Week 8

Question 1

B-Mode in Duplex ultrasound visualizes an _________, and is used to study __________.

Answer 1

Image, Anatomy

Question 2

Doppler in Duplex ultrasound visualizes __________, and is used to study ____________.

Answer 2

Velocity, Physiology

Question 3

Define the Doppler Effect

Answer 3

A change in Frequency when a reflector or source of sound is moving

Question 4

The difference between the frequency sent vs the frequency received is the ____________________.

Answer 4

Doppler Frequency Shift

Question 5

Doppler echoes are evaluated for what three things?

Answer 5

Timing (depth), Strength (amplitude), Frequencies

Question 6

What is the Doppler Equation?

Answer 6

∆ƒ = [2 v ƒo (cos ø)] / C

Question 7

Relation. Frequency shift and Cosine of the doppler angle.

Answer 7

Directly

Question 8

Relation. Frequency shift and Velocity.

Answer 8

Directly

Question 9

Relation. Speed of Sound and Frequency Shift

Answer 9

Indirectly

Question 10

Relation. Initial Frequency and Frequency Shift.

Answer 10

Directly

Question 11

The initial frequency is changed when it encounters what?

Answer 11

Moving reflectors

Question 12

What is an example of a moving reflector that Doppler would encounter?

Answer 12

RBCs

Question 13

The speed of blood is heard as _________ and is measured by _____________.

Answer 13

pitch, frequency

Question 14

The number of blood cells is heard as __________ and is measured by _____________.

Answer 14

loudness, amplitude

Question 15

Rearrange the Doppler Equation to solve for Velocity.

Answer 15

V = [∆ƒ C] / [2 ƒo (cos ø)]

Question 16

If there is a positive frequency shift, that means the reflector is moving (TOWARDS/AWAY) from the beam.

Answer 16

TOWARDS

Question 17

If there is a decrease in frequency, that means the reflector is moving (TOWARDS/AWAY) from the beam.

Answer 17

AWAY

Question 18

If a 10 MHz Doppler beam creates an echo read by the equipment at 10.005 MHz, what is the frequency shift?
A. 10 MHz
B. 5 MHz
C. 5 kHz
D. 10.005 Hz

Answer 18

C. 5 kHz

Question 19

If a + 3 kHz frequency shift was created by a reflector, the flow direction was \_\_\_\_\_\_\_\_\_\_\_.
A. Away from the Doppler Beam
B. Away from the head
C. Toward the head
D. Toward the Doppler Beam

Answer 19

D. Toward the Doppler Beam

Question 20

If a 2 MHz probe results in an echo of 1.998 MHz, what is the frequency shift?
A. + 2 kHz
B. -2 MHz
C. -2 kHz
D. + .998 MHz

Answer 20

C. -2 kHz

Question 21

Why is there a “2” in the Doppler Equation?

Answer 21

Because there are actually 2 doppler shifts in ultrasound.

1) when the moving RBC meets the sound beam
2) as it sends the echo back

Question 22

What does the velocity (or how it changes) tell us?

Answer 22

how tight a narrowing is in an artery

Question 23

What is the average speed of sound in soft tissue (C)?

Answer 23

1540 m/s

Question 24

What does ø measure?

Answer 24

the angle between the doppler beam and the flow direction

Question 25

ø must be (,or =) 90˚?

Question 26

cos 45˚ = ______.

Answer 26

0.71

Question 27

cos 30˚ = ______.

Answer 27

0.87

Question 28

cos 90˚ = ______.

Answer 28

0

Question 29

cos 60˚ = _______.

Answer 29

0.5

Question 30

cos 0˚ = _______.

Answer 30

1.0

Question 31

What is the Doppler angle?

Answer 31

the angle between the Doppler beam and the flow direction

Question 32

A decrease in angle = ____ cos, _____ frequency shift, ________ velocity

Answer 32

increase, increase, decrease

Question 33

What would the equation look like for calculating frequency shift using a 5 MHz probe, 100 cm/s velocity, and 60 degrees?

Answer 33

Frequency shift = 2 (5000 kHz) (1 m/s) (0.5) / 1540 m/s

Question 34

For the Doppler equation, frequencies should be measured in what unit? What unit should velocities be measured?

Answer 34

kHz, m/s

Question 35

If solving for velocity, what unit should your final answer be in?

Answer 35

cm/s

Question 36

What part of Duplex is used to see an image and study anatomy?

Answer 36

B-Mode

Question 37

What part of Duplex is used to visualize velocity and study physiology?

Answer 37

Doppler

Question 38

Define Doppler frequency shift.

Answer 38

The difference between the frequency sent vs the frequency received

Question 39

What does a moving reflector do?

Answer 39

Change the initial frequency

Question 40

0.5 = ______

Answer 40

cos 60

Question 41

0.87 = ______

Answer 41

cos 30

Question 42

1.0 = __________

Answer 42

cos 0

Question 43

0.71 = _________

Answer 43

cos 45

Question 44

0 = _______

Answer 44

cos 90

Question 45

The process of extracting the low Doppler frequency from the transducer's carrier frequency is called __________.

Answer 45

Demodulation

Question 46

Doppler shift = __________ - ____________

Answer 46

reflected frequency - transmitted frequency

Question 47

Velocity is defined by what?

Answer 47

magnitude AND direction

Question 48

When an angle exists between the direction of flow and the sound beam, the measured velocity is _______ than the true velocity.

Answer 48

Less