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Registry Review Exam Penny Flashcards

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1
Q

what type of wave is sound?

A

mechanical, longitudinal

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2
Q

The frequency ranges for ultrasound are:

A

> 20 kHz

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3
Q

The speed of sound in soft tissue is:

A

1540 m/s

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4
Q

Which of the following transducers fires the elements in groups?
a. linear sequenced array
b. phased array
c. continuous-wave transducer
d. single-element transducer

A

a

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5
Q

The unit for wavelength is:

A

millimeters

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6
Q

Enhancement is caused by:

A

weakly attenuating structure

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7
Q

The wavelength in a material having a propagation speed of 1.5 mm/us employing a transducer frequency of 5.0 MHz is:

A

0.3 mm

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8
Q

An ultrasound transducer converts:

A

electrical energy into mechanical energy

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9
Q

Arrange the following media in correct order from the lowest attenuation to the highst
a. air, fat, muscle, bone
b. muscle, fat, air, blood
c. fat, muscle, bone, air
d. muscle, air, fat, bone

A

c

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10
Q

Arrange the following media in terms of propagation speed, from lowest to highest:
a. air, fat, muscle, bone
b. bone, fat, air, muscle
c. bone, muscle, fat, air
d. muscle, air, fat, bone

A

a

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11
Q

If the frequency doubles, what happens to the wavelength?

A

decreases by one half

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12
Q

What happens to intensity if the amplitude of a signal is halved?

A

quartered

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13
Q

Which of the following would be used to describe the percentage of time that sound is on?
a. intensity
b. amplitude
c. SPTA
d. Duty factor

A

duty factor

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14
Q

A 3-dB gain would indicate an increase in intensity by:

A

2 times

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15
Q

Ignoring the effects of attenuation, the intensity of the ultrasound beam is usually greater at the focal zone because of :

A

the smaller beam diameter

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16
Q

Attenuation denotes:

A

progressive weakening of the sound beam as it travels

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17
Q

Which of the following has the lowest intensity?
a. SPTP
b. SATP
c. SPTA
d. SATA

A

d

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18
Q

What is the definition of the beam uniformity ratio?

A

the spatial peak intensity divided by the spatial average intensity

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19
Q

Continuous-wave Doppler has a duty factor of:

A

100%

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20
Q

The spatial pulse length is defined as the product of the ______ and the number of _____ in a pulse.

A

wavelength, cycles

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21
Q

With phased array transducers, the transmitted sound beam is steered by:

A

varying the timing of pulses to the individual piezoelectric elements

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22
Q

If the gain of an amplifier is 18 dB, what is the new gain if the power is reduced by half?

A

15 dB

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23
Q

Which of the following is true?
a. SPTA is always equal to or greater than SPTP
b. SPTP is always equal to or greater than SPTA
c. SATA is always equal to or greater than SATP
d. SPTA is always equal to or greater than SPTP

A

b

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24
Q

If the amplitude of a wave is increased threefold, the power will:

A

increase ninefold

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25
Q

Ultrasound attenuates an average of _____ dB/cm of travel for each megahertz of frequency.

A

0.7

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26
Q

If the intensity transmission coefficient is 0.74, the intensity reflection coefficient will be:

A

0.26

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27
Q

Acoustic impedance is defined as the product of:

A

the speed of sound in tissue and density of the tissue

28
Q

Rayleigh scattering is an example of:

A

a reflector whose size is smaller than the wavelength

29
Q

Assuming normal incidence, if medium 2 impedance is equal to medium 1 impedance:

A

100% of the intensity will be transmitted

30
Q

What is the total attenuation of a 3.5 MHz pulse after passing through 2 cm of soft tissue?

