US Physics Final
90 degree insonation, Doppler shift of RBC traveling at 200 cm/s...?
zero
What is the image shape of a vector array?
~trapezoidal, basically a sector with a flat top that does NOT come to a point...
equation for spatial pulse length
# of cycles x wavelength
___________________ occurs when the structure's dimensions are much smaller than the beam's wavelength? How does it redirect the sound wave? What is the relationship to frequency
-Rayleigh Scattering -Equally in ALL DIRECTIONS increases dramatically with frequency (Rayleigh scattering is proportional to frequency^4)
When a wave reflects off an irregular surface, it radiates in more than one direction. This form of reflection is called ____________ reflection or ____________. Advantage: _________________ Disadvantage: ___________________
-diffuse reflection or backscatter -Advantage: suboptimal angles can that can return to transducer -Disadvantage: lower strength than specular reflections
What does the backing material/damping element do?
-restricts the extent of PZT deformation -it is short in duration and length -It enhances axial resolution -The dampening material increases bandwidth, decreases the Q- factor, and lengthens the transducer case -Backing material decreases the duty factor at a particular PRF
When the boundary is smooth, the sound is reflected in only one direction in an organized manner. This reflection is called ____________. One limitation of this is ______________________________________________. The angle of incidence should be ____________________________.
-specular reflection. -Once the wave is slightly off-axis, the reflection does not return to the transducer. -Perpendicular
What sound value is ultrasound (2) What sound value is infrasound? (1)
0.02 MHz or 20 kHz less than 20kHz
3 ways the speed of sound in soft tissue can be represented as:
1) 1540 m/s 2) 1.54 km/s 3) 1.54 mm/microseconds
What dopplers have range specificity?
1) PW Doppler 2) color flow Doppler 3) power Doppler
5 synonyms or piezoelectric materials
1) PZT 2) active element 3) ceramic 4) crystal 5) lead zirconate titanate
There is a greater likelihood of cavitation bioeffects and a higher MI with (2 things)
1) additional negative pressure 2) lower frequency
What are 4 characteristics of reverberation?
1) appear in multiples 2) appear equally spaced 3) are located parallel to the sound beam's main axis 4) are located at ever-increasing depths
Four requirements for a quality assurance program are:
1) assesment of system components 2) repairs 3) preventive maintenance 4) record keeping
Color flow information provides ________________ velocity information (2)
1) average 2) qualitative
What are two reasons for fundamental imaging artifacts?
1) beam is very strong 2) many different superficial anatomic layers distort the sound beam
three devices measure the output of ultrasound transducers by absorption and what they do
1) calorimeter - measures the power of the whole beam 2) thermocouple - measure the sound beam's power at particular locations in the beam 3) liquid crystal - change color based on temperature
three consequences of using backing material are (3 things)
1) decreased sensitivity 2) wide bandwidth 3) low quality factor
What two factors affect frame rate?
1) depth 2) speed of sound in the medium
Mechanical Index (MI) depends on the (2 things)
1) frequency of the transmitted sound 2) rarefaction pressure of the sound wave
The five goals of a quality assurance program are:
1) guarantee proper operation of the system 2) detect gradual changes 3) minimize downtime 4) reduce the number of non-diagnostic exams 5) reduce the number of repeat exams
What two sonographer-controlled settings determine frame rate
1) imaging depth 2) number of pulses in each picture
3 summary statements from the AUIM on in vitro bioeffects:
1) in vitro bioeffects research is important 2) in vitro bioeffects are real 3) direct clinical significance should be viewed with caution
What does the matching layer do (2 things)
1) increases the efficiency of sound energy transfer between the active element and the body 2) protects the active element
two techniques used to study bioeffects are: The _______________ approach searches for a relationship between cause and effect. The _______________ approach searches for a relationship between exposure and response.
