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CORE EXAM > Physics 1 Module 3 & 4 > Flashcards

Physics 1 Module 3 & 4 Flashcards

1
Q

When electric pulses or voltage are applied to certain crystals they will produce sound waves

A

Reverse piezoelectric

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2
Q

What 4 variables affect sound as it travels through a medium?

A
  1. Pressure
  2. Density
  3. Particle motion
  4. Temperature
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3
Q

What can pressure be expressed as?

A

A sine wave

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4
Q

Regions of low density

A

Rarefactions

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5
Q

Regions of high density

A

Compressions

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6
Q

Back and forth particle motion parallel to direction of wave travel

A

Longitudinal waves

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7
Q

Perpendicular motion to wave travel

A

Transverse waves

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8
Q

What type of wave is a sound wave?

A

Longitudinal

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9
Q

Only solids can support which type of waves?

A

Transverse

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10
Q

When one type of wave is converted to another type of wave

A

Mode conversion

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11
Q

What’s an example of mode conversion?

A

Tissue-bone interface

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12
Q

A measurement of how often something happens; the number of complete variations an acoustic variable goes through in one second

A

Frequency

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13
Q

What is the unit for frequency?

A

Hertz

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14
Q

The time it takes for one cycle to occur

A

Period (in microseconds)

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15
Q

The length of space one cycle takes up commonly expressed in millimeters

A

Wavelength

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16
Q

How does an increase in frequency affect period and wavelength?

A

Decreased period and wavelength
F=1/T
F=c/wavelength

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17
Q

What is the equation for frequency in relation to period and wavelength?

A

F=1/T

F=c/wavelength

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18
Q

What is the speed of sound in soft tissue?

A

1.54 mm/microsecond

1540 m/second

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19
Q

What are the 3 ways to describe the strength of a wave?

A

Amplitude, intensity, power

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20
Q

Maximum variation of an acoustic variable

A

Amplitude

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21
Q

Power of wave divided by the area

A

Intensity

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22
Q

Total energy over the entire cross-sectional area

A

Power

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23
Q

A small change in amplitude results in what to intensity?

A

A large change in intensity

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24
Q

How is intensity related to power (p) and area (a)

A

I=P/a

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25
Q

Where is the beam most intense?

A

At the center

26
Q

What is the beam uniformity ratio?

A

BUR = SP/SA

27
Q

Where is the spatial average of the beam?

A

At the face of the transducer

28
Q

What is the equation for duty factor?

A

DF = TA/TP(PA)

29
Q

What does duty factor tell us?

A

The amount (percent) of time the transducer is “on”

30
Q

Which intensities combination is used for biological considerations in ultrasound?

A

SPTA

31
Q

M-mode, real time, doppler, continuous wave

A

Lowest to highest values of SPTA

32
Q

What are the SPTA values dependent on?

A

Depth

33
Q

What is the speed of sound in fat and in bone?

A

Fat: 1460 m/s
Bone: 4080 m/s

34
Q

What is the range equation?

A

D = c x t

35
Q

What does the D, C and t mean in the range equation?

A 
D= distance to the reflector AND BACK
C= average speed of sound in soft tissue
T= time for the ROUND TRIP
36
Q

How would you get the distance to the reflector in the range equation?

A

Divide by 2

37
Q

What is the 1 cm rule?

A

The time it takes sound to travel out and back to a depth of 1cm
13 microseconds

38
Q

The time it takes for one pulse to occur

A

pulse duration

39
Q

What is the pulse duration (PD) equation? What are the typical units?

A

PD = T x Cycles in a pulse (RD)

Microseconds

40
Q

The length of the pulse

A

Spatial pulse length

41
Q

What is the SPL equation? Units?

A

SPL = wavelength x RD

In mm

42
Q

How does RD relate to SPL?

A

Decreased ring down (# of cycles in a pulse) will decrease the SPL
Increased frequency = decreased wavelength = decreased SPL

43
Q

Decreased SPL does what for resolution?

A

Improves it

44
Q

Number of pulses emitted in one second

A

Pulse repetition frequency (PRF)

45
Q

The time from the beginning of one pulse to the beginning of the next

A

Pulse repetition period (PRP)

46
Q

What is another way of expressing the go-return time calculated by the range equation?

A

PRP= d/C

PRP is the equivalent of t

47
Q

What is the relationship between PRF and PRP?

A

Reciprocal

PRF = 1/PRP

48
Q

How is DF related to PD and PRP?

A

DF = PD/PRP x 100

49
Q

A medium with low compressibility will do what to sound velocity?

A

Increase

50
Q

As bulk modulus increases, what happens to velocity?

A

Increases

51
Q

Another way to describe bulk modulus

A

Stiffness

52
Q

If ONLY density increases, what happens to velocity?

A

Decreases

53
Q

Firing a second pulse before the first one returns

A

Range ambiguity/high PRF mode

54
Q

What is the limiting factor for PRF?

A

Depth

55
Q

Increased wavelength does what to:
A) frequency
B) SPL
C) Resolution

A

A) decreases
B) increases
C) decreases (lower SPL is better)

56
Q

Quantities including pressure, density, particle motion and temperature

A

Acoustic variables

57
Q

The effects that the tissue has on sound as it travels

A

Acoustic propagation

58
Q

The effects of sound on tissue as it travels

A

Bioeffects

59
Q

If the PRF of a system were to increase then what will happen to the duty factor?

A

It increases

60
Q

As the PRF increases what will happen to the transducer frequency?

A

There is no change

61
Q

If the region of interest doubles the depth then what will happen to the PRF?

A

It will half

62
Q

As the frequency of the prob is increased what is true of the PRF?

A

No change as they are unrelated

CORE EXAM (6 decks)

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