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SonoPhysics unit 2

chp9-13

QuestionAnswer
A device that converts one form of energy into another Transducer
Electrical energy from the system is converted into sound Transmission
Reflected sound pulse is converted into electricity Reception
What effect describes the property of certain materials to create a voltage when they are mechanically deformed piezoelectric effect
What is it called when piezoelectric materials change shape when voltage is applied to them? Reverse piezoelectric effect
what is it called when materials which covert sound inot electricity and vice versa piezoelectric or ferroelectric
what piezoelecgtric materials are manmade an?d found in clinical transducers lead zirconate titanate or pzt
What is PZT in an ultrasound transducer also known as ceramic, active element or crystal
Ultrasound transducer transmit what and coverts to what from electrical and converts to acoustic
Ultrasound X receive from what and converts to what Converts from acoustic to electrical
Car engine X converts from what to what chemical to motion
electric motor converts from what to what electrical to motion
lightbulb converts from what to what electrical to light and heat
muscle converts to what to what chemical to motion
Basic ultrasound X has the appearence of what cylindrical tube
The cylindrical tube, constructed out of metal or plastic , that protects the internal components of the X from damage, and also insulates the pt. from electrical shock is known as the case
what is the thin electrical barrier lining the inside of the case, that prevents spurious electrical signals in the air, unrelated to diagnostic info, from entering the X, also helping to prevent electrical noice from contaminating the the clinically impo the electrical shield
What is the thin barrier of cork or rubber that isolates or uncouples the internal components of the X from the case acoustic insulator
what prevents vibrations in the case from dnducing an electrical voltage in the pzt of the X acoustic insulator
what color is the acoustic insulator in most diagrams red
What is the PZT or active element the crystal itself
in a simple probe, the active element is shaped like what a coin
the characteristics of the sound beam emitted by the X are related to what the dim of the active element
the pzt is how thick and what color 1/2 wavelength thick, and is usually green
What provides an electrical connection btw the pzt and the system the wire
how does the wire work active element requires electrical contact so that during transmission the voltage from the US can cause the crystal to vibrate and produce an ultrasonic wave.
how does the crystal produce an image crystals vibration produces a voltage that must return to the system for processing into an image
what is positioned in front of the pzt at the face of the X the matching layer
what does the matching layer do increase the efficiency of the sound energy transfer btw the active element and the body, and protects the active element
how thick is the matching layer and how does it appear it is 1/4 thick and appears blue
what is bonded to the back of the active element? backing material, also known as damping element
what is backing material commonly made of epoxy resin impregnated with tungsten filaments
what happens when an electrical spike excites the PZT? backing material restricts the extent of the pzt deformation, emitted sound pulse is dampened;making short in duration and length
what does crystal dampening enhance axial res
what color does dampening material usually appear as yellow
what is the basic us x appearence cylindrical tube with sound pulse emitted from the front of the tube, which is placed on the skin and a wire connecting X to the US, extending from the back
What does the difference in impedance result from reflection at boundries
do larger reflections occur with smaller or larger impedences larger
how much greater is the impedence of the pzt vs the skin 20 times greater
How does the impedence of the matching layer work designed to be btw that of the active element and the skin, decreasing reflections at the skin/pzt boundry
what is the impedence btw the matching layer and the biologic media gel, it further increases the travel of sound into and out of the body
what is the greatest to least order of impedence pzt, matching layer, gel, skin
what is the backing materials essential role pulse creation for imaging X
what do long pulses do to axial res degrage them
what does damping material or backing material do to pzt crystal's ringing reduces it, making sound pulse short in length and duration, providing enhanced axial res
what are two charecteristics of dampening material high degree of sound absorption, and acoustic impedance similar to pzt
how does the damping element and pzt work similar, the sound wave created by pzt moves into the damping material and away from teh pt. sound energy is absorbed into the backing material.
what are additional consequences to backing material 1. decreased sensitivity 2. wide bandwidth 3. low quality factor
what is decreased sensitivity means X with this are less likely toconvert low level sound reflections to meaningful elect signals during recpt
what else does backing material reduce besides active element vibration during transmisstion vibration during reception too, making X less responsive
What is Resonant Frequency thwn tone is pure because it vibrates freely for a long time at a single freq
what inhibbits the cystal from vibrating freely backing material, it restricts the pzt
By the backing material restricting the pzt, what happens to the pulse emitted by the probe makes the pulse short in duration sound of a click vs steady tone
Does the sound click that results from the backing material restricting the probe above or below the X main freq both, sound at many different freq
what is bandwidth the range or difference btw the highest and lowest freq in a pulse
what is an imaging probe considered or id'd as with the bandwidth, short pulse, wide bandwidth, and sometimes appears green
Is Doppler short pulse and wide bandwidth No, long pulse, narrow bandwidth
does doppler use backing material no, that's what makes it have long pulses and narrow bandwidth
if a X has 3MHZ main freq that ranges 1MHZ to 5MHZ, what is the badwidth or range of freq 4, 5-1
what is the general rule for long and short duration events long, narrow bandwidth, short wide bandwidth
What is the quality factor unit and what is it related to unitless and related to bandwidth
what is the main freq divided by q factor being the main freq, is devided by the band width, QF=MF/BW
do wide bandwidth probes have high or low QF low
do narrow bandwidth X have high or low QF high
are imaging probes considered to have high or low QF
What does the difference in impedance result from reflection at boundries
do larger reflections occur with smaller or larger impedences larger
how much greater is the impedence of the pzt vs the skin 20 times greater
How does the impedence of the matching layer work designed to be btw that of the active element and the skin, decreasing reflections at the skin/pzt boundry
what is the impedence btw the matching layer and the biologic media gel, it further increases the travel of sound into and out of the body
what is the greatest to least order of impedence pzt, matching layer, gel, skin
what is the backing materials essential role pulse creation for imaging X
what do long pulses do to axial res degrage them
what does damping material or backing material do to pzt crystal's ringing reduces it, making sound pulse short in length and duration, providing enhanced axial res
what are two charecteristics of dampening material high degree of sound absorption, and acoustic impedance similar to pzt
how does the damping element and pzt work similar, the sound wave created by pzt moves into the damping material and away from teh pt. sound energy is absorbed into the backing material.
