A-Mode
Amplitude Modulation
Distance between transducer and structure determines where an echo is seen along hte time axis
1 dimensional image
Not used anymore
Analog Scan Converter
device in which data are represented by variable, measurable, physical quantities. Length, width, voltage or pressure
B-Mode
2D presentation of echo producing interfaces.
A mode signal converted to dots which vary in brightness depending on echo strength
Brightness Modulation
Cavitation
formation of cavities in a body tissue or an organ resulting from the sudden formation and collapse of low pressure bubbles by means of mechanical forces
Digital Scan Converter
image processing device that uses a stable electronic circuit to store and manipulate ultrasonic images in memory. The device then reconstructs and displays these images simultaneously to create one image
Doppler effect
change in observed frequency of a wave. Freq increases as source and observer get closer, decreases as they move apart
Gray Scale Imaging
series of shades from black to white the more shades the more realistically an image can be recorded and displayed
M-Mode
series of B-Mode dots are displayed on moving time base graph to show moving structures
basis of echocariography prior to real time scanning
used in conjunction with real time imaging in adult, pediatric and fetal echo
Piezoelectric Effect
Mechanical deformation occurs when an electrical field is applied to a crystal the crystal vibrates mechanically. When a crystal vibrates mechanically it creates an electrical field
3-D imaging
waves sent from many directions to the returns are used to build a volume image in 3 dimensions
4-D Imaging
3-d imaging with the addition of real time
Ultrasound
sound with freq above the limits of human hearing greater than 20kHz
Transverse Waves
Waves that move in an up and down motoin
Longitudinal Waves
Waves that move in a line
Compression
area of wave that gets closer together
Rarefaction
area of wave that spreads apart
Medium
material through which a wave is transmitted
Accoustic parameters
period
frequency
amplitude
power
intensity
wavelength
propagation
Period of wave
time
frequency of wave
1/time
amplitude of wave
“Bigness” of wave
dofference between peak and avg value of the wave
power
force
rate of energy transfer or rate which work is preformed
intensity
concentration of strength of a wave
Intensity = watts/cm^2
wavelength
distance from one peak to the next
propagation speed
speed wave travels through medium (avg 1540 soft tissue)
Hertz
measurement of frequency
Infrasound
sound below the human hearing level
Audible sound
20-20kHz
DMS frequency
2mHz-12mHz
Bio effects
any damage to tissue
ALARA as low as reasonably achievable
Intravascular Ultrasound
30MHz-40MHz
asses vessel walls characterize plaque morphology
transducer contained in a sheath attached to catheter
no air means high preq usable
Therapeutic Ultrasound
.5MHz-3MHz
beam intensity result in tissue temperature increases
4°C as deep as 5cm
increases blood flow
treats muscle spasms, tendonitis and bursitis
joint swelling
High Intensity Focused Ultrasound
HIFU
used for selective destruction of tissue volumes
cancerous lesions in liver, kidney, breast and prostate
focusing the beam allows energy concentration on affected area while sparing surround tissue
Wave Propagation
Worse in Gas
better in liquid
best in solids
Sound wave propagation
sound traveling pressure variation
regions of compression and rarefraction
particles vibrate back and forth
parallel to the directoin of travel
Mechanical Wave
needs physical interaction
must have medium
longitudinal
transverse
Electromagnetic Waves
travel in medium or vacuum
light, heat, X-rays, gamma rays TV rays
transer of energy through a varying electrical and magnetic field
Acoustic variables
Pressure
Density
Temperature
particle motion
Pressure
concentration of force
Pascals
varies cyclically as sound wave propagates
Density
p=mass/volume
compression increases
rarefraction decreases
non linear imaging Harmonic Imaging
units kg/m3
Temperature
any mechanical movement produces heat
sound wave vibrate the tissue and some wave energy is lost to heat with tissue
important in Bioeffects
Celcius
Kelvin
Fahrenheit
Particel Motion
particels of tissue being imparted with momentum and traveling into the locale of the nearest neighbors
osscillate back and forth about their original location allowing energy to propagate along the wave p[ath
particles DO NOT travel with the wave
ALARA
As Low As Resonably Achievable
short scan time
low power settings
short use of color and spectral
Attenuation
decrease in wave amplitude due to mechanical wave interaction wiht mnedium
units dB
absorption
reflection
refraction
Absorption
conversion of energy from wave to heat within medium
as Freq increases amount of energy lost increases
Reflection
sound wave changes direction and does not continue to travel forward
returns to source
foundtation for diagnostic ultrasound
Ultrasound based on processing these refelctions
Refraction
bending of wave
change in propagation velocity when angle of incidence is other than 0
Anechoic
without echoes
cysts
fluid filled organs
Hypoechoic
low level reflected signals
Hyperechoic
