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Sonography > Midterm review > Flashcards

Midterm review Flashcards

1
Q

Which best describes the elements in a linear sequential array transducer?

rectangular, 1/4 to 1/2 wavelength wide

rectangular, 1 wavelength wide

squares, 1 wavelength thick

rectangular, 1/4 wavelength thick

A

rectangular, 1 wavelength wide

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2
Q

What is the shape of the elements in an annular phased array transducer?

wedges

circles

wedges

squares

rectangles

A

Circles

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3
Q

Huygens’ Principle is based on_______

refraction

constructive indices

interference

transverse waves

A

Interference

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4
Q

Which type of transducer may produce grating lobes?

Single element

Multi-element

High frequency

Low frequency

A

Multi-element

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5
Q

In which region of a sound beam is focusing most effective?

the very shallow near zone

the end of the near zone

very deep in the far zone

throughout its entire length

A

The end of the near zone

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6
Q

Which has the greatest amount of attenuation?

muscle

water

fat

bone

A

Bone

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7
Q

Which of these intensities is the smallest?

SATP

SPTP

SATA

None of these

A

SATA

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8
Q

Which of the following will result in a minimum beam divergence deep in the far zone?

small diameter, high frequency

high frequency, large diameter

large diameter, low frequency

low frequency, small diameter

A

high frequency, large diameter

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9
Q

Two ultrasound systems produce pulses. One pulse is 0.4 µsec in duration and the other is 0.2 µsec long. Which pulse is most likely to provide the best radial resolution?

0.2µsec system

0.4 µsec system

they are the same

cannot be determined

A

0.2µsec system

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10
Q

The minimum number of active elements in a mechanical transducer is:

0

1

2

None of these choices are correct

A

1

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11
Q

All of the following describe dynamic recieve focusing except:

focusing occurs at many depths

may be used by single crystal transducers

delay pattern changes continuously throughout reception

automatically performed by the system

A

may be used by single crystal transducers

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12
Q

With regard to ALARA, what is the best way to image deeper?

increase output power

decrease PRF

decrease overall gain

decrease transducer frequency

A

decrease transducer frequency

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13
Q

What is the point or location where a beam reaches its smallest dimension?

near zone

penetration depth

focus

focal zone

A

focus

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14
Q

What is the result of decreasing the PZT thickness?

A decrease in the quality

An increase in the frequency of the transducer

An increase in the velocity of sound

A greater pulse duration

A

An increase in the frequency of the transducer

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15
Q

The focus of an ultrasound system is the location where the ______.

beam is the broadest

optimum transverse resolution is

frequency is the highest

finest depth resolution is obtained

A

optimum transverse resolution is

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16
Q

Which two controls determine a system’s temporal resolution?

frame rate and sector size

focal zones and sector depth

propagation speed and frame rate

depth of view and pulses per image

A

depth of view and pulses per image

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17
Q

Two ultrasound systems have near zone lengths of 8cm. At the focus, System G’s lateral resolution is 3.0 mm, whereas System P’s is 5.0 mm. Which system wwill produce higher quality pictures at their foci?

System G

System P

Both G and P

None of these choices are correct

A

System G

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18
Q

The average intensity across the beam’s entire cross-sectional area is termed

spatial average intensity

spatial peak intensity

temporal peak intensity

temporal average intensity

A

spatial average intensity

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19
Q

All of these decrease temporal resolution except:

lower frame rate

multi-focus imaging

deeper imaging

narrower sector

A

Narrower sector

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20
Q

What is most likely to occur if the diameter of a single, disc-shaped, unfocused transducer is increased?

The distance to the far field is reduced

The beam width in the near field is reduced

The beam width in the far field is reduced

The ultrasonic wavelength is increased

A

The beam width in the far field is reduced

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21
Q

Which of the following results in the least attenuation?

4 MHz sound, path length 2cm

4MHz sound, path length 8cm

6MHz sound, path length 8cm

6MHz sound, path length 4cm

A

4 MHz sound, path length 2cm

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22
Q

True or false
The acoustic impedance of the skin is greater than that acoustic impedances of both the matching layer and the piezoelectric element.

A

False

23
Q

Which of the following focusing techniques is different from the others?

Phased
curved crystal
fixed
lens

A

Phased

24
Q

While scanning in a water tank, what location in a sound beam has the highest intensity?

Focal point
focal zone
Fresnel zone
Fraunhofer zone

A

Focal point

25
Q

-10dB means that the intensity is reduced to ________ of its original value.

one-quarter

one-half

one-tenth

cannot be determined

A

one- tenth

26
Q

Which of the following is different from the others?

lens

mirror

phased

dynamic range

A

dynamic range

27
Q

All of the following occur with focusing except:

lower intensity at the focus

shorter near zone length

more compact focal zone

smaller diameter beam diameter at the end of the near zone

A

Lower intensity at the focus

28
Q

True or false?
One way for a sonographer can alter the axial resolution achieved during an exam is to adjust the maximum imaging depth.

A

False

29
Q

With B-mode, on which axis is the strength of the reflection input?

x-axis

y-axis

z-axis

A-mode

A

z- axis

30
Q

What is the time needed to make a single image if the frame rate of ultrasound system is 20 Hz?

