How many cycles per pulse are typically used in Doppler imaging?

1. Focusing of the sound beam is only accomplished within the:

 

a. focal area

b. focal zone

c. near field

d. focal region

2. What is the diameter of the sound beam at one near-zone length when using a 6-mm, 2.5-MHz transducer?

a. 3 mm

b. 6 mm

c. 9 mm

d. 12 mm

3. The ability to distinguish two structures in a path perpendicular to the sound beam describes:

a. spatial resolution

b. contrast resolution

c. temporal resolution

d. azimuthal resolution

4. The most common piezoelectric material used in diagnostic ultrasound transducers is:

a. quartz

b. tourmaline

c. barium titanate

d. lead zirconate titanate

5. Subdicing the elements in diagnostic ultrasound transducers is used to:

a. reduce grating lobes

b. narrow the bandwidth

c. increase temporal resolution

d. increase the near-zone length

6. Diagnostic frequencies range between:

a. 1.0 and 10.0 MHz

b. 2.0 and 12.0 MHz

c. 2.0 and 20.0 MHz

d. 3.5 and 15.0 MHz

7. Which of the following changes will improve axial resolution?

a. Increase in beam width

b. Increase in transducer frequency

c. Increase in imaging depth

d. Decrease in number of focal zones

8. During transmission, diagnostic ultrasound trans­ducers convert:

a. kinetic energy into thermal energy

b. acoustic energy into electrical energy

c. electrical energy into thermal energy

d. electrical energy into acoustic energy

9. Which of the following states, “Some materials produce a voltage when distorted by an applied pressure”?

a. Snell’s law

b. Huygens principle

c. Ohm’s acoustic law

d. piezoelectric principle

10. Which of the following is a negative effect of using a damping material in the transducer assembly?

a. low-quality factor

b. reduced sensitivity

c. narrowed bandwidth

d. increased pulse duration

11. How many cycles per pulse are typically used in Doppler imaging?

a. 2 to 20

b. 3 to 15

c. 5 to 30

d. 6 to 40

12. The sonographer can determine the depth of the focal zone when using a transducer with a(n):

a. internal focus

b. external focus

c. electronic focus

d. mechanical foc

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