what are additional consequences to backing material 1. decreased sensitivity 2. wide bandwidth 3. low quality factor
what is decreased sensitivity means X with this are less likely toconvert low level sound reflections to meaningful elect signals during recpt
what else does backing material reduce besides active element vibration during transmisstion vibration during reception too, making X less responsive
What is Resonant Frequency thwn tone is pure because it vibrates freely for a long time at a single freq
what inhibbits the cystal from vibrating freely backing material, it restricts the pzt
By the backing material restricting the pzt, what happens to the pulse emitted by the probe makes the pulse short in duration sound of a click vs steady tone
Does the sound click that results from the backing material restricting the probe above or below the X main freq both, sound at many different freq
what is bandwidth the range or difference btw the highest and lowest freq in a pulse
what is an imaging probe considered or id'd as with the bandwidth, short pulse, wide bandwidth, and sometimes appears green
Is Doppler short pulse and wide bandwidth No, long pulse, narrow bandwidth
does doppler use backing material no, that's what makes it have long pulses and narrow bandwidth
if a X has 3MHZ main freq that ranges 1MHZ to 5MHZ, what is the badwidth or range of freq 4, 5-1
what is the general rule for long and short duration events long, narrow bandwidth, short wide bandwidth
What is the quality factor unit and what is it related to unitless and related to bandwidth
what is the main freq divided by q factor being the main freq, is devided by the band width, QF=MF/BW
do wide bandwidth probes have high or low QF low
do narrow bandwidth X have high or low QF high
are imaging probes considered to have high or low QF low because they have backing material and wide bandwidth
Does Doppler have high or low QF High, no backing material and narrow bandwidth
if a 3mhz X with a band width of 4mhz, what is the qf 3/4 or .75 main freq/bandwidth
parameters of imaging X pulse with short duration and length, uses backing material to limit ringing, reduced sensitivity, wide BW, lower QF, improved axial res
non imaging X, like doppler creates CW or pulses with long duration and lenth, no backing mat, inc sensitivity, narrow BW, high QF, does not even make an image
shorter pulses have lower or higher q factor low
longer pulses have lower or hight qfactor high
how are pzt created expose material to a strong elect field at hi substantial temp, called polarization
what is polarization exposing material to a strong electrical field while heating them at high temp
what is the temp that the pzt is poloarized curie temp, or curie point
How do you destroy PZT exposure to high temp, above the curie point
what is depolariztion above the curie point, when the PZT properities are lost
Sterilization vs. Disinfection sterilization is destroying all micro org, with heat, chem, radiation, disinfect chem agent attempts to reduce germs
what do you clean a X with Cidex or other cold germacides
pulse length is directly or inversly related to pulse duration directly
qfactor is directly or inversly related to bandwidth inversley
pulse duration is inversley or directly related to bandwidth inversely
CW wave X produces what kind of electrical signal continuous that excites the active elem
is the freq of the cw probe equal to the freq of the electrical signal yes elect freq = acoustic freq
a pw creates what kind of electrical spike short duration electrical spike, travels thru the wire and strikes the cystals in the X
what does the freq of sound created by the active element of a pw depend upon the charect of the active element in the X
what are the two Charect of pw X speed of the sound in the pzt, and thickness of the pzt
what kind of relationship does sound have in pzt with the freq direct relationship
if the sound in pzt is faster, what kind of freq of sound will the be pulsed by the pwX will be higher
what is the range of osund in most pzt materials 4-6mm/us, 4 times greater than the speed in soft tissue
can the speed be adjusted in the pzt no
how does the thickness of the pzt crystal affect the freq for pw, thinner creates higher freq, so they are inversly related, the thickness and freq
thinner active elements create what kind of wavelenths and pulses higher freq sound pulses, shorter wavelengths
what are charact of high freq PW X thinner pzt crystals, and pzt with higher speeds
what are charact of low freq PW X thicker pzt crystals and pzt with lower speeds.
