# Physics-Range Equation and Axial Resolution

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1. A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The depth of the reflector is 10 cm in soft tissue. What is the go return time?
130 μs
2. A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The go-return time is 26 μs. What is the depth of the reflector?
2 cm
3. A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The go return time is 26 μs. What is the total distance that the pulse traveled?
4 cm
4. The maximum imaging depth (depth of view) during an ultrasound exam is 10 cm. The sonographer adjusts the imaging depth to 20 cm. What happens to the pulse repetition period?
• it is doubled
• PRP is directly related to imaing depth
5. The maximum imaging depth during an ultrasound exam is 10 cm. The sonographer adjusts the imaging depth by 20 cm. What happens to the pulse repetition frequency?
• it is halved
• PRF is inversely related to imaging depth
6. The imaging depth during an ultrasound exam is 10 cm. The sonographer adjust the imaging depth to 5 cm. What happens to the pulse repetition period?
• it is halved
• PRP is directly related to imaing depth
7. A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The imaging depth is 10 cm in soft tissue. What is the maximum pulse repetition frequency?
7.7 kHz or 7,700 Hz
8. A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The maximum imaging depth is 7.7 cm. What is the PRF?
10,000 Hz or 10 kHz
9. A sound wave is created by a transducer, reflects off an object, and returns to the transducer. The go-return time is 130 μs. What is the maximum PRF?
7,700 Hz
10. What is the ability to accurately distinguish two structures lying closely together called?
resolution
11. The ability to distinguish two structures lying closely together front-to-back or parallel to the sound beam is called ___________.
axial resolution
12. What are the other names for axial resolution?
LARRD - longitudinal, axial, range, radial, or depth resolution
13. Axial resolution is measured with units of __________.
length, mm or cm
14. The more cycles in a pulse, the __________ the numerical value or the range resolution is. (greater, lesser, same)
greater
15. If a new pulsed transducer has many more cycles in its pulse, the image accuracy __________. (improves, degrades, remains the same)
16. __________ frequency transducers generally have the best resolution. (high, low)
High
17. Which of the following transducers has the poorest axial resolution?
A. 1.7 MHz and 4 cycles/pulse
B. 2.6 MHz and 3 cycles/pulse
C. 1.7 MHz and 5 cycles/pulse
D. 2.6 MHz and 2 cycles/pulse
• C. 1.7 MHz and 5 cycles/pulse
• This is the longest pulse, it has the lowest frequency and the most ringing (more cycles/pulse)
18. In soft tissue, a 3 cycle, 1 MHz pulse has a length of a pulse is 4.5 mm. What is the axial resolution?
• 2.25
• 4.5 mm / 2
19. Which of the following transducers had the best axial resolution?
A. 1.7 MHz and 4 cycles/pulse
B. 2.6 MHz and 3 cycles/pulse
C. 1.7 MHz and 5 cycles/pulse
D. 2.6 MHz and 2 cycles/pulse
• D. 2.6 MHz and 2 cycles/pulse
• This is the shortest pulse. It has the highest frequency and the least ringing.
20. Two different transducers create sound pulses. One transducer is labled 5 MHz and the other, 3 MHz. Which transducer is more likely to create a more accurate image with relation to axial resolution? Which transducer probably has a lower numerical measure of axial resolution?
the 5 MHz transducer creates an image with better axial resolution and with a lower numerical measure
21. Two different transducers create pulses. Both transducers create sound with a frequency of 4 MHz. One transducer creates a pulse that comprises 6 cycles and the other, 3 cycles. Which transducer is more likely to create a more accurate image with relation to axial resolution? Which transducer has a lower measure of axial resolution?
3 cycle has better axial resolution and a lower numerical value
22. Two different transducers create pulses. One transducer is labled 5 MHz and the other, 3 MHz. The 3 MHz transducer creates a more accurate image with relation to axial resolution. Explain
The 3 MHz pulse must be shorter than the 5 MHz pulse. SInce 3 MHz has a longer wavelength than 5 MHz, the only way that the 3 MHz pulse is shorter is if the 3 MHz transducer rings less. Thus, the 3 MHz pulse is made of fewer cycles.

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 Author: aprilh4485 ID: 115783 Filename: Physics-Range Equation and Axial Resolution Updated: 2011-11-09 23:45:34 Tags: Sonography Folders: Description: Range Equation and Axial Resolution Show Answers:

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