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Name the Metric System from Billion to Billionth
 10^9 giga G Billion
 10^6 mega M Million
 10^ 3 kilo k thousand
 10^2 hecto h hundred
 10^1 deca da ten
 10^1 deci d tenth
 10^2 centi c hundredth
 10^3 milli m thousandth
 10^6 micro µ millionth
 10^9 nano n billionth

What is an appropriate unit for area?
sqaure yards

What is an appropriate unit for volume?
cm^3

How many milliliters are in 8 liters?
8000 ml

How many centimeters are in 3 meters?
300 cm

How many kilometers are in 3000 meters?
3 km

What is the reciprocal of 100?
1/100 or 0.01

What is the reciprocal of 1/8?
8

How many hertz is 3 MHz?
3,000,000 hertz

How many milliliters are contained in a jar filled with 5 liters of fluid?
5000 ml

How many liters are contained in 80 ml of fluid?
0.080 L

How many times bigger is a thousand than ten?
100 times

How much bigger is a billion than a million?
1000 times

How much smaller is a hundred than a thousand?
onetenth

Def. biologic tissue
media

All waves carry _____ from one location to another.
energy

Sound is a _____ wave in which particles in the medium move.
mechanical

Def. Area of increased pressure (squeezed together)
compressed

Def. Area of decreased pressure (stretched apart)
rarefied

Sound waves travel in _____ lines.
straight

Sound waves are ______ waves.
longitudinal

Def. the effects of the medium upon the sound wave
acoustic propagation properties

Def. the effects of the sound wave upon the biologic tissue through which it passes
biologic effects

Name the acoustic variables
pressure, density, distance

What is pressured measured in?
Pascals (Pa)

Def. concentration of force in an area
pressure

Def. concentration of mass in a volume
density

Def. measure of particle motion
distance

What is density measured in?
kg/cm^3

What is distance measured in?
ft, cm, mile, etc...

What are the acoustic parameters?
 period
 frequency
 amplitude
 power
 intensity
 wavelength
 propagation speed

Def. particles that move in a direction that is perpendicular to the direction that the wave propagates
transverse wave

Def. particles that move in the same direction that the wave propagates
longitudinal

Def. when the peaks or troughs of a pair of waves occur at the same time
InPhase Waves

Def. when the peaks or troughs of a pair of waves occur at different times
OutOfPhase

Def. when a pair of waves lose their individual characteristics and combine to form a single wave
interference

Def. the interference of a pair of inphase waves
constructive interference

Def. the interference of a pair of outofphase waves
destructive interference

Waves of with different ______ will undergo constructive and destructive interference.
frequencies

Two waves are traveling in a medium and arrive at a location at the same time. What event takes place?
interference (we don't know if they are insync)

What is the source of a sound wave?
ultrasound system and transducer

Def. the time it takes a wave to vibrate a single cycle, or the time from the start of a cycle to the start of the next cycle
period

What is period measured in?
seconds, ms, hours, etc...

What are the typical values for period?
.1µs to .5µs

Def. the number of particular events that occurs in a specific duration of time
frequency

What is frequency measured in?
Hertz

What are the typical values for frequency?
2 MHz to 10 MHz

Def. less than 20 Hz
infrasound

Def. between 20 Hz to 20 kHz
audible sound

Def. greater than 20 kHz
ultrasound

What are the relationships between period and frequency?
 inversely related
 reciprocals

What are the bigness parameters?

Def. the difference between the maximum or minimum value and the average or undisturbed value of an acoustic variable
Amplitude

What units can amplitude be measured in?
 pascals
 g/cm^3
 distance
 decibels (dB)

What are the typical values of amplitude?
1 MPa to 3 MPa

Def. the difference between maximum and minimum values of an acoustic variable
peaktopeak amplitude

Def. the rate of energy transfer or the rate at which work is performed
power

What is power measured in?
watts

What are the typical values of power?
4  90 milliwatts

How is power and amplitude related?
power is proportional to amplitude squared

How is intensity and amplitude related?
intensity is proportional to amplitude squared

How is intensity and power related?
intensity is proportional to power

Amplitude has increased by a factor of 3. How much has the power changed?
9fold

Amplitude has decreased by 1/2. How much has power changed?
1/4

Def. the concentration of energy in a sound beam
intensity

What is intensity measured in?
W/cm^2

What are the typical values of intensity?
.01  300 W/cm^2

What is the formula for intensity?
intensity (W/cm^2) = power (w) / area (cm^2)

Def. the distance or length of one complete cycle
wavelength

What is wavelength measured in?
meters, inches, cm, etc...

