Lesson 23 (Part 2) Flashcards Preview

Physics 1 > Lesson 23 (Part 2) > Flashcards

Flashcards in Lesson 23 (Part 2) Deck (29)
Loading flashcards...
1

What factors affect magnitude in spectral doppler? (2)

1. Speed of blood flow
- eg. within a stenosis
2. Doppler angle

2

What is the magnitude within a stenosis?

Faster

3

Doppler angle

Between the scan line and the blood flow

4

What can doppler flow affect?

The calculated Doppler velocity

5

What does a larger doppler angle mean? (2)

1. Smaller doppler shift
2. Slower velocity calculated
- without angle correct

6

What factors affect amplitude? (4)

1. Brightness
- intensity of the returning echo
2. Concentration of the RBCs
3. Reflectors
4. Impedance

7

What are the special controls for spectral doppler? (4)

1. Gate size/sample volume
2. Gain
3. Spectral invert
4. Baseline

8

What does gate size/sample volume affect?

Range of resolution

9

Range of resolution

Knowing exactly where the signal is coming from

10

What is the opposite of range resolution?

Range ambiguity

11

What does gain do in spectral doppler?

Amplifies the incoming echoes' voltage

12

Where are arteries normally compared to the baseline in spectral doppler?

Above the baseline
- positive signals

13

Where are veins normally compared to the baseline in spectral doppler?

Below the baseline
- negative signals

14

Can you move baseline?

Yes

15

What does wall filters do in spectral doppler? (2)

1. Cuts off slower flows
2. Gets rid of clutter

16

What is considered to cause clutter? (2)

1. Tissue motion
2. Valves

17

What can PRF affect?

Scale
- which velocities we can display

18

What happens if we decreases the PRF too much?

It will cause aliasing
- wrap around

19

What happens if we increase the PRF too much?

It will produce a poor signal
- wasted space

20

What does increasing the PRF try and show?

Faster flow speeds

21

What happens to the doppler shift when ingle correction increases?

It decreases

22

What is velocity calculated from?

From doppler shift

23

What does correcting the angle do?

Brings the calculated speed back up to its true value

24

What can spectral doppler be converted to?

An audible signal

25

What do higher frequencies have?

Higher pitches

26

What do lower frequencies have?

Lower pitches

27

Wy can we hear spectral doppler?

Because they are in kHz
- this is in audible range

28

What can audible signals do?

Be turned up or down
- volume

29

What can we do at areas of higher volumes/speeds?

Listen
- we can hear them