A

3.5 dB

31
Q

The thinner the piezoelectric element:

A

the higher the frequency

32
Q

The unit for impedance is:

A

Rayls

33
Q

A sound beam encounters an interface at a 90 degree angle. If the speed of sound in the first tissue is 1540 m/s and the speed of sound in the second tissue is 1460 m/s, which of the following numbers most closely approximates the angle of beam transmission?
a. -90
b. 90
c. >90
d. Need the impedance to compute angle of transmission

A

b

34
Q

ALARA stands for:

A

as low as reasonably achievable

35
Q

A decibel (dB) describes the:

A

ratio of two sound intensities

36
Q

The correct equation for Snell’s law is:

A

sin0t = (c2/c1) x sin0t

37
Q

The attenuation coefficient of sound in soft tissue can be defined by which of the following equations?
a. one half the frequency times the path length
b. frequency / 6
c. frequency / 2
d. frequency x 2

A

c

38
Q

The intensity transmission coefficient is equal to:

A

1 - intensity reflection coefficient

39
Q

The range equation explains:

A

distance to reflector

40
Q

The typical value for attenuation coefficient for 6-MHz ultrasound in soft tissue is:

A

3 dB/cm

41
Q

What be known in order to calculate distance to a reflector?

A

travel time, propagation speed

42
Q

Specular reflections:

A

occur when the interface is larger than the wavelength

43
Q

What is the reflected intensity from a boundary between two materials if the incident intensity is 1 mW/cm^2 and the impedances are 25 and 75?

A

0.25 mW/cm2

44
Q

The layer of material within the transducer which has an intermediate impedance between the transducer element and human tissue is known as the:

A

matching layer

45
Q

Which of the following relates bandwidth to operating frequency?
a. near zone
b. piezoelectrical material
c. quality factor
d. far zone

A

c

46
Q

The piezoelectric effect can best be described as:

A

Mechanical deformation that results from a high voltage applied to the face of the crystal that in turn generates a pressure wave

47
Q

Which of the following are most commonly used in ultrasound transducers?
a. lead zirconate titanate
b. barium sulfate
c. epoxy loaded with tungsten
d. quartz

A

a

48
Q

Differaction refers to:

A

Speading out of the ultrasound beam

49
Q

The preferred method for sterilizing ultrasound transducers is:

A

Cold sterilization

50
Q

A transducer with which frequency would have the thickest element(s)?
a. 2 MHz
b. 3.5 MHz
c. 5 MHz
d. 7.5 MHz

A

a

51
Q

Which of the following is best defined as the ability to discrimnate between two closely spaced reflectors?
a. temporal resolution
b. range accuracy
c. spatial resolution
d. amplification

A

c

52
Q

Which of the following is an effect of focusing?
a. improved lateral resolution
b. improved axial resolution
c. increased beam divergence in the near zone
d. higher frequency

A

a

53
Q

Bandwidth is:

A

the range of frequencies produced by the transducer

54
Q

What is the technique that permits virtual palpation of a lesion to determine the hardness or softness of tissue?

A

elastography

55
Q

The acoustic impedance of the transducer’s matching layer:

A

is chosen to improve transmission into the body

56
Q

If the amount of damping decreases, the bandwidth:

A

decreases

57
Q

The region where the sound beam is the smallest is referred to as the:

A

focus

58
Q

The near-zone length is determined by:

A

transducer frequency

59
Q

A two-element continuous-wave transducer:

A

is only used for spectral Doppler

60
Q

A wave’s initial intensity is 2 mW/cm2. There is an increase of 10 dB. What is the final intensity?

A

20 mW/cm2

61
Q

Which of the following is described best as a transducer that has multiple elements in a curved shape?
a. continuous-wave transducer
b. mechanical sector
c. curvilinear
d. Linear array

A

c

62
Q

What is the name of the control that compensates for attenuation related to path length?

A

time-gain compensation

63
Q

The echoes are stored before final display by the:

A

computer memory

64
Q

What portion of the ultrasound system drives the transducer?

A

pulser

65
Q

What Doppler mode uses the amplitude of the Doppler shift in order to produce an image demonstrating flow in a vessel?

A

Power Doppler

66
Q

How many different shades of gray can the human eye discern at one time?

A

100

PHYSICS (26 decks)

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