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300 Cards in this Set
- Front
- Back
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the_ axis or _ runs side to side.
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x-axis
horizontal |
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the _ axis or_ runs up and down.
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y- axis
vertical |
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two iteams that are not associated
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unrelated
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two iteams that are associated or affilliated
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related
proportional |
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two iteams that are associated. such that when one increases the other increases.
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directly related
directly proportional |
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two iteams are associated such as one iteam increases and the other decreases.
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inversely related
inversely proportional |
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when two numbers with a reciprocal relationship are multiplied together, the result is one.
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reciprocal
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units for length, distance, circumference
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cm, feet
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unit for area
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cm2 ft2
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unit for volume
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cm3 ft 3
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Increase by a factor mean
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to multiply by that number
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decreases by a factor mean
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to divide by that number
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a number followed by the word percent is_
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unitless
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a number in scientific notation form with a _ exponent has a value _
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positive
greater than 10 |
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a number in scientific notation form with an _ has a value between _ and _
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exponenet of zero
between 1 and 0 |
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1,000,000
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1.0 x 10 6
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0.000000124
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1.24 x 10-7
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1742
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1.742 x 103
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metric system
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g m k h da d c m u n
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in diagnostic ultrasound sound pulses travel through _ _ or _
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biological tissue
media |
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reflections arising from structures in the body return to the _ and are processed into _
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transducer
images |
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all waves carry _ from one location to another
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energy
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many different forms of waves exist including _,_,_,_
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heat sound
magnetic light |
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sound is a _ wave in which particles in medium move
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mechanical
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the _ in the medium vibrate back and forth from a fixed position
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molecules
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sound can not travel through a _
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vacuum
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sound must travel through a _ where molecules are alternately _ and _
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medium
compressed ( max) ( squeezed together) rarefied (min) stretched apart |
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sound travels in a _ line
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straight
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sound waves are _ waves
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longitudinal
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the effects of a medium upon a sound wave_
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acoustic propagation properties
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what are the efftects of the sound wave upon biologic_
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biological effect
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sound waves are identified by _ in a acoustic variables
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oscillations
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what are three acoustic variables
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pressure
density distance |
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definition for pressure and what is the unit
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concentration of force in an area
unit pascals |
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definition for density and the unit
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concentration of mass in a volume
unit kg/cm 3 |
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if one of these acoustic variables has a rhythmic oscillation than the wave is a _ wave
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sound
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if something other than pressure density or distance rhymically oscillates in a wave is _ a sound wave.
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not
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sound waves are also known as _ _
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acoustic waves
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after a wave is identified as a sound wave it is important to describe the waves _
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features
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seven _ _ are used to accurately describe the characteristics of a sound wave
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acoustic parameters
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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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in a transvers wave the particles in a direction that is _ to the direction of the wave.
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perpendicular
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in a _ _ particles move in the same direction that the wave propagates.
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longitudinal waves
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a pair of waves are considered _ _ when their peaks and troughs occur at the same time and the same location
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in phase
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more than one sound beam may travel in a _and on occasion multiple beams may arrive at an identical location at exactly the same time
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medium
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the waves lose their individual characteristics at that moment and combine to form a _ wave this combination is called_
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single
interference |
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both in phase and out of phase wave pairs undergo _ however, they combine_
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interference
differently |
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the interference of a pair of in phase waves results in a formation of a single wave greater amplitude is_
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constructive interference
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the interference of a pair of out of phase waves result in the formation of a single wave of lessor amplitude is_
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distructive interference
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waht happens when both frequencies of the waves differ
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both constructive & distructive interference
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_ describe features of a sound wave.