1) mechanistic approach 2) empirical approach
Artifacts include reflections that are described as: (5) things
1) not real 2) not seen on image 3) incorrect shape or size 4) incorrect position 5) incorrect brightness
What 3 factors determine the number of pulses per frame?
1) number of focal points 2) sector size 3) line density
Stable cavitation has: 1) _________________ bubble 2) _____________________________ and ___________________________ 3) __________________ MI Transient cavitation 1) ________________________ bubble 2) also called _____________ or __________________. 3) _______________________ and ________________________ 4) higher MI
1) oscillating bubble 2) microstreaming and shear stress 3) lower MI 1) bursting bubble 2) inertial or normal cavitation 3) shock waves and very high temperatures 4) higher MI
Two major functions of an ultrasound system are ______________________________________ and ____________________________.
1) preparation and transmission of electrical signals to the transducer, which creates a sound beam. 2) The reception of electrical signals from the transducer, with subsequent processing into clinically meaningful images and sounds.
What are the four commonly accepted principles of health care ethics?
1) respect for autonomy 2) nonmalificence 3) beneficence 4) justice
What 2 conditions are required for refraction?
1) sound wave must be obliquely incident to the border between 2 media 2) the media on either side of the border must have dissimilar propagation speeds.
3 disadvantages of pulse inversion harmonics:
1) the time required to create a frame is doubled, the frame rate is halved, and temporal resolution is reduced.
Two important bioeffect mechanisms are:
1) thermal 2) cavitation (non thermal)
Three devices for quality assurance are: (what do they do)
1) tissue equivalent phantom - evaluates gray scale 2) Doppler phantom - asses the characteristics of all Doppler modalities 3) beam profile/slice thickness phantom - determines elevational resolution
Six main components of an ultrasound system.
1) transducer 2) pulser and beam former 3) receiver 4) display 5) storage 6) master synchronizer
What are the 2 color maps?
1) velocity mode 2) variance mode
Artifacts result from (4 things)
1) violation of assumptions 2) equipment malfunction or poor design 3) the physics of ultrasound 4) operator error
Attenuation is determined by TWO factors:
1. PATH LENGTH ( distance) 2. FREQUENCY ( penetration)
What is the order of receiver operations?
1. amplification 2. compensation 3. compression 4. demodulation 5. reject
What are the six assumptions of imaging systems
1.sound travels in a straight line 2. sound travels directly to a reflector and back 3. sound travels in soft tissue at exactly 1,540m/s 4. reflections arise only from structures positioned in the beam's main axis 5. the imagine plane is very thin 6. the strength of a reflection is related to the characteristics of the tissue creating the reflection
The duty cycle of the continuous wave is ______________.
100%
What is the value of the duty cycle/factor for continuous wave ultrasound? (2)
100% or 1.0%
Which choice relates to the presence of gray shades in a Doppler spectrum? A. velocity B. frequency shift C. amplitude of the echo D. laminar flow
A) amplitude of the echo
Which of the following determines the gray scale in a Doppler spectrum? A) number of reflectors B) velocity C) frequency shift D) laminar flow
A) number of reflectors
All of the following are related to dedicated continuous wave Doppler transducers except A) wide bandwidth B) high quality factor C) higer sensitivity D) range ambiguity
A) wide bandwidth. Since dedicated continuous wave transducers do not use backing material, they have a NARROW BANDWIDTH.
How many elements in a phased array probe are used to create a single sound pulse?
ALL the active elements in a linear phased array probe are fired to create each sound pulse.
The Doppler shift occurs to what waves?
ALL waves coming from a moving wave source
All of the following are associated with a CW Doppler transducer except: A) narrow bandwidth B) increased sensitivity C) backing material D) high Q-factor
C) backing material
A maximum Doppler shift is obtained when the angle between the direction of blood flow and the direction of sound beam is A. 10 degrees B. 90 degrees C. 180 degrees D. 270 degrees
C. 180 degrees
A duplex ultrasound system displays _____ information. A. M-mode, two- dimensional image, and A mode B. A-mode and B-mode C. two dimensional image and Doppler D. two- dimensional image and M-mode
C. two dimensional image and Doppler.
__________________ is a mirror image artifact that appears on a ____________________ display.
Crosstalk spectral Doppler display
_________________________ changes the electrical signals within the receiver into a form more suitable for display on a monitor. Is it adjustable?
