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Which technique is internal focusing?
curved crystal
The diameter of a disc-shaped, unfocused piezoelectric crystal is 1 cm. What is the best estimate for the minimum lateral resolution of the US system?
5 mm
Which transducer has the lowest intensity at the end of the near zone?
6 MHz, 6 mm crystal diameter
The pulse duration does not profoundly influence the lateral resolution. T or F
True
The thing(s) that can be used to create focusing is/are
curved elements
lens
phasing of the voltage signals
ALL
The main factor that determines axial resolution is
spatial pulse length
Which of the following determine the focal length of a sound beam?
diameter of ceramic and frequency of sound
Which imaging mode accurately displays reflector depth?
A-mode
Would a pulse of 0.4 microsec or a pulse of 0.2 microsec produce the best radial resolution?
0.2 micro sec
Under which of the following conditions is axial resolution improved?
decreased spatial pulse length
In comparison to other locations along the length of an ultrasound beam, focusing is generally ineffective in the far zone. T or F
True
Huygens’ principle is based on ____.
interference
on the M- mode on which axis is the time represented
x- axis
The higher the frequency of the cycles within a pulse, the lower the numerical value of the axial resolution. T or F
True
In which region of a sound beam is focusing most effective?
the end of the near zone
Which imaging technique usually displays a single jagged line of varying heights?
A-mode
Which system will produce better images -- an axial resolution of 0.4 mm or 0.7 mm.?
0.4 mm
When using an instrument typical of today's imaging devices, a higher frequency transducer is likely to improve axial resolution. T or F
True
The area that starts at the beam's smallest diameter and extends deeper is:
the Fraunhofer zone
The diameter of an unfocused, disc-shaped piezoelectric crystal is 1.2 cm. The near zone length is 8 cm. What is the best estimate for the lateral resolution at depth of 16 cm?
1.2 cm
Changing the field of view changes the axial resolution. t or f
false
Which of the following transducers has the deepest focus?
6 MHz, 6 mm crystal diameter
largest frequency, largest diameter
Which of the following focusing techniques is different from the others?
phased
Which of the following transducers has the least divergence in the far field?
highest frequency, largest crystal diameter
One way that a sonographer can alter the axial resolution achieved during an exam is to adjust the maximum imaging depth. t or f
false
The focus of an ultrasound beam is the location where the ____.
optimum transverse resolution is
Pulsed ultrasound provides better depth resolution than continuous wave ultrasound. t or f
True
A sound beam is created by a round PZT crystal with a diameter of 10 mm. The focal depth of the sound beam is 8 cm. What is the diameter of the sound beam at a depth of 16 cm?
the same as the transducer diameter
What is the location where a beam reaches its smallest dimension?
focus
To which of the following do the x-axis of a b-mode, the y-axis of an m-mode and the x-axis of an a-mode all relate?
depth of view
A longer near zone length can be produced by
changing to a higher frequency transducer
Two ultrasound systems have near zone lengths of 8 cm. At the focus, System G's lateral resolution is 3.0 mm, while System P's is 5.0 mm. Which system will produce higher quality pictures at the foci?
System G
Which of the following determines the frequency of sound created by a pulsed wave transducer?
thickness and speed of sound in the ceramic
Which of the following transducers has the shallowest focus?
lowest frequency, smallest crystal diameter
What is the name of the region between the transducer and the smallest cross-sectional area of a sound beam?
near zone
Axial resolution affects structures that are
positioned along the scan beam
Which of the following has the same meaning as a transducer diameter?
aperture
With M-mode, hat is displayed on the y axis?
Depth of the reflector
If the axial resolution is 0.85 at the focal point, what is the axial resolution that is 3 cm deeper than the focal point
the same as 0.85 mm
The lateral resolution of an US system is 4 mm. 2 structures are seperated by 3 mm and lie side by sidein relation to the sound beams main axis.What will most likely appear on the display of the system?
One echo
All of the following terms describe the shape of a sound wave created by a tony fragment of PZT except
hourglass shaped
the ability to distinguish two objects parallel to the ultrasound beam is called
axial resolution
Which mode provides the foundation for real time, gray scale anatomic imaging?
