pod imaging radiology. txt

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kepling
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89521
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pod imaging radiology. txt
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2011-06-06 18:42:35
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pod imaging radiology
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pod imaging radiology
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  1. What charges are at the cathode and anode end of the x-ray machine?
    • Cathode = negative
    • Anode = positive
  2. Why is tungsten used in x-ray machines?
    • 1) High melting point
    • 2) high atomic number for better picture
  3. T/F: X-rays are waves and particles?
    T
  4. What happens to wavelength and frequency as the energy of the x-ray increases?
    • wavelength: decreases
    • frequency: increases
  5. What do low, moderate, and high x-rays interact with? Which is most common?
    • Low: entire atom
    • Moderate: electrons
    • High: nuclei
    • ** Moderate is most common
  6. How much x-ray is lost due to heat?
    99%
  7. What happens to other 1% of x-ray not lost to heat?
    • 10% = characteristic (deflected)
    • 90% = Bremsstrahlung, braking radiation
  8. Where do the characteristic and Bremsstrahlung interactionc occur?
    Anode
  9. What are 3 rxns of x-rays after leaving anode and coming into contact with the body?
    • 1) non-attenuating
    • 2) absorbed
    • 3) scattered
  10. Name the two important diagnostic x-ray interactions?
    • 1) Comptom effect: scattering of electrons
    • 2) Photelectric effect: making the picture via absorption
  11. What does a Compton effect photon interact with?
    Outer shell electrons
  12. kVp effects on Compton and Photelectric effects?
    • kVP increases = compton increases (very fuzzy)
    • kVp decreases = Photoelectric increases (dangerous)
    • ***a common ground must be established for a safe and effective x-ray
  13. What does photoelectric effect come in contact with?
    absorbed in inner shell electrons
  14. Which type of material interacts more with the photoelectric effect, bone or skin? Why?
    Bone b/c of higher density
  15. What color is a radiopaque and radiolucent x-ray?
    • Radiopaque: white
    • Radiolucent: black
  16. What is kVp?
    Kilovolt potential: quality of x-ray, can change the miliamp number causing it to drop
  17. What is mAs?
    Miliamps per second: quantity of x-rays (decreases with high kVp)
  18. What is the Anode Heel effect?
    higher x-ray intensity at cathode (-) end than anode (+) end so you want larger structures placed by cathode
  19. What happens to the anode heel effect as the anode angle decreases?
    Increases
  20. What safety feature is used to reduce scatter radiation?
    Grids
  21. T/F: Low ratio grids are better at picking up scatter radiation
    F, high ratio grids are more effective
  22. What safety feature is used to reduce x-ray amounts to the patient?
    Filters
  23. 2 filters used in podiatry and their mm Al equivalents?
    • 1) Inherent 1.5mm Al
    • 2) Added 1.0mm Al
    • Total 2.5mm Al
  24. What safety feature is used to reduce the does of x-ray needed?
    Screens
  25. How many screens are used in podiatry?
    1
  26. Name the five steps of conventional x-ray making?
    • Developing
    • rinsing
    • fixing
    • wash and dry
    • temp and time
  27. What plays the highest role on image reception and exposure?
    kVp
  28. Contrast:kVp ratios
    • increase kVp = decrease contrast (long scale)
    • Decrease kVp = increase contrast (short scale)
  29. Why is exposure time decreased during x-rays?
    Avoid blurriness from patient movement
  30. 15% rule of kVp?
    15% increase in kVp decrease mAs by 2 (vice-a-versa as well)
  31. Common SID measurement?
    21-40 inches
  32. Inverse square law of x-rays
    • Radiation intensity inversely proportional to square of distance from source
    • ** Smaller distance = greater intensity
    • ** larger distance = less intensity
  33. T/F SID affects quality of x-ray beam
    F
  34. common focal spot size?
    1.0 mm
  35. T/F kVp should be change in increments of 2?
    F, increments of 5

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