Lesson 22 (Part 4)

Question 1

What happens to the doppler shift if the doppler angle is doubled?

Answer 1

It gets doubled also

Question 2

What kind technique is used to yield doppler information in real time?

Answer 2

Autocorrelation

Question 3

Is doppler shift dependant on doppler angle?

Answer 3

Yes

Question 4

What happens to the frame rate if the ensemble length increases?

Answer 4

It decreases

Question 5

What technique is commonly used to detect echo doppler shifts in colour doppler intsruments?

Answer 5

Autocorrelation

Question 6

What reduces the frame rate of a colour doppler image?

Answer 6

1. Wider colour window

2. Increased ensemble length

Question 7

What does increasing ensemble length do to colour sensitivity?

Answer 7

Improves it

Question 8

What does increasing ensemble length do to accuracy?

Answer 8

Improves it

Question 9

What does increasing ensemble length do to frame rate?

Answer 9

Degrades it

Question 10

What are colour map baseline always represented by?

Answer 10

Black

Question 11

What happens to the frame rate when the width of the colour window is doubled?

Answer 11

It gets halved

Question 12

What does autocorrelation produce? (2)

Answer 12

1. The mean value of the doppler shift

2. Variance

Question 13

What does steering the colour window to the right and left change? (2)

Answer 13

1. The doppler angle

2. The doppler shift

Question 14

What are colour doppler frame rates compared to gray scale frame rates?

Answer 14

Less

- fewer

Question 15

What is doppler shift imaging compared to doppler power imaging? (4)

Answer 15

1. More sensitive
2. Angle independent
3. Aliasing independent
4. Speed independent

Question 16

What are the functions of doppler detector? (3)

Answer 16

1. Amplification
2. Phase quadrature detection
3. Sign determination