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DMS SonoSim Labs > DMS Physics Midterm > Flashcards

DMS Physics Midterm Flashcards

1
Q

What are the acoustic variables?

A

Pressure (Pa)

Density (kg/cm3 )

Distance (cm, feet, mile)

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2
Q

The effects of the medium upon the sound wave is called

A

Acoustic propagation properties

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3
Q

____ is the time to complete one cycle

Pulse duration

pulse period

period

duration period

A

Period

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4
Q

____ is the distance covered by one cycle

pulse length

wavelength

cycle distance

cycle duration

A

Wavelength

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5
Q

Propagation speed = ____ X wavelength

A

Frequency

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6
Q

A sound wave’s frequency is 10 MHz. The wave is traveling in soft tissue. What is its wavelength?

  1. 15 mm
  2. 54 mm
  3. 4 mm
  4. 77 mm

10 MHz

A

0.15 mm

wavelength = (1.54 mm/μs) / (frequency MHz)

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7
Q

If the frequency of an ultrasound wave is doubled what happens to the period?

Doubles

halved

remains the same

4 times greater

A

halves

Period and frequency = inversely related

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8
Q

The units of pulse repetition frequency are:

per second

msec

mm/μ

MHz

A

Per second (or Hz)

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9
Q

The tie from the beginning of a pulse until its end is ____

A

Pulse duration

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10
Q

What happens to the speed of sound in a medium when the bulk modulus of the medium increases?

A

Faster

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11
Q

If a wave’s amp is doubled, what happens to the power?

A

Quadrupled

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12
Q

Power of sound has units of ?

A

watts

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13
Q

The duty factor for continuous wave US is:

10.0

1%

  1. 0
  2. 0%
A

1.

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14
Q

What are the units of intensity?

A

Watts/ cm2

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15
Q

What happens to the speed of soundi n a medium when the bulk modulus of the medium decreases?

A

Slower

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16
Q

A pulse is emitted by a transducer and is traveling in soft tissue. The go-return time, or time of flight, of a sound pulse is 130 microseconds. What is the reflector depth?

10 cm

10 mm

10 m

130 mm

13 cm

A

10 cm

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17
Q

The rayl is the unit of

A

Impedance

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18
Q

Impedance is the ____ of ____ and ___

A

Product, propagation speed, density

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19
Q

Attenuation’s three components

A

Scattering, reflection, absorption

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20
Q

As the impedances of two media become vastly different the

Reflection increases

transmission increases

refraction increases

absorption increases

A

Reflection increases

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21
Q

The angle between an ultrasound pulse and the boundary between two media is 90 degrees. What is this called?

A

Orthogonal incidence

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22
Q

Refraction only occurs if:

A

There is an oblique incidence (other than 90 degrees) and different propagation speeds

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23
Q

With normal incidence, what factors affect refraction of ultrasound?

Propagation speeds

frequencies

attenuation coefficient

none

A

None

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24
Q

With right angle incidence, reflections are always generated at a boundary if the propagation speeds of the media are different.

T or F

A

False

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25
Q

___ is a redirection of ultrasound in many directions as a result of a rough boundary between two media

A

Scattering

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26
Q

Snell’s lay describes physics of ___

A

Refraction

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27
Q

The sonographer cannot change, directly or indirectly, the duty factor of an ultrasound machine

T or F

A

false

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28
Q

What has the greatest amound of attenuation?

Bone

fat

water

muscle

A

bone

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29
Q

Which of these factors has the greatest influence on PRP (pulse repetition period?)

Display depth

PZT thickness

Impedance of medium

Dynamic Range

A

Display depth

30
Q

The region from the transducer to the minimum beam cross sectional area is the:

A

Fresnel zone (near zone)

31
Q

Which of the following has a propagation speed closest to soft tissue?

Muscle

fat

bone

air

A

Muscle

32
Q

What is the location of the minimum cross sectional area of the US beam called?

A

Focus

33
Q

The dB is defined as the ___ of two intensities

A

Ration

34
Q

What is propagation speed determined by?

