Sono Physics Questions Flashcards
Color Doppler displays can present Doppler- ______ and Doppler-____
Shift, power
The visual display of Doppler information can be in the form of a ____-Doppler display or a ____-Doppler display
Color, Spectral
In medical applications, the flow of ______ is commonly the source of the Doppler effect. Doppler information is applied to ______ for audible evaluation and to _____ for virtual analysis
Blood, loudspeakers, displays
The motion that produces the Doppler effect is that of the?
Reflector
The Doppler effect is a change in echo_____
frequency
Transducers generate ultrasound _____ and receive returning _____
Pulses, echoes
The _____ is the interface between the patient and the instrument
Transducer
Sonography is accomplished by using a pulse-echo technique. The important information gained from this technique includes the _____ from which each echo originated and the ____ of each echo. From this information, the instrument can determine the echo ______ and ______ on the display
Location, strength, location, brightness
A sector can have a _____ or a ______
Pointed, curved
The shape of a sector scan is similar to a ______ of ______
Slice, pie
The linear scan has a _______ shape
Rectangular
A sector scan is composed of many scan lines with a common _____
Origin
A linear scan is composed of many _____, ______ scan lines
Vertical, parallel
The brightness of an echo, as presented on the display, represents the _____ of the echo
Strength
Ultrasound gray-scale scans ______-_____ images of tissue cross sections and volumes
Pulse-echo
The diagnostic ultrasound imaging method has two parts:
1. Sending _____ of _____ into the body
2. Using _____ received from the anatomy to produce a _______ of that anatomy
Pulses, ultrasound, echoes, image
Does scattering occur at smooth boundaries and within homogeneous media?
No
No reflection will occur with perpendicular incidence if the media _____ are equal
Impedances
What must be known to calculate the density of a reflector?
Travel time and speed
Can backscatter help make echo reception? less dependent on incident angle?
Yes
Reflection of sound in many directions while it encounters rough media junctions on particle suspensions is called______
Scattering
Under what two conditions does refraction not occur?
Perpendicular incidence & equal media propagation speeds
Refraction is a change in ______ of sound when it crosses a boundary. Refraction is caused by a change in ________ at the boundary
Direction, propagation speed
With perpendicular incidence, the reflected intensity depends on the_____
Density difference and impedance difference
Is there a reflection if the impedances of the media are equal?
Yes
With perpendicular incidence, two media ______ and the incident _____ must be known to calculate the reflected intensity
Impedances, intensity
With perpendicular incidence, two media ______ must be known to calculate the IRC
impedances
When ultrasound encounters a boundary with perpendicular incidence, the _____ of the tissues must be different to produce a reflection
Impedances
The imaging depth ____ while frequency increases
decreases
Is attenuation higher in bone than in soft tissue?
Yes
Absorption is the conversion of _____ to _____
Sound, heat
If frequency is doubled and path length is halved, attenuation is ____
unchanged
For soft tissue, if frequency is doubled, attenuation is _____, if path length is doubled, attenuation is ____, if both frequency and path length are doubled, attenuation is ____
Doubled, doubled, quadrupled
The attenuation coefficient in soft tissue ____ while frequency increases
increases
The attenuation coefficient is attenuation per _____ of sound travel
centimeter
Attenuation consists of ________
Absorption, reflection, and scattering
Attenuation is the reduction in _____ and _____ as a wave travels through a medium
amplitude, intensity
If amplitude is doubled, intensity is ____
quadrupled
If both power and area are doubled, intensity is _____
quadrupled
If area is doubled and power remains unchanged, intensity is _____
halved
If power is doubled and areas remains unchanged, intensity is _____
doubled
Intensity is proportional to ____ squared
amplitude
A unit for intensity is _____
mW/cm^2
Intensity is the ____ in a wave divided by _____
power, area
Amplitude is the maximum ____ that occurs in an acoustic variable
Variation
What is a typical DF for sonography?
0.1
For pulsed ultrasound, the DF is always_____
less than 1
The DF of a continuous wave is ___
1
SPL equals the number of cycles in the pulse multiplied by _____
wavelength
PD equals the number of cycles in the pulse multiplied by _____
period
What is the fraction of time that pulsed ultrasound is actually on?
