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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
Q

THIS TYPE OF DOPPLER MEASURES THE PRESENCE OF MOVING BLOOD CELLS BY DETECTING A DOPPLER SHIFT.

A

NON DIRECTIONAL DOPPLER AKA NON COHERET

DOESN’T DISTINGUISH THE DIRECTION OF BLOD FLOW

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25
Q

THIS TYPE OF DOPPLER DISTINGUISHES PATENCY & THE DIRECTION OF FLOW?

A

BIDIRECTIONAL DOPPLER

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26
Q

A FLOW THAT IS TOWARDS THE TRD WILL APPEAR ____ OF THE BASELINE.

A

ABOVE

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27
Q

IS FLOW TOWARDS THE TRD A POSITIVE OR NEGATIVE DOPPLER SHIFT?

A

POSITIVE

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28
Q

HOW WILL FLOW AWAY FROM THE TRD WILL SHOW ____ THE BASELINE.

WHAT TYPE OF DOPPLER SHIFT IS THIS?

A

BELOW

NEGATIVE

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29
Q

WHAT IS THE NML MPV VELOCITY & WHAT TYPE OF FLOW IS IT?

A

10-30 CM/S & IS HEPATOPETAL

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30
Q

THIS TYPE OF DOPPLER REQUIRES 2 CRYSTALS IN THE TRD AND ITS GREATEST ADVANTAGE IS ITS ABILITY TO ACCURATELY MEASURE VERY HIGH VELOCITIES.

A

CONTINUOUS WAVE DOPPER

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31
Q

WHAT ARE THE FUNCTIONS OF THE 2 CRYSTALS FOR CONTINUOUS WAVE?

A

1 CONSTANTLY TRANSMITS & 1 CONTINUOUSLY RECEIVES

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32
Q

WHAT ARE THE DISADVANTAGES OF CONTINUOUS WAVE?

A
  • INABILITY TO DETERMINE LOCATION OF THE MVG RBC (RANGE AMBIGUITY)
  • NO TGC
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33
Q

WHO USES CONTINUOUS WAVE D?

A

ECHO TECHS

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34
Q

SIMULTANEOUS ANATOMIC IMAGING & DOPLER IS CALLED?

A

DUPLEX IMAGING

35
Q

A DEDICATED CONTINUOUS WAVE TRD WILL NOT CONTAIN?

A

BACKING MATERIAL

36
Q

A DEDICATED CONTINUOUS WAVE TRD HAS:

A
  • UNDAMPENED TRANSMITTED SIGNAL
  • NARROW BANDWIDTH
  • HIGH QF
  • HIGHER SENSITIVITY***
37
Q

HOW MANY CRYSTALS DOES A PULSED WAVE DOPPLER HAVE?

A

1; IT ALTERNATES BETWEEN SENDING & RECEIVING U/S PULSES

38
Q

THIS CALCULATES THE TIME-OF-FLIGHT OF THE SOUND PULSE.

A

SAMPLE VOLUM OR GATE

39
Q

THE ABILITY TO SELECT THE EXACT LOCATION OF THE DOPPLER IS CALLED?

A

RANGE RESOLUTION, RANGE SPECIFICITY, OR FREEDOM FROM RANGE AMBIGUITY ARTIFACT.

40
Q

WHAT ARE THE DISADVANTAGES OF PULSED DOPPLER?

A

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
Q

EXAMS THAT SIMULTANEOUSLY PERFORM IMAGING AND PULSED DOPPLER ARE ALSO CALLED ?

A

DUPLEX

42
Q

WHAT CHARACTERISTICS DOES PULSED DOPPLER TRD HAVE?

A
  • LOW QF
  • LOWER SENSITIVITY
  • WIDE BANDWIDTH PULSES
43
Q

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.

A

ALIASING

44
Q

THIS IS THE HIGHEST DOPPLER VELOCITY THAT CAN BE MEASURED WITHOUT ALIASING.

