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PHYSICS > CH 19 - DOPPLER > Flashcards

CH 19 - DOPPLER Flashcards

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0
Q

THIS IS THE PROCESS OF EXTRACTING LOW DOPPLER FRQ FROM THE HIGHER TRD FRQ?

A

DEMODULATION

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1
Q

THIS IS HAPPENS WHEN THERE IS A CHANGE IN FREQUENCY DUE TO THE RELATIVE MOTION BETWEEN THE SOUND SOURCE & RECEIVER.

A

DOPPLER SHIFT AKA DOPPLER FRQ

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2
Q

WHAT IS THE FORMULA FOR DOPPLER SHIFT?

A

DOPPLER SHIFT (HZ) = REFLECTED FRQ - TRANSMITTED FRQ

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3
Q

WHEN THE RBC’S MOVE TWD THE TRD THE DOPPLER SHIFT IS ______.

A

POSITIVE; THE REFLECTED FRQ IS HIGHER THAN THE TRANSMITTED FRQ. (TRAIN COMING AT YOU)

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4
Q

WHEN THE RBC’S MOVE AWAY FROM THE TRD THE DOPPLER SHIFT IS ______.

A

NEGATIVE (TRAIN MOVING AWAY FROM YOU THE REFLECTED FRQ IS LOWER THAN THE TRANSMITTED FRQ)

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5
Q

DOPPLER FREQUENCIES INDICATE _____?

A

VELOCITY NOT SPEED.

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6
Q

______ IS A MAGNITUDE THAT INDICATES THE DISTANCE THAT A RBC MOVES IN 1 SEC. IT IS REPORTED IN_____.

A

SPEED. CM/S

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7
Q

THIS IS DEFINED BY A MAGNITUDE AND A DIRECTION.

A

VELOCITY

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8
Q

WHAT IS THE DOPPLER EQUATION?

A

2 x speed of blood x trd frq x cos
DOPPLER SHIFT =__________________________
prop of speed

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9
Q

DOPPLER SHIFT IS DIRECTLY RELATED TO ______ OF THE RBC’S.

A

VELOCITY

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10
Q

THE ____ THE VELOCITY, THE GREATER THE DOPPLER FRQ.

A

FASTER

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11
Q

What are the 2 doppler shifts during a clinical u/s exam?

A

1) occurs when the sound wave from trd strikes moving blood.

2) reflections returns to the trd from rbc.

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12
Q

Doppler shift is measured in?

A

Hz

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13
Q

Velocity is measured in?

A

distance/time (cm/s)

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14
Q

DOPPLER SHIFT IS ______ RELATED TO RBC SPEED & DIRECTION.

A

DIRECTLY

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15
Q

DOPPLER SHIFT IS ______ _____ RELATED TO THE TRD FRQ.

A

DIRECTLY PROPORTIONAL

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16
Q

IF THE BLOOD CELLS ARE MOVING _______ TO THE SOUND BEAM, THE ENTIRE DOPPLER SHIFT IS MEASURED.

A

PARALLEL

VELOCITY MEASUREMENT WILL BE 100% ACCURATE

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17
Q

IF THE SOUND BEAM AND FLOW DIRECTION ARE NOT PARALLEL WHAT DETERMINES HOW MUCH OF THE VELOCITY IS MEASURED?

A

DEPENDS ON THE COSINE OF THE ANGLE BETWEEN THE SB AND DIRECTION OF MOTION.

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18
Q

WHAT IS THE FORMULA TO CALCULATE MEASURED VELOCITY?

A

MEASURED VELOCITY = TRUE VELOCITY X COS 0

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19
Q

WHAT IS THE COSINE OF 0 DEGREES AND WHAT DIRECTION WITH THE FLOW BE?

A

COS OF 0 IS 1, BLOOD FLOW WILL BE TOWARD THE TRD.

THE COS OF 180 DEGREES IS -1 INDICATINGE A FLOW AWAY FROM THE TRD.

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20
Q

WHATIS THE MEASURED VELOCITY IF THE ANGLE IS 90 DEGREES?

A

0, DOPPLER SIGNALS AND VELOCITIES CANNOT BE MEASURED WHEN THE FLOW IS PERP TO THE BEAM.

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21
Q

WHAT IS THE COS OF 60 DEGREES?

