Lecture 21

Question 1

Ultrasound basics

Answer 1

A sound wave of a particular freq is sent out
It bounces off a stationary structure
It returns at the same frequency we sent out

Question 2

Doppler effect

Answer 2

Change in freq caused by the motion of a source, reflector or reciever

Question 3

Doppler of US

Answer 3

Change in frequency caused by the motion of the reflector

Question 4

Doppler shift is

Answer 4

Change in frequency

Question 5

Doppler shift

Answer 5

Depending on whether the object is moving closer or farther away, the freq will come back higher or lower

Question 6

Doppler shift equation

units

Answer 6

Fd=fR-fT

KHz

Question 7

In the doppler shift when thing are getting closer together frequency goes

Answer 7

Up

Postive shift

Question 8

Doppler shift getting farther apart, frequency goes

Answer 8

Down

Gives a negative fD

Question 9

Doppler shift equation with velocity

Answer 9

,, ,fD= 2 x f0 x v / c

,f0 - fundamental f aka transmitted fT
, v - speed of blood flow
, c- propag speed

Question 10

Velocity equation

Answer 10

V= 77 x fD / f0

Units cm/ms

Question 11

In doppler we (4)

Answer 11

Fire a particular frequency
Measure the frequency that returns
Figure out the doppler shift
Can calculate how fast an object is moving

Question 12

What happens in doppler if frequency goes up

Answer 12

When frequency goes up doppler shift goes up

Question 13

What happens when doppler shift goes up

Answer 13

Frequency goes up to compensate and velocity doesnt change

Question 14

Were not directly affecting the _____ by changing the frequency

Answer 14

Velocity

Question 15

The doppler shift is the different between

Answer 15

The sent and returning frequencies of the sound wave

Question 16

Doppler effect

Answer 16

Police speed detectors
Weather forecasting
Door openers
Burglar alarms

Question 17

So far with doppler angle we assume our probe is

Answer 17

Parallel to blood flow

Question 18

If the angle of interrogation is non-zero _____ doppler shift will occur

Answer 18

Less

Question 19

We incorporate ______ to compnsate for the lesser shift

Answer 19

cos (angl)

Question 20

Doppler angle is

Answer 20

Angle between teh sound beam and the vessel

Question 21

Cos 0

Answer 21

1

hitting the vessel straight on

Question 22

Cos 30

Answer 22

0.87

Question 23

Cos 60

Answer 23

0.5

Question 24

Cos90

Answer 24

O

Hitting the vessel perpendicular

Question 25

Decreased dopller shift measurement = _____ velocity measurement

Answer 25

Decreased

Question 26

Techniques to get closer to 0 degrees

Answer 26

Heel toe
Phase (steer)
Angle correct

Question 27

Angle correct on US machine

Answer 27

Tell the machine that were off and it compensates, increases the velocity back to where it should be

Question 28

Increase in doppler angle, the ____ error in the speed calculation

Answer 28

Increase

Question 29

0 degree = ____% error

Answer 29

0.4%

Question 30

70 degrees = ____% error

Answer 30

32%

Question 31

In real life we work under _____ degrees

Answer 31

60

Question 32

Doppler displays

Answer 32

Colour
Spectral
Audible

Question 33

Colour doppler aka

Answer 33

Colour flow imaging

Question 34

Colour doppler defined by

Answer 34

Presence, speed, charactter and direction of flow

Question 35

Colour doppler assess a _____ area at a time

Answer 35

Very large compared to spectral doppler

Question 36

Colour ___________ on gray scale image

Answer 36

Superimposed

Question 37

Colour doppler often steeres via ____, to get closer to ____ degree to avoid if vessels are parallel to the surface

Answer 37

Phasing

90 degrees

Question 38

If returning echoes have a different freq than from emitted, ________ has occured

Answer 38

Doppler shift

Question 39

Depending on the sign of doppler shift

Answer 39

Its towards or away

Colour will be assigned to pixels

Question 40

In colour doppler, multiple _______ are sent per _______

Answer 40

Pulses are sent per scan line

Vs. One per scan line in B mode

Question 41

Doppler shift is calculated within

Answer 41

The signal processor