Demodulation It is not adjustable.
_______________ presents processed data. The display may be a flat screen monitor, a transparency, a spectral plot, or a variety of other formats.
Display
Doppler shift is ________________ to velocity Doppler shift is ________________ to transducer frequency.
Doppler shift is directly related to velocity Doppler shift is directly related to transducer frequency
_______________________ is the science of identifying and measuring the characteristics of an ultasound beam that are relevant to its potential for producing biological effects.
Dosimetry
____________________ is a branch of medicine associated with population srtudies. It is empirical - that is an exposure response method - which utilizes clinical surveys. The best studies are (2 things)
Epidemiology 1) prospective 2) randomized
What happens when the signal to noise ratio is high? What happens when the signal to noise ratio is low?
HIGH (you want it to be high) - The signal is much stronger than the noise and the image is of high quality LOW - The strength of the signal is closer to the strength of the noise. The image contains a larger amount of visible contamination, and has less diagnostic value.
A higher frame rate has: __________________ imaging _____________ # of focus _____________ sector _____________ line density
Higher frame rate: shallower imaging single focus narrow sector low
____________________ is portions of an image that are brighter than surrounding tissues, or tissues that appear brighter than normal.
Hyperechoic
_________________ research indicates that very high intensities can cause genetic damage and cell death.
In vitro
In vivo research is performed ___________________________. In vitro is performed ____________________________.
In vivo- within the living body in vitro - outside the living body
What happens when a pulser is set to a low voltage? What happens when a pulser is set to a high voltage?
LOW- the reflected echoes are weak, and the entire image tends to be dark HIGH- the reflected echoes are stronger, and the entire image is brighter
A lower frame rate has: ___________________ imaging ___________________ # of focus ___________________ sector ___________________ line density
Lower frame rate: deeper imaging multi focus wide sector high
The amount of contrast harmonics produced may be estimated by a number called
Mechanical index
How does the system's display affect spatial resolution?
More lines on a monitor provide better spatial resolution. Fewer lines result in poor spatial resolution.
Can period and frequency be changed by the sonographer?
No
Will adjusting PRP to its maximum help avoid aliasing?
No, it will not.
Other than changing the angle is there an alternative action that will make color appear in a vessel?
No. Color will never appear in a vessel when the directions of flow and sound are perpendicular.
________________ appears as small amplitude echoes and results from many sources, including electrical interference, signal processing and spurious reflections.
Noise
What is noise?
Noise contaminates images with low-level undesirable information
What does OSHA stand for?
Occupational Safety and Health Administration
Nyquist limit equation
PRF/2
______________ has a bullet shaped profile. Velocity is _________ in the center of the lumen and __________________ at the vessel wall.
Parabolic flow highest gradually decreases
_____________________ occurs when a reflecting structure is located deeper than the imaging depth of the image. It is eliminated by increasing the _____________.
Range Ambiguity artifact PRP
______________ transforms the electrical signals from the transducer into a form more suitable for display.
Reciever
________________________ converts all negative voltages into positive voltages.
Rectification
______________________ places too many reflections on the image. The first and second reflections, closest to the transducer are ________, but the remaining echoes (which appear deeper) ______________________.
Reverberation artifact are real do not correctly correspond to true anatomic structures
______________________ or _______________________ places a smooth line around the "bumps" and evens them out.
Smoothing or enveloping
Which of the study techniques, mechanistic or empirical, is best with regard to ultrasound bioeffects?
