ULTRASOUND PHYSICS REVIEW| 113 PAGES| 837 QUESTIONS| WITH COMPLETE SOLUTIONS
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Ultrasound Physics
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Kaplan University
If the output power setting is at 50% and this indicates 0dB, increasing the power by: Correct Answer: 3dB will increase the power output by a factor of 2
An increase in power of 3dB indicates an increase of 2X the original power. Every 3dB that the power increases will double the power output....
ultrasound physics review| 113 pages| 837 questions| with complete solutions
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Ultrasound Physics
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ULTRASOUND PHYSICS REVIEW| 113 PAGES| 837 QUESTIONS| WITH
COMPLETE SOLUTIONS
If the output power setting is at 50% and this indicates 0dB, increasing the power by: Correct Answer:
3dB will increase the power output by a factor of 2
An increase in power of 3dB indicates an increase of 2X the original power. Every 3dB that the power
increases will double the power output. 50% x 2 = 100%
The doppler tracing demonstrates electrical noise. How can you reduce or eliminate this artifact?
Correct Answer: Increase the wall filter settings
Noise can be reduced by decreasing doppler gain, increasing wall filter settings or trying another wall
outlet.
Which of the following is true regarding the Curie point of a piezoelectric element? Correct Answer: If
the active PE crystal is heated to this temperature, the element will lose its piezoelectric properties.
Certain ceramic elements can be polarized by heating them above their Curie point. If the active
element is heated again, it will lose its piezoelectric properties
What dimension of the mass is being measured on this image? Correct Answer: AP
The spatial resolution on a CRT monitor is directly related to: Correct Answer: The number of lines per
frame
The vacuum tube TV (CRT) monitor interfaces two fields together to from an image frame. The more
lines in each field, the better the spatial resolution on the image
What system component is not needed when an LCD monitor is used? Correct Answer: digital to analog
converter
LCD monitors accept the digital signal and do not need the component
The matching layer for a txd is usually made of plastic and its approx: Correct Answer: ¼ of the probe
wavelength in thickness
If the radius of a blood vessel decreases by 50% what happens to the flow volume? Correct Answer:
decreases by 16
Radius decreases by 1/2, flow volume decreases by 2 to the fourth power (16x); if the radius decreases
to ⅓ original size, the flow volume decreases by 3 to the fourth power (81x). Note the significant change
in flow value from, a 50% reduction in radius to a 66% reduction in radius
Why is there no color flow displayed in the right hepatic vein: Correct Answer: The blood flow is
perpendicular to the beam at the zero degree angle and undetectable
,The txd is producing a beam that is perpendicular to he blood flow. The txd is evaluating the emotion of
reflectors moving toward or away from it and assigning the appropriate color. The blood in the vessel is
moving left to right, therefore no motion to and from the probe is detected or displayed as color on the
image
You switch from a 5MHz curved probe to a 2.5 MHz sector probe to image deeper in the abdomen. How
is the wavelength affected by the change to the new probe? Correct Answer: Doubles
Wavelength and freq are inversely related. If the freq is reduced by 50%, the wavelength will double
Curved PE element and acoustic lenses will improve which two types of resolution? Correct Answer:
elevational (vertical) and lateral
Curved elements and lenses will improve focusing and decreases slice thickness. This will improve lateral
and slice thickness resolution
Elevational resolution is determined by the height of the ultrasound beam. It is the ability to distinguish
two objects close together along the y-axis (vertical = elevational). The shorter = thinner the beam the
better the elevational resolution
Lateral resolution is defined as the ability of the system to distinguish two points in the direction
perpendicular to the direction of the ultrasound beam. It is also known as azimuthal resolution. Lateral
resolution is affected by the width of the beam and the depth of imaging
Which of the following imaging techniques would be used to best evaluate the volume of an irregular
mass? Correct Answer: 3D rendering
3D rendering refers to the creation of an image based on data acquired during the exam. It is considered
a type of post-processing. 3D techniques more accurately measure the volume of structures than 2D
imaging.
If you are performing an abdominal exam but inadvertently select the carotid preset on the machine,
how will this affect your exam? Correct Answer: Depth settings will be very superficial causing potential
non-visualization of the abdominal structures
The carotid preset will be set to a very low imaging depth due to the superficial course of the carotid
arteries. The preset for abdomen is set to begin at a much higher depth setting.
Which of the following is NOT adjustable by the Sonographer? Correct Answer: Demodulation
Demodulation occurs as the signal is converted into positive voltages (rectification) and smoothed
across the peaks of the voltage pulses. This process assists in processing the voltages for proper image
display of the returned signals. This is a preset function of the US system and not operator adjustable.
