Lecture 5

Question 1

Definition of amplitude

Answer 1

The maximum variation in acoustic variable

Question 2

(T/F) Amplitude is not the peak to peak difference, it is the maximum to the average, and the minimum to average difference.

Answer 2

True

Question 3

(T/F) As sound travels, it increases in amplitude

Answer 3

False

Question 4

(T/F) Bioeffects can be altered by the sonographer adjusting gain

Answer 4

False, adjusting POWER can alter bioeffects

Question 5

Definition of Power

Answer 5

Rate of energy transference

Question 6

Definition of Intensity

Answer 6

Concentration of power in an area

Question 7

Equation for Intensity

Answer 7

I = P/A

Question 8

Relationship between intensity and power

Answer 8

Directly related

Question 9

If power increases, intensity..

Answer 9

Increases

Question 10

If area decreases, intensity..

Answer 10

Increases

Question 11

Relationship between intensity and amplitude

Answer 11

Intensity is proportional to amplitude squared

Ex. If amplitude is doubled, intensity is multiplied 4x

Question 12

Relationship between power & amplitude

Answer 12

Power is proportional to amplitude squared

Ex. If amplitude is tripled, power is multiplied 9x

Question 13

Intensities vary in _____ & _____

Answer 13

Time & space

Question 14

Highest intensity attained is called

Answer 14

Peak intensity

Question 15

Second highest intensity attained is the

Answer 15

Pulse average intensity

Question 16

Lowest intensity is the

Answer 16

Average intensity

Question 17

Highest intensity in time & space

Answer 17

SPTP

Question 18

Lowest intensity in time & space

Answer 18

SATA

Question 19

Intensity related to tissue heating (exposure time)

Answer 19

SPTA

Question 20

Intensity related to cavitation

Answer 20

SPTP

Question 21

Definition of Attenuation

Answer 21

The weakening of sound as it travels

Question 22

Definition of Reflection

Answer 22

Redirection of sound back into a transducer

Question 23

How is the amount of reflection indicated on the display?

Answer 23

Brightness or pixel

Question 24

Definition of Absorption

Answer 24

Conversion of sound energy into heat

Question 25

Absorption occurs because

Answer 25

Sound is a mechanical wave

Question 26

Definition of Scatter

Answer 26

Redirection of sound into all directions

Question 27

Dominant factor in attenuation

Answer 27

Absorption

Question 28

Definition of Attenuation Coefficient

Answer 28

Amount of attenuation of sound per centimeter of travel

Question 29

Equation for AC

Answer 29

AC = f/2

Question 30

Total attenuation is dependent on ____ & ____

Answer 30

Frequency & path length

Question 31

2 Equations for Attenuation

Answer 31

``` A = 1/2 freq. x path length A = AC x path length ```

Question 32

Definition of Half Value Layer Thickness

Answer 32

Depth in tissue where intensity of sound is half the original value

Question 33

Equation for Half Value Layer Thickness

Answer 33

HVL = 3/AC

Question 34

If HVL increases, what happens to frequency?

Answer 34

Decreases