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160 Cards in this Set
- Front
- Back
- 3rd side (hint)
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Change in frequency is known as |
Doppler shift or Doppler |
DS or DF |
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Frequency of sound changes when _______ and _____ move closer together or farther apart |
Sound source and receiver |
SS and R |
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The process of extracting, the low Doppler frequency from the transducer carrier Frequency is known as? |
Demodulation |
D |
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When the Doppler shift is positive, blood cells are traveling away, or towards transducer? |
Towards transducer |
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Doppler shifts are in the range of (numerical value) |
20 Hz to 20,000 Hz or 20 kHz which is audible sound |
20 what |
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Doppler shift equals |
Reflected frequency - transmitted frequency |
What minus what |
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Is reflected frequency is higher than the transmitted frequency you have a positive or negative shift? |
positive |
P |
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When blood cells move away from the transducer, do you have a negative or positive shift? |
Negative |
N |
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Doppler frequency indicates |
Velocity, not speed |
V |
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Speed or magnitude indicates what |
Distance a RBC moves in one second |
D a RBC |
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Unit of speed is |
Centimeters per second Cm/s |
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Magnitude and direction is known as |
Velocity |
V |
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Doppler shift equation |
2 x vel of blood x trans freq x cos theta / prop speed |
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How are Doppler shift and velocity related? |
Directly related |
Dr |
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What does the 2 in the equation mean? |
The two is constant. It means transmitted and reflected shifts. |
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The actual data of Doppler shift is___with units of____ the derived information is |
Frequency and Hz |
F & Hz |
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The derived information is_____with units of____ |
Velocity and meters per second |
V & m/s |
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The X axis of Doppler spectrum equals |
Time |
T |
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The Y axis represents |
Doppler shift/velocity |
DS/V |
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How is Doppler shift related to the frequency of transmitted sound doubled? |
Directly related |
DR |
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What is being measured when the blood cells are moving? Parallel to the sound beam? When an angle exist between the direction of flow and the sound been, what happens with the |
The entire velocity is measured/when RBC moves away or towards the transducer velocity measurement is 100% accurate |
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When an angle exist between the direction of flow and the sound beam, what happens with the measurements |
The measure velocity is less than the true velocity |
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The percent of the true velocity depends on what |
The cosine of the angle between the sound beam and the direction of motion |
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Measured velocity equals______X _____ |
True velocity, X cosine theta |
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How is Doppler shift related to the cosine of the angle between the direction of flow and direction of sound? |
Directly related |
Dr |
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When you have a cosine of 0 or 180, flow is______to the sound beam |
Parallel |
P |
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Cosine of zero is one which means flow is moving___transducer the cosine of 180 |
Towards |
T |
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The cosine of 180° is negative one which means flow is moving___from transducer |
Away |
A |
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When the direction of flow is perpendicular or (90 degrees) to the sound beam, the measured velocity is |
Zero = 100% error no Doppler shift |
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Can Doppler shift and velocity be measured with perpendicular incidence? |
No |
N |
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What is the cosine of 60°? |
0.5 or 50% actual velocity and 50% error. |
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What is the cosine of 120° |
This is a negative Doppler shift -0.5 or 50% actual velocity and 50% error. |
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What is the most common clinical Doppler device? |
Bi directional this distinguishes direction of flow toward or away the transducer |
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What is a commonly use signal processing technique with bi directional Doppler |
Phase quadrature, or quadrature detection |
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How many crystals does a continuous wave Doppler have? What is the greatest advantage of continuous wave |
Two |
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What is the greatest advantage of continuous wave Doppler |
Ability to accurately measure high velocity’s, which measure severity |
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What is the primary disadvantage with continuous wave Doppler? |
Range ambiguity the exact location of the movie blood cells can’t be determined |
RA |
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What does range ambiguity mean? |
The overlap between the transmit and receive beams,
unable to determine location |
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What is another disadvantage of CW Doppler |
No TGC usage |
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Reflections located deeper, will have a_____amplitude |
Lower |
L |