The strongest conclusions are made when the mechanistic and empirical conclusions are in agreement.
T/F: Color flow Doppler exams tend to have lower temporal resolution than traditional two-dimensional, real-time imaging.
True
T/F: Color flow Doppler imaging incorporates pulsed Doppler principles and provides range resolution.
True
T/F: TGC cannot be used with continuous wave Doppler.
True
All intensities have units of?
W/cm2
Does increasing the scale have any other effect on a color Doppler image?
Yes. Increasing the color Doppler scale DECREASES THE SENSITIVITY to slow flows.
___________________ is noise resulting from the constructive and deconstructive interference of small sound wavelets.
acoustic speckle
Phased array ALWAYS means ____ or ____.
adjustable, multi-focus
Increasing the velocity scale eliminates _______________ and removes color from ___________________ on the image.
aliasing low level velocities
What happens when the color gain is set too low?
all color will disappear
What will happen will the pulsed Doppler gain is set to a level that is too low?
all gray scale will disappear
The pulser determines _______________, _______________, and _______________. The beam former determines the firing delay patterns for __________________________________.
amplitude, PRP, PRF phased array systems
__________________ is an extreme form of hypoechoic, meaning entirely without echoes (echo-free)
anechoic
What is oblique?
any angle other than 90 degrees
The beam former also adjusts electrical spike voltages to reduce lobe artifacts in a process called _______________
apodization
reducing the strength of side and grating lobes can be achieved through a process called ____________________.
apodization
grating lobes are created by
array transducers
________________ is essentially an error in imaging.
artifact
Beams that are most likely to create harmonics are least likely to create ______.
artifacts
How does transducer output affect noise?
as the sonographer increases output power the signal-to-noise ratio also increases
_____________ states that, with a steady flow, the sum of all forms of energy is the same everywhere.
bernoulli's principle
________________ describes the relationship between velocity and pressure in a moving fluid.
bernoulli's principle
What do you call a doppler instrument that is negative or positive?
bidirectional
What is the image shape of a convex transducer?
blunted sector
________________ determines the brilliance of the displayed image.
brightness
Intensities and other output measures can be derived from signals from a:
calibrated hydrophone
______________________ is the interaction of sound waves with microscope, stabilized, gas bubbles in the tissues.
cavitation
how do you calculate measured pressure?
circulatory pressure + hydrostatic pressure
________________ is the prescense of false echo signals arising from locations outside of the main sound beam. Sources of clutter can include (3 things)
clutter 1) side lobes 2) grating lobes 3) section thickness artifact
3 units of amplitude
cm, pascals, g/cm^3
What is caused by setting the color gain to a level that is too high?
color confetti
_________________, often described as "reverberation with the spaces squeezed out" appears as a ___________________________ directed ____________. It is also known as ___________________. It is located ___________________________.
comet tail artifact, solid hyperechoic line ring down artifact parallel to the sound beams main axis
Frequencies measured at the transducer are produced from many different locations along the ultrasonic beam with what transducer?
continuous wave
______________ determines the range of brilliances within the displayed image
contrast
________________ or _________________ reflectors redirect sound waves in directions other than back toward the transducer. The amplitude of the reflection may be __________________. In this case reflectors (3) things...
curved or oblique less than expected 1) are absent on the image 2) appear too weak on the image 3) appear different from other similar reflecting boundaries
The __________________ is the region close to the transducer where images are inaccurate. It extends from the transducer to the shallowest depth from which meaningful reflections appear.
dead zone
Amplification is often measured with units of ______________.
decibels
Amplitude _____________ with depth
decreases due to attenuation
What 2 things is acoustic impedance determined by?
density & stiffness
Power doppler: detects _________________ looks at _________________ of signal used to _______________________________
detects slow flow looks at amplitude of signal used to find the lumen of a high grade stenosis
reflection can only occur if the impedances are ________________.
different
What is the relation of amplitude and power?
