Chapters 9-11 Final Flashcards
What is another name for the near field?
a. focal zone
b. far field
c. Fresnel zone
d. Fraunhofer zone
Fresnel Zone
True or False
The focal point is the region around the focus where the beam is relatively narrow?
False
The sound beam exits the probe and immediately enters the __________ zone.
Fresnel
The diameter of the active element is 16mm, and the near zone length is 10cm. The focal zone is 6cm long. Based on this information answer the following questions:
- What is the best estimate of the diameter or width of the sound beam as it exits the transducer?
- What is the diameter of the sound beam at a depth of 10cm?
- At what depth is the focus?
- At which of the following depths is the beam widening?
- 16mm
- 8mm
- 10cm
- 11.64cm
Which of the following terms does not belong?
a. focus
b. end of the near zone
c. Fraunhofer
d. focal point
Fraunhofer
True or False
The sonographer can change the location of the focus with modern ultrasound systems.
True
Transducer diameter and focal depth are directly or inversely related?
directly
Frequency and focal depth are directly or inversely related?
directly
The smaller diameter PZT beam will create?
lower frequency and shallow focus
The larger diameter PZT beam will create?
higher frequency and deep focus
A pair of 8MHz probes are identical except for the element diameter. The active element diameters are 6mm and 12mm, respectively. The sound beam of which probe will have a shallower focus?
6mm
Crystal diameter and beam divergence are directly or inversely related?
inversely
Which size crystals will improve lateral resolution in the far field? (large or small)
large
Small sound sources that create V-shaped beams that are inconsistent between large and small is a principle called the ___________ principle.
Huygens
True or False
Small transducer diameters produce a beam with less divergence.
false
True or False
High frequency beams will produce less divergence.
True
Which of the following probes creates a beam with the most divergence?
a. 4mm diameter, 4MHz
b. 6mm diameter, 8MHz
c. 4mm diameter, 2MHz
d. 5mm diameter, 8MHz
4mm diameter, 2MHz
Lateral resolution is best at the?
focus
Does Axial resolution change?
Yes or No
No
Lateral resolution is improved in the far field the best with?
higher frequency sound beams
True or false
The sonographer can adjust the internal focusing.
False
When a beam becomes focused, it?
has a focal zone that gets smaller
True or False
The diameter of the ceramic and frequency of sound determine sound beam.
true
Axial resolution is also called
a. range
b. lateral
c. angular
d. transverse
range
True or False
Axial resolution measures the ability of a system to display two structures that are very close together when the structures are parallel to the sound beam’s main axis.
True
In soft tissue, a 4 cycle, 2MHz pulse has a pulse length equal to 5mm. What is the axial resolution?
1.54mm
If there are more cycles in a pulse, the numerical value of radial resolution is more, less or the same?
More
Lateral resolution is also called?
a. axial
b. range
c. depth
d. transverse
transverse
Lateral resolution is imaged best in the near field with a SMALL, or LARGE diameter crystal?
Small
EXTERNAL or INTERNAL focusing is the most common form of fixed focusing.
Internal
True or false
Phased array means fixed focusing
False
HIGH or LOW frequency transducers have the best resolution.
High
Lateral resolution equals
beam diameter
In clinical imaging, axial resolution ranges from?
.1 to 1.0mm
When the number of cycles in a pulse increases while the frequency remains the same, the image quality IMPROVES, DEGRADES, REMAINS THE SAME.
Degrades
True or False
Axial and lateral resolution are measured in distance.
True
Since the high-frequency sound beams provide enhanced longitudinal and lateral resolution, why isn’t ultrasound with a frequency of 100MHz used in diagnostic imaging?
This was a bonus question…
Attenuation
When displayed on an oscilloscope, the amplitude information of a B-mode is routed into the?
z-axis
An A-mode display looks like?
skyline
The M-mode appears as a group of?
horizontal wavy lines
What is the only mode that provides information about a reflector’s changing location with respect to time?
M-mode
With A-mode, what is displayed on the y-axis?
amplitude of the reflected signal
Which of the display modes is mainly used for ophthalmology?
A-mode
With B-mode, which axis is related to the strength of refection?
z-axis
Which display mode is used primarily to assess the motion of cardiac walls?
M-mode
With A-mode, what is displayed on the x-axis?
depth
Which display mode was the first form of gray scale imaging?
B-mode
Which display mode has an invisible dot that moves across the system’s display and with that brightness of the dot will indicate the strength of the reflection?
B-mode