DF
SPL is the _____ of _____ that a pulse occupies while it travels
Length, space
PD is the ______ it takes for a pulse to occur
time
The PRP _____ while PRF increases
decreases
what is the time from the beginning of one pulse to the beginning of the next?
PRP
PRF is the number of _____ occurring in 1 second
pulses
CW stands for____
Continuous Wave
Impedance is ____ multiplied by _____
density, propagation speed
If two media have the same propagation speed but different densities, will the one with the higher density have the higher impedance?
Yes
If two media have the same density but different propagation speeds, will the one with the higher propagation speed have the higher impedance?
Yes
In nonlinear propagation, additional frequencies appear that are ____ and ______ multiples of the fundamental frequency. They are called ______
Odd, even, harmonics
Nonlinear propagation means that _____
The waveform changes shape while it travels
If two media have different stiffnesss, will the one with the higher stiffness have the propagation speed?
Yes
Waves can carry _____ from one place to another
Information
If frequency in soft tissue is doubled, propagation speed is _____
Unchanged
If propagation speed is doubled and frequency is held constant, the wavelength is _____
Doubled
Sound is a ______ wave
Mechanical longitudinal
Sound travels most slowly in _____
Gases
Sound travels fastest in ______
Steel
Propagation speed in bone is _____ that in soft tissue
higher than
Wavelength in soft tissue ______ while frequency increases
Decreases
Propagation speed is determined by the _______
Medium
The average propagation speed in soft tissues is _____ m/s or _____mm/us
1540, 1.54
Propagation speed increases if ______ is increased
Stiffness
The ______ and _______ of a medium determine propagation speed
Density, stiffness
Wavelength is equal to _______ divided by ______
propagation speed, frequency
Propagation speed is the speed with which a _______ moves through a medium
Wave
Wavelength is the length of _____ over which one cycle occurs
space
Period decreases while _____ increases
Frequency
Period is the _____ it takes for one cycle to occur
Time
The unit of frequency is ____, which is abbreviated as _____
Hertz, Hz
Frequency is the number of ____ an acoustic variable goes through in a second
cycles
Acoustic variables include ____
Pressure, density, and particle motion
Ultrasound is sound with a frequency greater than _____
20,000 Hz
Sound is a traveling variation in quantities called _____ variables
Acoustic
A wave is a traveling variation is quantities called _____ variables
Wave
Heating depends most directly on ____
SATA Intensity
Conditions under which cavitation may occur are best described by ____
Peak rarefactional pressure
Bioeffects have been observed in experimental animals with intensities greater than _____
100 mW/cm^2 SPTA
Bioeffects have been observed in experimental animals with focused intensities greater than____
1 mW/cm^2 SPTP
Focal lesions have been observed in experimental animals with intensities greater than ____
100 mW/cm^2 SPTA
Is the available epidemiologic data sufficient enough to make a final judgment on the safety of diagnostic ultrasound?
No
What is currently used to indicate output on display?
Mechanical index
Is there no possible hazard involved in the use of diagnostic ultrasound?
No
Should ultrasound not be used as a diagnostic tool because of the bioeffects it can produce?
No
No independently confirmed, significant bioeffects in mammalian tissues have been reported at intensities below _____
10 mW/cm^2 SATA
Is there any known risk with the current use of diagnostic ultrasound?
Yes
Are there any bioeffects that ultrasound produces in small animals under experimental conditions?
No
What mechanism of ultrasound can produce bioeffects?
Cavitation
What can relate to heating?
Absorption
what acoustic parameter has been documented in ultrasound epidemiologic studies published thus far?
Intensity and pulsing conditions
A device commonly used to measure the output of diagnostic ultrasound instruments is a _____
hydrophone
A typical output intensity for an ultrasound imaging instrument is ____
3.5 MHz
What Doppler has the highest output intensity?