1 s

0.02 s

0.05 s

15 Hz

A

0.05 s

31
Q

Which type of transducer utilizes time delay beam steering as the primary method to direct the beam throughout the field of view?

Phased array

Annular array

Linear sequential array

Mechanical sector

A

Phased array

32
Q

An ultrasonic pulse is traveling in soft tissue. Which of the following is most important in the determination of the frequency of sound?

the propagation speed of the ultrasound transducer’s matching layer

the thickness of the transducer’s backing material

the impedance of the transducer’s matching layer

the propagation speed of the transducer’s active element

A

the propagation speed of the transducer’s active element

33
Q

What determines the frequency of a sound beam from a pulsed transducer?

voltage applied to the PZT

PZT thickness

frequency of the system

PRF of the pulser

A

PZT thickness

34
Q

Two ultrasound systems are identical except for the diameter of the transducer’s piezoelectric crystal. Which system has the deepest focus?

the sytem with the smaller diameter crystal

the one with the larger diameter crystal

their foci will be at the same depth

cannot determine

A

the one with the larger diameter crystal

35
Q

What is the process of adjusting for path length related attenuation called?

compression

compensation

time-gain compensation

reconfirmation

A

compensation

36
Q

Which of the following results in the most attenuation?

4MHz sound, path length 2cm

4MHz sound, path length 8cm

6MHz sound, path length 8cm

6MHz sound, path length 4cm

A

6MHz sound, path length 8cm

37
Q

The diameter of a disc-shaped, unfocused pzt crystal is 1.2cm. The near zone length is 8cm. What is the best estimate for the lateral resolution at a depth of 16cm?

16 cm

8cm

1.2 cm

0.6cm

A

1.2 cm

38
Q

Which of the following actions will improve the signal-to-noise ratio?

increase dynamic range

increase receiver gain

increase output power

increase time-gain compensation

A

increase output power

39
Q

Which reciever function creates an image of comparable brightness from top to bottom?

receiver gain

output power

swept-gain compensation

amplification

A

swept-gain compensation

40
Q

Which PZT crystal would have the lowest possible frequency?

6 mm thick, 4 cm diameter, 4.0mm/µs propagation speed

8 mm thick, 2cm diameter, 2.0 mm/µs propagation speed

4mm thick, 9cm diameter, 5.0 mm/µs propagation speed

2 mm thick, 6cm diameter, 6.0 mm/µs propagation speed

A

8 mm thick, 2cm diameter, 2.0 mm/µs propagation speed

41
Q

What is the rationale for ALARA principle?

carbon footprint

climate change

patient exposure

cavitation

A

Patient exposure

42
Q

What is the advantage of using a 1 1/2 imensional array transducer?

improved elevational resolution

improved lateral resolution

imporved axial resolution

improved temporal resolution

A

improved elevational resolution

43
Q

What is the thickness of the matching layer of a 2MHz pulsed wave transducer?

1.54 mm

0.77 mm

half the wavelength of the sound wave in the PZT

one-quarter the wavelength of sound in the matching layer

A

one-quarter the wavelength of sound in the matching layer

44
Q

True or false?
The higher the frequency of the cycles within a pulse, the lower the numerical value of the axial resolution.

A

True

45
Q

The lateral resolution of an ultrasound system is primarily determined by the _____.

width of the sound pulse

length of the ultrasound pulse

duration of the sound pulse

none of the above

A

Width of the sound pulse

46
Q

Which of the following lists orders the impedance from highest to lowest?

skin, gel, matching layer, PZT

PZT, gel, matching layer, skin

gel, PZT, matching layer, skin

PZT, matching layer, gel, skin

A

PZT, matching layer, gel, skin

47
Q

What is the lowest of all the temporal intensities?

temporal peak intensity

temporal average intensity

spatial peak intensity

spatial average intensity

A

Temporal average intensity

48
Q

The lateral resolution of an ultrasound system is 4mm. Two structures are separated by 3mm and lie side by side in relation to the sound beam’s main axis. What will most likely appear on the system’s display?

two bright echoes, 7 mm apart

one echo

two bright echoes, 3 mm apart

two weak echoes, 4 mm apart

A

one echo

49
Q

Which of the following will improve a system’s temporal resolution?

increased frequency

increased PRF

increased line density

increased sector angle

A

increased PRF

50
Q

The sonographer reduced the sector size from 90 degrees to 30 degrees. Frame rate, however, did not change. What else happened?

imaging depth decreased

pulse duration increased

multi-focus was turned on

PRF was increased

A

Multi-focus was turned on

51
Q

Which of the following is not considered a component of an ultrasound system?

master synchonizer

pulser

reciever

image instensifier

A

image intensifier

52
Q

What is the actual time that an US machine is creating a pulse?

duty factor

period

pulse period

pulse duration

A

Pulse duration

53
Q

Which of the following actions would cause a PZT crystal to lose its special properties?

breaking in pieces

exposing it to high temperatures

exposing it to electrical current

exposing it to low pressures

A

exposing it to high temperatures

54
Q

Which of these means adjustable focusing or multi-focusing?

dynamic aperture

phased array

frequency agility

harmonics

A

Phased array

Sonography (39 decks)

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