Knobology and Physics Flashcards
Fresnel
Near field
Fraunhofer
Far field
The region around the focus where the beam is relatively narrow
Focal zone
Create images that are more accurate than from other depths.
Reflections from the focal zone
Describes the maximum distance into the body than an ultrasound system is imaging.
Depth of view
The markers along the edge of an image…
indicate depth
Increases the amplitude of the returning signals
Receiver gain
This creates a brighter image
Increasing the amplitude of the returning signals
adjusts gain according to depth
TGC
TGC stands for…
Time Gain Compensation
main sound beam lobe
central beam axis
focal region, area
the 3 spatial resolution dimensions
axial resolution, lateral resolution, slice thickness
the sound beam profile characteristics
main sound beam lobe, central beam axis, focal region
creates the appearance of smaller dot sizes on the screen.
Increased axial resolution
Determined by the beam width
•A narrow beam width gives a good lateral resolution
•The lateral resolution is best at the focus (transition zone)
•Higher frequency results in better lateral resolution due to beam being less divergent
lateral resolution
slice thickness
Apodization
•The ability to depict the movement of structures accurately
•Temporal resolution is very important in the depiction of moving objects, such as the heart
•Temporal resolution is determined by the frame rate
temporal resolution
refers to how closely positioned two reflectors can be to one another and still be resolved as two different objects on the display
Spatial resolution
When structures are displayed as separate images we say that they are…
resolved
Names for axial resolution:
L-A-R-R-D
•Longitudinal
•Axial
•Range
•Radial
•Depth
• decrease temporal resolution
• improve lateral resolution
• increase sensitivity of the sound beam
Multiple focal zones
