midterm

Question 1

How are frequency and period related?

Answer 1

indirectly (up,down)

Question 2

How are wavelength and frequency related?

Answer 2

indirectly

Question 3

How are amplitude and power related?

Answer 3

directly (up, up)

Question 4

How are wavelength and intensity related?

Answer 4

unrelated

Question 5

How are stiffness and sound speed related?

Answer 5

directly

Question 6

How are acoustic velocity and density related?

Answer 6

indirectly

Question 7

How are power and intensity related?

Answer 7

directly

Question 8

The higher the transducer frequency, the _____ the wavelength.

Answer 8

shorter

Question 9

What are the 5 parameters of pulsed wavelength?

Answer 9

Pulse Duration (PD)
Pulse Repetition Period (PRP)
Pulse Repetition Frequency (PRF)
Spatial Pulse Length (SPL)
Duty Factor (DF)

Question 10

Which would have the lowest acoustic velocity? Bone, Fat, Muscle, or Air?

Answer 10

Air

Question 11

Which way do longitudinal waves move?

Answer 11

Same direction as the wave’s propagation (parallel)

Question 12

Which way do transverse waves move?

Answer 12

Perpendicular to the wave’s propagation

Question 13

What is the frequency range for human hearing?

Answer 13

20 to 20,000 Hz

Question 14

What is the lower frequency limit for ultrasound?

Answer 14

20,000 Hz

Question 15

Which medium would have the slowest acoustic velocity? Gas, Liquid, Tissue, or Metal.

Answer 15

Gas

Question 16

Propagation speed and frequency _____ have a relationship.

Answer 16

Do not

Question 17

If frequency decreases by one half, the wavelength will automatically _____ in length.

Answer 17

double

Question 18

If frequency is soft tissue is double, what happens to propagation speed?

Answer 18

unchanged

Question 19

Regions of lowest particle concentration?

Answer 19

Rarefactions

Question 20

3m/s is equal to ____ cm/s

Answer 20

300

Question 21

Period and velocity have ______ relationship.

Answer 21

No

Question 22

Sound propagates faster in materials with greater________.

Answer 22

Bulk modulus

Question 23

If amplitude is doubles, intensity will ________.

Answer 23

quadrupled

Question 24

Another name for stiffness is_______.

Answer 24

Bulk modulus

Question 25

Intensity is = ______

Answer 25

amplitude squared

Question 26

The transmit output (power) control will NOT affect the ________, that leaves the transducer.

Answer 26

Frequency

Question 27

Increasing the SPL, occurs with a _____ ______ transducer.

Answer 27

Low frequency

Question 28

What is the typical value for Duty Factor in diagnostic ultrasound imaging?

Answer 28

0.2-5%

Question 29

The time from the beginning of one pulse to the beginning of the next pulse, is directly affected by the _____ ______.

Answer 29

Imaging depth

Question 30

The duty factor is the time the transducer ____ _____.

Answer 30

emits sound

Question 31

What pulse characteristic is determined by both the sound source and the medium?

Answer 31

SPL

Question 32

The number of pulses per second emitted by an ultrasound machine is the ______.

Answer 32

Pulse repetition frequency

Question 33

The pulse duration is the time from the beginning of a pulse to the

Answer 33

end of the same pulse

Question 34

As the imaging depth increases, the pulse repetition frequency must

Answer 34

decrease

Question 35

What will happen to the duty factor if the PRF is increased?

Answer 35

It will increase

Question 36

What is the SPL for two cycles of ultrasound having a wavelength of 2mm?

Answer 36

4mm

Question 37

The total length of one complete cycle

Answer 37

Spatial Pulse Length (SPL)

Question 38

The total time of one complete cycle

Answer 38

Pulse duration (PD)

Question 39

The number of pulses that occur in one second

Answer 39

Pulse Repetition Frequency (PRF)

Question 40

What must be present for sound reflections to occur at the interface of two structures?

Answer 40

a difference in acoustic impedance of the media at 90 degrees.

Question 41

For soft tissue, if path length is doubled, attenuation is ______.

Answer 41

doubled

Question 42

Snell's law describes what?

Answer 42

Refraction

Question 43

What is needed for refraction to occur?

