DMU physics final

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patty.espinoza26@yahoo.com
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35656
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DMU physics final
Updated:
2010-09-19 02:38:47
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ultrasound physics
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DMU physics final review
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  1. A linear array transducer creates a _____ image
    rectangular
  2. contrast agents are
    • called microbubbles
    • can be swallowed
    • strong reflectors of ultrasound
  3. shallow imaging has
    • higher frame rate
    • shorter go-return time
    • superior temporal resolution
  4. when frame rate increases, ____ resolution improves
    temporal
  5. harmonic frequency arises from
    non-linear behavior
  6. low MI has _____ harmonics
    no
  7. high line density improves individual images with images containing more detail. this improves
    spatial resolution
  8. a damaged crystal array
    • displays a single shadow on the overall image
    • has to be reported
  9. what is the dynamic range of an ultrasound system that can process voltages ranging from 5 volts to 5000 volts
    60 dB
  10. with linear phased array transducers, ___ crystals are fired to create each sound pulse
    all
  11. high MI causes
    • bubbles to rupture
    • strong harmonics
  12. fundamental frequency is
    frequency created by the transducer
  13. affects the number of pulses
    • sector size
    • line density
    • number of focal points
  14. dynamic range is measured in
    dB
  15. a mechanical transducer has
    mechanical steering
  16. frame rate is affected by
    • speed of sound in the medium
    • imaging depth
  17. harmonic frequency is
    • twice the fundamental frequency
    • the second harmonic frequency
  18. artifacts created by array transducers are called
    grating lobes
  19. frame rate and Tframe are ______________ related
    inversely
  20. if a transducer transmits a fundamental frequency of 2 MHz the harmonic frequency will be
    4 MHz
  21. the main advantage of multiple focal zones is it provides excellent ____ resolution
    later
  22. the amount of contrast harmonics produced can be estimated by a number called ---
    the mechanical index (MI)
  23. slice thickness resolution is also called
    elevational resolution
  24. an amplifier increases a voltage from 5 to 5000 volts. how many decibels of gain is this?
    40
  25. imaging depth and number of pulses in each picture
    • determine frame rate
    • are controlled by the sonographer
  26. what determines the frame rate on an ultrasound machine
    • imaging depth
    • speed of sound in the medium
  27. what increases temporal resolution
    • narrow sector
    • single focus
    • shallow imaging
    • low line density
  28. contrast harmonics result from
    non linear behavior of microbubbles
  29. number of lines per frame and the frame rate determine the
    PRF
  30. wide sector image will
    • inferior temporal resolution
    • lower frame rate
    • more pulses per frame
  31. if a sonographer turns off the multi-focus feature, what would happen?
    temporal resolution improves
  32. dynamic aperture is a form of
    • recieve electronic focusing
    • accomplished by varying the number of crystals being used to recieve the reflected signal coing back from the body
  33. convex transducers have a blunted ____top
    fan shaped
  34. annular arrays
    • use inner crystals for shallow regions
    • have larger diameter rings that have a deep focal length
    • use outer crystals to image outer regions
    • have small diameter rings with a shallow focus that diverges rapidly
  35. phased arrays typically have _____ crystals
    100 - 500
  36. linear switched or sequential arrays
    • rectangular shaped
    • large transducers with approx 200 crystals or elements arranged in a line that are fired at different times in sequence

    have no steering and are fixed focusing

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