Ultrasound Physics

Card Set Information

Author:
Qwizdom100
ID:
104276
Filename:
Ultrasound Physics
Updated:
2012-08-26 12:27:55
Tags:
Test
Folders:

Description:
Notes
Show Answers:

Home > Flashcards > Print Preview

The flashcards below were created by user Qwizdom100 on FreezingBlue Flashcards. What would you like to do?


  1. pressure, density, and particle vibration; sound wave quantities that vary in space and time
    acoustic variables
  2. region of low density and pressure in a compressional wave
    rarefaction
  3. reduction in differences between small and large amplitudes. region of high density and pressure in a wave
    compression
  4. wave in which the particle motion is parallel to the direction of wave travel (compressional wave)
    longitudinal wave
  5. number of cycles per second
    frequency
  6. unit of frequency, one cycle per second; unit of pulse repetition frequency, one pulse per second.
    hertz
  7. T/F
    A wave is a traveling variation of some quantity or quantities.
    True
  8. T/F
    Sound is a traveling variation of acoustic variables.
    True
  9. T/F
    Acoustic variables include pressure, density, and particle motion.
    True
  10. T/F
    A cycle is one complete variation in pressure or other acoustic variable.
    True
  11. T/F
    Frequency is the number of cycles in a wave that occur in 1 second.
    True
  12. One hertz is one cycle per second. The abbreviation for hertz is Hz.
    True
  13. T/F
    One kilohertz is 1000 cycles per second. The abbreviation for kilohertz is kHz.
    True
  14. T/F
    One megahertz is one million cycles per second. The abbreviation for megahertz is MHz.
    True
  15. sound of frequency too low for human hearing (<20 hertz)
    Infrasound
  16. sound of frequency too high for human hearing (>20,000 hertz)
    Ultrasound
  17. imaging depth
    penetration
  18. time per cycle
    period
  19. the common unit for period in ultrasound
    microsecond (μs)
  20. Period = 1/Frequency
    T (μs) = 1 / f (MHz)
  21. If frequency increases, period _______.
    decreases
  22. length of space over which a cycle occurs
    wavelength
  23. T/F
    Wavelength is commonly expressed in millimeters.
    True
  24. the speed with which a wave moves through a medium
    propagation speed
  25. Wavelength is = propagation speed (c) divided by frequency
    λ (mm) = c (mm/μs) / f (MHz)
  26. If frequency increases, wavelength ______.
    decreases
  27. the resistance of a material to compression
    stiffness
  28. Propagation speeds are highest in ______ and lowest in ______.
    • solids (highest)
    • gases (lowest)
  29. Propagation speed values in soft tissue range from _____ to _____.
    1.44 to 1.64 mm/μs
  30. The average propagation speed of sound in tissue is _____.
    1.54 mm/μs
  31. progression of travel
    propagation
  32. sound propagation in which the propagation speed depends on pressure causing the wave to shape to change and harmonics to be generated
    nonlinear propagation
  33. the primary frequency in a collection of frequencies that can include odd and even harmonics and subharmonics
    fundamental frequency
  34. frequencies that are even and odd multiples of another, commonly called fundamental or operating frequency
    harmonics
  35. a wave in which cycles repeat indefinitely; not pulsed.
    continuous wave
  36. ultrasound produced in pulsed form by applying electric pulses or voltages of one or a few cycles to the transducer
    pulsed ultrasound
  37. a brief excursion of a quantity from its normal value; a few cycles
    pulse
  38. T/F
    With continuous wave ultrasound, cycles repeat indefinitely. Pulsed ultrasound consists of pulses separated by gaps in time. A pulse is a few cycles of ultrasound.
    True
  39. number of pulses per second
    pulse repetition frequency or pulse repetition rate
  40. interval of time from the beginning of one pulse to the beginning of the next
    pulse repetition period
  41. PRF is commonly expressed in
    kilohertz
  42. PRP is commonly expressed in
    milliseconds
  43. PRP (ms) = 1 / PRF (kHz)
  44. If pulse repetition frequency increases, pulse repetition period ______.
    decreases
  45. Interval of time from beginning to end of a pulse
    pulse duration
  46. T/F
    Shorter pulses, compared with longer ones, improve the quality of sonographic images.
    True
  47. T/F
    Sonographic pulses are typically 2 or 3 cycles long. Doppler pulses are typically 5 to 30 cycles long.
    True
  48. Pulse duration = period (time for one cycle) X number of cycles in the pulse (n)
    PD (μs) = n X T (μs)
  49. T/F
    Pulse duration is the time for a pulse to occur.
    True
  50. T/F
    If frequency is increased, period is decreased, reducing pulse duration. If the number of cycles in a pulse is reduced, pulse duration is decreased.
    True
  51. fraction of time that pulsed ultrasound is on
    duty factor
  52. T/F
    Longer pulses increase the duty factor because the sound is on more of the time.
    True
  53. DF = PD (μs) / PRP (μs)
    DF =( PD (μs) X PRF (kHz) ) / 1000 (kHz / MHz)
  54. T/F
    If pulse duration increases, duty factor ______.
    increases
  55. if PRF increases, pulse repetition period _____ and duty factor ________.
    • decreases
    • increases
  56. length of space over which a pulse occurs
    spatial pulse length
  57. Spatial pulse length = length of each cycle X the number of cycles in the pulse
    SPL (mm) = n X λ (mm)
  58. T/F
    Spatial pulse length is the length of space that a pulse takes up.
    True
  59. T/F
    If the number of cycles in a pulse increases, spatial pulse length increases. If frequency increases wavelength and spatial pulse length decrease.
    True
  60. T/F
    Shorter pulses improve sonographic image resolution.
    True
  61. range of frequencies contained in an ultrasound pulse; range of frequencies within which a material, device, or system can operate.
    bandwidth
  62. bandwidth divided by operating frequency
    fractional bandwidth