What are the typical values of wavelength?
.15  .8 mm

What determines wavelength?
sound source and medium

What is the formula between wavelength and frequency?
wavelength (mm) = 1.54 mm/µs / frequency (MHz)

What type of wavelength creates better images?
shorter wavelength

Def. the distance that a sound travels through a medium in 1 second
propagation speed

What is propagation speed measured in?
meters per second, mm/µs

What are the typical values of propagation speed?
500 m/s to 4000 m/s

What determines the propagation speed?
medium

What is the speed of sound in soft tissue?
1,540 m/s

What is the formula for speed of sound?
speed (m/s) = frequency (Hz) x wavelength (m)

What two characteristics of a medium effect the speed of sound?
stiffness and density

Def. describes the ability of an object to resist compression
stiffness

Def. describes the relative weight of a material
density

What is the relationship between stiffness and speed?
directly related

What is the relationship between density and speed?
inversely related

What terms can describe stiffness? They are opposite of stiff.
elasticity and compressiblity

What acoustic parameters are determined by the sound source?
period, frequency, amplitude, power, intensity, wavelength

What acoustic parameters are reciprocals?
period and frequency

What acoustic parameters can be adjusted by the sonographer?
amplitude, power, intensity

What acoustic parameter is determined by both the sound source and the medium?
wavelength

What acoustic parameter is determined by the medium only?
propagation speed

T/F A wave with a frequency of 15,000 MHz is ultrasonic?
true

T/F If amplitude is increased to 3 times it's original value, intensity is increased 6fold.
false 9fold

T/F If power is halved intensity is reduced by 1/4.
false it's halved

T/F propagation speed increases as frequency increases.
False

Medium 1 has a density of 9 and a stiffness of 6.
Medium 2 has a density of 8 and a stiffness of 6.
Which medium will be slower?
Medium 1

If the power in a beam is 1 watt and the area is 5 cm^2, what is the beam's intensity?
.2 W/cm^2

If intensity remains the same while the power is doubled, what has happened to the beam area?
doubled

A sound beam travels a total of 10 cm in 2 seconds. What is the speed of sound?
5 cm/sec

T/F Propagation speed increases as frequency increases.
false

T/F Propagation speed increases as frequency decreases.
False

T/F Propagation speed does not change as frequency increases.
True

What is the wavelength of 3 MHz sound in soft tissue?
.51 mm

The effects of sound waves on tissue in the body are called ______.
bioeffects

The effects of tissue on sound waves are called ______.
Acoustic propagation properties

The effects of a medium on an ultrasound wave are called ________.
acoustic propagation properties

T/F Continuous wave sound can create diagnostic images.
false pulse sound

What is pulsed sound?
a collection of cycles that travel together

2 components of pulsed sound
 transmit, talking, "on" time
 receive, listening, "off" time

Def. the actual time from the start of a pulse to the end of that pulse
Pulse duration

What is pulse duration measured in?
seconds, µs, ms, etc...

What are the typical values of pulse duration?
.3µs to 2µs

What are the formulas for pulse duration?
 pulse duration (µs) = # of cycles x period (µs)
 pulse duration (µs) = # of cyles / frequency (MHz)

What are the 2 characteristics of long duration pulses?
 many cycles in the pulse
 individual cycles with long periods

What are the 2 characteristics of short duration pulses?
 few cycles in the pulse
 individual cycles with short periods

Which type of pulse duration is desirable for imaging?
shorter duration pulses improve image accuracy

Def. the distance from the start to the end of a pulse
Spatial Pulse Length

What is spatial pulse length measured in?
mm, inches, etc...

What are the typical values for spatial pulse length?
.1 to 1 mm

What is the formula for spatial pulse length?
spatial pulse length (mm) = # of cycles x wavelength (mm)

What are 2 characteristics of long pulse length?
 many cycles in the pulse
 cycles with longer wavelengths

What are the 2 characteristics of short pulse length?
 fewer cycles in the pulse
 cycles with shorter wavelengths

Which type of spatial pulse length is more desirable?
shorter pulses create more accurate images

Def. the time from the start of one pulse to the start of the next pulse
Pulse Repetition Period

What is pulse repetition period measured in?
units of time, ms

What are the typical values for pulse repetition period?
100µs to 1 ms

Pulse repetition period is controlled by what?
Sound source specifically imaging depth

Def. the maximum distance into the body that an ultrasound system is imaging
Depth of View

What are the 2 components of pulse repetition period?
 transmit time
 receive time

What is transmit time also known as?
pulse duration

What happens to the depth of view when the listening time and pulse repetition period lengthen?
deeper imaging

What happens to the depth of view when the listening time and pulse repetition period shorten?
shallower imaging

Def. the number of pulses that an ultrasound system transmits into the body each second
Pulse Repetition Frequency

What is pulse repetition frequency measured in?
hertz

What are the typical values of pulse repetition frequency?
1000 to 10000 hertz

How is pulse repetition frequency and depth of view related?
inversely

What are the relationships between pulse repetition frequency and pulse repetition period?
inversely related and reciprocals

What is the easiest formula to remember PRF and PRP?
PRF x PRP = 1

T/F Two waves can have identical pulse repetition frequencies , even if their pulse repetition periods are different.
False

T/F Two waves can have identical PRFs, even if their periods are different.
True

T/F PRF and PRP are determined only by the imaging depth.
True

Def. the percentage or fraction of time that the system is transmitting a pulse
Duty Factor

What is unit for duty factor?
none. it's a percentage therefore dimensionless

What are the typical values for Duty Factor?
.2% to .5%

What is the relationship between depth of view and duty factor?
inversely related

