ARDMS SPI STUDY GUIDE QUESTIONS AND CORRECT ANSWERS

ARDMS SPI STUDY GUIDE QUESTIONS
AND CORRECT ANSWERS
InA2softA2tissue,A2ifA2theA2frequencyA2ofA2aA2waveA2isA2increasedA2theA2PropagationA2Spee
dA2(PS)A2will...A2-A2Ans--
RemainA2theA2SameA2becauseA2stiffnessA2andA2densityA2affectA2PropagationA2Speed.

WhatA2isA2theA2audibleA2range?A2-A2Ans--20-20,000Hz

>20,000Hz=Ultrasound

FrequencyA2isA2measuredA2inA2-A2Ans--HertzA2(Hz)
isA2
CyclesA2perA2Second

NotA2affectedA2byA2sonographerA2

IncreaseA2Frequency;A2DecreaseA2Depth

AA2periodA2isA2theA2lengthA2ofA2timeA2itA2takesA2forA2-A2Ans--
oneA2completeA2wavelengthA2toA2passA2aA2fixedA2point

PRPA2isA2determinedA2byA2-A2Ans--TransmitA2timeA2andA2receiveA2time.

PeriodA2isA2measuredA2inA2-A2Ans--TimeA2(μs)

WhenA2theA2sonographerA2changesA2theA2imagingA2depthA2whatA2parametersA2areA2chan
ged?A2-A2Ans--PRP,A2PRF,A2DutyA2Factor

WhatA2isA2dutyA2factor?A2-A2Ans--
TheA2percentageA2orA2fractionA2ofA2timeA2thatA2theA2systemA2isA2transmittingA2aA2pulseA2(T
imeA2SoundA2isA2ONA2orA2ON-Time).

PropagationA2SpeedA2inA2SOFTA2TISSUEA2-A2Ans--1.54A2mm/μs
(1540A2m/sec)

UnitA2ofA2measurementA2forA2PulseA2Duration,A2DutyA2Factor,A2PRP,A2andA2PeriodA2-
A2Ans--Time,A2(μs)


PulseA2durationA2isA2determinedA2byA2-A2Ans--SoundA2SourceA2Only

PulseA2DurationA2isA2controlledA2byA2-A2Ans--theA2ultrasoundA2systemA2andA2transducer

PulseA2DurationA2FormulaA2-A2Ans--pulseA2durationA2(μs)A2=A2#A2cyclesA2inA2pulse/
frequency(MHz)

,PD=A2NumberA2ofA2cyclesA2inA2Pulse/A2Frequency(Hz)

SpatialA2PulseA2LengthA2(SPL)A2(measurement)A2-A2Ans--
TheA2distanceA2thatA2aA2pulseA2occupiesA2inA2spaceA2fromA2theA2startA2toA2theA2endA2ofA2a
A2pulse.A2
(mm)

TypicalA2valuesA2forA2spatialA2pulseA2lengthA2inA2softA2tissue.A2-A2Ans--0.1A2toA21.0A2mm

SpatialA2pulseA2lengthA2isA2determinedA2byA2-A2Ans--soundA2sourceA2andA2medium

SpatialA2PulseA2LengthA2isA2directlyA2proportionalA2toA2-A2Ans--
theA2NumberA2ofA2CyclesA2inA2theA2Pulse
andA2
theA2Wavelength

(DirectlyA2ProportionalA2meansA2thatA2increasedA2SPLA2willA2increaseA2bothA2theA2number
A2ofA2cyclesA2inA2theA2pulseA2andA2theA2wavelengthA2ifA2increased).


SpatialA2pulseA2lengthA2isA2inverselyA2proportionalA2toA2-A2Ans--FrequencyA2(MHz)

(InverselyA2ProportionalA2meansA2thatA2increasedA2SPLA2willA2lowerA2frequency.A2ThisA2is
A2becauseA2axialA2resolutionA2isA2betterA2withA2lowerA2frequency)


PulseA2DurationA2(PD)A2-A2Ans--
TheA2actualA2timeA2fromA2theA2startA2ofA2aA2pulseA2toA2theA2endA2ofA2thatA2pulse;A2aA2singl
eA2transmit,A2talking,A2orA2"on"A2time.A2
TimeA2theA2pulseA2isA2onA2typicallyA2measuredA2inA2(ms).