Duplex pulsed doppler
Which controls affect instrument output intensity
Transmit, output
The tissue of greatest concern regarding bioeffects in an abdominal scan is the _____
fetus
No bioeffects have been observed in nonhuman mammalian tissues at thermal index values of less than ____
2
No bioeffects have been observed in nonhuman mammalian tissue at mechanical index values of less than _____
0.4
No bioeffects have been observed in nonhuman mammalian tissue at peak rarefactional values of less than _____
0.4
ALARA is an abbreviation for ____
As Low As Reasonably Achieved
A tissue equivalent _______ has an attenuation of approximately 0.5 dB/cm-MHz and a propagation speed of 1.54 mm/us. A _____ does not mimic tissue but provides a means for measuring some aspect of instrument performance
Phantom, test object
Can test objects and phantoms be used by the instrument operator?
Yes
A ______ test object is useful in checking the accuracy of Doppler spectral displays
String
Tissue equivalent phantoms attempt to represent some acoustic property of _____
Tissues
A _____ phantom is useful in simulating physiologic ______ conditions for a Doppler instrument
Flow, flow
Does the string test object measure volumetric flow rate?
No
Do all hydrophones consist of a small element mounted on the end of a needle?
No
A needle hydrophone contains a small ______ element
Transducer and piezoelectric
Because of its small size, can a hydrophone measure spatial details of a sound beam?
Yes
A hydrophone _____
Produces a voltage
What is part of the circulatory system?
Heart, arteries, arterioles, capillaries, venules, and veins
The _____ are the tiniest vessels in the circulatory system
Capillaries
Doppler ultrasound can detect flow in the _____
Heart, arteries, veins
To flow is to move in a _____
stream
The characteristic of a fluid that offers resistance to flow is called _____
viscosity
Poise is a unit of ______
Viscosity
Pressure is ______ per unit area
force
Pressure is ______
Omnidirectional
Flow is a response to pressure _______ or ________
difference, gradient
If the pressure is greater at one end of a liquid-filled tube or vessel than it is at the other, the liquid will flow from the _______- pressure end to the _______- pressure
higher, lower
The volumetric flow rate in a tube is determined by _____ difference and _______
pressure, resistance
Flow increases if _______ increases
pressure difference/gradient
While flow resistance increases, volumetric flow rate ______
Decreases
If pressure difference is doubled, volumetric flow rate is _____
doubled
If flow resistance is doubled, volumetric flow rate is _____
halved
Flow resistance in a vessel depends on _____
Vessel length, vessel radius, blood viscosity
Flow resistance decreases with an increase in ______
vessel radius
Flow resistance depends most strongly on _____
Vessel radius
Volumetric flow rate decreases with an increase in _______
Vessel length and blood viscosity
When the speed of a fluid is constant across a vessel the flow is called ____ flow
plug
______ flow occurs when straight parallel streamlines describing the flow are altered
Disturbed
_____ flow involves random and chaotic flow patterns, with particles flowing in all directions
Turbulent
Turbulent flow is more likely _____ to a stenosis
Distal
A narrowing of the lumen of a tube is called a _____
Stenosis
Proximal, to, at, and distal to a stenosis _____ must be constant
Volumetric flow rate
Poiseuilles equation predicts a ______ in flow speed with a decrease in vessel radius
Decrease
The continuity rule predicts a ____ in flow speed with a localized decrease in vessel diameter
increase
In a stenosis, the pressure is _____ the proximal and distal values
Less than
Added forward flow and flow reversal in diastole can occur with ____ flow
Pulsatile
While stenosis diameter decreases, _____ passes through a maximum
Flow speed at & proximal to the stenosis
The ____ effect is used to detect and measure _____ in vessels
Doppler, flow
Motion of an echo-generating structure causes an echo to have a different _____ from that of the emitted pulse
Frequency
The Doppler shift is the difference between ______ and ______ frequencies
Received, emitted
when incident sound direction and reflector motion are not parallel, calculation of the reflected frequency involves the _____ of the angle between these directions
Cosine
For blood flowing in a vessel with a plug flow profile, the Doppler shift is ____ across the vessel
Constant
Which Doppler angl yields the greatest Doppler shift?
