Intensity - EXAM II Flashcards

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1
Q

What is energy?

A

The ability to do work.

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2
Q

What is power?

A

Energy per unit time.

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3
Q

What are the units for sound intensity?

A

power per unit area

or

Power / Area

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4
Q

What are the units for power?

A

watts

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5
Q

What are the units for intensity?

A

W/m2

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6
Q

What are the usual units for intensity in ultrasound?

A

mW/cm2

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7
Q

Intensity =

A

Intensity = amplitude2 / 2pV

p=density
V=speed

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8
Q

What happens to intensity if you double the amplitude?

A

it is increased x4 because of the exponent (power of 2)

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9
Q

What happens to intensity if amplitude is increased x3?

A

Intensity = x9

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10
Q

What is the relationship between Amplitude and Frequency?

A

They are independent of each other.

There can be the same frequency, but different amplitude.

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11
Q

What are the two basic parameters in measurements of intensity?

A

Space and Time

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12
Q

What are the two types of measurement of intensity?

A

Peak and Average

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13
Q

What is the highest instantaneous intensity measurement at a given moment?

A

TP - Temporal Peak

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14
Q

What is the average intensity over time?

A

TA - Temporal Average

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15
Q

What is the highest intensity in the area?

A

SP - Spatial Peak

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16
Q

What is the average intensity over the area?

A

SA - Spatial Average

17
Q

If TP = TA What kind of ultrasound is it?

A

CW, Always on

Peak Intensity = Average Intensity

18
Q

What is another type of intensity measurement?

A

Im: Average intensity measured at the most intense half-cycle.

19
Q

What is the final type of intensity measurement?

A

PA - Pulse average

The average intensity for the duration of the pulse itself.

20
Q

What type of measurement is PA?

A

Time

21
Q

What type of measurements can PA be combined with?

A

Spatial:

SPPA
SAPA

22
Q

List the Intensities in order of highest to lowest

A
SPTP
Im
SPPA
SPTA
SATP
SAPA
SATA
23
Q

What do all of the letters mean in reference to intensity?

A

They are different ways of measuring energy.

Over space and time.

24
Q

What is BUC?

A

Beam uniformity coefficient.

It suggests the level of uniformity across the area.

25
Q

BUC =

A

BUC = SP / SA

26
Q

What is considered a good BUC measurement?

A

1.00

Suggests uniformity across the beam area.

27
Q

What makes a less uniform beam intensity?

A

A higher BUC

28
Q

What is Dosimetry?

A

The study of effects of exposure of body signals used in diagnostic testing, such as ultrasound, X-ray , MRI, etc.

AKA Bioeffects

29
Q

What are the two bioeffects of ultrasound?

A

Cavitation and Heat