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151 Cards in this Set
- Front
- Back
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define unrelated?
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two items that are not associated.
ex: hair color & shoe size |
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define directly related or directly proportional?
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two items that are associated such that when one item increases the other increases.
ex: clothing size to one's weight |
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define related or proportional?
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two items that are associated oor affiliated. relationship does not have to be specific.
ex: Santa to Christmas |
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define inversely related or inversely proportional?
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two items are associated such that when one increases, the other decreases.
ex: car's gas mileage to engine size |
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define reciprocal relationship?
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when two numbers with a reciprocal relationship are multiplied together the result is one.
ex: 2 and 1/2 |
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what does increase by a factor imply?
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multiplication
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what does decrease by a factor imply?
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division
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what is the unit for a number followed by a percent sign?
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unitless
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what are the units associated with length?
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meter, centimeter, feet etc
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what are the units associated with area?
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cm2, ft2,
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what are the units of volume?
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cm3, ft3
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what does 10^9 or giga stand for?
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G or a billion
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what does 10^6 or mega stand for?
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M or a million
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what does 10^3 or kilo stand for?
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k or a thousand
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what does 10^2 or hecto stand for?
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h or a hundred
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what does 10^1 or deca stand for?
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da or ten
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what does 10^-1 or deci stand for?
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d or tenth
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what does 10^-2 or centi stand for?
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c or hundredth
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what does 10^-3 or milli stand for?
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m or thousandth
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what does 10^-6 or micro stand for?
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u or a millionth
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what does 10^-9 or nano stand for?
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n or billionth
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sound is considered what kind of wave in whih particles in the medium move?
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mechanical
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all waves carry what?
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energy
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in ultrasound, sound pulses travel through biologic tissue or?
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media
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sound cannot travel through what?
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a vacuum.
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the squeezing together of molecules is called?
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compression
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the stretching of molecules is called?
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rarefaction
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compression and rarefaction are necessary for sound to do what?
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move through a medium
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in what direction does sound travel?
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a straight line
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what kind of waves are sound waves?
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longitudinal
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what are the three acoustic variables? and what are they used for?
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pressure, density and distance. they are used to distinguish between sound waves and ther types of waves.
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what are the units for pressure?
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pascals Pa
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what are the units for density?
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kg/cm^3
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what are the seven acoustic parameters?
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period
frequency amplitude power intensity wavelength propagation speed |
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how do particles move in a transverse wave?
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they move in a direction that is perpendicular to the direction that the wave propagates.
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how do particles move in a longitudinal wave?
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in the same direction that the wave propagates.
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what are in phase waves?
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waves that have their peaks at the same time and the same location. aka in step
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what are out of phase waves?
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two waves that have their peaks occurring at different times and so do their troughs. aka out of step
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what is interference??
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when more than one wave arrives at an identical location at the exact same time and they combine to form a single wave.
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what is constructive interference?
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a pair of in phase waves resulting in the formation of a single wave of greater amplitude than either of its components.
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what is destructive interference?
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the resultant wave is small than one of its components. caused by out of phased wave.
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what are parameters?
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they describe features of a sound wave
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tissue is also called?
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the medium
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what is period?
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the time it takes a wave to vibrate a single cycle, or the time from the start of a cycle to the start of the next cycle.
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what units is period reported in?
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seconds
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what determines period?
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the sound source only and cannot be changed by the sonographer
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what is frequency?
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the number of particular events that occurs in a specific duration of time.
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what units are frequency reported in?
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herz (Hz) = 1cycle/second
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what determines the frequency of a sound wave?
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sound source only and is not adjustable.
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when the frequency of a sound wave is less than 20Hz it is considered?
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infrasound
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what is the range for audible sound?
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between 20 Hz and 20kHz
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what is the range for ultrasound?
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greater than 20 kHz.
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how does frequency effect diagnostic sonography?
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it affects the penetration and image quality.
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how are period and frequency related?
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inversely
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as frequency increases what happens to period?
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it decreases
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as period increases what happens to frequency?
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it decreases
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if period remains unchanged what happens to frequency?