what is the math relationship freq = sounds speed in pzt mm/us/2xthickness mm
what is the shape of the sound beam as it leaves the X the same as the diam of the X
what happens to the shape of the sound beam as it leaves the X and progesses it will narrow like a funnel until it reaches it's smallest diam, then it will start to expand or diverge
what are 5 terms that describe the shape of sound beam focus, near zone, focal length, far zone, focal zone
focus is also called focal point
where is the focus located where the beam diam is the narrowest, for a round disc shape it's 1/2 the width of the beam as it was when it left X
What is the near zone also called near field, or frenel zone
what is the region of the near zone from the X to the focus, the beam will gradually narrow to the near zone
in a disc shaped crystal, the beam leaves the X as the same diam as the active elem, but what happens at the end of the near zone the beam narrows to only 1/2 of the width of the active elem
is the focus located at the begining of the near zone or the end of the near zone end
what else is focal point called focal depth or near zone length
what is the focal length the distance from the X to the focus
Far zone is also called far field or Fraunhofer zone`
where is the far zone region starting at the focus and extending deeper
what happens to the beam within the far zone diverges or spreads out
what is the diam of the beam at the begininning of the far zone beam is 1/2 as wide as it is at the X
what happens to the beam when it's 2 near zone lengths beam is wider htan the active element
focal zone is what region around the focus where the beam is relatively narrow
what kind of images does the focal zone derrive more accurate images than those form other depths.
how much of the focal zone is located in the near field half
how much of the focal zone is located in the far field half
Focal zone can be known as a region where the beam is what an the image is what narrow and the image detail is superior
when the sound beam exits the probe, it goes into what zone, and what is the beam diam near or fresnal zone where the beam is exact the diam it was as it left the X
After the fresnal zone, what zone does the beam enter and what happens to the diam enters the near zone and gets narrow
somewhere in the end of the near zone, what zone does the beam enter and what happens to the diam of the beam initial port of the focal zone, where the beam cont to get narrow until it's narrowest pnt is reached, the focus
What marks the end of the near zone the focus
what's the distance to the X to the focus called focal length, focal depth, near zone length
What marks the begining of the far or fraunhofer zone when the beam starts to diverge or widen, the beam is still considered to be in the focal zone
The focal zone is partially in what two zones near and far zones
does the beams width eventually exceeds that of the X yes
Can you change the location of the focus yes, on some X
what are adjustable focal systems called phased array
2 charact of a fixed X transducer diam, freq of the sound
What is the relationship between the X diam and the focal depth directly related
will the beam of the larger active element have a deeper or shallow focus deeper
what is the relationship btw freq and focal depth directly related
2 charact of shallow focus smaller diam pzt and lower freq
2 charact of deep focus larger diam pzt and higher freq
the equation for focal depth focal depth(cm)=diam(mm)^2xfreq/6.16
another way equation for focal depth with wavelenth focal depth,cm= diam,mm^2/40xwavelength,mm
what two factors determine the spread of the beam in the far field 1. trans diam, 2. freq of the sound
do smaller diam crystals produce beams that spread out more or less in the deep far zone field more
the relationship btw crystal diam and beam divergence is inversely related
do larger diam crystals improve lateral resolution in the far field? yes, becuase the diverge less
what is the relationship btw freq and beam divergence inversely related
do high freq sound beams improve lateral res in the far field yes because the diverge less
2 factors of less divergence larger diam and higher freq
2 factors of more divergence smaller diam and lower freq`
what is the shape of spherical waves v shape, also known as diffraction patterns, and huygens wavelets.
hudgens wavelets are produced by what hudgens sources
what does hudgens principle state large active elem may be thought of as millions of tiny, distinct sound sources creating a v shape
hourglass shape is a result of what interference of many huygnes sound wavelets emitted, constructive interfearence
no soundbeam is a result of what deconstructive interference
huygens principle explains the shape of image X sound beam based upon what inphase and out of phase wavelets interfering with ea other
Resolution refers to what accuarcy in imaging, msr detail in an image
Lateral res id's what type of structures structures that are perpendicular to the sound beam
Axial Res equals what Longitudinal Res
Lateral Res anything isn the path of the sound beam
what is real time known as temporal
elevational is what the thickness of the beam, sliced thickness
Lateral res can distinctly see two structures when they are side by side or perp to the sound beam, in the sound beam's path
what question does lateral res answer the dist two structures can be apart and sitll produce 2 dist echoes on an ultrasound image
what units is lateral res msr in cm mm any unit of distance
what type of numbers are perfered in lateral res smaller numbers b/c they indicate accuarte images
what determines lateral res the width of the sound beam
do narrow beams have better lateral res yes
does lateral res change with depth and if so why yes because beam diam varies with depth causing lateral res to varie with with depth too
what are other names for lateral res angular, transverse azimuthal res
what does LATA stand for lateral, angular, transverse, azimuthal, all of the names for lateral res
when is lateral res the best at the focus, at the end of the near zone
is lateral res good or poor in the focal zone good
what is the math relationship btw lat res lateral res, mm = beam diam, mm
what is better axial or lateral and why axial, b/c shorter pulses than they are wide, making the numerical for axial less then lateral res
how many images will be observed if 2 reflectors are side by side and are closer than the beams width only one image
do higher or lower freq improve axial and lateral res higher freq
why do axial res improve with higher freq because shorter pulses assoc with hi freq
why does lateral res improve in the far field hi freq pulses diverge less than low freq, making hi freq sound beams narrower than low freq