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Does a continuous wave transducer create an atomic images |
No |
N |
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Simultaneous anatomic imaging and Doppler is called |
Duplex imaging, which means it runs two things at one time |
DI |
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Continuous wave transducers do not have continuous wave transducers have |
Backing material |
Bm |
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Continuous wave transducers have___ bandwidth ___Qf___sensitivity |
Narrow bandwidth , high, QF, high sensitivity, undampened transmitted signal |
N H H |
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What increases the efficiency of sound transmitted in and out the body |
Matching layer |
ML |
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Continuous wave transducers, detect____amplitude and Doppler shifts |
Low |
L |
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How many crystals does a pulsed wave Doppler have |
One |
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Biggest advantage with pulse wave Doppler is |
Being able to select the exact location where velocities are measured, called range resolution |
RR |
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What does range resolution mean? |
You can select the exact location where velocities are measured |
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What is placed on a 2-D image when using Doppler? |
Sample gate or sample volume |
SG or SV |
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What is being calculated when this is placed on the image? |
Time of flight |
TOF |
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What is a disadvantage with PW Doppler |
Aliasing |
A |
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What does aliasing mean? |
High velocity flow in one direction is incorrectly displayed as traveling in opposite direction or a false identity. Most common area associated with pulse wave Doppler. |
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Aliasing occurs only with |
PW Doppler |
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Pulse wave Doppler has ___ qf ___ sensitivity ___ bandwidth |
Low quality factor Lower sensitivity Wide bandwidth |
L L W |
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Aliasing occurs when The Doppler sample rate is___compared to the measure blood velocities. |
Low |
L |
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Highest Doppler frequency or velocity that can be measured without the appearance of aliasing is called |
The Nyquist limit for the Nyquist frequency |
Ny |
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What is the Nyquist limit equation? |
Nyquist limit = PRF/2 |
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How do you find the PRF |
PRF (hz) = 77000(cm/s) / depth (cm) |
What’s the equation |
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What are two ways to avoid aliasing |
Raise the Nyquist limit, and reduce Doppler shift |
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Deep sample volumes, create___PRF and create aliasing |
Low |
L |
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When the sample volume is shallow, that equals___PRF |
High |
H |
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High PRF is associated with velocity being sampled___times with a___Nyquist limit. This makes you accurately measure high velocity’s without aliasing. |
Many High |
M H |
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___Frequency creates more aliasing |
Higher |
H |
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How are Doppler shift and frequency related |
Directly related |
DR |
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To get less aliasing you need ___PRF (shallow gate) ___frequency ___velocity |
High PRF Low frequency Slower velocity |
H L S |
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Five ways to avoid aliasing artifact: adjust the scale (PRF/ Nyquist limit) to its ______, (which is the best way to avoid aliasing) select a more___sample volume, select a___frequency, shift the___, Use a___ Transducer Doppler |
Maximum Shallow Lower Baseline CW |
M S L B C |
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Does a shallow sample volume increase or decrease PRF |
Increase |
I |
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Using a baseline shift, only eliminates the appearance of |
Aliasing |
A |
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Grayscale in a Doppler system is related to |
Amplitude of reflected signal or number of RBC creating reflections |
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True or false Color flow is a form of to the Doppler |
True |
T |
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The color and color flow indicates |
Blood flow velocity’s |
Bf vel |
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Color Doppler does provide direction of flow Meaning, it’s a … ____ wave Has range _______ and ________ |
Pulsed Range resolution Aliasing |
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Which Doppler reports average/mean velocities |
Color Doppler |
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Which 2 Dopplers measure peak velocity |
Pulsed and continuous Doppler spectral measures peak velocity |
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Color Doppler uses a dictionary or___to convert measured velocities into colors that appear on the image |
Look up table |
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What do the colors with velocity mode mean ? two things |
Flow direction and velocity |
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The black bar in the middle of the color map indicates |
No Doppler shift |
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Colors closer to the black line with velocity mode mean___velocity |
Low velocity |
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What other mode provide some more information than velocity mode |
Variance mode |
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What information does variance mode provide? |
Distinguishes laminar flow from turbulent flow and this is side to side |
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Colors on the left side of the variance mode map indicate |
