Lesson 22 (Part 4) Flashcards Preview

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Flashcards in Lesson 22 (Part 4) Deck (16)
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1

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

It gets doubled also

2

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

Autocorrelation

3

Is doppler shift dependant on doppler angle?

Yes

4

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

It decreases

5

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

Autocorrelation

6

What reduces the frame rate of a colour doppler image?

1. Wider colour window
2. Increased ensemble length

7

What does increasing ensemble length do to colour sensitivity?

Improves it

8

What does increasing ensemble length do to accuracy?

Improves it

9

What does increasing ensemble length do to frame rate?

Degrades it

10

What are colour map baseline always represented by?

Black

11

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

It gets halved

12

What does autocorrelation produce? (2)

1. The mean value of the doppler shift
2. Variance

13

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

1. The doppler angle
2. The doppler shift

14

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

Less
- fewer

15

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

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

16

What are the functions of doppler detector? (3)

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