how does focusing improve lateral res by concentrating the sound energy into a narrower beam
what are 3 methods of focusing 1. external focusing with a lens 2. internal focus, curved active element 3. phased array focus with the electronics of the us system
Phased array focusing is reserved for what types of X and is it adjustable Array X with multiple active elem and very adjustable
Lens focusing is external and fixed, conventional and or mechanical
curved active element is internal, fixed, conventional or mechanical
electronicfocus is phased array, and adjustable
can the focal depth and extent of focusing be changed with external and internal focusing methods no, they are fixed
with exeternal focusing, where is the lens placed on the X infront of the PZT
What narrows the beam in the focal zone with external focusing the arc of the lens will become more prominent, causing the degree of focus to inc, and the beam narrowing in the focal zone
how does Curvature of PZT or internal focusing concentrate the sound energy inot a narrower or tighter beam a curved pzt crystal, the curvature becomes more pronounced, the degree of focus inc, most common form of fixed focusing
how is internal focus achieved with a curved pzt crystal
is electronic focusing, or phased array focusing used on single elem X no only multi element transducers
which is more versatile fixed or phased phased
what are 4dist. alterat
Lateral res id's what type of structures structures that are perpendicular to the sound beam
Axial Res equals what Longitudinal Res
Lateral Res anything isn the path of the sound beam
what is real time known as temporal
elevational is what the thickness of the beam, sliced thickness
Lateral res can distinctly see two structures when they are side by side or perp to the sound beam, in the sound beam's path
what question does lateral res answer the dist two structures can be apart and sitll produce 2 dist echoes on an ultrasound image
what units is lateral res msr in cm mm any unit of distance
what type of numbers are perfered in lateral res smaller numbers b/c they indicate accuarte images
what determines lateral res the width of the sound beam
do narrow beams have better lateral res yes
does lateral res change with depth and if so why yes because beam diam varies with depth causing lateral res to varie with with depth too
what are other names for lateral res angular, transverse azimuthal res
what does LATA stand for lateral, angular, transverse, azimuthal, all of the names for lateral res
when is lateral res the best at the focus, at the end of the near zone
is lateral res good or poor in the focal zone good
what is the math relationship btw lat res lateral res, mm = beam diam, mm
what is better axial or lateral and why axial, b/c shorter pulses than they are wide, making the numerical for axial less then lateral res
how many images will be observed if 2 reflectors are side by side and are closer than the beams width only one image
do higher or lower freq improve axial and lateral res higher freq
why do axial res improve with higher freq because shorter pulses assoc with hi freq
why does lateral res improve in the far field hi freq pulses diverge less than low freq, making hi freq sound beams narrower than low freq
how does focusing improve lateral res by concentrating the sound energy into a narrower beam
what are 3 methods of focusing 1. external focusing with a lens 2. internal focus, curved active element 3. phased array focus with the electronics of the us system
Phased array focusing is reserved for what types of X and is it adjustable Array X with multiple active elem and very adjustable
Lens focusing is external and fixed, conventional and or mechanical
curved active element is internal, fixed, conventional or mechanical
electronicfocus is phased array, and adjustable
can the focal depth and extent of focusing be changed with external and internal focusing methods no, they are fixed
with exeternal focusing, where is the lens placed on the X infront of the PZT
What narrows the beam in the focal zone with external focusing the arc of the lens will become more prominent, causing the degree of focus to inc, and the beam narrowing in the focal zone
how does Curvature of PZT or internal focusing concentrate the sound energy inot a narrower or tighter beam a curved pzt crystal, the curvature becomes more pronounced, the degree of focus inc, most common form of fixed focusing
how is internal focus achieved with a curved pzt crystal
is electronic focusing, or phased array focusing used on single elem X no only multi element transducers
which is more versatile fixed or phased phased
what are 4dist. alterations sound beams undergo 1.beam diam in near field and focal zone narrows,2.focus moved closer to the X, reducing length of near field 3.beam diam beyond focal zone widens 4. size of the focal zone is reduced
when the beam in the cocal zone widens it does what to lateral res focusing will improve later res in the near and focal zones and degrde lateral res beyond the focal zone
what determines Freq cw electrical freq from us
what determines pw freq thickness of the ceramic and speed of sound in ceramic
what dtermines focal length diam of ceramic and freq of sound
what determines focal length diam of ceram and freq of sound
what determines beam divergence diam of ceramic and freq of sound
what determines lateral res beam width
what are 4 effects of focusing 1.beam diam in near and focal zone is reduced 2. focal depth is shallow 3. beam diam in far zone inc 4. focal zone is smaller
whast are 3 basic modes of display or formats 1. amplitude mode 2. brightness mode 3. motion mode
Amode appears as a series of what upward spikes
how does a mode work sound pulse emitted from X, a dot moves at a constant speed across systme's display, reflection returns to the X, it's process and dot is deflicted upwards on the screen
The height of the upward deflection is proportional to what in a mode amplitude of the returning echo
strong echos in a mode create what kind of spikes strong spikes
what does the x axis on an amode represent reflector depth, derived from the time of flight infor of the sound pulse
they y axis represents reflection of what amplitude
what are a modes accurate in determining the depth of reflectors
B mode appears as what dots of varying brightness
what happens as a b mode emitts a sound pulse from the X an invisible dot moves at a constant speed across system display, when reflection returns to the X,it's processed and the invisible dot is turned on
what indicates the strength of reflection in the B mode the brightness of the dot, weaker reflections appear as dark gray dots, strong reflections are whiter bright dots.
