Ultrasound Flashcards by abbie anderson

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”

a traveling variation of one or more quantities

a wave. (transferring energy)

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_____ 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

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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

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sound propogates through a ________

sound wave are ________ and ___________

medium

mechanical and longitudinal

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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

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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

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________ 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 -

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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)

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As sound propagates through a medium
 there are changes in the medium, what are
 acoustic variables (5)

Pressure
Density
Area
Temperature

Position/distance

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As wave propagates the particles are compressed
together and stretched apart changing the ______ which affects (acoustic variables) ___ , _____, and __________

medium

Pressure, Volume, Density

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pressure _____ in compression phase
pressure ________ in rarefaction

Units - ?

Increased

Decreased

pounds per square inch (lbs/in2), Pascals (Pa)

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volume ______ area in compression
__________ area in rarefaction

Units - ?

Decreased,  Increased

centimeters cubed, cc, cm3

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density _______ in compression
and ______ in rarefaction

Units –?

Increased, Decreased

grams per cubic centimeters, g/cc3

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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

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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

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_______ 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)