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parameters
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the _ of a sound wave is u.s system and transducer
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source
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the tissue is also called the _
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medium
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_ is 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
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period
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units for period
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sec, msec usec
t=1/f |
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period is determined by _ only
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source
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period is not _
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adjustable
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_ is the number of particular events that occur in a specific duration of time
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frequency
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units for frequency
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hz khz mhz
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frequency is determined by_
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source
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frequency is not _
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adjustable
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infrasound or infrasonic is
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less than 20hz
below human hearing |
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audible sound is
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20hz- 20khz
human hearing |
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ultrasound is
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greater than 20khz
above human hearing |
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period and frequency are _related to each other
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inversely
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period and frequency are _
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reciprocal
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three parameters describe the size or magnitude or strength of a sound wave
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amplitude
power intensity |
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_ is the bigness of a wave
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amplitude
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amplitude is the _ between the maximun value and the average or undisturbed value of an acoustic
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difference
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_ is also the difference between the minimum value and the average value of the acoustic variable
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amplitude
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_ _ _ _ is the difference between maximum and minimum values of an acoustic variable
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peak to peak amplitude
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therefore peak to peak amplitude is_ the value of the amplitude
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twice
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_ rate of energy transfer or the rate at which work is performed
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power
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units for power
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watts
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power is determined by _
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source
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_is the concentration of energy in a sound beam
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intensity
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_ relates to how the power in a wave spreads or is ddistributed in space
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intensity
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intensity depends on_
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power in the beam and area
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intensity is determined by _
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source
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intensity is _
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adjustable
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amplitude, power and intensity are three parameters that describe the _ or _ of the wave
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magnitude
strength |
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_ is the distance or length of one complete cycle
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wavelength
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wavelength units
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m,cm,mm
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wavelength is not _
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adjustable
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wavelength & frequency are _ related
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inversely
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the _ the frequency the _ the wavelength
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lower
longer |
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__ is the distance that a sound wave travels through a medium in 1 second
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propagation speed
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speed is ,measured in units of_
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per second
mm, us and distance divided by time |
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speed is determined by _ only
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medium
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speed is not affected by the nature of the
_ _ |
sound wave
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all speed regardless of the frequency travels at the _ speed through any specific medium.
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same
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speed is not _
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adjustable
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what si the speed of soft tissue _ _ _
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1540 m/s
1.54 u /sec 154,000 cm/sec |
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speed =
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frequency x wavelength
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order of speeds of sound in biological tissues from low to high
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air lung fat water brain soft tissue liver kidney blood muscle tendon bone
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what are the two characteristics of a medium affect the speed of sound
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stiffness& density
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_ describes the ability of an object to resist compression
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stiffness
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stiffness& speed are _ related
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directly
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as materials become_ the speed of sound in the material_
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stiffer
increases |
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_describes the relative weight of a material.
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density
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density and speed are _ related
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inversely
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speed is determined by the _ and _ of the medium
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density and stiffness
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materials that are _ but not dense will have the fastest speed
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stiff
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materials that are not as _ and very dense will have the slowest speed
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stiff
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_ has an exceedingly low stiffness
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air
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five additional parameters needed to completely describe _ _
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pulsed sound
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in diagnostic u.s _ _ sound cannot create anatomic images
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continuous wave
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rather, imaging systems produce short burst or pulses_ _ to create every picture of anatomy
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acoustic energy
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what is pulsed sound
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a pulse of u.s is a collection of cycles that travel together
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_ must have a begining and a _
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pulse
end |
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although a pulse is made up of individual cycles the entire pulse moves as a _ _
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single unit
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pulsed ultrasound has two components _ and _
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on transmit talking time
off receive listening time |
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_ _ is the actual time from the start of the pulse to the end of that pulse
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pulse duration
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_ _ is a single transmit talking or on time
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pulse duration
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pulse duration units
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sec msec usec
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pulse duration is not
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adjustable
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pd _ x_
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# of cycles x period
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pd = _ / _
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# of cycles / frequency
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pulse duration is directly related to
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# of pulses in a cycle
period |
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pulse duration is inversely related to
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frequency
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what two characteristics create pulses of long duration
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many cycles in the pulse
individual cycles with long periods |
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what are two characteristics create pulses of short duration
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few cycles in a pulse
individual cycles with short periods |
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in clinical imaging a pulse typically contains _ to _ cycles
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2 - 4
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which type of pulse is more desirable in diagnostic imaging why ?
