Exam 1 Flashcards
Definition of longitudinal wave
Draw the wave
2D waves with rarefaction used during ultrasound
Definition of transverse wave
Give an example
Draw the wave
3D ultrasound waves
Ex. Ocean waves
What type of waves do x-rays use
Electromagnetic
What are the 2 types of transverse waves used in ultrasound
Mechanical and Electromagnetic
A mechanical waves needs this to travel
And is usually in __ or __
Medium
2D or 3D
T or F
Electromagnetic waves do not need mediums and can travel through vacuums
True
Electromagnetic waves do not need anything and are always
3D
Name all the classifications of sound
Infrasound
Audible
Ultrasound
Diagnostic
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
Which travels faster, lower frequency or higher frequency
Lower frequency
Lower frequency is easier to
Pass through
Higher frequency allows for
Better images/details
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
In the principal of superposition describe the relationship between wave amplitude and in-phase waves
Amplitude wave will increase with in-phase
In the principal of superposition describe the relationship between wave amplitude and out-phase waves
Amplitude wave will decrease with out-of phase waves
Definition of constructive interference
Occurs when 2 waves are in-phase w/ each other
Definition of destructive interference
Occurs when 2 waves are out of phase with one another
Definition of Huygen’s Principle
Sound radiates in all directions from a point source
What is the equation and units for pressure
Pressure = Force/Area
Units = Pa or N/m^2
Equation for frequency and period/time
f = 1/T
T = 1/f
What are the SI units
Meter (m) - Length
Kilogram (kg) - Mass
Seconds (s) - Time
What unit is not an SI unit
cm
What is the relationship of period and frequency
Inversely proportional
seconds x cycles/sec =
Hertz or Hz
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
1
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.
