RAD-172 CH.29 DISTORTION & MOBILE RADIOGRAPHY

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anatomy12
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268287
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RAD-172 CH.29 DISTORTION & MOBILE RADIOGRAPHY
Updated:
2014-04-07 00:45:05
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xray
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xray
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  1. Distortion is caused by ____
    from tube angle and position of the patient
  2. what is distortion
    Distortion is the misrepresentation of the _____ or ___ of the structures being examined
    • A geometric property that affects the quality of the radiographic image
    • size or shape
  3. what is visible still when contrast and density are poor
    distortion and detail
  4. size distortion is also known as
    magnification
  5. all size distortion is controlled by what
    SID (FFD) and OID (OFD)
  6. In all instances what increases the resolution of recorded detail
    reduced size distortion (magnification)
  7. what is one way to reduce size distortion
    getting rid of OID
  8. what is the main objective in most radiography
    minimize magnification as much as possible
  9. how do we control size distortion (magnification) as a tech
    positioning the body part accurately and fixing tube to maximize SID and minimize OID
  10. why will magnification occur of the true object
    because there is always a small bit of OFD
  11. OFD has a _____ relationship with ______
    • direct relationship with
    • magnification(size distortion)

    as ofd increases magnification (size distortion) increases
  12. what is critical in regards to both magnification (size distortion) and resolution
    OFD
  13. A further OFD reduces or increases magnification
    increases
  14. the greater the SID the ____ the ______
    • smaller
    • magnification
  15. SID and magnification have a ____ relationship
    why
    • inverse
    • when SID increases straighter photons interact with the body causing less magnification (relation to divergence of the beam)
  16. what is the magnification formula
    what is the object size formula
    • SID/SOD (SID - OFD)
    • IS(image size)/MF (magnification Factor)
  17. shape distortion deals with what two things
    foreshortening and elongation
  18. when does foreshortening occur
    when the boject is at an angle (rotated) and the CR is perpendicular to the film the image will appear shorter (squashed together) when compared to the object
  19. In an lpo position of the body what side appears bigger on a radiograph
    the side rotated away so the right side
  20. what is elongation
    type of distortion that occurs when object is parallel to the film the central ray is angled
  21. how can we avoid shape distortion
    the farther the part is from the CR the greater ____
    • by careful alignment of the CR w/ anatomy
    • distortion
  22. incorrect centering may occur from what
    centering of the tube (misalignment of CR) or incorrect positioning of the part
  23. what is spatial distortion
    when the CR is at an angle but the the object and film are parallel to each other
  24. what is the standard sid used for an ap chest portable (3)
    • 40 SID
    • 56 SID
    • 72 SID
  25. what is the best grid to use when doing an ap chest portable
    • using an lower ratio grid (6:1 8:1) with high frequency (178-200 lpi)
    • this grid permits wide exposure and centering latitude
  26. what are the types of mobile units used
  27. how do we see distinct air fluid levels on an ap chest
    position patient semi erect or erect and the tube must be parallel to the floor in order to see distinct air fluid levels
  28. what wave form is produced by a high frequency mobile unit
    ripple wave
  29. in world war 1 who developed the xray rube to be used at patients bed side
    picker corporation

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