highly echogenic tissues
moderate to high reflected signals
calcified echoes
strongly echoic
usually with acoustic shadows
Complex
mixed echogenicity
with or without shadowing
Transducers
Device that converts energy from one form to another
Transducer components
Crystal
matching layers
Damping material
Transducer case
electronic cable
Crystal
diameter determines beam shape
like beam of flashlight
shape is region in the patient which sound travels
matching layers
provide an acoustic connection between crystals and skin
reduces amount of reflection from large acoustic mismatch
allows wave to travel into the body
gel
Damping material
decrease secondary reverberations of crystal with returning signals
reduces the ring time and results in an increase in depth resolution (axial)
Trasducer Case
provides housing for all internal components
Electronic cable
caontains bundle wires to cary electrical signals to and from the crytals
B-scan (Static scan)
uses series of B-mode images to biuld a 2 d image of tissue
transducer attached to articulated arm to provide system with position and orientation
no longer used due to numerous drawbacks
Real Time B-Mode
provides cinematic view of the area being evaluated by displaying a rapid series of images sequentially
Real Time Imaging
all modern systems use real time approach
signals integrated into a scan converter for 2d image display
Real time movie
Frame Rate
Hz
images per second
2 factors Sound speed in medium
depth of imaging
higher frame rate better temporal resolution and image quality
Temporal resolution
ability to precisely position a moving structure
important in adult and fetal echo
high rate yields better movies but worse photographs
imaging depth
shallow depth incrases frame rate and resolution
deeper decreases frame rate and degrades resolution
depth and frame rate inversely related
operator controlled
Focus
Single Focus
Multi Focus
Single Focus
only 1 sound pulse is transmitted down the scan line
high frame rate
superior resolution
inferior lateral resolution
Multi Focus
Adj number of focus Pulses
longer time
decreases frame rate
inferior temporal resolution
superior lateral resolution
lateral resolution
ability to distinguish between structures that are side by side
sector size
field of view
operator controlled
size increases number of pulses increases
reverse
Amplitude Modulation
Distance between transducer and structure determines where an echo is seen along hte time axis
1 dimensional image
Not used anymore
A-Mode
reverse
device in which data are represented by variable, measurable, physical quantities. Length, width, voltage or pressure
Analog Scan Converter
reverse
2D presentation of echo producing interfaces.
A mode signal converted to dots which vary in brightness depending on echo strength
Brightness Modulation
B-Mode
reverse
formation of cavities in a body tissue or an organ resulting from the sudden formation and collapse of low pressure bubbles by means of mechanical forces
Cavitation
reverse
image processing device that uses a stable electronic circuit to store and manipulate ultrasonic images in memory. The device then reconstructs and displays these images simultaneously to create one image
Digital Scan Converter
reverse
change in observed frequency of a wave. Freq increases as source and observer get closer, decreases as they move apart
Doppler effect
reverse
series of shades from black to white the more shades the more realistically an image can be recorded and displayed
Gray Scale Imaging
reverse
series of B-Mode dots are displayed on moving time base graph to show moving structures
basis of echocariography prior to real time scanning
used in conjunction with real time imaging in adult, pediatric and fetal echo
M-Mode
reverse
Mechanical deformation occurs when an electrical field is applied to a crystal the crystal vibrates mechanically. When a crystal vibrates mechanically it creates an electrical field
Piezoelectric Effect
reverse
waves sent from many directions to the returns are used to build a volume image in 3 dimensions
3-D imaging
reverse
3-d imaging with the addition of real time
4-D Imaging
reverse
sound with freq above the limits of human hearing greater than 20kHz
Ultrasound
reverse
Waves that move in an up and down motoin
Transverse Waves
reverse
Waves that move in a line
Longitudinal Waves
reverse
area of wave that gets closer together
Compression
reverse
area of wave that spreads apart
Rarefaction
reverse
material through which a wave is transmitted
Medium
reverse
period
frequency
amplitude
power
intensity
wavelength
propagation
Accoustic parameters
reverse
time
Period of wave
reverse
1/time
frequency of wave
reverse
“Bigness” of wave
dofference between peak and avg value of the wave
amplitude of wave
reverse
force
rate of energy transfer or rate which work is preformed
power
reverse
concentration of strength of a wave
Intensity = watts/cm^2
intensity
reverse
distance from one peak to the next
wavelength
reverse
speed wave travels through medium (avg 1540 soft tissue)
propagation speed
reverse
measurement of frequency
Hertz
reverse
sound below the human hearing level
Infrasound
reverse
20-20kHz
Audible sound
reverse
2mHz-12mHz
DMS frequency
reverse