directly
frequency of the transducer is ______________ related to the value of the Doppler shift?
directly
What is the relationship between PRP and depth?
directly related
what is the relationship between scattering and frequency?
directly related
The maximum turbulence is detected....
distal to site of stenosis
__________________ is a special form of shadowing that appears as a hypoechoic region extending down from ________________________. It prevents ______________________. It is also called.
edge shadow, the edge of a curved reflector visualization of the true anatomy scan. shadowing by refraction
During transmission, the transducer transforms _______________ into ____________________. During reception, it converts thew returning __________________ into ____________________.
electrical energy ----> acoustic energy acoustic energy ----->
A 1 1/2 dimensional array transducer has a few elements in the up and down direction to focus the beam in the thickness plane. This improves _____________________ resolution.
elevational
Slice thickness resolution is also called _______________________. It is measured in a direction ____________________ to the imaging plane.
elevational resolution, perpendicular
Blood moves from regions of higher energy to lower energy. This is called ___________________.
energy gradient
What does multiple pulses represent?
ensemble length
_____________________ studies the interaction between sonographer, patient, and equipment in order to optimize the well being of sonographers in their professional environment
ergonomics
what is the equation for pressure gradient?
flow x resistance
______________________ also called ____________________ is a special form of enhancement in which a side-to-side region of an image appears brighter than tissues at other depths. it is most at the ____________. It results from _________________. Structures at the _______________ appear brighter than those at other depths.
focal enhancement/focal banding focus increased intensity at the focus focus
Temporal resolution is determined by __________. The units of temporal resolution are ___________________.
frame rate, hertz
Multi focusing decreases __________________ and diminishes __________________________.
frame rate, temporal resolution
The Doppler effect is observed as a change in _____________ and has the units of ___________________.
frequency, seconds
_______________________ image created by processing reflections that have the same frequency as the transmitted sound
fundamental image
_____________________ will appear throughout the spectrum when the pulsed Doppler gain is set too high.
gray scale noise
If area doubles, intensity is __________________.
halved
_____________________ reduces an image's noise content
harmonic imaging
_________________ is the percentage of blood made up of red blood cells.
hematocrit
____________________ is a portion of tissue or an image that has differing echo characteristics throughout.
heterogeneous
axial resolution improves with ___________________ frequency
higher
Coded excitation provides ____________________ signal to noise ratio _____________________ axial resolution _____________________ spatial resolution ______________________ contrast resolution _______________________ penetration
higher signal to noise ratio improved axial resolution improved spatial resolution improved contrast resolution deeper penetration
What happens if blood flow is sampled in the center of laminar flow?
higher velocity than if sampled toward edges
Higer pixel density results in __________________ spatial resolution, whereas lower pixel density ________________ spatial resolution
higher, degrades
Slice thickness artifact fills in _____________________ such as _________. Slice thickness artifact is reduced with ____________________ imaging planes, such as those created by a _____________________________ transducer.
hollow structures, cysts thinner 1 1/2 array transducer
___________________ is a portion of tissue of an image that has similar echo characteristics throughout.
homogeneous
_____________________ or ________________ is a small transducer that measures the characteristics of a sound beam. Since it is small, the acoustic pressure is measured at ______________________ within the sound beam. It measures the ______________, _______________, ______________, and ________________.
hydrophone or microprobe specific locations measures: period, pulse duration, PRP, PRF
___________________ introduces an error in measurement based on the site of measurement.
hydrostatic pressure
Enhancement artifact appears as a _____________________ region beneath tissues with _____________________________.
hyperechoic abnormally low attenuation
____________________ is portions of an image that are not as bright as surrounding tissues, or tissues that appear less bright than normal
hypoechoic
What is the most effective way to eliminate aliasing on a color flow image?
increase the velocity scale
By changing to a transducer with a longer pulse duration while PRP stays constant, duty factor _______________.