  63. nonspecific term referring to amplitude or intensity
    strength
  64. maximum variation of an acoustic variable or voltage
    amplitude
  65. power divided by area
    intensity
  66. rate at which work is done; rate at which energy is transferred
    power
  67. T/F
    If beam power increases, intensity increases. If beam area decreases (focusing), intensity increases.
    True
  68. force multiplied by displacement
    work
  69. conversion of sound to heat
    absorption
  70. decrease in amplitude and intensity with distance as a wave travels through a medium
    attenuation
  71. portion of sound returned from a media boundary; echo
    reflection
  72. diffusion or redirection of sound in several directions upon encountering a particle suspension or a rough surface
    scattering
  73. reflection
    echoes
  74. unit of power or intensity ratio; the number of decibels is 10 times the logarithm (to the base 10) of the power or intensity ratio.
    decibel
  75. attenuation per centimeter of wave travel
    attenuation coefficient
  76. time it takes a wave to vibrate a single cycle
    period
  77. Period is determined by the ________ _______.
    sound source
  78. the number of particular events that occur in a specific duration of time. in ultrasound, the number of cycles that occur in one second
    frequency
  79. Diagnostic range of frequency in ultrasound
    2 MHz - 10 MHz
  80. Frequency is determined by the ______ _______.
    sound source
  81. Frequency and period have what type of relationship
    inversely proportional and a reciprocal relationship
  82. distance or length of one complete cycle
    wavelength
  83. wavelength is determined by the ______ ______ and the _____.
    sound source and medium
  84. shorter wavelengths produce ______ quality images
    higher
  85. frequency and wavelength have a _______ relationship as long as they are in the same medium
    inverse
  86. the distance that a sound wave travels through a medium in 1 second
    propagation speed
  87. propagation speed is determined by the
    medium
  88. order the medium that sound travels the fastest in (normal states of matter)
    • solids
    • liquids
    • gases
  89. 2 medium characteristics that affect propagation speed
    • stiffness
    • density
  90. propagation speed and stiffness are ______ related
    directly
  91. other name for stiffness
    bulk modulus
  92. propagation speed and density are ______ related
    inversely
  93. the difference in the maximum value and the average or undisturbed value of an acoustic variable may also be the difference between the minimum and the average
    amplitude
  94. amplitude is _______ by the sonographer
    adjustable
  95. the difference between the maximum and minimum values of an acoustic variable
    peak-to-peak amplitude
  96. rate of energy transfer
    power
  97. power is measured in
    watts
  98. power is _____ by the sonographer
    adjustable
  99. power is ______ to the amplitude ______
    • proportional
    • squared
  100. concentration of energy in a sound beam
    intensity
  101. intensity = power/cross sectional area
  102. Intensity is measured in
    watts/cm ^2
  103. intensity is _______ by the sonographer
    adjustable
  104. intensity and power are ________
    proportional
  105. intensity is proportional to the amplitude _______
    squared
  106. What parameters describe pulsed sound?
    • pulse duration
    • pulse repetition period
    • pulse repetition frequency
    • duty factor
    • spatial pulse length
  107. the actual time from the start of a pulse to the end of that pulse
    pulse duration
  108. pulse = # cycles X period
  109. pulse duration = # cycles / frequency
  110. pulse duration is ______ to the number of cycles in the pulse
    proportional
  111. pulse duration is ______ proportional to the period
    directly
  112. Pulse duration is _______ proportional to the frequency
    directly
  113. long pulses have either
    • many cycles
    • individual cycles with long periods
  114. short pulses have either
    • few cycles in the pulse
    • individual cycles with short periods
  115. clinical imaging uses pulses that contain how many cycles
    2-4
  116. distance from the start of a pulse to the end of that pulse
    spatial pulse length
  117. SPL = # of cycles X λ
  118. SPL is ______ proportional to the number of cycles
    directly
  119. SPL is ______ proportional to the wavelength
    directly
  120. SPL is _______ proportional to frequency
    inversely
  121. The major difference between SPL and PD
    • SPL refers to distance
    • PD refers time
  122. time from the start of one pulse to the start of the next pulse . includes the pulse duration and the listening time
    PRP
  123. PRP is related to the ____ of view
    depth
  124. PRP and imaging depth are ______ related
    directly
  125. the number of pulses that are transmitted into the body each second
    Pulse repetition frequency
  126. depth of view and PRF are ______ related
    inversely
  127. PRP and PRF are _______ related and ______
    inversely related and reciprocals
  128. seconds (PRP) go with hertz (PRF)
    milliseconds (PRP) go with ______ (PRF)
    kilohertz
  129. the percentage of time or fraction of time that the system is transmitting a pulse
    duty factor
  130. duty factor% = (pulse duration / PRP) X 100
  131. a duty factor of 1 would refer to a ______ wave
    continuous wave
  132. a duty factor of 0 means the system is _____
    off
  133. duty factor is _____ related to imaging depth
    inversely
  134. What are the 7 parameters required to completely characterize a sound wave?
    • period
    • frequency
    • wavelength
    • speed
    • amplitude
    • power
    • intensity
  135. tissue/material through which the sound waves travel
    medium
  136. 3 parameters describe the size, magnitude, or strength of a sound wave
    • amplitude
    • power
    • intensity
  137. 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

What would you like to do?

Home > Flashcards > Print Preview