Physics Boards Review Part 1

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Author:
dorkfork
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288520
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Physics Boards Review Part 1
Updated:
2014-11-07 16:24:45
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doppler physics ultrasound
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Part 1
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  1. What type of medium has has the highest absorption coefficient? (air, bone, or soft tissue(water)
    Bone
  2. The propagation speed is fastest in? (soft tissue, bone or air)?
    Soft tissue
  3. For soft tissue, if the path length is doubled, total attenuation will:
    Double
  4. If the attenuation coefficient for muscle is 5.0 dB at 3MHz, what is the attenuation coefficient at 6MHz?
    10
  5. The portion of sound energy redirected towards the sound source is called:
    Reflected
  6. If the acoustic output is set at 0 dB, this indicates:
    Reference intensity level
  7. If the half value layer thickness for muscle is 4cm at 2MHz, the HVL thickness at 4MHz is ___cm.
    2
  8. If the amplitude is increased by a factor of 2, intensity:
    Increases by a factor of 4
  9. The maximum pressure variation that occurs in a cycle is termed:
    Amplitude
  10. An ultrasound field in soft tissue experiences an intensity reduction of 9 dB. This is equivalent to ____ Half Intensity Depth(s).
    3
  11. The tissue property that determines the amount of refraction at an interface is:
    Velocity
  12. If the reflection intensity coefficient at an interface is 25%, what is the transmission intensity coefficient?
    75
  13. Acoustic impedance is equal to:
    Density x velocity
  14. The propagation speed through the medium is NOT dependent on:
    Frequency
  15. If the initial intensity is reduced to 25%, this is equivalent to ____ dB.
    6
  16. Which of the following is an example of a specular reflector?
    Diaphragm
  17. If the acoustic power is doubled, intensity will:
    Double
  18. If the wavelength is decreased by 1/4 , the frequency will:
    increase by 4
  19. What is the typical transmission coefficient at a soft tissue/air interface?
    0.1
  20. As the temperature decreases, the propagation speed in tissues would:
    Decrease
  21. If the total attenuation at 2 MHZ = 20 dB, the total attenuation at 4 MHz is ____ dB.
    40
  22. Which of the following accounts for the greatest portion of the attenuation rate at an air/soft tissue interface?
    Reflection
  23. Which of the following types of media would have the highest characteristic acoustic impedance value?
    soft tissue/air (99.9% reflected back)
  24. Decreasing the beam area to 1/6 of the original will result in:
    increasing intensity
  25. Which of the following conditions is most likely to produce the greatest amount of refraction? (0 degrees = normal incidence)
    Muscle/bone interface - 20 degree incidence
  26. If the wavelength for a sound field = 2 mm, which of the following interfaces would most likely behave as a specular reflector?
    4.0 mm
  27. If the wavelength for a sound field is 1 mm, which of the following reflectors would behave as a non-specular reflector?
    0.5 mm
  28. If the transmission coefficient is 60% at an interface, the reflection coefficient is:
    40
  29. Which of the following would have the lowest absorption coefficient?
    Water
  30. Which of the following mediums would have the largest half intensity depth in cm?
    soft tissue
  31. The sonographic pattern displayed distal to a region with a low attenuation rate is termed:
    Enhancement
  32. What is the typical per cent reflection at a muscle/bone interface?
    50
  33. Which of the following factors accounts for the greatest portion of the attenuation rate in soft tissue?
    Absorption
  34. If the acoustic output is increased by 9 dB, the resulting intensity has increased by a factor of:
    8
  35. The theory/principle that relates the angle of incidence to the angle of refraction is:
    Snell's law
  36. A large amplitude pulse (voltage) from the pulser results in:
    Increasing transmit intensity
  37. Which control changes the intensity of the transmitted pulse?
    Acoustic power
  38. Increasing the pulse repetition frequency will:
    Decrease the maximum imaging depth
  39. The primary method that the sonographer uses to control frame rate during real time imaging is:
    Imaging depth
  40. The initial amplitude is determined by :
    Acoustic power control
  41. According to the range equation, which of the following are required to calculate the distance to the reflector?
    Propagation speed and round trip time
  42. The signal processing function that eliminates the negative component of the signal is termed:
    Rectification
  43. The System Gain function is performed in the:
    Beam former
  44. Reflector B is twice the distance from the transducer as reflector A. It takes ______ times as long for an echo to arrive from reflector B as from reflector A.
