Term
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Definition
Mechanical wave in which particles in a medium move
waves are identified by oscillations in acoustic variables
variables distinguish bt these and other waves: pressure, density, and distance |
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Term
| ________ is a longitudinal, mechanical wave |
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Definition
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Term
| ______________ wave particles move in a direction that is perpendicular to the direction that the wave propagates |
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Definition
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Term
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Definition
| particles move in the same direction that the wave propagates |
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Term
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Definition
| waves lose their individual characteristics and combine to form a single wave |
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Term
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Definition
| a pair of out-of phase waves combine to form one of lesser amplitude |
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Term
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Definition
| at some moments in time, waves are in phase while at other moments the waves are out of phase- possible due to varying ? |
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Term
| Which sound parameters can be changed by the sonographer? |
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Definition
Amplitude, Power, Intensity
All three are directly related, one increases they all go up |
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Term
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Definition
*time it takes to complete a single cycle
*time from the start of one cycle to the start of the next cycle
*units: any unit of time
*.1 to .5 microseconds
*det by soundsource, not affected by medium
*cannot be changed by sonographer |
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Term
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Definition
*det by soundsource,not medium
*cannot be changed by sonographer
*clinical imaging freq= 2MHz-10MHz
*cycles/sec or Hertz |
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Term
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Definition
*Above the limits of human hearing
*Above 20,000Hz |
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Term
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Definition
*can be heard by humans
*between 20Hz and 20,000Hz |
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Term
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Definition
*frequency so low it cannot be heard by humans
*freq less than 20Hz |
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Term
Affects penetration and detail (axial resolution)
1. less penetration but better detail
2. better penetration less resolution |
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Definition
Frequency
1. higher
2. lower |
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Term
| period and frequency are ________ |
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Definition
reciprocal
period(sec) X frequency(MHz)= 1 |
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Term
| as frequency decreases, period _____ |
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Definition
| increases; they are inversely related |
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Term
| parameters describe the size or strength or magnitude of a sound wave |
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Definition
| Amplitude, Power, Intensity |
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Term
| difference between the min or max value and the avg value of an acoustic variable |
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Definition
| Amplitude- measured in pascals (Pa) |
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Term
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Definition
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Term
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Definition
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Term
10^9 billion
10^6 million
10^3 thousand
10^2 hundred
10^1 ten
10^-1 tenth
10^-2 hundredth
10^-3 thousandth
10^-6 millionth
10^-9 billionth |
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Definition
giga G
mega M
kilo k
hecto h
deca da
deci d
centi c
milli m
micro
nano n |
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Term
| power is proportional to the waves amplitude squared |
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Definition
| power is directly related to amplitude |
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Term
concentration of energy in a soundbeam
relates to how the power in a wave spreads or is distributed in space |
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Definition
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Term
| the rate at which work is performed |
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Definition
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Term
distance or length of one complete cycle
determined by source and medium
cannot be changed by sonographer |
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Definition
wavelength
soft tissue ranges from 0.15 to 0.8mm
measured in any unit of length |
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Term
| What is the speed of sound in soft tissue? |
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Definition
1540 m/s
1.54 mm/ m
1.54 km/s |
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Term
higher frequency=____________ wavelength
lower frequency= ____________ wavelength
_________ wavelengths generally produce higher quality images with greater details |
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Definition
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Term
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Definition
determined only by the characteristics of the medium (density and stiffness)
not affected by the sound source (frequency)
*a 10MHz and a 2MHz will travel the same speed when they travel thru the same medium |
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Term
Material Speed
________________________________________
air 330 m/s
water 1480 m/s
metals 2000-7000 m/s
bone 3500 m/s |
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Definition
| sound travels faster in solids, slower in liquids, slowest in gases |
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Term
stiffness increases; speed increases
density increases; speed decreases |
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Definition
stiffness and speed are directly related
density and speed are inversley related |
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Term
| 5 additional parameters used to describe pulsed sound |
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Definition
| pulse duration spatial pulse length pulse repetition period pulse repetition frequency duty factor |
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Term
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Definition
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Term
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Definition
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Term
| Soundwaves are identified by oscillations in which acoustic variables? |
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Definition
| Pressure Pa, Density, Distance |
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Term
| Bigness of a wave; all 3 are directly related |
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Definition
| power, amplitude, intensity |
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Term
| Period and ___________ have a reciprical relationship |
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Definition
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Term
| Intensity is the concentration of power in the beam. What is the formula? |
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Definition
| Intensity (w/cm^2)=power/beam area |
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Term
DESCRIBING PULSED WAVES
Shallow Imaging Deeper Imaging
Less Listening More Listening
Shorter PRP Longer PRP
Higher PRF Lower PRF
Higher Duty Factor Lower Duty Factor |
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Definition
| Because the sonographer has the ability to change depth, they are controlling: PRP, PRF, and the Duty Factor |
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Term
Reporting Intensities- Bio problems
Spatial
Temporal
Peak
Average
Pulsed |
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Definition
-refers to distance or space
-all time, transmit and receive
-max value
-mathmatically middle value
-only transmit time *is the avg intensity for the pulse duration |
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Term
Measuring Intensity- Bioeffects
Spatial or Temporal
Peak or Avg
Which is most relevant in tissue heating? |
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Definition
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Term
| Which intesity has the highest/ lowest intensity? |
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Definition
SPTP has the highest
SATA has the lowest
all intensities have units of watts/cm^2 |
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Term
| If amplitude is increased by a factor of 4, what is the change in power? |
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Definition
4x4= 16 times
power is proportional to amp^2 |
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Term
| Intensity is directly proportional to power. One inc, the other inc. What are power and intensity proportional to? |
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Definition
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Term
| Wavelength is soft tissue |
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Definition
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Term
| The higher the frequency, the __________ the wavelength and ___________ quality of pictures. |
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Definition
shorter
higher
The lower the frequency, the longer the WL |
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Term
| Frequency is measured in Hz which is another way of saying what? |
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Definition
| Number of cycles per second |
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Term
Related or Unrelated?
PRP and Period
Frequency and Speed
Frequency and Intensity
Frequency and Power
Duty Factor and Depth
PRF and PRP
PRP and Depth |
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Definition
Unrelated
Unrelated
unrelated
Unrelated
Inversely Related
Inversely Related
Directly Related |
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Term
Number of Cycles X Period=
# cycles/frequency= |
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Definition
Pulse Duration
Typically .3-2 microseconds |
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Term
| Transmit time + Receive time, can be changed by sonographer |
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Definition
| Pulse Repetition Period- it is directly related to depth so the sonographer has the ability to adjust |
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Term
| % or fraction of time actually spent working. Ranges from .002-.005 or .2%-.5% |
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Definition
Duty Factor
Pulse duration/PRP x 100= Duty Factor |
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Term
Speed
Air 330 m/s
Water 1480 m/s
Metals 2000-7000 m/s
Bone 3500 m/s |
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Definition
Speed is deternimed only by the medium
Stiffness and Speed are directly related
Density and Speed are inversley related |
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