A

.5

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22
Q

WITH A COS OF 60 DEGREES WHAT IS THE ACCURACY OF THE ACTUAL VELOCITY?

A

THE MEASURED VELOCITY AT 60 DEGREES IS 1/2 THE ACTUAL VELOCITY.

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23
Q

WHAT ARE THE BEST DOPPLER ANGLES?

A

HEEL TOE

OR SCAN INTERCOSTALLY

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24
THIS TYPE OF DOPPLER MEASURES THE PRESENCE OF MOVING BLOOD CELLS BY DETECTING A DOPPLER SHIFT.
NON DIRECTIONAL DOPPLER AKA NON COHERET | DOESN'T DISTINGUISH THE DIRECTION OF BLOD FLOW
25
THIS TYPE OF DOPPLER DISTINGUISHES PATENCY & THE DIRECTION OF FLOW?
BIDIRECTIONAL DOPPLER
26
A FLOW THAT IS TOWARDS THE TRD WILL APPEAR ____ OF THE BASELINE.
ABOVE
27
IS FLOW TOWARDS THE TRD A POSITIVE OR NEGATIVE DOPPLER SHIFT?
POSITIVE
28
HOW WILL FLOW AWAY FROM THE TRD WILL SHOW ____ THE BASELINE. | WHAT TYPE OF DOPPLER SHIFT IS THIS?
BELOW | NEGATIVE
29
WHAT IS THE NML MPV VELOCITY & WHAT TYPE OF FLOW IS IT?
10-30 CM/S & IS HEPATOPETAL
30
THIS TYPE OF DOPPLER REQUIRES 2 CRYSTALS IN THE TRD AND ITS GREATEST ADVANTAGE IS ITS ABILITY TO ACCURATELY MEASURE VERY HIGH VELOCITIES.
CONTINUOUS WAVE DOPPER
31
WHAT ARE THE FUNCTIONS OF THE 2 CRYSTALS FOR CONTINUOUS WAVE?
1 CONSTANTLY TRANSMITS & 1 CONTINUOUSLY RECEIVES
32
WHAT ARE THE DISADVANTAGES OF CONTINUOUS WAVE?
- INABILITY TO DETERMINE LOCATION OF THE MVG RBC (RANGE AMBIGUITY) - NO TGC
33
WHO USES CONTINUOUS WAVE D?
ECHO TECHS
34
SIMULTANEOUS ANATOMIC IMAGING & DOPLER IS CALLED?
DUPLEX IMAGING
35
A DEDICATED CONTINUOUS WAVE TRD WILL NOT CONTAIN?
BACKING MATERIAL
36
A DEDICATED CONTINUOUS WAVE TRD HAS:
- UNDAMPENED TRANSMITTED SIGNAL - NARROW BANDWIDTH - HIGH QF - HIGHER SENSITIVITY***
37
HOW MANY CRYSTALS DOES A PULSED WAVE DOPPLER HAVE?
1; IT ALTERNATES BETWEEN SENDING & RECEIVING U/S PULSES
38
THIS CALCULATES THE TIME-OF-FLIGHT OF THE SOUND PULSE.
SAMPLE VOLUM OR GATE
39
THE ABILITY TO SELECT THE EXACT LOCATION OF THE DOPPLER IS CALLED?
RANGE RESOLUTION, RANGE SPECIFICITY, OR FREEDOM FROM RANGE AMBIGUITY ARTIFACT.
40
WHAT ARE THE DISADVANTAGES OF PULSED DOPPLER?
ALIASING, WHICH IS AN INACCURATE MSMT OF HIGH VELOCITY SIGNALS. SHOWS HIGH VELOCITY FLOW IN 1 DIRECTION IS INCORRECTLY DISPLAYED AS TRAVELING IN OPPOSITE DIRECTION.
41
EXAMS THAT SIMULTANEOUSLY PERFORM IMAGING AND PULSED DOPPLER ARE ALSO CALLED ?
DUPLEX
42
WHAT CHARACTERISTICS DOES PULSED DOPPLER TRD HAVE?
- LOW QF - LOWER SENSITIVITY - WIDE BANDWIDTH PULSES
43