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it remains unchanged
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what kind of other relationship does frequency and period have?
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reciprocal.
period x frequency = 1 |
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what are the three parameters that describe the bigness of the wave?
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amplitude
power intensity |
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what is amplitude?
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the bigness of a wave. it is the difference between the maximum value and the average value.
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what are the units of amplitude?
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can assume any unit of any of the acoustic variable. pa, g/cm^3, m, etc
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what determines amplitude?
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the sound source controls amplitude, but it can be adjusted by the sonographer.
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what is the formula for amplitude?
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maximum value - average value or
minimum value - average value |
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what is power?
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the rate of energy transfer or rate at which work is performed.
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what are the units for power?
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watts
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what determines power?
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the sound source determines the power, but it can be adjusted by the sonographer.
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how are power and amplitude related?
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power is proportional to the amplitude.
power = amplitude^2 |
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what is the formula for power?
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power=amplitude^2
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what is the formula for frequency?
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1/period
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what is the formula for period?
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1/frequency
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what is intensity?
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the concentration of energy in a sound beam.
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what are the units associated with intensity?
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watts/square centimeter
W/cm^2 |
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what is the formula for intensity?
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power/area or amplitude^2/area
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what determines intensity?
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initially the sound source, but intensity changes as it propagates through a medium. it is adjustable by the sonographer.
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how is intensity related to power?
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intensity is proportional 'to power
ex: if a wave's power is doubled , the intensity is doubled. |
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how is intensity related to amplitude?
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intensity is proportional to amplitude squared.
intensity=amplitude^2 |
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what is wavelength?
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the distance or length of on complete cycle.
ex: a train, wavelength is the length of one boxcar in a train. |
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what is wavelength measured in?
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meters
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what determines wavelength?
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the source and the medium
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Is wavelength adjustable?
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no
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what is the formula for wavelength?
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velocity/frequency
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what is the relationship between wavelength and frequency?
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inversely related as long as the wave remains in one medium.
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what is the speed of sound in soft tissue?
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1540 m/s
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why is wavelength important in ultrasound?
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shorter wavelengths produce higher quality images with greater detail
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what produces a shorter wavelength?
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higher frequency probes
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what is propagation speed?
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the distance that a sound wave travels through a medium in one second
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what are the units associated with propagation speed?
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m/s
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what determines propagation speed?
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the medium and it can not be adjusted by the sonographer.
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what is the speed of sound through air?
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330 m/s
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what is the speed of sound in fat, liver, blood, muscle, tendon and bone?
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1450 m/s, 1560 m/s, 1560 m/s, 1600 m/s, 1700 m/s, 3500 m/s
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sound travels faster in what substance?
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sound travels the fastest through a solid substance, slower in liquids, and the slowest through gases.
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what is the formula for velocity?
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speed (m/s) = frequency x wavelength
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what are the two characteristics of a medium that affect the speed of sound?
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stiffness and density
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what is stiffness?
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it described the ability of an object to resist compression.
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how does stiffness affect speed?
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they are directly related. as materials become more stiff, the speed of sound in the material increases.
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the degree of stiffness may also be described with the terms?
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elasticity or compressibility which are the opposite of stiff
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what is density?
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the relative weight of a material.
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how does density affect speed?
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they are inversely related. as materials become more dense (heavier), the speed of sound in the material decreases.
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if two media are equally stiff which one will have a lower speed?
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the denser medium will have a lower speed
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what is the rule of thumb for remembering stiffness and density?
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stiffness and speed both start with "S". Stiffness increases, speed increases.
Density increases, speed decreases |
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what are the parameters that can be adjusted by the sonographer?
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amplitude, power and intensity
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what are the parameters that cannot be adjusted by the sonographer?
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period, frequency, wavelength, speed
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what parameter is determined strictly by the medium?
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speed
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which parameter is determined by the medium and the source?
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wavelength
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which parameters are determined by the source?
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period, frequency, amplitude, power and intensity
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what are bioeffects?
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the effects of the sound wave on tissue in the body
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what are acoustic propagation properties?
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the effects of tissue unsound waves.
