US Physics 91-120

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amadaperedo
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224338
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US Physics 91-120
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2013-06-19 22:43:19
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Physics
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Physics
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  1. Attenuation of the sound beam increases with increasing:
    Path length, Absorption, Frequency and Scattering reflection
  2. You are imaging a rounded mass with irregular borders. The mass has a much slower propagation speed than surrounding tissue. What sound-tissue interaction will be encountered as the ultrasound propagates through this interface?
    Refraction, Reflection, Absorption and Scattering
  3. You are imaging a structure that is highly attenuating. Which imaging effect do you expect to encounter?
    Shadowing
  4. When you are educating your patient about the sonographic exam, sound travels through air from your mouth to your patient's ears. Which of the following is true regarding the speed of sound travel through air?
    The speed of sound in air is slower than the speed of sound in soft tissue.

  5. In the illustration, if the propagation speed is unchanged at the interface, which most correctly describes the sound-tissue interaction that will take place when the ultrasound wave strikes the depicted interface?
    Scattering
  6. You have increased the transmit power while performing a pelvic ultrasound examination. This action increases which of the following?
    Penetration, Acoustic power, Image brightness and Voltage applied to the transducer elements
  7. If sound waves of 3 MHz, 5MHz, and 10 MHz are transmitted through the same section of anatomy, reflection from which frequency would reach the transducer first?
    Reflectionsfrom all three frequencies would have nearly identical transit times
  8. What would you change if the image does not show adequate penetration and the far field displays noise instead of tissue?
    Decrease transmit frequency
  9. For pulsed ultrasound, which of the following factors determine the frequency of the sound wave?
    Transmitter frequency
  10. You have decreased the acoustic power by -3 dB. Which of the following most accurately describes this adjustment?
    The intensity has been halved
  11. Which of the following describes sound propagation through a vacuum?
    Sound cannot travel through a vacuum
  12. When your patient asks you how much longer the ultrasound test will take, his voice is in the audible frequency range. Which of the following frequencies is in the audible frequency range?
    10 kHz
  13. The maximum cyclical change in a quantity is known as:
    Amplitude
  14. Bulk modulus is closely related to which of the following qualities?
    Stiffness
  15. Which most correctly describes sound propagation in a medium?
    Molecules oscillate back and forth to propagate sound waves but do not move from one end of the medium to another
  16. Which of the following terms denotes the time it takes for a cycle to occur?
    Period
  17. If the number of cycles in a pulse is increased but the wavelength remains the same, which of the following is true?
    The pulse duration is increased
  18. Which of the following is most likely also to decrease beam intensity?
    Increasing beam area
  19. Which of the following best characterizes an ultrasound wave in human tissue?
    Mechanical longitudinal wave
  20. The regions of low pressure and density that are formed during sound propagation are termed:
    Rarefactions
  21. The sound propagation speed used to calibrate range-measuring circuits on diagnostic sonography instruments is:
    1540 m/s
  22. Which of the following properties would result in increased propagation speed of sound through a medium?
    Increased stiffness
  23. Which of the following frequencies is considered to be ultrasound?
    2 MHz
  24. You are performing a sonographic exam on a large patient. Which transducer would provide the least amount of signal attenuation?
    2.5 MHz
  25. Which of the following increases as frequency increases?
    Absorption, Scattering and Attenuation

  26. Which statemen about the two pulse trains displayed above is true? Each represents a signal versus time.
    A has a lower frequency than B
  27. What is the velocity of an ultrasound wave in bone?
    4080 m/s
  28. The speed of sound is defined as the:
    Speed at which the sound wave propagates through the medium
  29. A longitudinal wave is characterized by:
    Particlemotion occurring perpendicular to the direction of propagation
  30. Wavelength is measured in:
    Millimeters

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