THIS ONLY EXIST WITH PULSED DOPPLER & IS CAUSED BY TOO HIGH RBC VELOCITIES. DOPPLER CANNOT KEEP UP WITH THE SPEEED OF RBC'S & DISPLAYS AS MVG IN WRONG DIRECTION.
ALIASING
44
THIS IS THE HIGHEST DOPPLER VELOCITY THAT CAN BE MEASURED WITHOUT ALIASING.
NYQUIST LIMIT
45
WHAT IS THE FORMULA FOR NYQUIST?
NYQUIST LIMIT (HZ) = PRF (HZ)/2
46
THE SAMPLING RATE OF PULSED DOPPLER IS THE SYSTEM'S ___ ___ ____
PULSED REPETITION FRQ
47
WHEN THE SAMPLE VOLUME IS SHALLOW, THE PRF IS __, SO THE NYQUIST IS ____.
HIGH, HIGH
48
WHEN THE SAMPLE VOLUME IS DEEP THE PRF IS ___ SO THE NYQUIST LIMIT IS ____.
LOW, LOW
49
WHAT CAUSES MORE ALIASING?
- FASTER BLOOD VELOCITY - HIGHER FRQ TRD - DEEP GATE (LOW PRF)
50
WHAT ARE THE 5 TECHNIQUES TO AVOID ALIASING ARTIFACTS?
1) ADJUST THE SCALE TO ITS MAX. 2) SELECT A LOWER FRQ TRD 3) SELECT A NEW U/S VIEW WITH A SHALLOWER SAMPLE VOLUME 4) USE CONTINUOUS WAVE DOPPLER 5) USE BASELINE SHIFT (ONLY CHANGES APPEARANCE DOESN'T CORRECT ANYTHING)
51
EITHER THE AMPLITUDE OF THE REFLECTED SIGNAL OR THE # OF RBC CREATING THE REFLECTION ARE RELATED TO:
GRAY SHADES OF A SPECTRUM
52
THIS TYPE OF DOPPLER ASSESSES VELOCITIES AT A SPECIFIC LOCATION, WIT 2D COLOR FLOW.
COLOR FLOW DOPPLER
53
COLOR DOPPLER REPORTS ____ VELOCITIES WHEREAS PULSED AND CONTINUOUS WAVE DOPPLER REPORTS IN ___ VELOCITIES.
AVERAGE; PEAK
54
WHAT ARE THE 2 MOST COMMONLY USED MODES OF COLOR MAP?
VELOCITY MODE & VARIANCE MODE
55
WITH VELOCITY THE BLACK REGION INDICATES ______ DOPPLER SHIFT; COLOR ABOVE THE BLACK STRIPE MEANS ____ DOPPLER SHIFT; COLOR BELOW THE BLACK STRIPE MEANS ____ DOPPLER SHIFT.
NO DOPPLER SHIFT TWDS THE TRD OR POSITIVE AWAY FROM TRD OR NEGATIVE
56
THE COLORS THAT APPEAR BELOW THE BLACK STRIPE THAT IS CLOSEST TO THE BLACK STRIPE INDICATES ____ VELOCITIES.
SLOWER VELOCITY
57
COLORS THAT ARE FARTHER BELOW THE BLACK STRIP INDICATE _____ VELOCITIES ____ THE TRD.
FASTER; AWAY FROM
58
WHAT DOES BART MEAN?
BLUE AWAY & RED TWD
59
THIS MODE DISTINGUISHES BETWEEN LAMINAR FLOW FROM TURBULENT.
VARIANCE
60
COLORS FROM THE LEFT SIDE OF VARIANCE MAPS MEANS?
LAMINAR
61
COLORS FROM THE RT SIDE OF MAP MEANS?
TURBULENT
62
HOW DO YOU PREDICT FLOW DIRECTION WITH A SECTOR IMAGE?
ID TYPE OF COLOR THEN PUT FINGER ON TWD COLOR AND SLIDE TO AWAY COLOR.
63
HOW DO YOU PREDICT FLOW DIRECTION WITH RECTANGULAR IMAGE?
PUT FINGER ON "HOME" (PLACE WHERE COLOR DOESN'T RUN INTO BOX), ID IF COLOR IS TWD OR AWAY, MOVE FINGER TWDS OR AWAY FROM BOX.
64
THIS IS MULTIPLE U/S PULSES USED TO DETERMINE VELOCITIES.