the x axis of a b mode represents what reflector depth, derived from time of flight info of the sound pulse
amplitude info on a b mode is routed to what axis z
what is the first form of gray scale imaging and is the basis for all other grayscale imaging including real time b mode
M mode appears as a group of what horizontal wavy lines
what does m mode's lines represent on paper the changes in depth
in m mode, a line that moves up and down represents what moving towards and away from the X
a straight line in m mode represents what stationary reflector
the x axis of the m mode represents what time
y axis of the m mode represents what depth, which is derived from the time of flight info
since m mode is arises from a singel penetration into the body, the sampleing rate of m mode is very high and equal to pulse repetition frequency of the system
what is m mode used to detect cardiac wall motion and it's use is declining
Bscan is when the X does what paints w/ ea scan line, moving the X across the pt, articulator
What is C mode constant depth mode, non depth adjustable, don't use this anymore
how many frames/sec is m mode 1800 frame/sec, rapid moving structures
when the beam in the cocal zone widens it does what to lateral res focusing will improve later res in the near and focal zones and degrde lateral res beyond the focal zone
what determines Freq cw electrical freq from us
what determines pw freq thickness of the ceramic and speed of sound in ceramic
what dtermines focal length diam of ceramic and freq of sound
what determines focal length diam of ceram and freq of sound
what determines beam divergence diam of ceramic and freq of sound
what determines lateral res beam width
what are 4 effects of focusing 1.beam diam in near and focal zone is reduced 2. focal depth is shallow 3. beam diam in far zone inc 4. focal zone is smaller
whast are 3 basic modes of display or formats 1. amplitude mode 2. brightness mode 3. motion mode
Amode appears as a series of what upward spikes
how does a mode work sound pulse emitted from X, a dot moves at a constant speed across systme's display, reflection returns to the X, it's process and dot is deflicted upwards on the screen
The height of the upward deflection is proportional to what in a mode amplitude of the returning echo
strong echos in a mode create what kind of spikes strong spikes
what does the x axis on an amode represent reflector depth, derived from the time of flight infor of the sound pulse
they y axis represents reflection of what amplitude
what are a modes accurate in determining the depth of reflectors
B mode appears as what dots of varying brightness
what happens as a b mode emitts a sound pulse from the X an invisible dot moves at a constant speed across system display, when reflection returns to the X,it's processed and the invisible dot is turned on
what indicates the strength of reflection in the B mode the brightness of the dot, weaker reflections appear as dark gray dots, strong reflections are whiter bright dots.
the x axis of a b mode represents what reflector depth, derived from time of flight info of the sound pulse
amplitude info on a b mode is routed to what axis z
what is the first form of gray scale imaging and is the basis for all other grayscale imaging including real time b mode
M mode appears as a group of what horizontal wavy lines
what does m mode's lines represent on paper the changes in depth
in m mode, a line that moves up and down represents what moving towards and away from the X
a straight line in m mode represents what stationary reflector
the x axis of the m mode represents what time
y axis of the m mode represents what depth, which is derived from the time of flight info
since m mode is arises from a singel penetration into the body, the sampleing rate of m mode is very high and equal to pulse repetition frequency of the system
what is m mode used to detect cardiac wall motion and it's use is declining
Bscan is when the X does what paints w/ ea scan line, moving the X across the pt, articulator
What is C mode constant depth mode, non depth adjustable, don't use this anymore
how many frames/sec is m mode 1800 frame/sec, rapid moving structures
Mechanical X contains what type of active elements single, circular, disc shaped and it's physically moved
What is the min number of active elem in a mechanical X 1
what is the image created by a mechanical X fan or sector shaped
How does the pzt crystal in a mech X work rotate around a single point with a motor, scan plane is produced by the mech steering
do mech X have a fixed focal depth yes
what is the focal depth of the mech X called conventional, mechanical, or fixed focusing
what are the two methods of fixed focusing mechanical X uses Internal focusing, with the use of a curved active element, or External focus, the use of acoustic lens
what planes does focusing happen on with mechanical X both horizontal and vertical planes because fo the hourglass shape
what happens to the mechanical X if one of the crystals are damaged, entire image is lost, since there is only one crystal
Array transducer contain how many active elements many, moving parts w/in the X, collection of Active elem
Elements are what a slab of pzt cut into a collection of seperate pcs
Ea active elem is connected by what in array X A WIRE TO ITS OWN ELECTRONIC CIRCUITRY IN THE US SYS
what is a channel in an array X combination of active elem, wire and syst electronics
how can array X excite single or groups of elements in various ways during trans b/c ea elem has its own electrical connection
with array X, what happens during reception ea individual crystal produces a small electronic signal that returns to the systems rcvr
what are 3 types of array X linear, annular and convex
what are linear X arrangement active elem are arranged in a straight line
annular active element arrangement elem are arranged as circular rings with common center
convex active element arrangement active element are arranged in a bowed or arched line. X could also be curved r curvilinear array
the footprint on a linear array x is how many cm on ea side one
does the linear phase array have any moving parts no
what is phasing when a beam is steered and focused using an electrical technique
how many elements does the ftprint have on a linear phased array x 100-300 elemen along the face of the probe, placed compactly side by side, the elem is rectangular and narrow
what is the width of the elements in a linear phased array x 1/4 to 1/2 of the sound's wavelength
what is the image shape of the phased array X fan or sector shaped, similar to that of a mechanical X
how is the 2d image built up with a phased array X electronic steering process called phasing
how does phasing or electronic steering wk in a phased transducer sound beams are elect transmitted in different directions w/out the use of moving parts, pulses are directed in a pattern similar to that of the sweeping of a windshiled wiper