For this reason the process is often called "demodulation" or "detection". Though coined during the
development of radio technology, they sound intuitively correct for ultrasound as well. The first
ultrasound signal processing technique is quadrature detection, or IQ as it's sometimes called
,_________________ refers to the ability of a system to detect low-amplitude echoes accurately. Correct
Answer: sensitivity
Sensitivity refers to the ability of a system to detect low-amplitude echoes accurately.
The bandwidth refers to the range of frequencies produced by the probe.
The dynamic range refers to the number of levels of gray displayed on the image.
The quality factor refers to the purity of the sound wave.
What is the best way to increase beam penetration? Correct Answer: Decrease frequency
Decreasing transducer frequency will increase sound penetration
________________ is defined as the range of frequencies contained in the US pulse. Correct Answer:
Bandwidth
Decreasing the pulse repetition period leads to: Correct Answer: a decrease in the maximum depth that
can be imaged
If the PRP decreases, the PRF will increase which means shorter pulses are emitted more quickly. The
shorter pulses will travel a shorter distance than the pulses emitted from a lower PRF. The imaging
depth will decrease with a decrease in PRP.
Pulse repetition frequency (PRF): Number of pulses occurring in 1 s. Usually expressed in kHz. Pulse
repetition period (PRP): Time from the beginning of one pulse to the beginning of the next. Usually
expressed in microseconds
The more bits per pixel, the _________________ shades of grey on the image and ________________
improves. Correct Answer: more, contrast resolution
What part of the ultrasound system is responsible for changing the element function back and forth
from transmit to receive? Correct Answer: beam former
The beam former is responsible for switching the element function back and forth between transmit and
receive.
Beamforming is a common signal processing technique used to create directional or spatial selectivity of
signals sent to or received from an array of sensors or antennae. These arrays can be found in many
different devices that transmit and receive either electromagnetic or acoustic waves.
If the Sonographer increases the size of the field of view, the frame rate will ___________________.
Correct Answer: decrease
increasing the area to be scanned will require an increase in time to process the increased # of scan lines
for display causing a decreased frame rate. Frame rate is indirectly related to the size of the field of
view. Increased size of the FOV = slower (decreased) frame rate. If the question read "If the size of the
field of view doubled, how would the frame rate be affected?" Then the answer could be more specific
to say that the frame rate would decrease by 50%.
, In order to improve spatial resolution and the signal-to-noise ratio, ______________________ uses
frequency modulation to manipulate the transmitted beam. Correct Answer: Coded excitation
Spatial resolution is a measure of the accuracy or detail of a graphic display, expressed as dots per inch,
pixels per line, lines per millimeter, etc. It is a measure of how fine an image is, usually expressed in dots
per inch (dpi).
As the transducer frequency increases, the spatial pulse length ____________________. Correct
Answer: decreases
Spatial pulse length is the length of one pulse composed of multiple cycles. SPL = # cycles X wavelength;
Normal US range 0.1 - 1.0mm; The shorter the pulse length, the better the axial resolution. Axial
resolution = 1/2 SPL
If you increase the sector angle from 45 to 90 degrees and reduce the line density by 50%, what
happens to the frame rate? Correct Answer: unchanged
Doubling the sector size will double the number of scan lines and reduce the frame rate by 50%. BUT if
the line density is reduced by 50% when the sector size doubles, the frame rate does not change.
Producing and processing more scan lines takes for time = frame rate is reduced. # and density of scan
lines are indirectly related to frame rate. Because the sector size was doubled, the frame rate will be
reduced by 1/2 UNLESS line density changes too.
Which operator control can be used to adjust the image contrast? Correct Answer: dynamic range
Dynamic Range/Compression - adjusts the range of grays displayed on the image; changes the contrast
level of the image; increased/larger dynamic range = decreased image contrast
The pulse repetition period in 2D imaging is determined by: Correct Answer: imaging depth
The imaging depth and PRF are directly related. PRP = 1 / PRF The imaging depth establishes the PRF and
PRP.
The range equation is used to determine the: Correct Answer: distance to a reflector
The range equation is used by the US system to place the echoes on the image properly.
When Harmonic imaging is turned on, it primarily improves ___________ resolution. Correct Answer:
Lateral
Harmonic imaging improves spatial resolution with the greatest effect on lateral resolution. Harmonic
beams are narrower than the fundamental beam so lateral resolution is improved. Other benefits of
harmonic imaging include reduced image clutter and increased signal to noise ratio.
What portion of the TGC curve is the deepest region attenuation compensation can occur? Correct
Answer: knee
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