DOPPLER PACKETS
65
THIS IS THE # OF PULSES PER SCAN LINE WITHIN THE COLOR GATE.
PACKET SIZE
66
WHAT ARE THE ADVANTAGES TO A LARGE PACKET?
- MORE ACCURATE VELOCITY MSMT | - MORE SENSITIVE TO LOW FLOW
67
WHAT ARE THE DISADVANTAGES TO A LG PACKET?
- MORE TIME NEEDED TO ACQUIRE DATA - REDUCED FRAME RATE - DECREASED TEMPORAL RESOLUTION
68
THIS IS A NON- DIRECTIONAL COLOR DOPPLER THAT ID'S THE PRESENCE OF A DOPPLER SHIFT.
POWER DOPPLER
69
WITH POWER DOPPLER IS THE AMPLITUDE OF THE REFLECTION DIRECTLY RELATED TO THE NUMBER OF MVG BLOOD CELLS?
YES
70
WHAT ARE THE ADVANTAGES OF USING POWER DOPPLER?
- INCREASED SENSITIVITY TO LOW FLOW - UNAFFECTED BY DOPPLER ANGLES - NO ALIASING
71
WHAT ARE THE DISADVANTAGES TO USING POWER DOPPLER?
- NO MSMT OF VELOCITY OR DIRECTION - LOWER FRAME RATES - SUSCEPTIBLE TO MOTION OF THE TRD
72
WHAT IS POWER DOPPLER ALSO KNOWN AS?
ENERGY MODE & COLOR ANGIO
73
ON SPECTRAL DISPLAYS LOW FRQ DOPPLER SHIFT ARTIFACTS ARE CALLED? AND WITH COLOR?
CLUTTER | GHOSTING
74
WHAT IS ELIMINATES LOW FRQ DOPPLER SHIFTS; AND IS A "REJECT FOR DOPPLER"?
WALL FILTERS
75
THIS IS A SPECIAL FORM OF MIRROR IMAGE ARTIFACT THAT ARISES ONLY WITH SPECTRAL DOPPLER. IT APPEARS AS AN ID DOPPLER SPECTRUM ABOVE & BELOW THE BASELINE.
CROSSTALK
76
WHAT CAUSES CROSSTALK?
DOPPLER RECEIVER GAIN TOO HIGH OR INCIDENT ANGLE NEAR 90 DEGREES
77
THIS IS A TOOL THAT BREAKS THE COMPLEX SIGNAL INTO ITS BASIC BLDG BLOCKS AND ID'S THE IND VELOCITIES THAT MAKES UP THE REFLECTED DOPPLER SIGNAL.
SPECTRAL ANALYSIS
78
WHAT ARE THE 2 METHODS OF SPECTRAL ANALYSIS?
1) FAST FOURIER TRANSFORM (FFT) | 2) AUTOCORRELATION
79
THIS METHOD OF SPECTRAL ANALYSIS IS A DIGITAL SIGNAL PROCESSING TECHNIQUE THAT IS USED WITH PULSED & CONTINUOUS WAVE DOPPLER.
FAST FOURIER TRANSFORM
80
THIS METHOD OF SPECTRAL ANALYSIS IS A DIGITAL PROCESSING TECHNIQUE THAT IS USED TO ANALYZE COLOR DOPPLER IMAGING.
AUTOCORRELATION
81
WHAT ARE THE ADVANTAGES TO FFT?
- VERY ACCURATE | - DISPLAYS ALL COMPONENTS: TIME, VELOCITY, FRQ SHIFT, FLOW DIRECTION & AMPLITUDE
82
WHAT IS THE FORMULA FOR RESISTIVE INDEX?
RI = VELOCITY (MAX) - VELOCITY (MIN)/ VELOCITY (MAX)
83
WHAT IS THE RESISTIVITY INDEX?
- A QUANTITATIVE MSMT OF THE VASCULAR RESISTANCE OF THE ARTERIAL SYSTEM. - IS A RATIO
84
THIS IS THE MEAN VELOCITY FOR THE ENTIRE CARDIAC CYCLE.
PULSATILITY INDEX
85
WHAT IS THE FORMULA FOR PULSATILITY INDEX?
PI = VELOCITY(MAX) - VELOCITY(MIN)/ VELOCITY(MEAN)

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