how is the sound beem steered in a phased array X electronically without use of moving parts
how are the sound beams focused in a phased array X focused electronically
can the focus be altered in a phased array sound beam yes, the system has controls that allow the sonographer to modify the depth and amt of focusing of the sound beam, which the tech can match teh beams parameters to the clinical circumstances
can the sonographer adjust the focal depth of phased array X yes,can also transmit mult beams down the same scan line ea with different focal depth, providing multi focusing capability
what happens if one of the crystals are damaged will make the x results inconsistant or erratic beam steering and focusing, hard to be determined because ea pulse emitted by many elements in the probe
how many crystals are fired in a phased X all or many are fired to create ea sound beam
what type of interference does the phased X create constructive and destructive to create a single sond pulse with particular characteristics
what determines the focus and direction of the sound beam in a phased X the overall pattern of the electrical signals from the ultrasound system
how do electrical spikes form an ultrasound system steer the beam in different directions with a phased array X 1.ea active elem creates a sm sound wavelet 2. the wavelets combine to form a single sound beam 3.electrical signals are lined up and will arrive at ea of their respective active elem@exactly the same time=soundbeam dir
what is the two step approach in determining the beams direction 1. draw a line connecting the electrical spikes 2. draw another line that is perpindicular to the dotted line extending out from the X
how do we know when the sound beam is steered when the spike line is sloped
what is the amt of time the electrical signals aree seperated ten nanoseconds or ten billionths of a second, which createsa single unified sound beam that is directed downward
how does the pattern of phasing work starts w/an elect spike that excites the upper active elem1st, followed instantly by a 2nd spike that strikes the next pzt cystal and so on
how does a slope pattern of phasing work excites the lowest active element first,and the second happens instantly from bottom to top, the time difference is the same 10 nanosecs, directed upward direction
how is beam steering achieved with a phased X ea electrical pattern creating ea pulse is slightly different than teh pattern be4 it, making it a vector shape
the electronics within the ultrasound system that create the sweep patteren is called what beam former
when the spike line is straight in a phased X, what type of sound is produced an unfocused sound beam is created.
how does the pattern of electrical spikes from the beam former focus the sound beam during transmission in a linear phased X by using a curved pattern creates a focused sound beam, the outer cystals are excited earler than the inner cystals, making the beam straight ahead since there is no predominant slope
when is the sound beam focused with a phased X when the spike line is curved
a beam with a more curved electrical pattern will have a deeper or shallower focus shallower focus, but will be directed straight ahead
a phased patteren with an electrical outward or d shape will have what type of beam a defocused beam, which has no application in diagnostic imaging
a beam with an electronic pattern of a slope does what to the sound beam of a phased X steers the sound beam
an electronic pattern thats curvature with a phased X is doing what to the sound beam focusing the sound beam
how does a phased array system create images with multiple foci transmitted the system must send multiple sound beams down ea scan line
what happens when an image is created with three focal points with linear three distinct sound pulses are transmitted in ea scan line, ea electrical spike will have diff degree of curvature; greatest curve creats the beam with the shallowest foci,least curve has the deeper focus
does focus occur during reception too wth linear yes, during reception when sound arrives at the X, mult elements are xcted along the front of the probe,elements create elect signals that return via mult channels to us rcvr
when can the most accurate image be created when the ultrasound rcvr does what with linear introduce time delays to some of the electrical signals during reception
what do optimal time delays used during receive focusing change depend on with linear depth at which the reflection was created
as the transducer listens for reflections, what happens to the delay patterns during receive focusing witb linear phased arrays they change continuously
does the sonographer control dynamic receive focusing with linear phased arrays no, it's performed automatically by the system
how do the annular phased active elements appear disc like
what type of steering does annular phased X use mechanical steering
how is the 2d image built up with annular phased X physically rotating the ringed element array so taht it transmits sound beams in different directions
is electronic steering possible with annular phased X no
what is the primary advantage of annular phased X multiple transmit focal zones creat ea scan line of the image
what does the term phased array mean either adjustable or multi focus, multi focus is the term that applies to annular array
annular phased array means what focused
what type of depths does the annular X collect finformation from inner crystal of the annular phased array X creates a shallow focus beam and collects info only form the shallowest depths, all other info from the crystal's sound pulse is ignored
what part of the annular crystal sound pulse is where info is stored info from the focal zone, which gets progressively deeper with every ring
an annular array compromising 4 ringed elements transmits how many pulses 4 pulses down ea scan line, ea with a different focal depth, with an image compromised from only the focal zones of ea crystal
What is the image shape of an annular X fan or sector shaped, b/c of the array X being mechanical
what happens when an array X has a damaged crystal a sector of the image is droped, side to side
what happens if the inner most ring is lost in the image of an annular X the most superficial region of the image is lost
what happens if the outer most ring is lost in the image of an annular X a deeper horizontal band of the image is lost
which probe has the largest acoustic footprint and creates a rectangular iamge a linear sequential array X
how many pzt does a linear sequential array have 120 to 250 rectangular shaped strips of pzt arranged side by side in a line, and are much larger than those found in linear phased array
how big are the crystals in a linear sequential array ea crystal is 1 in width, which is large, up to 10cm long
the beam steering in a linear sequential array works how some but not all of the crystals are fired simultaneously to create ea sound beam