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short duration pulses
because they create of greater accuracy |
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_ _ _ is the distance that a pulse occupies in space from start to the end of a pulse
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spacial pulse length
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what are the units of spl
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mm
any units of distance |
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spl is determined by _and _
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source and medium
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spl is not _
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adjustable
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spl= _x_
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# of cycles x wavelength
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spl is directly related to _ +_
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# of cycles
wavelength |
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what two characteristics create pulses of long duration
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many cycles in the pulse
individual cycles with long periods |
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what are two characteristics create pulses of short duration
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few cycles in a pulse
individual cycles with short periods |
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in clinical imaging a pulse typically contains _ to _ cycles
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2 - 4
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which type of pulse is more desirable in diagnostic imaging why ?
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short duration pulses
because they create of greater accuracy |
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_ _ _ is the distance that a pulse occupies in space from start to the end of a pulse
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spacial pulse length
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what are the units of spl
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mm
any units of distance |
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spl is determined by _and _
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source and medium
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spl is not _
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adjustable
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spl= _x_
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# of cycles x wavelength
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spl is directly related to _ +_
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# of cycles
wavelength |
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spl is inversely related to _
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frequency
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two characteristics create long pulses
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many cycles in a pulse
cycles with longer wavelength |
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_ _ _ is the time from the start of the pulse to the start of next pulse
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pulse repetition period
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prp includes on _ _ plus on _ _
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pulse duration
listening time |
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units for prp
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ms
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prp is determined by _ + _
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source and imaging depth
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prp is
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adjustable
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the depth of view describes the
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maximum distance into the body that an ultrasound system is imaging
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t or f does the sonographer contro; the depth of view
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tru
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prp and imaging depth are
__ related |
directly
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as depth of view increases prp _
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increases
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what are two components of prp
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transmit time
receive time |
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transmit time is called the _ _
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pulse duration
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the sonographer can not change the _ _ because it is characteristic of the transducer and has a fixed volume
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pulse duration
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the transducer is receiving signals from reflections in the body during the _ _
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listening time
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by changing the _ _ sonographers alter the depth of the image
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listening time
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with a deeper imaging the listening time and the prp _
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lengthen
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with shallow imaging the listening time and the prp _
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shorten
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only the listening time portion of the prp is changed when the sonographer alters the _ _
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imaging depth
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prf is defined by
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number of pulses that an u.s system transmit into the body each second
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prf units
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hz,khz, mhz
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prf is determined by
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source and imaging depth
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prf is _
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adjustable
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when the system is imaging _ the prf is _
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shallow
high |
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when the system is imaging _ the prf is lower
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deeper
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prf is unrelated to _
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frequency
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prf + depth of view are _ related
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inversely
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prp + prf are _ related
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inversely
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when the pulse repetition frequency _ the repetition period _
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increases
decreases |
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the pulse repetition period and pulse repetition frequency have a special relationship called a _
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reciprocal
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_ _ is the percentages or fraction of time that the system is transmitting a pulse
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duty factory
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what are units for duty factor
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none
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df is determined by
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source
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df is
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adjustable
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df= _ / _ x _
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pd / prp x 100
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with shallow imaging
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less listening
shorter prp higher prf higher duty factor |
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with deeper imaging
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more listening
longer prpr lower prp lowere duty factor |
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parameters that describe pulsed and continuous waves
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period
frequency wavelegnth propagation speed ngth |
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by adjusting the imaging depth the operator changes
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prp
prf df |
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intensities may be reported in various ways with respect to _ + _
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time and space
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the different measurements of intensities are important in the study of _
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bioeffects
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_ intensity is the most relevant intensity with respect to tissue heating
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SPTA
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all intensities have units of
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watts /cm 2
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because peak measurements are larger than average measurements_ intensity has the highest value and _ has the lowest value
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sptp
sata |
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what number describes the spread of a beam in space
