Exam 1 Flashcards Flashcards by Nya Sanchez-Fernandez

Definition of longitudinal wave
Draw the wave

2D waves with rarefaction used during ultrasound

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Definition of transverse wave
Give an example
Draw the wave

3D ultrasound waves
Ex. Ocean waves

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What type of waves do x-rays use

Electromagnetic

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What are the 2 types of transverse waves used in ultrasound

Mechanical and Electromagnetic

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A mechanical waves needs this to travel
And is usually in __ or __

Medium
2D or 3D

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T or F
Electromagnetic waves do not need mediums and can travel through vacuums

True

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Electromagnetic waves do not need anything and are always

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Name all the classifications of sound

Infrasound
Audible
Ultrasound
Diagnostic

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Name the ranges for all classifications of sound
Infrasound
Audible
Ultrasound
Diagnostic

I - < 20Hz
A - 20-20,000 Hz (20kHz)
U/S - >20kHz
D - 2-20 MHz

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Which travels faster, lower frequency or higher frequency

Lower frequency

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Lower frequency is easier to

Pass through

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Higher frequency allows for

Better images/details

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What is the principal of wave superposition

When path of 2 waves intersect, motions and energy of molecules that each wave individually causes are added together

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In the principal of superposition describe the relationship between wave amplitude and in-phase waves

Amplitude wave will increase with in-phase

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In the principal of superposition describe the relationship between wave amplitude and out-phase waves

Amplitude wave will decrease with out-of phase waves

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Definition of constructive interference

Occurs when 2 waves are in-phase w/ each other

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Definition of destructive interference

Occurs when 2 waves are out of phase with one another

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Definition of Huygen’s Principle

Sound radiates in all directions from a point source

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What is the equation and units for pressure

Pressure = Force/Area
Units = Pa or N/m^2

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Equation for frequency and period/time

f = 1/T
T = 1/f

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What are the SI units

Meter (m) - Length
Kilogram (kg) - Mass
Seconds (s) - Time

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What unit is not an SI unit

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What is the relationship of period and frequency

Inversely proportional

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seconds x cycles/sec =

Hertz or Hz

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Prefixes are always ____ SI units are always ___

First, last

Name these powers of 10 with their prefix, symbols and numbers. 10^6 10^3 10^-2 10^-3 10^-6 10^-9

10^6 - 1,000,000, Mega, M 10^3 - 1,000, Kilo, k 10^-2 - 0.01, Centi, c 10^-3 - 0.001, milli, m 10^-6 - 0.000001, micro, us 10^-9 - 0.000000001, nano, n

Name the recipricol of 10^6.

Mega, 10^6, 1,000,000, M reciprocal is micro, 10^-6, 0.000001, m

Name the reciprocal of 10^3

10^3, kilo, 1,000, k reciprocal is milli, 10^-3, 0.001, m

What is 10^9

Giga, 1,000,000,000, G

What is the reciprocal of 10^9

10^-9, 0.000000001, nano

What is the speed of sound for the following Air Fat Tissue Cranial Bone Lung

A - 330 m/s F - 1,450 m/s T - 1,540 m/s CB - 4,080 m/s L - 500 m/s

As heat rises, sound will

Travel faster

If the environment is cold what will that do to the speed of sound

Will cause speed of sound to be slower

Power is proportional to

Waves amplitude^2

Definition of amplitude Name it's units

Is the "bigness" of the wave Difference between resting value and max value (or min) of acoustic variable Pa, Volts

Definition of period

Time it takes a wave to vibrate a single cycle

Definition of frequency Name it's units

Number of particular events that occur in a specific duration of time Hertz

Definition of wavelength

Distance or length of one complete cycle

Definition of density

Concentration of mass in a volume

Definition of stiffness

Describes the ability of an object to resist compression

Definition of power

Rate of energy transfer or the rate at which work id performed

Definition of half value layer thickness

Distance sound travels in tissue tha reduces the intensity of sound to one-half its original value

Definition of acoustic impedance

Important tissue property that influences the amount of reflection

Definition of dB's

Common unit for measuring signals

Definition of attenuations

Decrease in intensity, power, and amplitude as sound travels

Definition of Snell's law media changes. What is the equation?