what is the usual direction of the linear sequential array parallel to ea other and usually directed straight ahead
how does beam focusing work with lenear sequential array it's achieved electronically, perform both transmit and rcv focusing using electronic time delays
how is transmit focusing achieved with linear sequential array with curvature pattern phased excitation of the active element, where the outer elements are fired first b4 the inner crystals
how is recieving focus achieved with linear sequential array dynamically by introducing electronic delays in the signals returning from the X elements to the US system following echo rcption, altering the rcv focal depth variably
what type of focus is commonly used with linear sequential array electronic focusing
what was used in basic linear sequential array X fixed focusing techniques, such as curved active elements
what is the image shape of a linear sequential array X square, the image is never wider than the X
what happens to a linear sequential array X when a pzt is damaged a section drops out of the image from top to bottom so only the pzt that's damaged are affected
Can a linear sequential array steer a sound beam electronically yes, this creates a parallelogram-shaped image rather than a rectangular image
how do beam formers of linear sequential array steer sound beams by introducing sloped-shaped delays in teh electical xcitation spikes of the elements creating the beam
how is a rectangular grayscale anatomic image created during color doppler exams with a linear array
in a doppler exam with linear array, linear seq, does the electrical patterns creating the sound beams have a slope, and what direction is the sound beam directed no they don't have a slope and they are directed straight down, however the color doppler image is parallelogram shaped, b/c the electrical spike patterns creating the doppler sound beams are sloped
how many crystals does a convex array X have and what is the shape, and how are they arranged there are 120 to 250 rectangular shaped strips of pzt arranged side by side in a bowed line, making the array large
how long is the acoustic foot print on a convex footprint 10 cm, ea crystal is 1 wavelength in width
how are the crystals fired in a conves array X some but not all of the crystals are fired simultaneously to create a single sound beam
how do the crystals beam travel from a convex probe b/c the crystals are arranged in an arc, the pulses travel in different directions as tehy radiate out from the X
are the sound beams parallel to ea other from a convex X no
focusing in a modern convex X is acheived how electronically
transmit focusing is achieved how with a convex X curved spike line pattern, exciting the active elements in the fired group with appropriate delays in a curved spike line pattern
with a convex X, how is dynamic rcv focusing achieved by introducing varying electrical delays in the signals returning from teh X to the us during echo rcptn
what is the image shape of a convex X blunt sector shaped, the image appears to have a bite at the near field of the sector, the curvature corresponds directly to the convex array ftprint
what happens to the image of a convex X when a crystal is damaged a drop out appears in the image from top to bottom
vector array is a combo of what technologies linear sequential and linear phased
how is the sound beam steered in a vector array X sloped electronical delay patterns can be intorduced that steer the sound beams of teh linaear array in a variety of directions
how many crystals and what are their shape and arrangement in a vector X 120-250 reectanfular shaped strips of pzt material arranged side by side in a line
is the ftprint of a vector large or small small, usually only a couple of cm
how does the linear technology apply to the vector X some but not all crystals are fired simultaniously to create a single ssound beam
how does the phased array tech apply to the vector X beam former are delayed in a sloped spike-line patternas they excite a group of elements in a vector, resulting in beams radiating out in dif directions from the face of the X
what type of beam focusing is used in vector array X electronic focusing, both transmit focusing and dynamic rcv focusing improve image quality over a great range of depth
what is the image shape of a vector array X trapezoidal images, at intermediate and deep depths appears like a sector but is flat on top
mechanical transducer has what type of effect on images when active element malfunciton loss of entire image
linear and conves arrays transducer has what type of effect on images when active element malfunciton drop out of image info from top to the bottom of the image, location of the line corresponds to broken crystal
phased arrays transducer has what type of effect on images when active element malfunciton erratic steering and focusing, extent to which the image is affected is variable
annular phased arrays transducer has what type of effect on images when active element malfunciton horizontal or side to side band dropout at a particular depth
mechanical transducer's image shape, steering technique and focusing technique sector, mechanical, fixed
linear switched transducer's image shape, steering technique and focusing technique rectangular, electronic, electronic
phased array transducer's image shape, steering technique and focusing technique sector, electronic, electronic
annular phased transducer's image shape, steering technique and focusing technique sector, mechanical, electronic
convex transducer's image shape, steering technique and focusing technique blunted sector, electronic, electronic
vector transducer's image shape, steering technique and focusing technique trapezoidal, electronic, electronic
what is resolution accuracy in imaging
what else applies in addition to axial resolutiona and lateral res slice thickness or elevational res
what does image res actually deals with 3-dim spaces shallow to deep, side to side and above to below the imagin plane
slice thickness is measured in what direction perpendicular to the imaging plane or above to below the imaging plane
a beams measurable thickness varies with what depth
what shape of active elements provide the thinnest ultrasound slices and the best elevational res within a focal zone disc shaped
where are disc shaped crystals found mechanical and annular phased array
with disc shaped crystals, a circle is created when the sound beam is sectioned in what direction perpindicular to the beam's main axis
with disc shaped crystals, what determines the lateral res lateral res, or beams diam is the width of the circle in one direction
with disc shaped crystals, what determines the elevational res the ht of the circle indicates the beam thickness, or the elevational res. elevational res is identical to teh lateral res with disc shaped crystals
