*bioeffects Flashcards

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1
Q

bioeffects categorized as (2)

A

thermal or mechanical

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2
Q

extent of thermal effects is determined by (5)

A
  1. output power
  2. frequency
  3. exposure time
  4. focal zone position
  5. decreased field of view (increased line density)
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3
Q

mechanical bioeffects include (2)

A

cavitation

radiation

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4
Q

cavitation bioeffect can be classified as (2)

A

stable or transient

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5
Q

TI means

A

sound increased tissue by 1 degree celcius

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6
Q

TI is most commonly associated with what variation in intensity (SPTP, SPPA, SPTA, SATP, SAPA, SATA)

A

SPTA

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7
Q

AIUM states no adverse effects have been observed for an UNfocused beam having a SPTA < ??

A

unfocused beam <100 mW/cm2

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8
Q

AIUM states no adverse effects have been observed for a FOCUSED beam having a SPTA < ??

A

<1 w/cm2

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9
Q

what is the typical output intensity of a beam?

A

<1 w/cm2

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10
Q

order of intensity graded from highest to lowest

A
SP TP
SP PA
SP TA
SA TP
SA PA
SA TA
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11
Q

factors that cause changes in intensity (6)

A
  • pulse length
  • depth of focus (beam is narrower)
  • multiple focal zones
  • frame rate
  • line density
  • PRF (increase in duty factor)
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12
Q

AIUM standard for TI in soft tissue

A

TIS <2

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13
Q

AIUM standard for TI in bone

A

TIB <1.5 (higher attenuation in bone) - fetal bone at risk

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14
Q

stable vs transient cavitation

A
stable = oscillating bubbles create waves / shear forces on nearby cells 
transient = oscillating bubbles POP
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15
Q

mechanical index is proportionatal to

A

peak rarefractional pressure

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16
Q

mechanical index is inversely related to

A

frequency

17
Q

a hydrophone measures

A

output of diagnostic US images (acoustic pressure)

18
Q

Weakest to strongest intensity ultrasound (4)

A
  • 2D ultrasound
  • M mode
  • colour doppler
  • PW spectral / duplex pulsed
19
Q

FDA ISPTA =

A

720 mW/cm2

20
Q

AIUM standard for mechanical index < ?

A

<1.9

21
Q

*Transient cavitation is most dependent on the

A

Ultrasound pulse

22
Q

*Cavitation is the interaction of the sound wave with:

A

Microscopic gas bubbles found in tissues

23
Q

*Which organization regulates US equipment

A

FDA

24
Q

*Cavitation is the result of

A

Pressure changes in soft tissue causing the formation of gas bubbles

25
Q

*absorption of the sound beam is highest in

A

Bone

26
Q

*heating of soft tissue is proportional to

A

Frequency

27
Q

*Repeated gripping of the transducer is more commonly associated with

A

De Quervian’s disease

28
Q

*research has shown TCD imaging results in

A

A rapid increase in the temp of the cranium

29
Q

*biological studies of the cytoskeleton have shown

A

Ultrasound-induced changes are temporary

30
Q

*Experimentation on living tissue in an artificial environment describes

A

Ex vivo

31
Q

*heat is most dependent on which intensity

A

SATA

32
Q

*pulses can induce cavitation in mammals with a peak intensity exceeding

A

10 MPa or 3300 W/cm2

33
Q

*higher intensities are necessary to produce bioeffects with a:
Focused or unfocused transducer?

A

Focused transducer

34
Q

*Which type of cavitation involves the microbubbles already present in tissues?

A

Stable

35
Q

*The average intensity during the PRP defines the

A

Temporal average

36
Q

*Which eye position in relation to the monitor reduces occupational injuries

A

eyes are even with the top of the monitor

37
Q

*Exposure to a fetus to ultrasound is dangerous above

A

41 C

38
Q

*pressure changes in soft tissue are most likely to result in

A

Cavitation

39
Q

*microbubbles will expand and collapse when

A

Pressure is applied