Exposures II

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Anonymous
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25891
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Exposures II
Updated:
2010-07-06 22:03:36
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Review for exam two
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  1. What are the geometric properties of radiographic image quality?
    • Recorded Detail
    • Distortion
  2. How does radiographic image detail compare to actual object detail?
    All radiographs display less detail than the object being imaged
  3. How is resolution affected by an increase in OID?
    resolution decreases
  4. How is resolution affected by an increase in SID?
    Resolution Increases
  5. Why does motion reduce recorded detail?
    Because it failt to permit enough time for a well defined image to form. The image is spread over a linear distance and appears blurred
  6. What are the two types of distortion?
    • Size distortion
    • Shape distortion
  7. How is size distortion affected by an increase in SID?
    as SID increases Magnification decreases
  8. What is foreshortening and what causes it?
    forshortening projects the object so it appears shorter than it really is. It occurs when the part is improperly aligned
  9. What is elongation and what causes it?
    Elongation projects the object so it appears to be longer than it really is. It occurs when the tube or the image receptor is improperly aligned
  10. What is proper alignment?
    When the CR is perpendicular toboth the anatomical part and the image receptor.
  11. What is the first step in the film critique process?
    • Classification of the image
    • - is it within acceptance limits
    • - optimal or not optimal
  12. When should a film be repeated?
    when it is outside acceptance limits
  13. If the image is within acceptance limits, why would the flim critique process continue?
    To decided if the image is optimal or not optimal if not optimal what would you do to fix it in the future
  14. If an image is not optimal should it always be repeated?
    No! Evaluation should be done to figure out how to fix it for future exams
  15. What is a photographic problem and what are some possible ways to correct it?
    a technical factor problem with visibility of detail and can be further classified as denisity or contrast problems
  16. What is quality control?
    aspect of quality assurance that monitors technical equiptment to maintain quality standards
  17. What is the process of sensitometry?
    to monitor the processor DAILY to determine if its performing within limits
  18. What is the acceptance limits for collimation and what adverse effects may occur if collimation is outside of acceptance limits?
    • +/- 3% of SID are the acceptance limits
    • If the light field is bigger than x-ray field you clip anatomy
    • if the light field is smaller than x-ray field you increase patient dose
  19. What is the acceptance limits for SID and what adverse effects may occur if SID is outside of acceptance limits?
    • acceptance limits- calculated SID +/- 2% of actual SID
    • If calculated SID is too short magnification occurs resolution decreases and density too dark and patient dose increases
    • if calculated SID is too long less magnification increases resolution and density decreases
  20. What is the difference between reproducibility and linearity?
    • Reproducibility
    • Linearity
  21. What is the unit of measurement for resolution?
    line pairs per millimeter
  22. As film/screen speed increases, what happens to resolution?
    Resolution decreases
  23. As focal spot size decreases, what happens to penumbra?
    penmubra decreases
  24. As grey scale bit depth increases, what happens to resolution?
    Resolution increases
  25. As spatial frequency increases, what generally happens to MTF?
    MTF decreases
  26. Why is size distortion always magnification in film/screen rediography?
    Because minification can only occur in digital radiography
  27. What are the sources for resolution loss in CR technology?
    light scatter
  28. What are the sources of resolution loss for direct and indirect digital radiography?
    • Direct- divergence of light and the dead spaces
    • Indirect- dead space btwn dector elements
  29. What are the acceptance limits for exposure time settings?
    +/- 5%

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