PulseA2LengthA2-A2Ans--TheA2distanceA2ofA2theA2pulseA2startA2toA2endA2orA2the
durationA2orA2lengthA2ofA2aA2singleA2pulseA2
PulseA2LengthA2isA2typicallyA2measuredA2inA2(mm).

theA2abilityA2ofA2anA2objectA2toA2resistA2compressionA2andA2relatesA2toA2theA2hardnessA2ofA
2aA2medium?A2-A2Ans--Stiffness.A2


Think:
↑A2StiffnessA2↑A2Speed
↓A2DensityA2↑A2Speed

AnA2increaseA2inA2pulseA2repetitionA2frequencyA2wouldA2leadA2to:A2-A2Ans--
IncreasingA2pulseA2repetitionA2frequency,A2increasesA2dutyA2factor.

↑A2PRFA2↑A2DutyA2Factor

, WhichA2ofA2theA2followingA2wouldA2haveA2theA2highestA2propagationA2speed?A2-A2Ans--
BoneA2hasA2theA2highestA2propagationA2speed,A2atA22000-4000A2m/s.

WhatA2hasA2theA2lowestA2propagationA2speed?A2-A2Ans--
airA2technicallyA2hasA2theA2lowestA2propagationA2speedA2atA2300A2m/s

WhichA2hasA2theA2SlowestA2PropagationA2Speed?A2
Water
SoftA2Tissue
Bone
LungA2tissueA2-A2Ans--LungA2Tissue

AsA2imagingA2depthA2increases,A2theA2pulseA2repetitionA2frequencyA2(PRF)A2must:A2-
A2Ans--DecreaseA2


AsA2imagingA2depthA2increase,A2pulseA2repeitionA2freqencyA2(PRF)A2decreases.

↑A2ImagingA2DepthA2↓A2PRF

WhatA2describesA2theA2amountA2ofA2refractionA2thatA2occursA2atA2anA2interface?A2-A2Ans--
Snell'sA2law

Refraction:A2theA2redirectionA2ofA2theA2transmittedA2soundA2beam

Snell'sA2lawA2describesA2theA2angleA2ofA2transmissionA2atA2anA2interfaceA2basedA2onA2theA
2angleA2ofA2incidenceA2andA2theA2propagationA2speedsA2ofA2theA2twoA2media.


PressureA2isA2typicallyA2expressedA2in:A2-A2Ans--PascalsA2(Pa)

TheA2typicalA2rangeA2ofA2frequencyA2forA2diagnosticA2ultrasoundA2imagingA2isA2-A2Ans--1-
20A2MhzA2isA2theA2typicalA2rangeA2ofA2frequencyA2forA2diagnosticA2ultrasoundA2imaging.

TheA2attentuationA2coefficientA2inA2softA2tissueA2isA2equalA2to:A2-A2Ans--
AttentuationA2CoeffcientA2=A21/2A2(oneA2halfA2ofA2theA2frequencyA2inA2softA2tissue)

TheA2attentuationA2coeffcientA2(inA2dB/
cm)A2isA2theA2rateA2atA2whichA2soundA2isA2attentuatedA2perA2unitA2depth.

MicroA2isA2denotedA2as:A2-A2Ans--MicroA2isA2denotedA2asA2millionthA2(µ)

WhatA2isA2describedA2asA2theA2distanceA2overA2whichA2oneA2cycleA2occurs?A2-A2Ans--
WavelengthA2isA2distanceA2overA2whichA2oneA2cycleA2occurs,A2orA2theA2distanceA2fromA2th
eA2beginningA2ofA2oneA2cycleA2toA2theA2endA2ofA2theA2sameA2cycle.

Remember,A2itA2asksA2forA2distanceA2overA2whichA2oneA2cycleA2occurs.