ULTRASOUND PHYSICS REVIEW
If the output power setting is at 50% and this indicates 0dB, increasing the power by: -
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? - 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? - 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? - AP
The spatial resolution on a CRT monitor is directly related to: - 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? - 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: - ¼ of the probe
wavelength in thickness
If the radius of a blood vessel decreases by 50% what happens to the flow volume? -
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: - The blood flow is
perpendicular to the beam at the zero degree angle and undetectable
,ULTRASOUND PHYSICS REVIEW
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? - 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? -
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? - 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? - 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? - 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
,ULTRASOUND PHYSICS REVIEW
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. - 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? - Decrease frequency
Decreasing transducer frequency will increase sound penetration
is defined as the range of frequencies contained in the US pulse. -
Bandwidth
Decreasing the pulse repetition period leads to: - 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. - more, contrast resolution
What part of the ultrasound system is responsible for changing the element function
back and forth from transmit to receive? - 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.
, ULTRASOUND PHYSICS REVIEW
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
. - 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. - 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
. - 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? - 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? - 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: - imaging depth
If the output power setting is at 50% and this indicates 0dB, increasing the power by: -
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? - 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? - 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? - AP
The spatial resolution on a CRT monitor is directly related to: - 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? - 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: - ¼ of the probe
wavelength in thickness
If the radius of a blood vessel decreases by 50% what happens to the flow volume? -
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: - The blood flow is
perpendicular to the beam at the zero degree angle and undetectable
,ULTRASOUND PHYSICS REVIEW
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? - 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? -
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? - 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? - 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? - 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
,ULTRASOUND PHYSICS REVIEW
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. - 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? - Decrease frequency
Decreasing transducer frequency will increase sound penetration
is defined as the range of frequencies contained in the US pulse. -
Bandwidth
Decreasing the pulse repetition period leads to: - 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. - more, contrast resolution
What part of the ultrasound system is responsible for changing the element function
back and forth from transmit to receive? - 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.
, ULTRASOUND PHYSICS REVIEW
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
. - 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. - 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
. - 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? - 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? - 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: - imaging depth