What is the formula for duty factor?
duty factor (%) = (pulse duration / PRP) x 100

What are the factors that determine shallow imaging?
 less listening
 shorter PRP
 higher PRF
 higher duty factor

What are the factors that determine deeper imaging?
 more listening
 longer PRP
 lower PRF
 lower duty factor

Def. refers to the intensity of the beam at different locations or distances
Spatial Intensity

Def. the maximum intensity
peak intensity

Def. the mathematical middle intensity
Average Intensity

Def. refers to the intensity at all time, transmit and receive
Temporal Intensity

Def. refers to the intensity at the transmit time
Pulsed intensity

Def. the beams intensity at the location where it is maximum
spatial peak intensity

Def. the beams intensity across the entire crosssectional area
spatial average intensity

Def. the beams intensity at the instant in time of its maximum value
temporal peak

Def. the average intensity during the most intense halfcycle
I max

Def. the average intensity during the pulse duration
pulse average intensity

Def. averaging the intensity during the entire PRP (includes both the transmit and recieve times)
temporal average intensity

T/F Intensities may be reported in various ways with respect to time and space.
True

The different measurements of intensities are important in the study of ________.
bioeffects

______ intensity is the most relevant intensity with respect to tissue heating.
SPTA

What units are all intensities are measured in?
watts/cm^2

What intensity if the highest and which is the lowest?
 SPTP is the highest
 SATA is the lowest

Def. describes the spread of a beam in space
beam uniformity coefficient or SP/SA factor

Def. describes the relationship of beam intensities with time
duty factor

Continuous wave ultrasound. The pulse average and temporal average intensities are the ______.
Same

T/F For continuous wave ultrasounds, SPTA = SPPA and SATA = SAPA.
True

T/F When pulsed and continuous waves have the same SPTP, the continous wave will have the higher intensity.
True

T/F When pulsed and continuous waves have the same SATP intensities, the continuous wave will have the higher SPTA intensity.
True

Rank the types of intensities from largest to smallest.
SPTP > Im > SPPA > SPTA > SATA

Def. the weakening of sound as it travels in the body
attenuation

Def. strengthening of the ultrasound signal
amplifying

Def. the unit that quantifies the strength of sound beams as they are created by tranducers and travel through the body
Decibels

Def. Decibels that are increasing in strength or getting larger.
Positive Decibels

Def. decibels that are decreasing in strength or getting smaller
negative decibels

The 3 decibel rule.
a change of 3 decibel is equal to doubling or having the intensity of the ultrasound beam

The 10 decibel rule.
a change of 10 decibels it equal to 10fold or onetenth of the intensity of the ultrasound beam

A reduction in the intensity of a sound beam to onehalf of its original value is _____dB.
3 dB

A reduction in the intensity of a sound beam to onequarter of its original value is ______ dB.
6 dB

10 dB means that the intensity is reduced to ______ of its original value.
onetenth

dB is a mathematical representation with a ______ scale.
logarithmic and relative

T/F We need one intensity to calculate dB.
False

A wave's intensity is 2mW/cm^2. There is a change of +9 dB. What is the final intensity?
16 mW/cm^2

2 factors determine attenuation
 path length
 frequency of sound

3 processes contribute to attenuation
 reflection
 scattering
 absorption

Def. when the wave's energy strikes a boundary and is redirected back toward the sound source
Reflection

2 types of reflection
specular and diffuse

Def. type of reflection when sound is reflected back by a smooth boundary and in only one direction
Specular reflection

Def. type of reflection when sound is reflected back by and irregular surface and radiates in more than one direction
Diffuse reflection

Def. random redirection of sound in many directions that occurs when the tissue interface is smaller or equal to the wavelength of the sound beam
Scattering

Def. a special form of scattering that occurs when the structure's dimensions are much smaller than the beam's wavelength and the sound wave is redirected equally in all directions
Rayleigh Scattering

Def. occurs when ultrasonic energy is converted into another energy form, such as heat
absorption

Def. the number of decibels of attenuation that occurs when sound travels one cm
Attenuation coefficient

What is the attenuation coefficient measured in?
dB/cm

What is the formula for total attenuation?
total attenuation (dB) = atten coefficient (dB/cm) x distance (cm)

What is the formula for attenuation coefficient in soft tissue?
atten. coef. (dB/cm) = frequency (MHz) / 2

Def. the distance that sound travels in a tissue that reduces the intensity of sound to onehalf its original value
halfvalue layer thickness

What are typical values for halfvalue layer thickness?
.25  1 cm

What are synomyns for halfvalue layer?
penetration depth, depth of penetration, halfboundary layer

2 factors that determine halfvalue layer thickness
 the medium
 the frequency of sound

Def. the acoustic resistance to sound traveling in a medium
impedance

What is the formula for impedance?
impedance (rayls) = density (kg/m^3) x prop. speed (m/s)

What unit is impedance measured in?
rayls

What are the typical values for impedance?
1.25 to 1.75 Mrayls

What is another name for acoustic impedance?
characteristic impedance


