Week 9

Question 1

If you change transducers from an 8 MHz to a 4 MHz, how will the waveform be affected?

a. increase in amplitude
b. decrease in amplitude

Answer 1

b. decrease in amplitude

Question 2

If the blood flow increases, the Doppler shift _______.

Answer 2

increases

Question 3

Doppler waveforms show changes in _________ _________ over time. When velocities change, _________ change.

Answer 3

Frequency shifts, f-shifts

Question 4

You should steer the Doppler beam toward the _________ point of the vessel. Why?

Answer 4

lowest, this will yield in better Doppler angles and therefore better waveforms

Question 5

If the vessel is more vertical than horizontal, you should steer the beam ________.

Answer 5

vertically

Question 6

When measuring velocities, you should use the _________ sample volume size to avoid what?

Answer 6

smallest, other vessels and slower flow along the wall

Question 7

A large SV will cause what? Why?

Answer 7

Spectral broadening, because slower velocities from along the wall will fill in the spectral window

Question 8

When is a time you should use a large SV?

Answer 8

When searching for a small flow in an occlusion

Question 9

You should place the sample volume at the _______ point of velocity. This is especially true in a _________.

Answer 9

highest, stenosis

Question 10

Velocities will __________ on the outside of a curve.

Answer 10

increase

Question 11

In the presence of a calcification, how should you measure the velocity directly underneath it?

Answer 11

You should steer the sv under the plaque from both ends

Question 12

What would result from overgain in your waveform?

Answer 12

overestimation of velocity

Question 13

What is it called when your Doppler scale is set too low and a portion of the waveform appears as artifact on the opposite side?

Answer 13

Aliasing

Question 14

Flow _________ the beam is above the baseline.

Answer 14

toward

Question 15

Flow __________ the beam is below the baseline.

Answer 15

away from

Question 16

Doppler angle = the angle between the _________ _________ and ___________ ____________.

Answer 16

Doppler Beam and flow direction

Question 17

What is the best way to find a 60º angle?

Answer 17

1. Beam steer in the direction of the artery
2. Set the angle correct to 60º
3. Use “fine steer”, heel and toe probe, and/or find a location in the area of interest where the angle correct is parallel to the walls/flow.

Question 18

State the 10 steps for the best order to get a velocity measurement using doppler controls

Answer 18

1. Get long view on axis
2. Steer the Doppler beam same way as vessel
3. Place Sample volume small and center stream
4. Adjust gain to see and hear
5. Invert if needed
6. Set Scale correctly
7. Set Baseline correctly
   8 Overgain and then reduce to avoid speckles outside the waveform
8. Set angle cursor to 60º and adjust beam steer parallel to walls
9. Adjust “fine steer” or heel and toe to make cursor parallel to flow

Question 19

What is the advantage of CW Doppler?

Answer 19

Large focal zone (sample volume)

Question 20

What is the disadvantage of CW Doppler?

Answer 20

Hear everything in the Doppler beam’s path

Question 21

In a zero-crossing detector, the device counts the number of times the echo wave does what?

Answer 21

crosses the zero line

Question 22

When are wall filters typically needed?

Answer 22

In abdominal vasculature

Question 23

The brighter the dot on a waveform, the ________ RBCs there are.

Answer 23

more

Question 24

Adjusting the output power up on the transducer does what?

Answer 24

increases the amplitude of the transmitted beam, and increases the amplitude of the echoes received