Pulse Repetition Frequency Review (Lesson 4b) Flashcards
1
Q
What is the black band in a colour scale and what does it represent?
A
Black band = baseline
Represents signals that either have NO doppler shift or a low doppler shift that is not visualized due to wall filtering
2
Q
What is the normal colour scale for a Carotid US?
A
30-40cm/s
3
Q
What is the normal colour scale for a normal venous US exam?
A
Less than 20cm/s
4
Q
What is the normal colour scale for a cardiac US exam?
A
60-80cm/s
5
Q
What is aliasing?
A
Velocity or DS that goes beyond the maximum detectable velocity or frequency shift
6
Q
What is the Nyquist Limit?
A
The highest detectable Doppler frequency shift without aliasing
7
Q
When does aliasing occur?
A
When the highest Doppler shifted frequency exceeds 1/2 of the PRF
8
Q
What is the Nyquist Limit equation?
A
Nyquist Limit = 1/2 PRF