Answer 43

Difference in propagation speeds oblique incidence

Question 44

Sound may be attenuated by all of the following except. Reflection, scattering, conversion of sound to heat, absorption, or compression.

Answer 44

Compression

Question 45

The intensity transmission coefficient at the interface between two structures equals 1%. What is the intensity reflection coefficient?

Answer 45

99%

Question 46

You are scanning an interface at normal incidence in which the acoustic impedance is unchanged from one medium into the other. What will occur?

Answer 46

there will be no reflected sound.

Question 47

For soft tissue, there is approx ____ dB of attenuation per cm for each MHz of frequency.

Answer 47

0.5

Question 48

A 7.5 MHz transducer should generally be used for?

Answer 48

superficial structures

Question 49

When a sound wave strikes a much smaller or very small particle what happens?

Answer 49

Raleigh's scattering

Question 50

What factor is responsible for determining acoustic impedance?

Answer 50

density

Question 51

The attenuation coefficient is soft tissue is approx. one half the _______.

Answer 51

Frequency

Question 52

A smooth reflector is specular if ______.

Answer 52

It is larger than the ultrasound beam

Question 53

A non-specular reflector will produce______.

Answer 53

Backscatter

Question 54

When frequency decreases, attenuation ________.

Answer 54

Decreases

Question 55

What is the total amount of attenuation that occurs if a 5MHz sound beam travels through 4 cm of soft tissue?

Answer 55

10dB

Question 56

A reflector with a rough surface is non specular or diffuse and will cause _______.

Answer 56

Backscatter

Question 57

Rayleigh scatter is proportional to frequency______.

Answer 57

to the fourth power

Question 58

A sound wave strikes a boundary at 90 degrees. They have the same impedance. What % of the sound wave will be reflected?

Answer 58

0%

Question 59

Attenuation is measured in ______.

Answer 59

Decibels

Question 60

The bending of ultrasound beam.

Answer 60

Refraction

Question 61

What intensity is vital to the study of bioeffects and safety in ultrasound?

Answer 61

SPTA

Question 62

How much of a wave's intensity is reflected at a boundary between soft tissue and bone?

Answer 62

30-50%

Question 63

Diffuse reflection is also known as

Answer 63

backscatter

Question 64

____% or more of the incident energy is transmitted forward at a boundary between soft tissues.

Answer 64

99%

Question 65

What is a way to express the beam uniformity coefficient?

Answer 65

SP/Sa factor

Question 66

An interface that reflects in all directions is

Answer 66

Diffuse

Question 67

Acoustical impedance is the product of

Answer 67

speed of sound and amplitude.

Question 68

Reflector depth is determined by

Answer 68

time and propagation speed

Question 69

What is the range equation?

Answer 69

d=1/2ct

Question 70

The ensemble length in color Doppler refers to the ____.

Answer 70

Number of pulses per scan line

Question 71

What is the result in increasing the wall filter during Doppler sampling?

Answer 71

reduced display of low-frequency shifts along baseline

Question 72

A pulse repetition frequency that is one half the Doppler frequency will result in _____.

Answer 72

Aliasing

Question 73

The Doppler effect is a change is ______.

Answer 73

Frequency

Question 74

The Doppler frequency shift heard on a speaker or seen on a spectrum analyzer is the difference between the transmitted frequency and ______.

Answer 74

Received frequency

Question 75

Doppler shift frequencies are typically within the range of___ to ___ kHz.

Answer 75

20Hz to 20 kHz

Question 76

Doppler shift is zero when the angle between the sound direction and the movement (flow) direction is ____ degrees.

Answer 76

90 degrees

Question 77

What Doppler technique does NOT provide range resolution?

Answer 77

Continuous wave Doppler

Question 78

Color Angio (Power Doppler) will provide what information?

Answer 78

Blood flow strength (amplitude)

Question 79

Doppler frequency shift is caused by _____.

Answer 79

relative motion between the transducer and the reflector

Question 80

Doppler shift is not dependent on _____.

Answer 80

amplitude

Question 81

Blood flows from a point of _____ to ____.

Answer 81

high-pressure energy to a point of low-pressure energy