Physics 1 Module 3 & 4

Question 1

When electric pulses or voltage are applied to certain crystals they will produce sound waves

Answer 1

Reverse piezoelectric

Question 2

What 4 variables affect sound as it travels through a medium?

Answer 2

1. Pressure
2. Density
3. Particle motion
4. Temperature

Question 3

What can pressure be expressed as?

Answer 3

A sine wave

Question 4

Regions of low density

Answer 4

Rarefactions

Question 5

Regions of high density

Answer 5

Compressions

Question 6

Back and forth particle motion parallel to direction of wave travel

Answer 6

Longitudinal waves

Question 7

Perpendicular motion to wave travel

Answer 7

Transverse waves

Question 8

What type of wave is a sound wave?

Answer 8

Longitudinal

Question 9

Only solids can support which type of waves?

Answer 9

Transverse

Question 10

When one type of wave is converted to another type of wave

Answer 10

Mode conversion

Question 11

What’s an example of mode conversion?

Answer 11

Tissue-bone interface

Question 12

A measurement of how often something happens; the number of complete variations an acoustic variable goes through in one second

Answer 12

Frequency

Question 13

What is the unit for frequency?

Answer 13

Hertz

Question 14

The time it takes for one cycle to occur

Answer 14

Period (in microseconds)

Question 15

The length of space one cycle takes up commonly expressed in millimeters

Answer 15

Wavelength

Question 16

How does an increase in frequency affect period and wavelength?

Answer 16

Decreased period and wavelength
F=1/T
F=c/wavelength

Question 17

What is the equation for frequency in relation to period and wavelength?

Answer 17

F=1/T

F=c/wavelength

Question 18

What is the speed of sound in soft tissue?

Answer 18

1.54 mm/microsecond

1540 m/second

Question 19

What are the 3 ways to describe the strength of a wave?

Answer 19

Amplitude, intensity, power

Question 20

Maximum variation of an acoustic variable

Answer 20

Amplitude

Question 21

Power of wave divided by the area

Answer 21

Intensity

Question 22

Total energy over the entire cross-sectional area

Answer 22

Power

Question 23

A small change in amplitude results in what to intensity?

Answer 23

A large change in intensity

Question 24

How is intensity related to power (p) and area (a)

Answer 24

I=P/a

Question 25

Where is the beam most intense?

Answer 25

At the center

Question 26

What is the beam uniformity ratio?

Answer 26

BUR = SP/SA

Question 27

Where is the spatial average of the beam?

Answer 27

At the face of the transducer

Question 28

What is the equation for duty factor?

Answer 28

DF = TA/TP(PA)

Question 29

What does duty factor tell us?

Answer 29

The amount (percent) of time the transducer is “on”

Question 30

Which intensities combination is used for biological considerations in ultrasound?

Answer 30

SPTA

Question 31

M-mode, real time, doppler, continuous wave

Answer 31

Lowest to highest values of SPTA

Question 32

What are the SPTA values dependent on?

Answer 32

Depth

Question 33

What is the speed of sound in fat and in bone?

Answer 33

Fat: 1460 m/s Bone: 4080 m/s

Question 34

What is the range equation?

Answer 34

D = c x t

Question 35

What does the D, C and t mean in the range equation?

Answer 35

``` D= distance to the reflector AND BACK C= average speed of sound in soft tissue T= time for the ROUND TRIP ```

Question 36

How would you get the distance to the reflector in the range equation?

Answer 36

Divide by 2

Question 37

What is the 1 cm rule?

Answer 37

The time it takes sound to travel out and back to a depth of 1cm 13 microseconds

Question 38

The time it takes for one pulse to occur

Answer 38

pulse duration

Question 39

What is the pulse duration (PD) equation? What are the typical units?

Answer 39

PD = T x Cycles in a pulse (RD) | Microseconds

Question 40

The length of the pulse

Answer 40

Spatial pulse length

Question 41

What is the SPL equation? Units?

Answer 41

SPL = wavelength x RD | In mm

Question 42

How does RD relate to SPL?

Answer 42

Decreased ring down (# of cycles in a pulse) will decrease the SPL Increased frequency = decreased wavelength = decreased SPL

Question 43

Decreased SPL does what for resolution?

Answer 43

Improves it

Question 44

Number of pulses emitted in one second

Answer 44

Pulse repetition frequency (PRF)

Question 45

The time from the beginning of one pulse to the beginning of the next

Answer 45

Pulse repetition period (PRP)

Question 46

What is another way of expressing the go-return time calculated by the range equation?

Answer 46

PRP= d/C | PRP is the equivalent of t

Question 47

What is the relationship between PRF and PRP?

Answer 47

Reciprocal | PRF = 1/PRP

Question 48

How is DF related to PD and PRP?

Answer 48

DF = PD/PRP x 100

Question 49

A medium with low compressibility will do what to sound velocity?

Answer 49

Increase

Question 50

As bulk modulus increases, what happens to velocity?

Answer 50

Increases

Question 51

Another way to describe bulk modulus

Answer 51

Stiffness

Question 52

If ONLY density increases, what happens to velocity?

Answer 52

Decreases

Question 53

Firing a second pulse before the first one returns

Answer 53

Range ambiguity/high PRF mode

Question 54

What is the limiting factor for PRF?

Answer 54

Depth

Question 55

Increased wavelength does what to: A) frequency B) SPL C) Resolution

Answer 55

A) decreases B) increases C) decreases (lower SPL is better)

Question 56

Quantities including pressure, density, particle motion and temperature

Answer 56

Acoustic variables

Question 57

The effects that the tissue has on sound as it travels

Answer 57

Acoustic propagation

Question 58

The effects of sound on tissue as it travels

Answer 58

Bioeffects

Question 59

If the PRF of a system were to increase then what will happen to the duty factor?

Answer 59

It increases

Question 60

As the PRF increases what will happen to the transducer frequency?

Answer 60

There is no change

Question 61

If the region of interest doubles the depth then what will happen to the PRF?

Answer 61

It will half

Question 62

As the frequency of the prob is increased what is true of the PRF?

Answer 62

No change as they are unrelated