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beam uniformity coefficient or sp/sa factor
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unit for sp/sa
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unitless
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the _ _ describes the relationship of beam intensities with time
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duty factor
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for continuous wave u.s the beam is always _
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on
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forcont wave u.s pulse average and temperal avg intensities are the _
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same
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thus spta =
and sata = |
sppa
sapa |
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when pulsed and cont wave sound have the same _ intensities the cont wave beam has the higher _ intensity
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satp
sata |
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the rank of intensities from largest to smallest
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sptp sppa spta sata
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which intensitiy is most related to tissue heating
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spta
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as sound travels in the body it weakends or _
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attenuates
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after a sound wave is received by a transducer, converted into electricity and returned to the u.s system it is strengthened or _
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amplified
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a standard measurement tool called _ _ is used to report these changes
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decibel notation
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decibals are based on a mathematical construct called_
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logarithms
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the _ is a novel method of rating numbers
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logarithm
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log 1 = log 2= log 4= log 1/2 =
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0, 0.3, 0.6, -0.3
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decibel notation is _
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logarithmic
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decibal notation does not measure absolute number rather decibels report _ _
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relative change
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since decibels are always comparisons _ intensities are required to use decibels
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two
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the two intensities are the _ ( or starting level) and the actual level at the time of measurement
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reference
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decibelsa are a _ the actual level is divided by the starting level
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ratio
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postitive decibels report signals that are _ in strength or getting _
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increasing
larger |
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when the wave intensitiy doubles the relative change is
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+ 10 db
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negative decibels describe signals that are _ in strength or getting_
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decreasing
smaller |
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when the wave intensity is reduced to half its original value the relative change is
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-3 db
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a sound wave _ as it propagates in a medium
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weakens
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this decrease in intensity power and amplitude is called
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attenuation
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attenuation is determined by two factors
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path length
frequency of sound |
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the further the sound travels the _ the attenuation and the _ the beam becomes
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greater
weaker |
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distance and attenuation are _ related
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directly
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attenuation in soft tissue depends upon the waves _
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frequency
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frequency and attenuation are _ related
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directly
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_ is measured in decibels and reported as a relative change, not as an absolute change
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attenuation
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more attenuation requires
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long distance
higher freq |
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less attenuation requires
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shorter distance
low freq |
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attenuation and propagation speed are_
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unrelated
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three processes that contribute to attenuation
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reflection
scattering absorption |
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_ is likely to occur when the dimension of the boundary is larger
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reflection
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two forms of reflection
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specular and diffuse
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when the boundary is smooth the sound is reflectedon only one direction is an organized manner
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specular
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one limitation of specular reflection is that once the wave is slightly off axis the reflection does _ return to the transducer
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not
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when a wave reflects off an irregular surface it radiates in more than one direction is called
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diffuse reflection
or back scatter |
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the advantage of diffuse reflections that
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interfaces at subotimal angles to the sound beam can still produce reflections that the transducer will recieve
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the disadvantages of diffuse reflections that
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backscatter signals have a lower strength than specular reflections
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_ of ultrasound is the random redirection of sound in many directions
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scattering
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sound scatters when the tissue interface is _ that is equal to or less the wavelength of the incident sound beam
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small
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_ frequency sound beams scatter more than _ frequency beams
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higher
lower |
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scattering is _ related to frequency
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directly
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_ _ is a special form of scattering that occurs when the structures dimensions are much smaller than the beams wavelength
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rayleigh scattering
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rayleigh scattering redirects the sound wave _ in all directions
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equally
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_ results in rayleigh scattering
|
rbc
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rayleigh scattering increases dramtically with _ frequency
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increasing
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scattering is related to _ raised to the power of 4
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frequency
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when frequency doubles rayleigh scattering is _ times greater
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16
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_ occurs when ultrasonic energy is converted into another energy form such as heat
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absorption
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absorption is _ related to frequency
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directly
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as a result of absorption _ frequency waves attenuate more than lower frequency
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higher
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sound travels in _ undergoes extensive absorption
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bone
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_ is a process whereby sound energy is extracted from a wave by absorption scatteringand reflection
