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Intro > Ch. 24 Bioeffects > Flashcards

Ch. 24 Bioeffects Flashcards

1
Q

amount of acoustic energy the patient receives

A

acoustic exposure

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2
Q

Lowest to highest intensities for various imaging modalities

A

gray scale, m-mode, color doppler, pulsed wave doppler

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3
Q

measures period, PRP, PRF and pulse duration, amplitude and beam shape

A

hydrophone

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4
Q

What devices measure output of ultrasound trdx by absorption

A

calorimeter, thermocouple, liquid crystal

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5
Q

uses absorption, the sound beams total power is calculated by measuring the temperature rise and time of heating

A

calorimeter

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6
Q

uses a tiny electric thermometer, temperature rise is related to the power of the sound beam at the particular location where the device is positioned

A

themocouple

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7
Q

change color based on temp, provides insight into the shape and strength of the sound beam

A

liquid crystal

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8
Q

the ______ must outweigh the _______

A

benefit, risk

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9
Q

what are standard intensities

A

50-500 W/cm2

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10
Q

Science of identifying and measuring the characteristics of an ultrasound beam that are relevant to its potential for producing biological effects

A

dosimetry

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11
Q

research that is preformed with in the living body of an an animal or plant

A

in vivo

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12
Q

research that is preformed outside the living body and in an artificial evironment, indicate high ultrasound intensities can cause genetic damage and cell death

A

in vitro

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13
Q

something has the potential to produce bioeffects, searches for a relationship between cause and effect

A

mechanistic approach

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14
Q

based on acquisition and review of information from patients or animals exposed to ultrasound, seeks a relationship between the exposure and response

A

empirical approach

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15
Q

bioeffects that result from temperature elevation

A

thermal

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16
Q

interaction of the sound waves with microscopic, stabilized, gas bubbles in the tissues

A

cavatation

17
Q

two forms of cavatation

A

stable, transient

18
Q

useful predictor of maximum temp increase under most clinical relevant conditions, combination of temp and exposure time, related to output power and properties of the tissue

A

thermal index

19
Q

thermal index three forms

A

TIS, TIB, TIC (soft tissue, bone, calvarium-head).
TIS-, or soft tissue thermal index, assumes that sound is traveling in soft tissue
TIB-or bone thermal index, assumes that bone is at or near the focus of the sound beam (think fetal exams)
TIC-or cranial bone thermal index, assumes that cranial bone is in the sound beam’s near field

20
Q

maximal heating is related to the beams ______ intensity

A

SPTA

21
Q

Current FDA regulation for max intensity is

A

720 mW/cm2

22
Q

A temp increase of up to ______C has not shown any bioeffects

A ___to___C rise in testicular temp can cause infertility

No fetal defects have been observed at temperatures less than

A

2

2 to 4

39C

23
Q

pressure changes that cause the formation of bubbles, can produce severe tissue damage

A

cavitation

24
Q

gaseous nuclei already present, expand and collapse with pressure, bubbles can absorb a large amount of acoustic energy

the fluids surrounding the cells undergo____and the cells are exposed to _____

A

stable cavitation

25
Q

will stable cavitation bubbles bust

A

no, low MI

26
Q

dependent on the pressure of the ultrasound pulse, produces highly localized violent effects (shock waves and high temp)
AkAs: inertial or normal cavitation

A

transient cavitation

27
Q

will transient cavitation bubbles burst

A

yes

28
Q

a calculated number related to the likelihood of harmful bioeffects from cavitation

A

mechanical index

29
Q

Lower MI:
_______ cavitation
_______ pressure
_______ frequency

A

less, less, higher

30
Q

Higher MI:
_______ cavitation
_______ pressure
_______ frequency

A

more, more, lower

31
Q

indicator of cavitation, equal to the peak rarefractional pressure divided by the square root of the frequency

A

MI

32
Q

ratio of acoustic power produced by the trdx and the power required to raise the temp of tissue 1 degree C, relates to attenuation (heat) and SPTA

A

TI

33
Q

Preventing Bioeffects:
_______ the machine you use
Keep the exam as ____ as possible
Always start with lowest possible ______
Follow _______ principles
Use ________ _____ to optimize image
Keep track of ______ and ____ values on screen
Be extremely cautious when using doppler in ______ trimester of pregnancies

A

know, short, power, alara, receiver gain, mi, ti, first

34
Q

Keep TI values below

A

1

35
Q

Keep MI values below

A

1

36
Q

branch of medicine associated with population studies, it is an empirical survey method,

A

epidemiology

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