Which of the following best describes apodization?

1. Reducing the impedance difference between the crystal and the skin is the primary function of which of the following transducer components? 

a. aqueous gel

b. damping layer

c. matching layer

d. backing layer

2. A sound beam demonstrates the most uniform intensity in the:

a. far field

b. near field

c. focal zone

d. focal length

3. What is the near-zone length of a 6-mm, 5-MHz transducer?

a. 5 mm

b. 10 mm

c. 15 mm

d. 30 mm

4. Which of the following changes will improve temporal resolution?

a. increase in beam width

b. increase in focal zone depth

c. decrease in imaging depth

d. decrease in dynamic range

5. The near-zone length of a 3-mm, 10-MHz transducer is:

a. 5 mm

b. 7 mm

c. 10 mm

d. 15 mm

6. Which of the following transducer elements has the longest focal length?

a. 7 mm, 2.5 MHz

b. 2 mm, 7.5 MHz

c. 5 mm, 10.0 MHz

d. 3 mm, 15.0 MHz

7. The distance from the face of a focused transducer to the point of spatial peak intensity is termed the:

a. focal region

b. pulse duration

c. focal length

d. spatial pulse length

8. The narrowest diameter of a sound beam is termed the focal:

a. zone

b. area

c. point

d. region

9. Which of the following best describes apodization?

a. widening of the sound beam in the near zone

b. scattering of the sound beam distal to the focal point

c. irregular excitation of the elements in an array to reduce grating lobes

d. creation of a new sound wave with greater amplitude than the original wave

10. Which of the following determines the diameter of the focus?

a. spatial pulse length

b. thickness of the element

c. diameter of the transducer

d. propagation speed of the element

11. The impedance of the damping layer is:

a. less than the element’s

b. similar to the element’s

c. greater than the element’s

d. twice that of the element’s

12. The purpose of backing material in the transducer assembly is to:

a. decrease the bandwidth

b. increase the pulse duration

c. protect the components from moisture

d. reduce the number of cycles in a pulse


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