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PHYS 216 > Particle Motion And Wave Propragation > Flashcards

Particle Motion And Wave Propragation Flashcards

1
Q

At the most basic levels of sonography what are the five steps ?

A
  1. Operator control
  2. Transducer activation (Sending)
  3. Sound interaction
  4. Transducer action (receiving)
  5. Image display
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2
Q

What is the Piezoelectric effect?

A

When pressure waves are applied to certain crystals they produce electric pulses or a voltage

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3
Q

What is reverse piezoelectric effect?

A

When electric pluses or voltages are applied to certain crystals they produce sound waves

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4
Q

What does the term acoustic mean?

A

Refers to sound

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5
Q

What is propagation?

A

Refers to travel

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6
Q

What is acoustic Propagation?

A

Refers to the effect tissues cause on sound

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7
Q

What does Bioeffects mean?

A

Refers to the effects of a ultrasound on tissue

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8
Q

What is sound?

A

Sound is a propagation variation (a wave).

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9
Q

What can an sound waves carry?

A

Sound waves can carry energy not matter

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10
Q

Does sound waves require a medium to travel?

A

Yes

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11
Q

What are variables?

A

Qualities of waves

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12
Q

What variables apply when sound travels through mediums?

A
  1. Pressure
  2. Density
    -Rarefaction-low density
    -compressions-high density
  3. Particle motion
  4. Temperature
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13
Q

What is density?

A

The concentration of particles or mass per unit of volume

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14
Q

What is rarefactions

A

Regions of low density

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15
Q

What are compressions?

A

Areas of high density

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16
Q

In terms of sound what role does temperature play?

A

Sound is an energy.
Energy creates heat

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17
Q

What are sound waves?

A

Sound is a mechanical wave and therefore, requires a medium to travel

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18
Q

What are the two types of sound waves?

A

Longitudinal and transverse waves

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19
Q

What are longitudinal waves?

A

Back and forth particle motions parallel to direction of wave travel

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20
Q

What are transverse waves?

A

Perpendicular motion to wave travel

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21
Q

What types of mediums support longitudinal waves?

A

Solids, liquids and gases

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22
Q

What mediums can support transverse waves?

A

Solids only

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23
Q

What is mode conversion?

A

When one type of wave is converted into another form.
An example of this may occur at a tissue bone interface

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24
Q

In terms of waves what is common to all waves? 6

A
  1. Frequency
  2. Period
  3. Wavelength
  4. Propagation speed
  5. Amplitude
  6. Intensity
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25
Q

What is Frequency?

A

Simply a measurement of how often something happens.

With sound we can say it is the number of complete variations goes through in one second

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26
Q

What is the unit of frequency?

A

Hertz (Hz)

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27
Q

What frequency does ultrasounds run on?

A

MHz (megahertz)

28
Q

What is period (T)?

A

The time it takes for one cycle to occur

29
Q

How is Period measured?

A

Period is measured in seconds, or in ultrasound in microseconds

30
Q

What is wavelength?

A

The length of space one cycle takes up

31
Q

What is the formula for frequency?

A

F=1/T and W=C/F

32
Q

What does the Frequency formula tell us about the relationship?

A

If Frequency increases time and wavelength decrease. and vice versa

33
Q

What is propagation speed (c)?

A

The speed with which the wave moves through a medium

34
Q

How much is Propagation speed (c)?

A

1.54 mm/us or 1540 m/sec

35
Q

What are variables we need to find wave strength?

A

Amplitude, intensity, and power

36
Q

What is amplitude?

A

Maximum variation of an acoustics variation

37
Q

What is intensity?

A

Power of wave divided by the area

It is also equal to amplitude squared

38
Q

What is power?

A

Total energy over the entire cross- sectional area

39
Q

What is the formula for power/intensity?

A

I= P/A

40
Q

In a sound beam where is the intensity the greatest?

A

Greatest and the centre and falls off near the periphery

41
Q

What is Spatial intensities?

A

The greatest intensity found across the beam. This is called the spatial peak.

42
Q

Where is the Spatial peak found? And what is it?

A

Near the centre of the beam, and is the place of the beam with the greatest intensity

43
Q

What is spatial average? And where is it found?

A

Average intensity measured over the entire beam, it is usually found at edge of the transducer or the edge of the flashlight

44
Q

How are SP(spatial peak) and SA(spatial average) related

A

They are related based on the uniformity ratio (BUR)

45
Q

What is the Uniformity ratio (BUR)

A

BUR= SP/SA

46
Q

What is Temporal Peak (TP)?

A

The greatest intensity found in the pulse

47
Q

What is pulse average?

A

Average for all values found inside a pulse

48
Q

Can TP and PA be used interchangeably?

A

Yes, they are almost identical and can be used interchangeably

49
Q

How do we convert the SP to SA

A

Divide it by BUR

50
Q

How do we convert SA to SP

A

X BUR

51
Q

How do we convert TP to TA?

A

We X DF

52
Q

How do we convert the TA to TP

A

We divide by DF

53
Q

Considering SPTA what different modes of ultrasounds from lowest value to the highest are available

A
  1. M mode
  2. Real Time B mode
  3. Doppler
  4. Continuous wave (no dead time SPTP)
54
Q

Ultrasound machines are calibrated to what speed?

A

1540 m/s

55
Q

If Ultrasounds machines are calibrated to C, Does that velocities do the same?

A

No velocities actually differ in different tissues and as a result artifacts may occur

56
Q

What is the actual velocities found in fat?

A

1460 m/s

57
Q

What is the actual velocity found in bone?

A

4080 m/s

58
Q

What is the distance equation?

A

D = C x T

59
Q

In the distance equation what is D?

A

D is the distance to the reflector and back

60
Q

What is C in the distance equation?

A

C is the average speed of sound in soft tissue

61
Q

What is T in the distance formula?

A

T is the time for the round trip

62
Q

How do we get the distance to the reflector?

A

We get the distance and then divide it by 2

63
Q

What is the 1 CM rule?

A

In 13 microseconds the sound wave travels to and back from a object 1 cm away

64
Q

What are two categorizes of waves and what type of wave is used in ultrasound?

A

Two types of waves are electromagnetic and mechanical.

Ultrasound uses mechanical

65
Q

Which combined intensity has the lowest value

A

SATA

66
Q

What is the purpose of describing intensities in both space and time?

A

This terminology is needed to asses for bioeffects since we must consider the amount of sound transmitted into the patient along with the time of exposure

67
Q

How does the intensity change when the area of the sound beam is reduced by half?

A

It is halved because intensity is indirectly proportional to the area

PHYS 216 (8 decks)

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