the better/increased resolution of the visible radiographic image however patient dose increases (not good ALARA).
  31. What is the definition for latitude?
    the margin of error in using the exposure factors to produce a diagnostic image
  32. What are the types or latitude?
    • wider the latitude = more margin of error (“a forgiving film”), usually this type of film has lower scale contrast
    • narrower the latitude = less margin of error ( requires greater exposure accuracy), usually this type of film has higher scale contrast

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