# US Physics 31-60

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 Author: amadaperedo ID: 224333 Filename: US Physics 31-60 Updated: 2013-06-19 22:44:00 Tags: physics Folders: Description: Physics Show Answers:

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1. The mass you are imaging has a diameter of 35 mm. This value can also be expressed as:
3.5 cm
2. Relative measurement of intensity based on a logarithmic scale is expressed in:
Decibels
3. Which prefix equals 10-³?
Milli
4. When you change the transmit frequency, which of the following is altered?
Number of cycles per second
5. While performing a Doppler ultrasound examination, you adjust the pulse repetition frequency to 12 kHz. This can also be expressed as:
12,000 Hz
6. In sound wave propagation, a region of elevated pressure is termed:
Compression
7. When you switch from a 2.5 MHz to a 5 MHz transducer, the sound wavelength:
Halves
8. Wavelength depends on what two factors?
Frequency and propagation speed
9. Which of the following human tissue has the highest rate of attenuation of an ultrasound wave?
Lung
10. The propagation speed for sound is lowest in which of the following biological tissues?
Fat
11. Which of the following factors does not affect impedance?
Frequency
12. You are imaging a structure containing two media having the same acoustic impedance. What will occur at the boundary of the two structures?
All of the sound will be transmitted
13. What is the purpose of the gel coupling between the transducer and the skin?
To provide a medium for sound transmission since ultrasound does not propagate through air
14. The unit of impedance is the:
Rayl
15. With absorption, acoustic energy is converted to:
Heat
16. The intensity transmission coefficient at the interface between two structures equal 1/100. What us the intensity reflection coefficient?
99/100
17. Which of the following is an example of a Rayleigh scatterer?
Red blood cell

18. Which of the following sound interactions produced the shadows indicated by the arrows on the image?
• Refraction
• Edge shadowing with curved interfaces/appears bend
19. In order to display a structure on your sonographic image, the sound beam must be reflected at the interface. What is required for sound reflection at the interface of two structures?
A difference in the acoustic impedance of the media
20. An example of a specular reflector is:
Pericardium
21. What system control can you adjust to compensate for the effect of sound attenuation in the body?
TGC
22. While imaging a cyst, you notice shadowing posterior to each lateral border of the cyst. What is the source of the shadows?
Bending of the sound beam due to different media propagation speeds
23. The algebraic summation of waves leading to patterns of minima and maxima is called:
Interference
24. An interaction of echoes that leads to reinforcement rather than to partial or total cancellation is known as:
Constructive interference
25. Which phenomenon is associated with a pattern produced by a sound beam after passing through a small aperture?
Diffraction
26. What sound parameter is determined only by the medium?
Propagation speed
27. Snell's law describes:
The angle of sound transmission at an interface between media having different propagation speeds.
28. As a general observation about media in diagnostic sonography, sound propagates faster in materials with greater:
Stiffness
29. During the performance of a sonogram you would be most likely to encounter refraction in this view:
Curved interface
30. You may observe sound attenuation by all of the following: Reflection, Scattering, Conversion of sound to heat and Absorption.
EXCEPT: Compression

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