Retration is caused by the change in speed experienced by a wave when it changes mediums sin (transmission angle)/sin (incident angle) = Speed of medium 2/speed of medium 1

Definition of attenuation coefficient

Number of decibels of attenuation that occurs when sound travels one cm

Definition of total attenuation

Total decrease in sound energy in decibels, after sound has traveled through a medium for given distance

Definition of PD

Pulse duration Actual time from the start of a pulse to the end of that pulse

Definition of PRP and PRF

PRP - The time from the start of one pulse to the start of the next pulse PRF - Number of pulses that an ultrasound system transmits into the body each second

Definition of intensity

Concentration of energy in a sound beam

Define the following terms. TA PA TP IM SP What combo has the highest value?

TA - Temporal avg. - Avg. inten during entire PRP PA - Pulse average - Avg. inten during PD TP - Temporal peak - Meas. max inten at one time IM - Avg. inten during most intense half-cycle SP - Spatial peak - Beams location at max

Definition of conservation of energy

Total energy cannot be created or destroyed

Define this equation. %R + %T = 100%

% of reflection coefficient + % of transmission coefficient must equal 100%

Define the relationship between the following: Power Intensity Amplitude

Power and intensity is proportional to amplitude^2 Power is proportional to intensity

Wavelength x Frequency = ?

Speed of sound (c) (m/s)

What is the equation for total attenuation?

TA = F x PL x AC

What is the equation for density? What are the units for density?

Stuff (kg)/volume Units - kg/m^3

What is the average density for rarefaction?

50 kg/m^3

What is the average density for compression?

150 kg/m^3

Is period adjustable? Is it fixed?

Not adjustable Quanitity is fixed

Is freqeuncy adjustable? Is it fixed?

Not adjustable Quanitity is fixed

Draw a wave and put these labels in the correct spots: Amplitude Crest Trough Nodes Period Antinodes

Look at pic on review

Draw Huygen's Principal

Look at pic on review

What is the equation for power?

Work/time

In terms of the relationship between power and amplitude. If the amplitude increases by 5, then the power will (increase/decrease) by __?

Power will increase by 25 Power related to amplitude^2

What is the equation for half value layer thickness? What are the units?

3db/f x atten. co cm

If you don't see a frequency listed then you can assume it is

In terms of the relationship between HVLT and propagation beams, what happens to the beam after the half value distance after the beam propagates

Beam drops by 1/2

Decibels indicates the ratio between

2 amplitudes, intensities or powers

What equation would you use in terms of decibels for intensity and power ratios

-dB = 10 x log (I/Io) -dB = 10 x log (P/Po)

What equation would you use in terms of decibels for amplitude ratios

-dB = 20 x log (A/Ao)

Draw an example of attenuation

Look at review pic

What is attenuation directly related to?

Distance, & frequency

What is the attenuation coeff. of soft tissue?

0.77dB/MHz/cm

What beam's are related to Snell's Principal

Incident beam Transmitted beam Reflected beam

How do stiffness and density related to speed of sound?

Stiffness increases, speed increases Density increases, speed decreases

When you are increasing by 3dB the numbers will ____ as you move up the steps

Double

When you are decreasing -3dB the numbers will be ____ as you move down the steps

Be cut in 1/2

When you are incrwasing by 10 dB the numbers will be ___ ____

10 times largers

When you are decreasing by -10dB the numbers will be ___

1/10

What is the equation for pulse duration?

cycles/f or #cycles x period

What is the equation for PRF

1/PRP

What is the equation for PRP

1/PRF

PRF x PRP = ___ Due to

1 Due to being inversely related

What is the equation for HVLT

3dB/f x ac

What is the BUF

Beam uniformity factor

What is the equation for BUF

Spatial peak/spatial avg.