US Physics

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Qwizdom100
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107473
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US Physics
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2012-08-26 13:15:14
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Edelman
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  1. Which axis on a graph runs horizontally?
    x-axis
  2. Which axis on a graph runs vertically?
    y-axis
  3. Def. two items that are not associated
    unrelated
  4. Def. two items that are associated such that when one item increases, the other increases
    directly related or directly proportional
  5. Def. two items that are associated or affiliated. However, the relationship between the two does not have to be specified
    related or proportional
  6. Def. two items are associated such that when one item increases, the other decreases
    inversely related or inversely proportional
  7. Def. when two numbers with a reciprocal relationship are multiplied together, the result is one. This is a special form of inverse relationship.
    Reciprocal relationship
  8. Name the Powers of Ten for the metric system up to billion and billionth. Include the Exponent, Prefix, Symbol, and Meaning
    • 10^9 giga G billion
    • 10^6 mega M million
    • 10^ 3 kilo k thousand
    • 10^2 hecto h hundred
    • 10^1 deca da ten
    • 10^-1 deci d tenth
    • 10^-2 centi c hundredth
    • 10^-3 milli m thousandth
    • 10^-6 micro µ millionth
    • 10^-9 nano n billionth
  9. What units correspond with length?
    cm, feet, etc.
  10. What units correspond with area?
    cm^2, ft^2, etc.
  11. What units correspond with volume?
    cm^3, ft^3, etc.
  12. What type of energy are sound waves?
    mechanical
  13. Pressure is measured in what units?
    pascals (Pa)
  14. Density is measured in units of what?
    kg/cm^3
  15. Distance is measured in units of what?
    cm, mm, ft, miles, etc.
  16. Name are the 3 accoustic variables.
    pressure, density, distance
  17. What are the 7 accoustic parameters?
    • period
    • frequency
    • amplitude
    • power
    • intensity
    • wavelength
    • propagation speed
  18. Def. particles move in a direction that is perpendicular (at right angles) to the direction that the wave propagates
    transverse waves
  19. Def. particles move in the same direction the the wave propagates
    longitudinal waves
  20. Def. when a pair of waves peak (maximum value) occur at the same time and at the same location. similarly, the troughs (minimum values) occur at the same time
    in-phase
  21. Def. peaks or troughs of two waves occur at different times
    out-of-phase
  22. Def. when two waves combine to form a single wave
    interference
  23. Def. the interference of a pair of in-phase waves results in the formation of a single wave of greater amplitude than either of its components
    constructive interference
  24. Def. the interference of a pair of out-of-phase waves results in the formation of a single wave of lesser amplitude than either of its components
    destructive interference
  25. What type of interference occurs when the frequencies of the waves differ?
    both constructive and destructive interference will occur
  26. What do waves transfer from one location to another?
    energy
  27. Describe sound waves.
    sound waves are a series of compressions and rarefactions
  28. Two waves are traveling in a medium and arrive at a location at the same time. What event takes place?
    interference
  29. Which types of waves will exhibit both constructive and destructive interference?
    waves of different frequency
  30. Def. describe the features of a sound wave.
    parameters
  31. What is the source of a sound wave in US?
    the ultrasound system and transducer
  32. Def. the time it takes a wave to vibrate a single cycle, or the time from the start of a cycle to the start of the next cycle
    Period
  33. Period is reported in units of what?
    milliseconds
  34. What are the typical values for period in ultrasound?
    .1-.5 µs
  35. What determines the period?
    the sound source only
  36. Can the period be adjusted by the sonographer?
    no
  37. Def. the number of particular events that occurs in a specific duration of time
    frequency
  38. What does hertz mean?
    per second
  39. Frequency is reported in what unit?
    hertz which = 1 cycle/per second
  40. What are the typical values for hertz in ultrasound?
    2 MHz - 10 MHz
  41. Frequency is determined by what?
    the sound source only
  42. Can the sonographer adjust frequency?
    no
  43. What is the audible range of human hearing?
    20 Hz to 20,000 Hz
  44. Def. sound below 20 Hz which is below the threshold for human hearing
    infrasound
  45. Sound above 20,000 Hz which is above the threshold for human hearing
    ultrasound
  46. Why is frequency important in diagnostic sonography?
    frequency affects penetration and image quality
  47. What is the relationship between period and frequency?
    inversely related and they are also reciprocals
  48. What 3 parameters describe the size, strength, or magnitude of the sound wave?
    amplitude, power, intensity
  49. Def. describes the "bigness" of a wave. it is the difference between the maximum value and the average or undisturbed value of an acoustic variable. (also the difference of the minimum value and average value)
    amplitude
  50. Amplitude can be in units of what?
    any of the acoustic variables (pressure, density, particle motion) also relatively in decibels
  51. What is the typical value in ultrasound for pressure amplitude?
    1 MPa to 3 MPa
  52. Amplitude is determined by what?
    initially the sound source but it decreases as the sound propagates which depends on the characteristics of the medium and sound wave
  53. Can the sonographer adjust amplitude?
    yes
  54. How is amplitude measured?
    it's measured from the middle value to the maximum value
  55. How is peak-to-peak amplitude measured?
    the difference between maximum and minimum values of an acoustic variable
  56. Def. the rate of energy transfer or the rate at which work is performed describes the "bigness" of the sound wave
    power
  57. Power is measured in what?
    watts
  58. What is the typical value for power in ultrasound?
    4 to 90 milliwatts
  59. What determines power?
    initially the sound source but it decreases as the sound propagates which depends on the characteristics of the medium and sound wave
  60. Can the sonographer adjust power?
    yes
  61. What is the relationship between power and amplitude?
    • direct relationship
    • power is proportional to the wave's amplitude squared
  62. Def. the concentration of energy in a sound beam. it relates to how the power in a wave spreads or is distributed in space. describes the sounds "bigness"
    intensity
  63. Intensity is measured in units of what?
    watts/square centimeter
  64. What are the typical values for intensity in ultrasound?
    .01 to 300 W/cm^2
  65. How is intensity determined?
    initially the sound source but it decreases as the sound propagates which depends on the characteristics of the medium and sound wave
  66. Can the sonographer adjust intensity?
    yes
  67. All three "bigness" parameters (amplitude, power, intensity) are ______ related.
    directly
  68. What is relationship between intensity and power?
    power and intensity are directly proportional
  69. What is the relationship between intensity and amplitude?
    intensity is directly proportional to amplitude squared
  70. Def. the distance or length of one complete cycle
    wavelength
  71. Wavelength is measured in units of what?
    mm, meters, etc.
  72. What are typical values for wavelength?
    .15 to .8 mm
  73. What determines wavelength?
    source and medium
  74. Can the sonographer adjust wavelength?
    no
  75. What is the relationship between wavelength and frequency?
    inversely proportional
  76. What is the rule that defines the relationship between frequency and wavelength of sound in soft tissue?
    To find wavelength of a sound wave in soft tissue, divide 1.54 mm by the frequency in MHz
  77. Why is wavelength important in diagnostic ultrasound?
    shorter wavelengths produce higher quality images with greater detail
  78. Def. the distance that a sound wave travels through a medium in 1 second
    propagation speed
  79. Propagation speed is measured in units of what?
    meters per second, mm/µs, etc.
  80. What are the typical values for propagation speed in ultrasound?
    500 m/s to 4000 m/s depending on the tissue
  81. What determines propagation speed?
    determined by the medium only
  82. Can the sonographer adjust propagation speed?
    no
  83. What is the speed of sound in soft tissue?
    1,540 m/s
  84. What characteristics of a medium determine the speed of sound in that medium?
    • stiffness
    • density
  85. Def. describes the ability of an object to resist compression.
    stiffness
  86. Def. describes the relative weight of a material
    density
  87. How does stiffness affect speed?
    stiffness and speed are directly related
  88. How does density affect speed?
    density and speed are inversely related
  89. Elasticity and compressiblity refer to what type of media?
    non-stiff
  90. What 5 additional parameters describe pulsed sound?
    • pulse duration
    • pulse repetition period
    • pulse repetition frequency
    • duty factor
    • spatial pulse length
  91. Def. a collection of cycles that travel together with a beginning and move as a single unit
  92. pulsed sound
  93. What are the two components of pulsed ultrasound?
    • transmit, talking, "on" time
    • receive, listening, "off" time
  94. Def. the actual time from the start of a pulse to the end of that pulse with a fixed duration
    pulse duration
  95. What are typical values for pulse duration?
    .3 to 2 µs
  96. What determines pulse duration?
    the sound source
  97. What are the formulas for pulse duration?
    pulse duration (µs) = # cycles X period