is the sliced thickness affected in array probes like phased, linear and convex? no, with phasing the beam is focused or narrowed only side to side in the imaging plane, which improves lateral res
how do you get a thinner slice with array probes such as phased, linear and convex array X an acoustic lens is placed on the probe making the beam thickness =to active elem, @focal pnt beam is min value,greater depths beam gets substantially greater, thicker than it is wide
for the x, what res is the best, and what follows that res axial is the best followed by lateral and then elevational res
what types of newer X create improved slice thickness resolution 1-1/2 dim arrays, they create thinner beams with improved slice thickness res over greater range of depth
how does the new 1-1/2 d array X improve elevational res by focusing the beam in the thickness plane
beams created by single element X are what shape hourglass shape
off axis sound beams are called what side lobes
reflections arising within the side lobes create what degrade lateral resolution
grating lobes are smiliar to what side lobes
grating lobes are created by what transducers array transducers
what effects does grating lobes have on images degrade lateral res and reuduce image quality
side lobes from mechanical scan heads do what to image quality diminish image quality by degrading lateral res
what process can elliminate side and grating lobes apodization, alters increased strength by firing central crystals with more force lessening side crystal firing
grating lobes can be eliminated if teh strength of electrical spikes does what differ from element to element
how do modern X designed to keep the sound beam narrow over substantial depth range by dynamic aperture, changing the number of crystals along the face of the probe used to tranxmit pulses and rcv reflections, also known as variable aperture or dynamic aperture
aperature means what opening or hole, considered to be known as a listening hole or the number of rcv reflected echoes
dynamic aperature improves what resolution lateral at wide ranges of depths
what is static scanning one frame at a time
the ability to create a numerous frames ea sec is considered to be what frame rate
what are the two factors that determine frame rate sounds speed in the medium and the depth of imaging
speed of sound in soft tissue is considered to be constant at 1.54 km/s
what determines the frame rate the max imaging depth
what units msr frame rate hz
temporal resolution is considered to be what accuracy in time, describes the ability to accuratlyposition moving structures from instant to instant
temporal resolution is excellent when when the system produces many framerates per sec
what determines temporal res framerate
units for temporal res hz
what is the relationship btw framerate and time for one frame inversley related, and are recipricols
what are the 2 system controls responsible for setting ultrasound system frame rate imaging depth, and nubmer of pulses in ea pic
how does imaging depth effect temporal res and frame rate shallow imaging increases frame rate and temp res, they are inversly related
shallowing imagin depth short or long go-return time shorta
shallowing imaging has shorter or longer t frame shorter
is the frame rate lower or higher with shallow imaging higher
superior temporal res happens in shallow or deep imaging shallow
what depths create long go-return time deep
what imaging depth creates longer Tframe deep
lower frame rate happens in shallow or deep depths deep
inferior temp res is present in what types of depths deep imaging
Tframe = what Tframe = #pulsesxprp
imaging depth and Tframe rate have what type of relationship directly related
higher frame rates are possible with fewer or more pulses present fewer pulses
pulses per frame and frame rate have what type of relationship inversely related
what 3 factors effect the nubmer of pulses needed to create an image number of pulses per scan line (multi vs single), sector size and lines per angle of sector(line density)
multi focusing does what to frame rate and temp res decreases framerate and diminshes temp res
single focus has how many pulses per scan line one
single focus has what type of Tframe shorter
single focus has what kind of frame rate higher
single focus has what type of temporal res superior temp res
single focus has what type of lateral res inferior lateral res
multi focus has how many pulses per scan line many
multi focus has what length of Tframe longer
multi focus has what level of frame rate lower
multi focus has what type of temp res inferior temp res
multi focu has what type of lateral res superior lateral res
what negative effect does multi focal have neg effect on temporal res
what benifits does multi focal have improves the accuracy of teh individual images
what makes multi focal scan lines superior lateral res b/c its narrow over a wide range of depths
what is the trade off with multi focal balance btw temporal res and lateral res
what happens when the sector size, or field of view is expanded number of pulses required to make an image increase, but temporal res decreases
narrow sector has how many pulses per frame rate fewer
narrow sector has longer or shorter Tframe shorter
narrow sector has whast type of frame rate higher
narrow sector has what type of temp res superior
wide sector has how many pulses per frame rate more
wide sector has longer or shorter Tframe longer
wide sector has what type of frame rate lower
wide sector has what type of temporal lateral res inferior
field of view and frame rate have what type of relationship inversley
what is line density when the systems can alter the spacing btw sound beams
what is the differnce btw low line density and high line density low line is when lines are spaced far apart, high line density is when lines are packed closely together
what happens when there is a high line density the number of pulses increase and temp res decreases
can you change the spacing between the lines some systems allow you to, others do not
what is the plus to having high line density even though it decreases temp res, it increases accuracy of the individual images
what is improved spatial res with high line density, ea image contains more detail
facts about low line density widely spaced lines, fewer pulses per frame, shorter Tframe, higher frame rate, superior temp res, inferior spatial res
facts about high line density tightly packed lines, more pulses per frame, longer Tframe, lower frame rate, inferior temp res, super spatial res
when is temp res better, and how do you obtain better temp res higher frame rate; shallow imaging, single focus, narrow sector, low line density
then is temp res poor and how is this achieved lower frame rate; deeper image, multi foci points (which improves lateral res), wide sector, high line density (which improves spatial res, good for structures that don't move)
Created by: summer1