|
attenuation
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total attenuation depends upon the _ of sound and the _ the beam travels
|
frequency
distance |
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a term tha has simplified the reporting of attenuation is the _ _
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attenuation coefficient
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_ _ is the number of decibels of attenuation that occurs when sound travels one centimeter
|
attenuation coefficient
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what are the units for attenuation coefficient
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db/cm
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if sound travels to a depth of 5 cm the attenuation coefficient remains 2 db/cm and the total attenuation of the beam is
|
10 db 5 x 2
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total attenuation =
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atten coeff x distance
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attenuation coefficient and the frequency are _ related
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directly
|
|
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the attenuation coefficient is one half of the _
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frequency
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attenuation coefficient =
|
freq/2
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_ has an extremely high attenuation
|
air
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_ attenuate dramatically because of scattering and absorption
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lung
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_ absorbs ultrasound energy to a large extent, which results in substantial _
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bone
attenuation |
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this attenuation is for less than that found in _ _
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soft tissue
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_ attenuates twice as much when traveling accross the fibers as when traveling along the length of the fibers
|
half value layer thickness
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half value layer may also be described as the _ of tissue that result in _ db
|
depth
3 |
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units for half value layer are
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centimeters or any unit for distance
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other names for half value layer thickness
|
penetration depth
depth of penetration holf boundary layer |
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the half value layer thickness depends on two factors
|
medium
frequency |
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high frequency sound also results in _ half valuse layer
|
thin
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low frequency sound also results in _ half value layer
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thick
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the _ produced as sound moves from one medium to another forms tha basis for ultrasonic imaging
|
reflection
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_ is critical to u.s ability ti image structures located eep in the body
|
transmission
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the _ _ is an important tissue property that influences the amount of reflection
|
acoustic impedance
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_ is the acoustic resistance to sound traveling in a medium
|
impedance
|
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impedance =
|
density x speed
|
|
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impedance is a characteristic of the _ through which sound travels
|
medium
|
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_ of an u.s. wave depends upon the difference in acoustic impedances of the two media at a boundary
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impedance
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units for impedance=
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rayls
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impedance is determined by
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medium
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a tissues impedance is _ not measured
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calculated
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the _ at which the wave strikes the boundary determines the behavior of the pulse
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angle
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three types of angles
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acute
right obtuse |
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angles with measure other than 90 degrees are also called _ angles
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oblique
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_ _ means that the incident sound beam strikes the boundary at excatly 90 degrees
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normal incidence
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normal incidence is also called
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perpendicular
orthogonal right angle 90 degrees |
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_ _ occurs when the incident sound beam strikes the boundary at any angle other than 90 degree
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oblique incidence
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other names for oblique
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not a right angle
non - perpendicular |
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a _ wave propagating through the body will eventually strike a boundary between two media
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sound
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the pulse may then divide into two parts with one part redirected _ and the other continuing in the _ direction
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backward
forward |
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incident intensity is the sound waves intensity immediately _ it strikes a boundary
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before
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reflected intensity is the intensity of the portion of the incident soound beam that _ striking a boundary returns back in the direction from which it came
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after
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transmitted intensity is the intensity of the portion of the incident beat that _ striking a boundary _ _ in the same general direction tha it was traveling
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after
continues forward |
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there is conservation of _ at the boundary
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energy
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as a result incident intensity = _ + _
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reflected + transmitted
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the _ of the intensity tha bunces back when a sound beam strikes the boundary between two media is intensity reflection coeffecient coeffifient
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percentage
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in clinical imaging _ _ of a sound waves intensity is reflected at a boundary between two soft tissues
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very little
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a _ percentage of the wave is reflected when sound strikes a boundary such as between soft tissue and bone or between soft tissue or air
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greater
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the _ of u.s intensity that passes in the forward direction when the beam strikes on interface between two media is called ITC
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percentage
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_ of the sound wave intensity is trnsmitted at a boundary between soft tissue
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smaller
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the coefficiant _ and _ are both reported as percentages and are therefore dimentionless
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IRC + ITC
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as sound beam strikes a boundary _ is conserved
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energy
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IRC+ ITC =
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100 %
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what happens at the boundary between two media
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conservation of energy
reflected + transmitted = incident irc +itc = 100 % |
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intensities are reported with
units of _ |
w/cm2
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when a sound beam strikes a tissue boundary at a 90 degree angle reflection occurs only if the media on either side of the boundary have _ _
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different impedances
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the percentage of the incident beam that is reflected is related to the difference in the _ of the tissue
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impedances
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no _ will occur if the two media have identical impedances
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reflection
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a _ reflection will occur if the impedances are slightly different
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small
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