B-mode or brightness mode
Which of the following transducers have the shallowest focus?
lowest frequency, smallest crystal diameter
Two ultrasound systems have the near zone length of 8cm. At the focus, system S’s lateral resolution is 3.0mm while system C’s is 5.0 mm. Which system is most likely to appropriately display two small body structures that lie, one in front of the other, at depths of 8.6 and 9.0mm.
cannot be determined
Axial resolution is affected by…
wavelength
Which of these terms means adjustable focusing or multi focusing?
phased array
The near zone length should be kept as short as possible. t or f
false
Lateral resolution is affected by…
beam diameter
Which transducer has the lowest intensity at the end of the near zone?
6MHz, 6mm crystal diameter
highest frequency, largest diameter
Axial resolution is equal to
one-half spatial pulse length
The shorter the pulse length the better the resolution?
True
The mode that produces lines related to changing position of reflectors in the body with respect of time is called…
m-mode
A natural, unfocused beam diverges…
In the Fraunhofer zone
The higher the frequency of the cycles within a pulse, the lower the numerical value of the axial resolution. t or f
true
Beam diameter is consistent size throughout the near zone. t or f
false
Which situation produces the best axial resolution?
4 MHz with 2 cycles per pulse
highest frequency, fewest cycles per pulse
A sound beam is created by a round PZT crystal with a diameter of 10mm. the focal depth of the sound beam is 8cm. What is the diameter of the sound beam at a depth of 16cm?
the same as the transducer diameter
Axial resolution is inversely related to
spatial pulse length
With A mode, what is displayed on the y axis
amplitude of the reflected signal
All of the following are true of the focus except
it is at the start of the fresnel Zone
With B-mode, which axis is related to the strength of the reflection?
The z-axis is related to reflection strength
Axial resolution is improved with
transducers with higher frequency
As sound travels deeply into the far zone, the beam diverges or spreads out. Which of the following will result in a minimum beam divergence deep in he far zone?
high frequency, large diameter
Which of the following determine the spread of a sound beam in the far field?
diameter of ceramic and frequency of sound
The lateral resolution of an US system is 4mm. Two structures are separated by 3mm and lie side by side in relation to the sound beams main axis. What will most likely appear on the display of the system?
one echo
Huygens principle is based on
interference
On the M-mode on which axis is the time represented?
x axis
Two ultrasound systems are identical except for the diameter of the transducers piezoelectric crystal. which system has the deepest focus?
the one with the larger diameter crystal
With A-mode, what is displayed on the X-axis?
depth of reflector
If the axial resolution is 0.85 at the focal point, what is the axial resolution that is 3cm deeper than the focal point
the same as 0.85 mm
Under which of the following conditions is axial resolution improved
decreased spatial pulse length
Which of the following has the same meaning as transducer diameter?
aperture
Two ultrasound systems are identical except for the pulse repetition period (PRP) of the emitted pulse. Which system will have the deeper focus?
their foci will be at the same depth
Which of these techniques is consistent with variable or multifocusing?
electronic
A natural, unfocused beam diverges
In the Fraunhofer zone
A sound beam is created by a round PZT crystal with a diameter of 10mm. The focal depth of the sound beam is 8cm. What is the diameter of the sound beam at a depth of 16 cm?
the same as the transducer diameter
which imaging modality places time-of-flight information on the x-axis and echo amplitude on the y-axis
A-mode
The ability to distinguish two objects parallel to the ultrasound beam is called
axial resolution
Decreasing spatial pulse length
improves axial resolution
On the A-mode on which axis is the depth represented?
x-axis
the shorter the pulse length the better the resolution. t or f
true
Which of the following transducers will have the poorest axial resolution
1.7 MHz & 5 cycles per pulse
lowest frequency and most cycles
lateral resolution is equal to
beam width
the shorter the pulse duration, the better the picture. t or f
true
pulsed ultrasound provides better depth resolution than continuous wave ultrasound. t or f
true
If system A has resolution of 1,000,000 pixels with 4 bits and System B has 750,000 pixels with 12 bits. Which wll have a better longitudinal resolution?
Cannot be determined with this information
Which transducer has the lowest intensity at the end of the near zone?
6MHz, 6mm crystal diameter
biggest frequency, largest diameter
Lateral resolution is affected by…
the beam diameter
Axial resolution is inversely related to
spatial pulse length
Which of the following determine the focal length of a sound beam?
diameter of ceramic and frequency of sound
which of the following determine the spread of a sound beam in the far field?
diameter of ceramic and frequency of sound
with a specific ultrasound system and transducer, the systems axial resolution is invariant, and the sonographer can do nothing to improve it. t or f
true
A longer near zone length can be produced by changing…
to a higher frequency transducer