    2
  45. The sonographer has increased the size of the sector width to image a large mass. What can the sonographer do to maintain the same temporal resolution before this adjustment?
    Decrease the number of focal zones.
  46. Increasing the number of scan lines per frame improves:
    Detail resolution
  47. If the gain is increased by 9 dB, the power has been increased by a factor of:
    8
  48. Adjusting the TGC controls affects the settings in the:
    Beam former
  49. Which of the following transducer arrays utilizes electronic beam steering?
    Sector
  50. On an A-Mode display, the height of the spike represents:
    The echo intensity
  51. The computer parameter that limits the number of gray levels available to display on the image matrix is:
    Number of bits in computer word
  52. Which of the following system components generates the signals to focus and steer the sound field?
    Beam former
  53. The pulse repetition period is the reciprocal of:
    Pulse repetition frequency
  54. In cardiac imaging, reducing the size of the sector angle will:
    Increase the frame rate
  55. The ability to distinguish between adjacent structures producing echo amplitudes of similar amplitude is termed:
    Contrast resolution
  56. The typical dynamic range in the amplifier is:
    60-100
  57. What is the maximum number of displayed shades of gray in a 7-bit processor?
    128
  58. Which of the following digital scan converters would display the best contrast resolution?
    8 bit
  59. In which of the following modes is time the unit of measurement on one axis?
    M-mode
  60. How many levels of information can a single bit represent?
    2
  61. Preprocessing programs are performed in the:
    Image processor
  62. Postprocessing programs are performed in the:
    Display
  63. The use of cine loop will primarily improve _________ resolution
    Temporal
  64. During real time imaging, if the scan line density is reduced to 1/4, the maximum frame rate is:
    Increased by a factor of 4
  65. In clinical applications, maximum reflection amplitude occurs with:
    Normal incidence
  66. At a muscle/fat boundary, the percentage of sound energy reflected will be:
    60 %
  67. As sound propagates through the medium, amplitude:
    Decreases
  68. As frequency increases, half intensity depth:
    Decreases
  69. Propagation speed is determined by the:
    Medium
  70. By altering the imaging depth, the period of the wave:
    Remains unchanged
  71. At a soft tissue/air interface, the percentage of sound transmitted will be:
    0.1%
  72. Determine the power if the amplitude of the wave is 4.
    • 16 = 42
    • Power = amplitude2
  73. The _______ is a unit of measurement used to express the difference or ratio between two variables.
    decibel
  74. The sonographer can change the sound field intensity by manipulating:
    Transmit power
  75. For soft tissue, which of the following would most likely be used to represent a 50% reduction in intensity?
    -3 dB
  76. The total attenuation for a 10 MHz sound field in soft tissue at 2 cm is _____ dB.
    10dB
  77. Increasing intensity increases
    Propagation speed
  78. At soft tissue interfaces, the percentage of ultrasound energy transmitted is approximately _____ %,
    99
  79. Which of the following has an average propagation speed of 1.54 mm/µs?
    Muscle, soft tissue
  80. As sound propagates through the medium, intensity:
    Decreases
  81. Frequency is determined by the:
    Piezoelectric element
  82. The best example of a Rayleigh scatterer is:
    Red blood cell
  83. The initial amplitude is determined by :
    Acoustic power control
  84. As propagation speed and density values increase, acoustic impedance:
    Increases
  85. Determine the attenuation coefficient in dB/cm for a 10 MHz sound field in soft tissue.
    10dB/cm
  86. The attenuation rate will increase if there is an increase in:
    frequency
  87. A region of high pressure, high density is:
    Compression
  88. Wavelength is determined by the:
    • Frequency
    • (increase frequency to decrease wavelength)
  89. To maximize reflection from a specular reflector, the sonographer should strike the interface at ______ degrees.