0
To proceed from a measurement of Doppler-shift frequency to a calculation of flow speed, _____ must be known or assumed
Doppler angle
If operating frequency is doubled, the Doppler shift is ________
Doubled
Color-Doppler instruments present two-dimensional, color-coded images representing _______ that are superimposed on gray-scale images representing _______
Flow, anatomy
Color-Doppler instruments use an _____ technique to yield Doppler information in real-time
Autocorrelation
Are the angle dependencies of Doppler shift displays and Doppler-Power displays different?
Yes
Is color only used to represent flow direction, in Color-Doppler Instruments?
No
Approximately ____ pulses are required to obtain one line of Color-Doppler information
10
Whats increases if the Doppler angle is increased?
Effect of angle error
Decreased distal resistance normally causes end diastolic flow to ____
Increase
Flow reversal in diastole indicates ____
High distal resistance
Do higher flow speeds always produce a higher Doppler shift on a spectral display?
No
Does turbulent flow produce a narrower spectrum?
No
Does disturbed flow produce a narrower spectrum?
No
If all the cells in a vessel were moving at the same constant speed, the spectral trace would be a ____ line
Thin horizontal
Spectral broadening is a ______ of the spectral trace
Vertical thickening
Increasing ensemble length ____ color sensitivity and accuracy and _____ frame rate
improves, decreases
What control can help with clutter?
wall filter
Color map baselines are always represented by _____
Blue
Doubling the width of a color window produces a ____ frame rate
Quadrupled
Steering the color window to the right or the left produces a _____ frame rate
unchanged
Autocorrelation produces ___
The mean value of Doppler shift, variance
Steering the color window to the right or left changes ____
Frame rate, PRF, Doppler angle, Doppler shift
Color Doppler frame rates are ___ gray-scale rates
less than
Is angle important in transverse color-Doppler views through vessels?
Yes
Compared with Doppler shift Imaging, Doppler Power Imaging is ______
More sensitive, angle-dependent, aliasing-independent, Speed independent
Doppler-power imaging indicates the ____ of flow
presence
An earlier gat time means ____ sample volume depth
a shallower
Doppler signal power is proportional to _____
Cell concentration
Does Doppler ultrasound provide information about flow conditions only at the site of measurement?
No
What can reduce the frame rate of a Color-Doppler image?
Wider color window, increased ensemble length
The _____ technique is commonly used to detect echo Doppler shifts in color-Doppler instruments
Autocorrelation
Increasing the ensemble length _____ the frame rate
decreases
A pulsed wave Doppler system is a _____ system
Sampling
How many crystals are in a CW probe?
2
Which component determines direction and separates Doppler shift voltages into separate forward and reverse channels?
Phase quadrature detector
What’s the Doppler angle range?
30-60
How long are the typical imaging pulses for 2D?
2-3 cycles
What is the pulse length for Doppler instruments?
5-30 cycles
What equals the width of the sample volume?
Beam width
A _____ gate length is desired when searching for a blood vessel.
Longer
A _______ gate length improves the quality of the spectral display.
Shorter
What is represented on the horizontal axis of a spectral display?
Time
What is represented on the vertical axis of a spectral display?
Doppler-shift frequency
How is the amplitude or power of each Doppler-shift frequency at any instant presented?
Brightness/color
What is Doppler signal power proportional to?
Blood cell concentration
Where will a sonographer see a “Tardus Parvus” waveform?
Upstream (proximal) stenoses
What happens if the spectral gain is too high?
Spectral broadening
How many Doppler samples per scan line are in an average color Doppler display?
100-400
How many frames per second is in a typical color Doppler display?
5-50
With Doppler, how does the sonographer control or adjust the PRF?
Scale control
What is the minimum number of pulses per scan line (ensemble length) for Doppler?
3
What is the most common ensemble length?
10-20
What must be considered with an increased ensemble length?
Lower frame rates
The combination of which three values display the sign, magnitude, and variance of Doppler shifts?
Hue, saturation, luminence
Where is phasic flow found?
Veins
What happens to sound when it encounters a tissue interface with equal impedances?
No echo
How can speckle be reduced?
Spatial compounding
