# Shared Flashcard Set

## Details

Ultrasound FIU Test 1
Ultrasound Physics Lecture 1-2 Test 1
51
Physics
Professional
10/17/2010

Term
 Sound
Definition
 Mechanical wave in which particles in a medium movewaves are identified by oscillations in acoustic variablesvariables distinguish bt these and other waves:  pressure, density, and distance
Term
 ________  is a longitudinal, mechanical wave
Definition
 sound
Term
 ______________ wave particles move in a direction that is perpendicular to the direction that the wave propagates
Definition
 transverse
Term
 longitudinal waves
Definition
 particles move in the same direction that the wave propagates
Term
 interference
Definition
 waves lose their individual characteristics and combine to form a single wave
Term
 destructive interference
Definition
 a pair of out-of phase waves combine to form one of lesser amplitude
Term
 frequencies
Definition
 at some moments in time, waves are in phase while at other moments the waves are out of phase- possible due to varying ?
Term
 Which sound parameters can be changed by the sonographer?
Definition
 Amplitude, Power, IntensityAll three are directly related, one increases they all go up
Term
 period
Definition
 *time it takes to complete a single cycle*time from the start of one cycle to the start of the next cycle*units: any unit of time*.1 to .5 microseconds*det by soundsource, not affected by medium*cannot be changed by sonographer
Term
 frequency
Definition
 *det by soundsource,not medium*cannot be changed by sonographer*clinical imaging freq= 2MHz-10MHz*cycles/sec or Hertz
Term
 Ultrasound
Definition
 *Above the limits of human hearing*Above 20,000Hz
Term
 audible sound
Definition
 *can be heard by humans*between 20Hz and 20,000Hz
Term
 infrasound
Definition
 *frequency so low it cannot be heard by humans*freq less than 20Hz
Term
 Affects penetration and detail (axial resolution)1. less penetration but better detail2. better penetration less resolution
Definition
 Frequency1. higher2. lower
Term
 period and frequency are ________
Definition
 reciprocalperiod(sec) X frequency(MHz)= 1
Term
 as frequency decreases, period _____
Definition
 increases; they are inversely related
Term
 parameters describe the size or strength or magnitude of a sound wave
Definition
 Amplitude, Power, Intensity
Term
 difference between the min or max value and the avg value of an acoustic variable
Definition
 Amplitude- measured in pascals (Pa)
Term
 10^9 billion
Definition
 giga G
Term
 10^-9 billionth
Definition
 nano n
Term
 10^9 billion10^6 million10^3 thousand10^2 hundred10^1 ten10^-1 tenth10^-2 hundredth10^-3 thousandth10^-6 millionth10^-9 billionth
Definition
 giga G mega Mkilo khecto hdeca dadeci dcenti cmilli mmicro nano n
Term
 power is proportional to the waves amplitude squared
Definition
 power is directly related to amplitude
Term
 concentration of energy in a soundbeamrelates to how the power in a wave spreads or is distributed in space
Definition
 Intensity w/cm^2
Term
 the rate at which work is performed
Definition
 power
Term
 distance or length of one complete cycledetermined by source and mediumcannot be changed by sonographer
Definition
 wavelength soft tissue ranges from 0.15 to 0.8mmmeasured in any unit of length
Term
 What is the speed of sound in soft tissue?
Definition
 1540 m/s1.54 mm/ m1.54 km/s
Term
 higher frequency=____________ wavelengthlower frequency= ____________ wavelength_________ wavelengths generally produce higher quality images with greater details
Definition
 shorterlongershorter
Term
 propagation speed
Definition
 determined only by the characteristics of the medium (density and stiffness)not affected by the sound source (frequency)*a 10MHz and a 2MHz will travel the same speed when they travel thru the same medium
Term
 Material Speed________________________________________air 330 m/swater 1480 m/smetals 2000-7000 m/sbone 3500 m/s
Definition
 sound travels faster in solids, slower in liquids, slowest in gases
Term
 stiffness increases; speed increasesdensity increases; speed decreases
Definition
 stiffness and speed are directly relateddensity and speed are inversley related
Term
 5 additional parameters used to describe pulsed sound
Definition
 pulse duration spatial pulse length pulse repetition period pulse repetition frequency duty factor
Term
 {image:|center}
Definition
Term
 [image]
Definition
Term
 Soundwaves are identified by oscillations in which acoustic variables?
Definition
 Pressure Pa, Density, Distance
Term
 Bigness of a wave; all 3 are directly related
Definition
 power, amplitude, intensity
Term
 Period and ___________ have a reciprical relationship
Definition
 frequency
Term
 Intensity is the concentration of power in the beam. What is the formula?
Definition
 Intensity (w/cm^2)=power/beam area
Term
 DESCRIBING PULSED WAVESShallow Imaging Deeper ImagingLess Listening More ListeningShorter PRP Longer PRPHigher PRF Lower PRFHigher Duty Factor Lower Duty Factor
Definition
 Because the sonographer has the ability to change depth, they are controlling: PRP, PRF, and the Duty Factor
Term
 Reporting Intensities- Bio problemsSpatialTemporalPeakAveragePulsed
Definition
 -refers to distance or space-all time, transmit and receive-max value-mathmatically middle value-only transmit time *is the avg intensity for the pulse duration
Term
 Measuring Intensity- BioeffectsSpatial or TemporalPeak or AvgWhich is most relevant in tissue heating?
Definition
 SPTA
Term
 Which intesity has the highest/ lowest intensity?
Definition
 SPTP has the highestSATA has the lowestall intensities have units of watts/cm^2
Term
 If amplitude is increased by a factor of 4, what is the change in power?
Definition
 4x4= 16 timespower is proportional to amp^2
Term
 Intensity is directly proportional to power. One inc, the other inc. What are power and intensity proportional to?
Definition
 Amplitude^2
Term
 Wavelength is soft tissue
Definition
 .15- .8mm
Term
 The higher the frequency, the __________ the wavelength and ___________ quality of pictures.
Definition
 shorterhigherThe lower the frequency, the longer the WL
Term
 Frequency is measured in Hz which is another way of saying what?
Definition
 Number of cycles per second
Term
 Related or Unrelated?PRP and Period Frequency and SpeedFrequency and IntensityFrequency and PowerDuty Factor and DepthPRF and PRPPRP and Depth
Definition
 UnrelatedUnrelatedunrelatedUnrelatedInversely RelatedInversely RelatedDirectly Related
Term
 Number of Cycles X Period=# cycles/frequency=
Definition
 Pulse DurationTypically .3-2 microseconds
Term
 Transmit time + Receive time, can be changed by sonographer
Definition
 Pulse Repetition Period- it is directly related to depth so the sonographer has the ability to adjust
Term
 % or fraction of time actually spent working. Ranges from .002-.005 or .2%-.5%
Definition
 Duty FactorPulse duration/PRP x 100= Duty Factor
Term
 SpeedAir 330 m/sWater 1480 m/sMetals 2000-7000 m/sBone 3500 m/s
Definition
 Speed is deternimed only by the mediumStiffness and Speed are directly relatedDensity and Speed are inversley related
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