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what is pulsed sound?
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a collection of cycles that travel together. they must have a beginning and an end. it moves as a single unit.
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what are the two components of pulsed ultrasound?
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transmit or "on" time
receive or "off" time |
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what is the percentage of time that the pulsed sound is talking?
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99.9%
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what is pulse duration?
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the actual time from the start of a pulse to the end of that pulse. it is a single transmit, talking or "on" time
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what are the units of pulse duration?
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time: seconds
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what determines pulse duration?
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the sound source only and is not adjusted by the sonographer
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what is the formula for pulse duration?
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# of cycles x period
#cycles/frequency (MHz) |
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what is the relationship of pulse duration and #of cycles, period and frequency?
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directly proportional to the # of cycles in the pulse.
directly proportional to the period inversely related to the frequency |
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what are the two characteristics that create pulses of long duration?
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many cycles in the pulse or
individual cycles with short periods |
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what are the two characteristics that create pulses of short duration?
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few cycles in the pulse or
individual cycles with short periods |
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what is spatial pulse length?
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the distance that a pulse occupies in space from the start to the end of a pulse.
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what are the units associated with spatial pulse length?
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meters
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what determines spatial pulse length?
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the source and the medium. it is not adjustable by the sonographer.
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what is the formula for spatial pulse length?
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# of cycles x wavelength
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what is the difference between pulse duration and pulse length?
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pulse duration is the time a pulse is on. pulse length is the distance of the pulse end to end
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what is pulse repetition period?
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the time from start of one pulse to the start of the next pulse. it includes one pulse duration plus one listening time.
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what are the units associated with pulse repetition period?
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seconds
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what determines pulse repetition period?
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sound source only and is adjustable by the sonographer
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Is PRP related to period??
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No! PRP is unrelated to period.It is related only to depth of view.
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what is depth of view?
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it describes the maximum distance into the body that an ultrasound system is imaging.
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how are pulse repetition period and depth of view related?
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as depth of view increases, pulse repetition period increases.
as depth of view decreases, pulse repetition period decreases. THEY ARE DIRECTLY RELATED |
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transmit time is also called
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pulse duration
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what happens to the listening time with deeper imaging?
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the listening time and the pulse repetition period lengthen
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what is the formula for pulse repetition period?
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1/pulse repetition frequency
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when the sonographer alters imaging depth what part is changed?
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only the listening time portion of the pulse repetition period
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what is pulse repetition frequency?
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is the number of pulses that an ultrasound system transmits into the body each second.
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what is the formula for pulse repetition frequency?
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1/pulse repetition period
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what are the units associated with pulse repetition frequency?
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Hertz (Hz)
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what determines PRF?
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the sound source only and it is adjustable by the sonographer
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how are pulse repetition frequency and depth of view related?
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they are inversely related.
as depth of view increases, pulse repetition decreases. as depth of view decreases, pulse repetition increases. |
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what is the relationship between pulse repetition period and pulse repetition frequency?
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they are inversely related.
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what is duty factor?
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is the percentage or fraction of time that the system is transmitting a pulse.
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what are the units associated with duty factor?
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none
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what determines duty factor?
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source only and it is adjustable by the sonographer.
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how is duty factor and imaging depth related?
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inversely. duty factor is higher when the system is imaging at shallow depths, and lower when imaging to greater depths.
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what is the formula for duty factor?
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(%) = pulse duration/prp x 100
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what are the maximum and minimum values for duty factor?
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max is 1 or 100% and the minimum is 0% or 0.2%
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shallow imaging produces?
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less listening
shorter PRP higher PRF higher duty factor |
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deeper imaging produces?
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more listening
longer PRP lower PRF lower duty factor |
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by changing imaging depth, the operator changes?
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prp, prf, duty factor,
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what parameters are adjustable by the sonographer?
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prp, prf, duty factor
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what parameters are not adjustable?
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pulse duration, spatial pulse length
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which parameters are determined by source?
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pulse duration, spatial pulse length, duty factor, PRP, PRF
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what parameter is determined by both source and medium??
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spatial pulse length
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