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Ultrasound Physics > Intensities Ch 5 > Flashcards

Intensities Ch 5 Flashcards

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1
Q

the beam’s power divided by it’s area

A

Intensity

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2
Q

Five key words related to reporting intensities of pulsed waves

A
  • SPATIAL
  • PEAK
  • AVERAGE
  • TEMPORAL
  • PULSED
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3
Q

Refers to distance or space,

does not have the same intensity at different locations within the beam

A

Spatial Intensity

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4
Q

Number of possibilities used to measure spatial intensity

A

Two possiblities, Isp and Isa

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5
Q

The beams intensity at the location where it is maximum

A

Isp (spatial peak intensity)

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6
Q

The average intensity across the beam’s entire cross-sectional area

A

Isa (spatial average intensity)

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7
Q

Refers to time
*with pulsed ultrasound, the transducer is usually receiving (listening), but for brief moments it is transmitting (talking)

A

Temporal

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8
Q

Number of methods of measuring intensity, pulsed waves

A 
Four methods,
Itp
Imax or Im
Ipa
Ita
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9
Q

Intensity of the beam at the instant in time of it’s maximal value

A

Itp (temporal peak intensity)

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10
Q

average intensity during the most intense half cycle

A

Imax or Im

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11
Q

average intensity during -the transmit time — is called

A

Ipa (pulse average intensity)

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12
Q

Averaging the intensity during the entire pulse repetition period—both the transmit and receive times— is called

A

Ita (temporal average intensity)

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13
Q

Measured during transmit time only

A

Pulse average intensity

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14
Q

Measured during both the transmit and receive times

A

Temporal average

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15
Q

The highest temporal intensity is _______ and it is slightly higher than ___________

A

Itp and it is slightly higher than Imax

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16
Q

Is lower than Imax, because it includes values over the entire pulse duration, and the tail end of the pulse is less intense than the beginning

A

Ipa (pulse average intensity)

17
Q

The lowest of all temporal intensities is ____________ because it is the only method that includes the receive and transmit time

A

Ita (temporal average intensity)

18
Q

Measured at the location where intensity is maximum, and at the instant in time that the most powerful fart of the pulse passes

A

Isptp (spatial peak/temporal peak)

19
Q

Measured at the location where intensity is maximum, averaged over the transmit time (pulse duration)

A

Isppa (spatial peak/pulse average)

20
Q

Measured at the location where intensity is maximum and averaged over all time, both the transmit and receive times

A

Ispta (spatial peak/temporal average)

21
Q

Measured over the entire cross-sectional area of the sound beam, and over all time

A

Isata (spatial average/temporal average)

22
Q

Temporal intensities From Largest to Smallest

A

Itp (temporal peak)
Imax (average of most intense half cycle)
Ipa (pulse average)
Ita (temporal average)

23
Q

All measurements have units of

A

W/cm^2

24
Q

Six different methods to measure and report intensities. Methods describe the same wave in a variety of ways

A 
SPTP (spatial peak/temporal peak)
SATP (spatial average/temporal peak)
SPTA (spatial peak/ temporal average)
SATA (spatial average/temporal average)
SPPA (spatial peak/pulse average)
SAPA (spatial average/pulse average)
25
Q

No independently confirmed significant bioeffects have been confirmed in mammalian tissue below (medical usage)

A

100W/cm^2

26
Q

Two bioeffects of ultrasound

A

Heat and cavitation

27
Q

As sound energy is transmitted through tissue, some energy is reflected and some energy is absorbed as

A

Heat

28
Q

The formation, growth and dynamic behavior of gas bubbles

A

Cavitation

29
Q

The peak intensity at the point in space where the intensity is the highest, and that occurs when the ultrasonic emitting device is “on”
* It is the highest of the measured intensities

A

SPTP (spatial peak/ temoporal peak

30
Q

The average power output of the device over the pulse repetition period, divided by a reference, usually that of the transducer face

  • yields the lowest, and more commonly used measures of intensity
  • most quickly determined & most frequently quited by manufacturers
A

SATA (spatial average/ temporal average)

31
Q

The peak intensity over a selected area, such as the transducer face, that occurs when the ultrasonic emitting device is “on”

A

SATP (spatial average/ temporal peak)

32
Q

The maximum spatial intensity when the sound beam is “on” average over the pulse reptition period

A

SPTA (spatial peak/ temporal average)

33
Q

The pulse averaged intensity measured at the point in space where the value is maximal

A

SPPA (spatial peak/ pulse average)

34
Q

The pulse average intensity averaged over the beam cross-sectional area of the sound beam, averaged over the transmit time ( pulse duration)

A

SAPA (spatial average/ pulse average)

Ultrasound Physics (6 decks)

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