Laminar flow, which is normal or healthy |
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Colors on the right side of the variance mode map indicate |
Turbulent flow, which is pathology |
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With color Doppler multiple pulses are being used. These pulses are called. |
Packet or ensemble |
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What is an advantage of using a large packet? |
More accurate velocity measurements increased sensitivity to low flow (increase SNR) |
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Larger packets, disadvantages. There are three. |
Decrease frame rate Decreased temporal resolution Increased time frame |
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What Doppler only identifies the presence of a Doppler shift and good for slow flow? |
Power Doppler, which just looks at blood flow |
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True or false Power Doppler is a nondirectional color, Doppler |
True |
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Power Doppler is also called. There are two names for this. |
Energy mode/color Angio |
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What is being processed when using power Doppler |
Amplitude |
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How is the amplitude of reflection related to the number of moving RBCs? |
Directly |
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What are the two advantages of using power Doppler? |
Increase sensitivity No aliasing |
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What are two disadvantages of using power Doppler |
Lower Frame rate Decreased temporal resolution |
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Low-frequency Doppler artifact with pulsed or continuous are called |
Clutter |
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Low frequency Doppler artifact with color Doppler artifact is called |
Ghosting, artifact, or color flash |
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How do you eliminate ghosted artifact or color flash? |
wall filter, a.k.a. high pass filters, a.k.a. reject |
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Wall filter means it is eliminating___frequency Doppler shift around the baseline |
Low |
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A special form of mirror image artifact that arises only with a spectral Doppler is called |
Cross talk this shows above and below the baseline |
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True or false Crosstalk is a result from game being set to high and the incident angle is near 90° (instead of parallel) between the sound beam and flow. |
True |
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What is a tool that breaks down a group of RBC and identified individual velocities |
Spectral analysis |
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A form of spectral analysis that is a digital technique that processes both PW when you have a clear window with FFT you have what kind of flow& CW signals it’s called |
Fast Fourier transform FFT |
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When you have a clear window with FFT you have what kind of flow |
Laminar flow |
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The region between the baseline and spectrum is called |
Spectral window |
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When you have a failed in window with FFT you have turbulent or chaotic flow indicating |
Spectral broadening |
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What is spectral broadening? |
A wider range of velocities and Doppler shift within the sample value or sample gate |
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A faster form of spectral analysis used to analyze color flow. Doppler is called. |
Autocorrelation/correlation function |
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True or false Autocorrelation is computer-based/digital and it’s the average mean velocity information multiple equally spaced echoes caused by the bouncing of a sound in between two reflectors position |
True |
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Multiple equally spaced echoes caused by the bouncing of a sound in between two reflectors position parallel is called |
Reverberation |
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What appears as a solid, hyperechoic line downward, and there’s two names for it |
Comet tail and ring down artifact |
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Comet tail is more likely to appear when you have a ____ prop speed |
High |
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What is another reason that comet tail could occur |
Vibration, like gas bubbles |
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What artifact occurs as a hypoechoic, or anechoic region, extending downward from a high attenuation structure? |
Shadowing |
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Shadowing artifact is the same color as the image.___. |
Background |
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Shadowing happens when you have too much |
Attenuation |
Atten |
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How is shadowing related to the speed of sound? |
Unrelated |
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Hypoechoic region, extending downward from the edge of a curved reflector is called |
Edge shadowing |
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A decrease in___causes shadowing, this is because of___ |
Intensity Refraction |
Int Refr |
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What appears as a hyperechoic region beneath tissue with low attenuation? |
Enhancement |
Enh |
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Enhancement is the opposite of |
Shadowing |
S |
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How is enhancement related to speed? |
Unrelated |
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What is the artifact called where a side to side portion of the image appears brighter. There are two names for it |
Focal enhancement and focal banding |
FE FB |
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Focal enhancement or focal banding, has the same appearance as an incorrect vocal enhancement results from increased |