increases
When line density is high, the number of pulses per image ___________________, frame rate __________________, and the temporal resolution ______________________.
increases, drops, decreases
If color in the vein vanishes, what could cause this?
increasing the wall filter to a higher level
_____________________ is the process by which patients are educated about the essentials of a medical procedure.
informed consent
relationship of intensity and amplitude
intensity is proportional to amplitude^2
Field of view (sector size) and frame rate are _____ related?
inversely
Imaging depth and frame rate are ______________ related.
inversely
pulses per frame and frame rate are ___________ related
inversely
what is the relationship between duty factor and imaging depth?
inversely
What is the relationship between PRF and depth?
inversely related
What is the relationship between frequency and wavelength?
inversely related
What is the relationship between period and frequency?
inversely related
Frame rate and the time for one frame are _________ related and ___________
inversely related, reciprocals
__________________ describes structures with equal echo brightness
isoechoic
When a doppler shift occurs, what happens to the wavelength?
it changes
What occurs as the Doppler angle is increased?
it decreases the frequency shift
Grating and side lobes diminish image quality by degrading _________________________ resolution.
lateral
With multi-focus, each scan line has better _______ resolution because it is narrow over a wide range of depths.
lateral
If the RBC are traveling toward a transducer, the frequency emitted by the transducer is _______ the frequency reflected from the RBC
less than
wall filter eliminates what?
low frequency Doppler shifts
In general, transducer output is ___________________ when performing gray scale anatomic imaging and ___________________ when performing pulsed Doppler.
lowest, highest
How does a greater difference between 2 impedances affect reflection?
makes itstronger
__________________ maintains and organizes the proper timing and interaction of the systems components.
master synchronizer
Equation for amplitude
max-min/2
What is the only transducer that has a fixed focusing technique?
mechanical
What are the two transducers that have a mechanical steering technique?
mechanical transducers and annular phased transducers
Disc-shaped crystals are found in __________________ and ________________ transducers.
mechanical, phased arrau
Acousitc impedance is a property of the _______________ with the units ________________.
medium, Rayls
___________________ is created when sound reflects off a strong reflector, and is redirected toward a second structure. This redirection causes a ____________ or _______________ of the structure to incorrectly appear on the image. The artifact is located ___________ than the real structure. It may appear in conventional gray scale imaging or even color Doppler. The true reflector and artifact are _________ distances from the mirror.
mirror image artifact replica or second copy deeper equal
_____________________ is created when sound pulses glance off a second structure on the way to or from the primary reflector
multipath artifact
How do you calculate total attenuation?
multiply path length by attenuation coefficient
What is the anatomy of a TGC curve? What is the x-axis and the y-axis?
near gain, delay, slope, knee, far gain X-axis is TGC, Y-axis is depth
______________ is more likely to affect low-level hypoechoic regions rather than bright echogenic areas.
noise
Quality assurance programs should be based on _________________ standards.
objective
To calculate blood velocity using color-flow imaging, a sonographer must...?
place a sample volume in the major streamline or jet & set the angle correction parallel to the streamline
What are the two types of laminar flow?
plug and parabolic
Viscosity is measured in units of _________
poise
eddy currents are related to what two things?
post severe stenosis turbulent flow
intensity equation
power/area
what does the electrical shield transducer component do?
prevents electrical noise from contaminating the clinically important electrical signals used to create diagnostic images
What does the acoustic insulator transducer component do?
prevents vibrations in the case from inducing an electrical voltage in the PZT of the transducer
What does the case transducer component do?
protects the internal components and also insulates the patient
Does aliasing occur with pulsed or continuous wave Doppler?
pulsed
___________________ is the routine, periodic evaulation of an ultrasound system to guarantee optimal image quality.
quality assurance
Amplfication is also called _________________. Each signal undergoes an ___________________ of amplification. How does amplification affect signal to noise ratio? Amplification is often measured with units of ______________. Is it adjustable?
