Ultrasound Flashcards
what is “a disturbance or
variation that transfers energy progressively from point to
point in a medium and that may take the form of an elastic
deformation or of a variation of pressure, electric or magnetic intensity, electric potential, or temperature”
or
a traveling variation of one or more quantities
a wave. (transferring energy)
_____ is Traveling wave of acoustic variables
produced by a vibrating source
waves carry _____ – not matter
Transfer of energy occurs when particles in
the medium are ___________
sound
energy
compressed together
Sound is a _______ _____ that moves
through matter causing molecules of the
medium to vibrate.
Must have a ______ to propagate
Can’t travel in a vacuum
And is different from electromagnetic waves that don’t require a
medium
mechanical wave
medium
sound propogates through a ________
sound wave are ________ and ___________
medium
mechanical and longitudinal
Sound travels in a ________ wave in which Particle
motion is _________ to wave direction (compressional)
In a Transverse wave – particle
motion is _______ to wave direction (shear)
longitudinal, parallel
perpendicular
what are the other 4 types of waves?
-NONE of these are the answer to a SOUND WAVE. just know what these words mean as they will be used in tests as “distractors” rather than answers
Rayleigh (Surface Wave) – transversewave of particle motion of thin layer on the surface of the medium
Torsion – driving force performs an oscillatory twisting action about an axis
Love – long, surface wave
Lamb – generated in thin sheets of metal
________ is One complete variation of an acoustic
variable, one wave, one peak to one trough
________ is A description of progress through a cycle
One full cycle divided into 360 degrees of phase (see
diagram later)
Cycle –
Phase -
what are the 2 primary phases of a wave?
____ modulus states that ____________is the reduction in differences between small and large amplitudes. Region of high density and pressure related to ____________
_____ model states that ________ is the region of low density and pressure or area in the cycle where particles pulled apart. this is Related to medium ______
compression and rarefaction
Bulk’s modulus. compression. medium stiffness (like a bed)
young’s modulus, Rarefaction elasticity (how much it stretches- like young ppl)
As sound propagates through a medium there are changes in the medium, what are acoustic variables (5)
Pressure
Density
Area
Temperature
Position/distance
As wave propagates the particles are compressed
together and stretched apart changing the ______ which affects (acoustic variables) ___ , _____, and __________
medium
Pressure, Volume, Density
pressure _____ in compression phase
pressure ________ in rarefaction
Units - ?
Increased
Decreased
pounds per square inch (lbs/in2), Pascals (Pa)
volume ______ area in compression
__________ area in rarefaction
Units - ?
Decreased, Increased
centimeters cubed, cc, cm3
density _______ in compression
and ______ in rarefaction
Units –?
Increased, Decreased
grams per cubic centimeters, g/cc3
As particles are moved together and stretched apart
this causes friction. Friction is the conversion of
_________ to ________.
As sound _________ it changes the position of
particles in the medium.
energy, heat
propagates
what are the 6 characteristics of a soundwave?
which are determined by either one or both of what?
Frequency - source
Period - source
Wavelength - source and medium
Propagation speed - medium
Amplitude - source
Intensity - source
sound source and medium
_______ describe progress through a cycle
One full cycle divided into 360 degrees
phases of wave
_____ is Number of cycles per second
Ultrasound – frequency____ human hearing or >________ Hz (20 kHz)
Diagnostic imaging ___-____MHz
Infrasound – frequency____ human
hearing < ___ Hz
frequency
>, 20,000
1-20
<, 20
Higher frequency = _____ detail
Lower frequency = _____ penetration
better for both
period and frequency are ______ poportional
ineversely. as frequency increases, period decreases
t = 1/f
what is the avg period in us?
what is period determined by?
0.3 us
source
What is the period if the frequency is 4 Hz?
What is the period if the frequency is 4 MHz?
t = 1/4 = 0.25 sec
0.25 us
___ is the Length of space over
which one cycle occurs
it is _______ porportional to frequency
it is determined by ____
wavelength (mm)
inversely
source and medium
wavelength is ___ = period in _____
distance, time
___ is the Speed of sound through a medium. it is determined by _____
what is its
propagation speed (c)
medium
C m/s = f (Hz) x WL (m)
C mm/us = f (MHz) x WL (mm)
What is the wavelength if the propagation
speed is 330 m/s and the frequency is
1,000 HZ?
What is the wavelength if the propagation
speed is 1.54 mm/us and the frequency is
3 MHz?
what are Frequencies that are even and odd multiples of
another frequency (commonly called the
fundamental or operating frequency
what are they?
what do they look like?
where do they travel fastest?
harmonics
new frequencies created by
propagation of sound
Sound waves change shape as they travel through medium
Higher pressure parts of wave travel faster than
lower pressure parts
Fundamental frequency –
original frequency, sinusoidal
Harmonics – odd or even
multiples of the fundamental frequency
Example: if fundamental is 2MHz
Even = _____________
Odd = __________
4MHz, 8MHz, 12MHz
6MHz, 10MHz, 14MHz
if a male mosquito produces a frequency of 600 hz and a female of 400 hz, which frequency the male have to produce to get the female to mate?
his 2nd harmonic and will call to her 3rd
The harmonic frequencies are produced BY the
_______ while imaging with US.
tissue
Instrument ignores returning fundamental
frequencies and uses only _____ harmonics to create
the image.
Advantage is it helps _____________
Disadvantage is it has_________ and ______
2nd
eliminate some artifacts
poor spatial resolution and
less penetration
________ is the Maximum variation of an acoustic variable (Pressure, temperature, density, etc)
what does it depend on?
how are units determined?
amplitude. How far variable gets from its normal value
Maximum value – normal value
source
Units are determined by what variable being
measured
_______ is the rate at which work is done, rate at
which energy is transmitted by the transducer
into the body. its units are _______ -
what is it determined by?
what is its relationship to area?
____ is the power per area (Units - Watts/cm2)
how is it measured?
what is its relationship to power, amplitude and area?
power, Watts
source
Intensity –
intensity = amplitude2
Intensity is directly proportional to power, amplitude and area
power is indirectly proportional to area
What is the intensity if the amplitude is 2?
What is the amplitude if the intensity is 9?
4
3
what are the formulas for
frequency
propogation speed
intensity
F (MHz)= 1 / T (us)
C (mm/us) = F (MHz) x Wavelength (mm)
Intensity (mW/cm2) = Power (mW) / area (cm2)