    pulse duration (µs) = # cycles / frequency (MHz)
  98. What characteristics create pulses with long durations?
    • many cycles in a pulse
    • individual cycles with long periods
  99. What characteristics create pulses with long durations?
    • few cycles in the pulse
    • individual cycles with short periods
  100. Which type of pulse is more desirable in diagnostic imaging, and why?
    shorter duration pulses because they create images with greater accuracy
  101. Def. the distance a pulse occupies in space from the start to the end of a pulse
    spatial pulse length
  102. What are typical values for spatial pulse length?
    .1 to 1 mm
  103. What determines spatial pulse length?
    sound source and medium
  104. What is the formula for spatial pulse length?
    SPL (mm) = # cycles X wavelength (mm)
  105. Spatial pulse length is: 
    ______ proportional to the number of cycles in the pulse
    ______ proportional to wavelength
    ______ proportional to frequency
    • directly 
    • directly 
    • inversely
  106. What are the characteristics of short and long pulses?
    • Long:
    • many cycles in the pulse
    • cycles with longer wavelengths

    • Short 
    • fewer cycles in the pulse
    • cycles with shorter wavelengths
  107. Which type of pulse is the most desirable in diagnostic imaging?
    shorter pulses because they create more accurate images
  108. Def. the time from the start of one pulse to the start of the next pulse
    pulse repetition period
  109. What units are pulse repetition period reported in?
    units of time (ms)
  110. What are some typical values of pulse repetition period?
    100 µs - 1 ms
  111. What determines pulse repetition period?
    • sound source 
    • specifically imaging depth
  112. How are pulse repetition period and depth of view related?
    • directly related
    • prp increases depth of view increases
  113. What are the two components of pulse repetition period?
    • transmit time 
    • receive time
  114. What is the other name for transmit time?
    pulse duration
  115. When sonographers adjust the depth what are they actually adjusting?
    listening time
  116. How does listening time change with depth?
    depth increases listening time increases
  117. Def. the number of pulses that an US system transmits into the body each second 
    Pulse Repetition Frequency
  118. PRF units?
    Hz hertz
  119. Typical value of PRF?
    1000 - 10,000 hertz
  120. PRF determined by?
    • sound source
    • specifically max imaging depth
  121. PRF and imaging depth are ____ related.
    inversely
  122. Increasing depth will do what to PRF?
    lower PRF
  123. An US machine is imaging to a depth of 2 cm. How would the PRF be described?
    high 
  124. When the depth is increased to 20 cm, what happens to PRF?
    PRF is reduced
  125. How are PRP and PRF related?
    inversely and reciprocals 
  126. Formula for PRF and PRP
    PRF X PRP = 1

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