    90
  90. This artifact cannot occur at perpendicular incidence
    Refraction
  91. As sound propagates through a medium, power:
    Decreases
  92. A sound beam's wavelength is 0.5 mm. Which of the following would be an example of a nonspecular reflector?
    0.4 mm
  93. Impedance is equal to:
    c x p
  94. For an unfocused circular soundfield, the crystal diameter is 30 mm. What is the beam diameter in mm at a depth equal to twice the near field length?
    30
  95. Elevational resolution is related to:
    Beam width
  96. The intensity of a focused beam is generally:
    Highest in the focal zone
  97. The product of the period and the number of cycles in the pulse is:
    Pulse duration
  98. Axial resolution can be improved by using:
    Higher frequency transducers
  99. The type of real-time transducer that employs a combination of electronic focusing and mechanical steering is:
    Vector array
  100. The reverse piezoelectric effect is best described as:
    Mechanical deformation resulting from high voltage applied on crystal faces, generating ultrasound
  101. Which of the following transducers would be most useful for imaging superficial structures?
    5 MHz, superficial focus
  102. Lateral resolution is equal to:
    Beam area
  103. The unit of measurement for the duty factor is:
    Percent
  104. Increasing the pulse repetition period:
    Increases the maximum imaging depth that can be imaged
  105. For an unfocused sound field utilizing a 10 mm crystal diameter, the sound field diameter at the end of the near field will be ____ mm.
    5
  106. Grating lobes in electronic array systems:
    Are controlled with a process called subdicing
  107. As frequency increases, the beam width will:
    Decrease
  108. The principle that states that all points on a wavefront can be considered as point sources for the production of spherical secondary wavelets was postulated by:
    Huygen
  109. The ____ relates the bandwidth to operating frequency
    Quality factor
  110. For an unfocused circular sound field, the crystal diameter is 40 mm. What is the beam diameter 1cm from the crystal surface in mm?
    40
  111. The piezoelectric properties of the transducer will be lost if the crystal is heated above the:
    Curie point
  112. What is the most commonly used material for ultrasound transducer crystal elements?
    Lead zirconate titanate
  113. A decreased pulse duration produces:
    Better axial resolution
  114. The beam of an unfocused transducer diverges where?
    • In the Fraunhofer zone
    • Far Field
  115. The amount of divergence in the far field can be decreased by:
    Increasing the frequency or a larger crystal diameter
  116. The near field length of an unfocused transducer depends on:
    Frequency and diameter
  117. Extraneous sound energy emitted from a linear sequenced array are called:
    • Grating Lobes
    • Corrected by subdicing
  118. The spatial pulse length:
    Decreases with increasing frequency
  119. Transmit delay focusing in a linear array transducer will improve:
    Lateral resolution
  120. Axial resolution depends on the ______
    wavelength/frequency (higher frequency/shorter wavelength)
  121. The damping material will improve
    Increase damping material>>shorter pulse>>wider bandwidth>>better axial resolution
  122. For a given sound field, which of the following would demonstrate the lowest intensity value?
    SATA
  123. What type of tissue is most susceptible to the effects of cavitation?
    • Aerated lung tissue
    • Air in GI tract
  124. With all other parameters constant, increasing the acoustic output will:
    Increase intensity
  125. Which artifact is associated with reverberation and resonance in a small gas bubble or surgical staple?
    Comet tail
  126. Which control changes the intensity of the transmitted pulse?
    Acoustic power
  127. Increasing the number of scan lines per frame improves:
    Detail resolution
  128. The use of cine loop will primarily improve _________ resolution
    Temporal
  129. What system component generates the signals to focus and steer the sound field?
    Beam former

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