any damage to tissue
ALARA as low as reasonably achievable
Bio effects
reverse
30MHz-40MHz
asses vessel walls characterize plaque morphology
transducer contained in a sheath attached to catheter
no air means high preq usable
Intravascular Ultrasound
reverse
.5MHz-3MHz
beam intensity result in tissue temperature increases
4°C as deep as 5cm
increases blood flow
treats muscle spasms, tendonitis and bursitis
joint swelling
Therapeutic Ultrasound
reverse
used for selective destruction of tissue volumes
cancerous lesions in liver, kidney, breast and prostate
focusing the beam allows energy concentration on affected area while sparing surround tissue
High Intensity Focused Ultrasound
HIFU
reverse
Worse in Gas
better in liquid
best in solids
Wave Propagation
reverse
sound traveling pressure variation
regions of compression and rarefraction
particles vibrate back and forth
parallel to the directoin of travel
Sound wave propagation
reverse
needs physical interaction
must have medium
longitudinal
transverse
Mechanical Wave
reverse
travel in medium or vacuum
light, heat, X-rays, gamma rays TV rays
transer of energy through a varying electrical and magnetic field
Electromagnetic Waves
reverse
Pressure
Density
Temperature
particle motion
Acoustic variables
reverse
concentration of force
Pascals
varies cyclically as sound wave propagates
Pressure
reverse
p=mass/volume
compression increases
rarefraction decreases
non linear imaging Harmonic Imaging
units kg/m3
Density
reverse
any mechanical movement produces heat
sound wave vibrate the tissue and some wave energy is lost to heat with tissue
important in Bioeffects
Celcius
Kelvin
Fahrenheit
Temperature
reverse
particels of tissue being imparted with momentum and traveling into the locale of the nearest neighbors
osscillate back and forth about their original location allowing energy to propagate along the wave p[ath
particles DO NOT travel with the wave
Particel Motion
reverse
As Low As Resonably Achievable
short scan time
low power settings
short use of color and spectral
ALARA
reverse
decrease in wave amplitude due to mechanical wave interaction wiht mnedium
units dB
absorption
reflection
refraction
Attenuation
reverse
conversion of energy from wave to heat within medium
as Freq increases amount of energy lost increases
Absorption
reverse
sound wave changes direction and does not continue to travel forward
returns to source
foundtation for diagnostic ultrasound
Ultrasound based on processing these refelctions
Reflection
reverse
bending of wave
change in propagation velocity when angle of incidence is other than 0
Refraction
reverse
without echoes
cysts
fluid filled organs
Anechoic
reverse
low level reflected signals
Hypoechoic
reverse
highly echogenic tissues
moderate to high reflected signals
Hyperechoic
reverse
strongly echoic
usually with acoustic shadows
calcified echoes
reverse
mixed echogenicity
with or without shadowing
Complex
reverse
Device that converts energy from one form to another
Transducers
reverse
Crystal
matching layers
Damping material
Transducer case
electronic cable
Transducer components
reverse
diameter determines beam shape
like beam of flashlight
shape is region in the patient which sound travels
Crystal
reverse
provide an acoustic connection between crystals and skin
reduces amount of reflection from large acoustic mismatch
allows wave to travel into the body
gel
matching layers
reverse
decrease secondary reverberations of crystal with returning signals
reduces the ring time and results in an increase in depth resolution (axial)
Damping material
reverse
provides housing for all internal components
Trasducer Case
reverse
caontains bundle wires to cary electrical signals to and from the crytals
Electronic cable
reverse
uses series of B-mode images to biuld a 2 d image of tissue
transducer attached to articulated arm to provide system with position and orientation
no longer used due to numerous drawbacks
B-scan (Static scan)
reverse
provides cinematic view of the area being evaluated by displaying a rapid series of images sequentially
Real Time B-Mode
reverse
all modern systems use real time approach
signals integrated into a scan converter for 2d image display
Real time movie
Real Time Imaging
reverse
Hz
images per second
2 factors Sound speed in medium
depth of imaging
higher frame rate better temporal resolution and image quality
Frame Rate
reverse
ability to precisely position a moving structure
important in adult and fetal echo
high rate yields better movies but worse photographs
Temporal resolution
reverse
shallow depth incrases frame rate and resolution
deeper decreases frame rate and degrades resolution
depth and frame rate inversely related
operator controlled
imaging depth
reverse
Single Focus
Multi Focus
Focus
reverse
only 1 sound pulse is transmitted down the scan line
high frame rate
superior resolution
inferior lateral resolution
Single Focus
reverse
Adj number of focus Pulses
longer time
decreases frame rate
inferior temporal resolution
superior lateral resolution
Multi Focus
reverse
ability to distinguish between structures that are side by side
lateral resolution
reverse
operator controlled
size increases number of pulses increases
sector size
field of view