TGC |
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Focal enhancement results from increased created, win Sauner flex off strong reflectors and put a second copy deeper than the real structure |
Intensity |
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What is the artifact that is created when sound reflects off a strong reflector and puts a second copy deeper than the real structure |
Mirror, artifact |
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Can mirror image artifact appear on color Doppler |
Yes |
Y |
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What is a mirror image artifact that appears on spectral Doppler display called |
Cross talk |
CT |
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What is an artifact that occurs when sound goes through a medium at a speed other than 1540 m/s |
Speed error |
SE |
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True or false
When the medium speed is slower than that in soft tissue the go return time is long, putting in the reflector deep on the image overestimated |
True |
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When the medium speed is too fast, the reflectors are located___on the image and is underestimated |
Shallow |
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Speed errors are also called |
Range error artifact |
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What artifact appears when energy is transmitted in a direction other than the beams main axis and love artifacts is the second copy of the true |
Lobe artifact |
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Lobe artifacts, degrades___resolution |
Lateral resolution |
L |
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With lobe artifact, the true reflector and artifact are located___at the same depth |
Side-by-side |
SbS |
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What are lobes created by a single Crystal transducer called what are lobes created by array transducers |
Side lobes |
SL |
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What are lobes created by a re-transducers called |
Grating lobes |
gL |
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Grating lobes can be reduced by a process called |
Sub dicing |
Sd |
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The process of exciting elements close to the center of the sound beam with high voltage and exciting. The outer most elements with low voltage is called. |
apodization |
Apod |
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What artifact is created when a sound pulse changes direction during transmission? This is also called transmission with a bend This is the second copy of the reflector The copy is side-by-side or same depth Multiple views are required and degrades lateral resolution |
Refraction |
R |
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Refraction, occurs when a sound wave strikes ___angle, and have different prop speeds |
Oblique angle |
Ob |
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What artifact is related to the dimension of the beam that is perpendicular to the imaging plane? |
Slice thickness |
ST |
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What are the two synonyms for slice thickness? |
Section thickness, artifact, or partial, volume artifact |
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What resolution is determined by the thickness of the imaging plane |
Elevational resolution |
ER |
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Slice thickness artifact does what to cysts |
Fills it in |
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How do we fix slice thickness artifact |
Use a 1/2 dimensional array transducer |
1/2 |
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The ticker portion of the slice of image has___elevational resolution |
Increase |
I |
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What is the artifact that appears when sound pulses glands of a second structure on the way to or from the primary reflector? What others do not. This cannot be identified on the image most of the time. |
Multipath |
M |
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With Highline density you have___spatial resolution when image information is displayed on a monitor, spatial resolution artifact is affected by |
High |
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When image information is displayed on a monitor, spatial resolution artifact is affected by |
Number of horizontal scanlines |
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When the image information is in digital form, spatial resolution is related to |
Pixel density |
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Low pixel density mean, spatial resolution |
Degrades |
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Spatial resolution, artifact occurs when the pixel size is greater than the |
Reflector |
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What artifact occurs when a reflecting structure is located deeper than the imaging depth of the image |
Range ambiguity, artifact |
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How do you eliminate range ambiguity artifact |
Increase PRP and decrease PRF |
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What artifact appears as a small amplitude echoes and results from many sources |
Noise |
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Noise is more likely to affect, low-level, hyper or hypo regions |
Hypo |
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What is considered a noise resulting from a constructive and destructive interference of small sound wavelets a.k.a., Grainy |
Speckle artifact |
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How do you reduce speckle? |
Spatial compounding |
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Another form of noise, the presence of false Echo signals arising from locations outside of the main sound beam is called |
Clutter |
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What helps reduce an image noise content? |
Harmonic imaging |
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True or false Side, lobes, grating lobes and section thickness artifact are sources of clutter |
True |
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