A

Density and Stiffness

35
Q

What can be a unit of Amp.?

cm

Hz

msec

watts

A

cm

36
Q

Traveling through the same medium, if the frequency is doubled, the wavelength is :

A

Halved

37
Q

Traveling through the same medium, if the frequency is doubled, the propagation speed is

A

unchanged

38
Q

Which of the following is proportional to the square of the amp?

period

attenuation

power

frequency

speed

A

Power

39
Q

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

Duty factor

period

pulse period

pulse duration

\

A

Pulse duration

40
Q

The angle of incidence of an ultrasound beam is perpendicular to an interface. The two media have the same propagation speeds. What process cannot occur?

refraction

refleciton

transmission

attenuation

A

Refraction

41
Q

The production of a voltage from deformation is called

A

Piezoelectricity

42
Q

If we increase the frequency, the near zone length is:

Increased

decreased

unchanged

A

increased

43
Q

If we increase the transducer diameter, the beam diameter in the far zone is

Increased

decreased

unchanged

A

Increased

44
Q

If we increase the transducer diameter, the beam diameter in the far zone is:

increased

decreased

unchanged

A

Increased

45
Q

At the focus, the beam diameter is ___ the transducer diameter

A

Half

46
Q

Another name for Fresnel zone

A

Near zone

47
Q

Huygen’s Principle is based on

refraction

constructive indices

transverse waves

interference

A

interference

48
Q

Descriptions of the shape of a sound wave created by a tiny fragment of PZT

A

spherical, huygen’s wavelet, V shaped

49
Q

What are the effects of damping material?

A

decreased sensitivity, wide bandwidth, low quality factor

50
Q

Another name for backing material

A

Damping material

51
Q

How thick is the active element of a 3 MHz pulsed wave transducer?

  1. 54
  2. 51

half the wavelength of the sound wave in PZT

One quarter the wavelength of sound in the matching layer

A

Half the wavelength of the sound wave in PZT

52
Q

What are the needed conditions for refraction to occur at the boundary between two media?

A

Different propagtion speed and oblique incidence

53
Q

What remains when the reflected intensity is subtracted from the incident intensity?

1.0

incident intensity

transmitted intensity coefficient

transmitted intensity

A

transmitted intensity

54
Q

What is the equation for incident (starting) intensity?

A

reflected intensity + transmitted intensity

55
Q

What are the units of an incident intensity of a sound wave?

A

Watts/ cm2

56
Q

What is the amound of attenuation per centrimeter that a sound wave undergoes called?

A

Attenuation coefficient

57
Q

Which on cannot be a unit of frequency?

per day

cycles/sec

Hz

Hertz

cycles

A

Cycles

58
Q

What determines initial amp of US wave

A

transducer

59
Q

The speed of sound through bone is ___ soft tissue

A

higher than

60
Q

Units of pulse duration

A

units of time

61
Q

When reflection occurs with oblique incidence, the angle of reflection equals the angle of incidence. This is known as Snell’s law

T or F

A

False

62
Q

What occurs when piezoelectric materials change shape when a voltage is applied to them?

A

reverse piezoelectric effect

63
Q

The active element is ____ the wavelength

A

half

64
Q

A shorter pulse has a ___ Q factor

A

lower

65
Q

Compared to imaging transducers, non-imaging transducers have a _______ sensitivity.

A

Increased

66
Q

Pulse length is ____ related to pulse duration

A

directly

67
Q

Q factor is ___ related to bandwidth

A

inversely

68
Q

The spactial pulse length ____

determines penetration depth

generally decreases with frequency

related to amp

related to medium

A

generally decreases with frequency

69
Q

the fraction of time the pulsed transducer is on is the ____

A

Duty Factor

70
Q

The matching layer is ___ the wavelength thick

A

1/4

71
Q

What is the same meaning as transducer diameter

A

aperture

72
Q
A

DMS SonoSim Labs (4 decks)

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