A

NYQUIST LIMIT

45
Q

WHAT IS THE FORMULA FOR NYQUIST?

A

NYQUIST LIMIT (HZ) = PRF (HZ)/2

46
Q

THE SAMPLING RATE OF PULSED DOPPLER IS THE SYSTEM’S ___ ___ ____

A

PULSED REPETITION FRQ

47
Q

WHEN THE SAMPLE VOLUME IS SHALLOW, THE PRF IS __, SO THE NYQUIST IS ____.

A

HIGH, HIGH

48
Q

WHEN THE SAMPLE VOLUME IS DEEP THE PRF IS ___ SO THE NYQUIST LIMIT IS ____.

A

LOW, LOW

49
Q

WHAT CAUSES MORE ALIASING?

A
  • FASTER BLOOD VELOCITY
  • HIGHER FRQ TRD
  • DEEP GATE (LOW PRF)
50
Q

WHAT ARE THE 5 TECHNIQUES TO AVOID ALIASING ARTIFACTS?

A

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
Q

EITHER THE AMPLITUDE OF THE REFLECTED SIGNAL OR THE # OF RBC CREATING THE REFLECTION ARE RELATED TO:

A

GRAY SHADES OF A SPECTRUM

52
Q

THIS TYPE OF DOPPLER ASSESSES VELOCITIES AT A SPECIFIC LOCATION, WIT 2D COLOR FLOW.

A

COLOR FLOW DOPPLER

53
Q

COLOR DOPPLER REPORTS ____ VELOCITIES WHEREAS PULSED AND CONTINUOUS WAVE DOPPLER REPORTS IN ___ VELOCITIES.

A

AVERAGE; PEAK

54
Q

WHAT ARE THE 2 MOST COMMONLY USED MODES OF COLOR MAP?

A

VELOCITY MODE & VARIANCE MODE

55
Q

WITH VELOCITY THE BLACK REGION INDICATES ______ DOPPLER SHIFT; COLOR ABOVE THE BLACK STRIPE MEANS ____ DOPPLER SHIFT; COLOR BELOW THE BLACK STRIPE MEANS ____ DOPPLER SHIFT.

A

NO DOPPLER SHIFT
TWDS THE TRD OR POSITIVE
AWAY FROM TRD OR NEGATIVE

56
Q

THE COLORS THAT APPEAR BELOW THE BLACK STRIPE THAT IS CLOSEST TO THE BLACK STRIPE INDICATES ____ VELOCITIES.

A

SLOWER VELOCITY

57
Q

COLORS THAT ARE FARTHER BELOW THE BLACK STRIP INDICATE _____ VELOCITIES ____ THE TRD.

A

FASTER; AWAY FROM

58
Q

WHAT DOES BART MEAN?

A

BLUE AWAY & RED TWD

59
Q

THIS MODE DISTINGUISHES BETWEEN LAMINAR FLOW FROM TURBULENT.

A

VARIANCE

60
Q

COLORS FROM THE LEFT SIDE OF VARIANCE MAPS MEANS?

A

LAMINAR

61
Q

COLORS FROM THE RT SIDE OF MAP MEANS?

A

TURBULENT

62
Q

HOW DO YOU PREDICT FLOW DIRECTION WITH A SECTOR IMAGE?

A

ID TYPE OF COLOR THEN PUT FINGER ON TWD COLOR AND SLIDE TO AWAY COLOR.

63
Q

HOW DO YOU PREDICT FLOW DIRECTION WITH RECTANGULAR IMAGE?

A

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
Q

THIS IS MULTIPLE U/S PULSES USED TO DETERMINE VELOCITIES.

A

DOPPLER PACKETS

65
Q

THIS IS THE # OF PULSES PER SCAN LINE WITHIN THE COLOR GATE.

A

PACKET SIZE

66
Q

WHAT ARE THE ADVANTAGES TO A LARGE PACKET?

