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Vascular Registry > Ch. 1 Physical Principles/ Doppler Imaging > Flashcards

Ch. 1 Physical Principles/ Doppler Imaging Flashcards

1
Q

___: the difference between transmitted frequency and received frequency

A

Doppler shift

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2
Q

What are some factors that can cause spectral broadening?

A

-disease
-large sample volume
-can occur in normal vessels

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3
Q

Will PW or CW Doppler will always have spectral broadening and why?

A

CW because of the large sample volume (remember CW samples the whole length of the beam)

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4
Q

___: the filling in of the spectral window

A

Spectral broadening

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5
Q

___: number of cycles per second

A

Frequency

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6
Q

___: the number of pulses the US beam sends into the body each second

A

Pulse repetition frequency (PRF)

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7
Q

___: the time it takes the US beam to travel 1cm into the body and back

A

13 microsecond rule

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8
Q

What is the Doppler equation when solving for velocity

A

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9
Q

If this is the Doppler equation when solving for velocity what does each part represent and what is directly related

A

V= velocity
C= speed of sound in soft tissue (1540)
Fo= transducer freq
Cos 0= angle of incidence
Df= Doppler shift freq

Df and C are directly related with velocity

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10
Q

What is the Doppler equation when solving for Doppler freq

A

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11
Q

___: digital technique used to process both PW and CW Doppler

A

Fast Fourier transfer (FFT)

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12
Q

when the transducer has increased freq what happens to pen and res

A

increases freq= increased res, decreased pen

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13
Q

decreased freq= ___ res and ___ pen

A

decreased freq= decreased res, increased pen

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14
Q

what is the optimal angle of incidence for gray scale imaging

A

90 degrees

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15
Q

what is the optimal angle of incidence for doppler imaging

A

60 or less

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16
Q

which of the following has spectral broadening

A

the bottom one

17
Q

how are frame rate and depth related

A

inversely, meaning increased depth = decreased frame rate

18
Q

what artifact does this image show

A

aliasing

19
Q

___: the ability of the system to properly display flow

A

Nyquist limit

20
Q

what happens when PRF is greater than 1/2 the nyquist limit

A

aliasing

21
Q

what are some things you can do to fix aliasing

A

-increase scale
-lower baseline
-lower freq
-use CW doppler (doesn't alias)

22
Q

what is the speed of US through soft tissue

A

1540 m/sec

23
Q

what are the two types of CW doppler

A

-analog
-digital or spectral

24
Q

what are the benefits of CW doppler

A

does not alias

25
Q

what are the cons of CW doppler

A

large sample volume (entire course of US beam)

26
Q

when looking at this image of the color scale, which color is towards the transducer and which is away

A

top is always towards so in this case red
bottom is always away so in this case blue

27
Q

steps to determine flow direction with color doppler

A

1. locate the top two corners of color box
2. draw line straight down, whichever is outside of the box is the side of your transducer
3. you will them look at your scale to determine if flow is moving towards or away from your transducer

28
Q

is this flow moving towards or away from your transducer

A

toward

29
Q

which vessel is moving toward the transducer and which is moving away?

A

SFA= toward
SFV= away

30
Q

is the flow in this vessel moving toward or away from your probe?

A

toward

31
Q

true or false: the vessel on the top is moving away from your transducer

A

true

32
Q

how to determine flow direction with no color

A

1. draw a line straight down crossing through sample gate (some machines do this already)
2. Make the letter H with spectral gate
3. find where the lines intersect on the top and that is the side your probe is on

TIP: always remember + is towards - is away

33
Q

which direction is this flow going?

A

away

34
Q

what direction is this flow traveling?

A

toward

Vascular Registry (5 decks)

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