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CORE studying > Physics I > Flashcards

Physics I Flashcards

1
Q

Strength of the reflected and transmitted pulses are determined by what?

A

The impedances of the two mediums at the boundary

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2
Q

What is the formula for direct linear proportional relationship?

A

y = 3x

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2
Q

What is the formula for indirect linear proportional relationship?

A

y = 3/x^2

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2
Q

Attenuation is an example of what tpye of relationship?

A

nonlinear and exponential relationship

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2
Q

What is the formula for non-linear proportionality?

A

y = x^2

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2
Q

In a wave, what are compressions?

A

Areas of high pressure and density

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3
Q

In a wave, what are rarefactions?

A

Low pressure and density

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4
Q

What are 4 acoustic variables in a sound wave?

A
  • pressure
  • density
  • particle motion
  • temperature
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5
Q

Sound wave terms:

What is frequency?

A

How often something happens, number of cycles per second
units: hertz, kilohertz, and megahertz (m/c for US)

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6
Q

Sound wave terms:

What is a cycle?

A

One complete variation in pressure or acoustic variable

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7
Q

Sound wave terms:

What is frequency? (f)

A

1Hz = 1 cycle per second

Number of occurrences over a repeating event

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8
Q

Sound wave terms:

What is the formula for frequency?

A

propagation speed (m/s)
__________________________
wavelength (mm)

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9
Q

Sound wave terms:

What is period? (T)

A

Time it takes for once cycle to occur
units: seconds, microseconds

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10
Q

Sound wave terms:

What is the formula for period?

A

T (μs) = 1
_______
frequency (MhZ)

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11
Q

Sound wave terms:

What is a wavelength?

A

The length of space one cycle takes up
unit: millimeter (mm)

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12
Q

Sound wave terms:

What is the formula for wavelength?

A

wavelength (mm) = propagation speed (m/s)
__________________________
frequency (MHz)

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13
Q

Sound wave terms:

What is propagation speed?

A

The speed at which a wave moves through a medium
unit: meter/second; millimeter/microsecond

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14
Q

What is the average propagation speed in soft tissue in m/s and mm/μs?

A

1540m/s
1.54 mm/μs

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15
Q

What is the bulk modulus?

A

The stiffness is the resistance to compression, also called the hardness

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16
Q

What are the two periods of Pulsed Ultrasound?

A

Ringing and listening period

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17
Q

What is PRF? (pulse repetition frequency)

A

Number of pulses created by the system per second

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18
Q

What is PRP? (pulse repetition period)

A

Time from the start of one pulse to the start of the next
unit: milliseconds (ms)

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19
Q

What is PD? (pulse duration)

A

Actual time the pulse is on
unit: microsecond (μs)

20
Q

What is Duty Factor?

A

Fraction of time that pulsed US is on

21
Q

What is spatial pulse length?

A

Length of space occupied by a pulse

22
Q

What is bandwidth?

A

Range of frequencies contained within a pulse

23
Q

PRF and PRP have a relationship - describe it.

A

If PRF decreases, PRP increases.

24
Q

What unit does PRF use?

A
  • kilohertz
25
Q

Adjusting depth affects which: PRP or PRF?

A

Both!

26
Q

What controls PRP in soft tissue?

A

Depth & speed of sound

27
Q

What is the formula for Pulse Duration?

A

PD = n x T
(number of cycles in the pulse x the period)

28
Q

Sonographic pulses are typically how many cycles long?

A

2 - 3 cycles

29
Q

Doppler pulses are typically how many cycles long?

A

5 - 30 cycles

30
Q

_______ pulses improve quality of US images.

(shorter/longer)

A

shorter

31
Q

What is the Duty Factor formula?

A

DF = PD (μs)
_____ x 100
PRP (μs)

32
Q

What is the equation for SPL?

A

SPL (mm) = wavelength (mm) x number of cycles in the pulse

33
Q

SPL _______ (increase/decrease) when # of cycles in pulse _______ (increase/decrease), SPL ________ (increases/decreases) when frequency increases.

A

increases
increase
decreases

34
Q

What is happening to Transducer Frequency when:

Wavelength decreases
Penetration Distance decreases
Spatial Resolution improves

A

Frequency increases

35
Q

A higher transducer frequency = _____ (shorter/longer) wavelengths = ______ (more/less) penetration.

A

shorter
less

36
Q

What is the range of ultrasound frequencies contained in a pulse called?

A

Bandwidth

37
Q

What is the bandwidth for the curvilinear probe used for abdomens?

A

1 - 6 MHz

38
Q

What is the bandwidth for the linear probe used for superficial structures?

A

2 - 9 MHz

39
Q

What is the bandwidth for the cardiac probe?

A

1 - 5 MHz

40
Q

What is the bandwidth for the ML 6-15 probe used for paeds and neonates?

A

4 - 15 MHz

41
Q

What are 2 indicators of the strength of the sound?

A

Amplitude and intensity

42
Q

What is the definition of: amplitude of sound?

A

How loud it is

43
Q

What is the definition of: power of sound?

A

The time required to transfer energy

44
Q

What is the definition of: the intensity of sound?

A

Rate at which energy passes through a unit area

45
Q

What is an acoustic variable?

A

Pressure
Density
Particle Motion
Temperature

46
Q

What is the definition for a maximum variation that occurs in an acoustic variable?

A

Amplitude

47
Q

How is an amplitude of a pulse deteremined?

A

By how hard the crystals of the transducer are struck

48
Q

Power is the rate of what

A

The rate of energy transfer over time from one location to another (energy that travels along an ultrasound beam), measured in Watts

49
Q

If the transmit voltage (amplitude) is doubled, the power will be __________.

A

Quadrupled

50
Q

What is the formula for intensity?

A

power
_______
area

51
Q
A

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