receiver gain Amplification does not improve signal to noise ratio Decibels Yes, it is adjustable
What is the image shape of a linear sequential transducer?
rectangular
What are the two Doppler shift equations?
reflected - trasnsmitted frequency 2 x velocity of blood x transducer frequency x cos(-)/propagation speed
Snells law governs __________________.
refraction
__________________ is created when a sound pulse changes direction during transmission. It degrades ___________ resolution. the copy is _______.
refraction artifact lateral side by side
____________________ are created when a sound eave bounces back and forth between two strong reflectors.
reverberation
Slice thickness is also called ___________________ or ______________________. It is related to the dimension of the beam that is __________ to the imaging plane. _______________ is determined by the thickness of the imaging plane.
section thickness artifact or partial volume artifact. perpendicular elevational resolution
What is the image shape of a annular phased transducer?
sector
What is the image shape of a mechanical transducer?
sector
What is the image shape of a phased array transducer?
sector
___________________ refers to the ability of a system to display low-level echoes. Two forms are:
sensitivity normal and maximum
___________________ appears as a _______________________ or __________________ region extending downward from a highly attenuating structure. It is located _______________________ with abnormally high attenuation. It prevents _______________________. It is _______________ to the speed of sound in a medium.
shadowing hypoechoic or anechoic. below unrelated
Side lobes are created by what type of transducer?
single element transducers
What is the main advantage of high line density?
smaller gaps improve the accuracy of each individual image
What nonlinear behavior creates tissue harmonics?
sound travels faster in compressions and slower in rarefactions
Two forms if reflection ________________ and ________________ are created in soft tissue.
specular and diffuse
___________________ is created when sound wave propogates through a medium at a speed other than that of soft tissue (1.54 km/s or 1,540 m/s) Also called _________________. They appear as a ___________.
speed error artifact. range error artifact step off
Two forms of cavitation
stable and transient
Doppler color flow imaging produces an image composed of...?
stationary tissues in gray scale & moving tissues in color
__________________ archives the ultrasound studies. Typical devices (or media) can include computer hard drives, CD, DVD, videotape, magneto-optical discs, paper printouts, photographs, and USB drives.
storage
______________________ of each element in a linear array transducer reduces grating lobes along with apodization.
subdicing
The ________________ protects the sensitive electrical components in the receiver from the high voltages created during transmission.
switch
Proper methods for quality assurance programs are:
test under known, defined conditions use constant instrument settings use a phantom with measurable characteristics image in an identical environment
What knob is used to create a high contrast image?
the dynamic range knob
If you increase the depth or sector width, what happens to the frame rate?
the frame rate will increase
Assuming flow is constant, what happens in a region of blood vessel narrowing?
there is an increase in the velocity along with a corresponding decrease in pressure
Turbulent flow causes what three things?
thrill, murmur, and bruit
The pulser functions during ___________________
transmission
Refraction is basically...
transmission with a bend
Tissue harmonics are created during ___________________ and created by ________________. The are primarily created along ____________________________. They are _____________________ as sound leaves the transducer.
transmission, nonlinear behavior, the beam's main axis, not present.
Is transverse perpendicular or parallel? Is longitudinal perpendicular or parallel
transverse = perpendicular longitudinal = parallel
T/F: ITC and IRC are both unitless/percents.
true
With power modulation, __________________________________ are sent down each scan line; the second pulse is _________________________ of the first one.
two consecutive pulses, twice the strength.
In a standard Doppler, what is true about the reflected frequency produced by blood cells traveling away from the transducer.
ultrasounic
What is the relationship between PRF and frequency?
unrelated
What is the relationship between attenuation and propagation speed?
unrelated
What is the relationship between frequency and propagation speed?
unrelated
What is the relationship between pulse duration and imaging depth with frequency?
unrelated
Aliasing with CW Doppler can be avoided by...?
using a lower frequency Doppler