A
  • MORE ACCURATE VELOCITY MSMT

- MORE SENSITIVE TO LOW FLOW

67
Q

WHAT ARE THE DISADVANTAGES TO A LG PACKET?

A
  • MORE TIME NEEDED TO ACQUIRE DATA
  • REDUCED FRAME RATE
  • DECREASED TEMPORAL RESOLUTION
68
Q

THIS IS A NON- DIRECTIONAL COLOR DOPPLER THAT ID’S THE PRESENCE OF A DOPPLER SHIFT.

A

POWER DOPPLER

69
Q

WITH POWER DOPPLER IS THE AMPLITUDE OF THE REFLECTION DIRECTLY RELATED TO THE NUMBER OF MVG BLOOD CELLS?

A

YES

70
Q

WHAT ARE THE ADVANTAGES OF USING POWER DOPPLER?

A
  • INCREASED SENSITIVITY TO LOW FLOW
  • UNAFFECTED BY DOPPLER ANGLES
  • NO ALIASING
71
Q

WHAT ARE THE DISADVANTAGES TO USING POWER DOPPLER?

A
  • NO MSMT OF VELOCITY OR DIRECTION
  • LOWER FRAME RATES
  • SUSCEPTIBLE TO MOTION OF THE TRD
72
Q

WHAT IS POWER DOPPLER ALSO KNOWN AS?

A

ENERGY MODE & COLOR ANGIO

73
Q

ON SPECTRAL DISPLAYS LOW FRQ DOPPLER SHIFT ARTIFACTS ARE CALLED?

AND WITH COLOR?

A

CLUTTER

GHOSTING

74
Q

WHAT IS ELIMINATES LOW FRQ DOPPLER SHIFTS; AND IS A “REJECT FOR DOPPLER”?

A

WALL FILTERS

75
Q

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.

A

CROSSTALK

76
Q

WHAT CAUSES CROSSTALK?

A

DOPPLER RECEIVER GAIN TOO HIGH
OR
INCIDENT ANGLE NEAR 90 DEGREES

77
Q

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.

A

SPECTRAL ANALYSIS

78
Q

WHAT ARE THE 2 METHODS OF SPECTRAL ANALYSIS?

A

1) FAST FOURIER TRANSFORM (FFT)

2) AUTOCORRELATION

79
Q

THIS METHOD OF SPECTRAL ANALYSIS IS A DIGITAL SIGNAL PROCESSING TECHNIQUE THAT IS USED WITH PULSED & CONTINUOUS WAVE DOPPLER.

A

FAST FOURIER TRANSFORM

80
Q

THIS METHOD OF SPECTRAL ANALYSIS IS A DIGITAL PROCESSING TECHNIQUE THAT IS USED TO ANALYZE COLOR DOPPLER IMAGING.

A

AUTOCORRELATION

81
Q

WHAT ARE THE ADVANTAGES TO FFT?

A
  • VERY ACCURATE

- DISPLAYS ALL COMPONENTS: TIME, VELOCITY, FRQ SHIFT, FLOW DIRECTION & AMPLITUDE

82
Q

WHAT IS THE FORMULA FOR RESISTIVE INDEX?

A

RI = VELOCITY (MAX) - VELOCITY (MIN)/ VELOCITY (MAX)

83
Q

WHAT IS THE RESISTIVITY INDEX?

A
  • A QUANTITATIVE MSMT OF THE VASCULAR RESISTANCE OF THE ARTERIAL SYSTEM.
  • IS A RATIO
84
Q

THIS IS THE MEAN VELOCITY FOR THE ENTIRE CARDIAC CYCLE.

A

PULSATILITY INDEX

85
Q

WHAT IS THE FORMULA FOR PULSATILITY INDEX?

A

PI = VELOCITY(MAX) - VELOCITY(MIN)/ VELOCITY(MEAN)

PHYSICS (2 decks)

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