Ch. 10 Axial and Lateral Resolution Flashcards
__________________ is the ability to create accurate images.
resolution is the ability to create accurate images.
____________________ Resolution measures the ability of a system to display two structures that are very close together when the structures are parallel (front to back) to the sound beam’s main axis.
Axial Resolution measures the ability of a system to display two structures that are very close together when the structures are parallel (front to back) to the sound beam’s main axis.
What does LARRD stand for?
Longitudinal
Axial
Range
Radial
Depth
Axial Resolution is measured in ________
Axial Resolution is measured in millimeters (mm)
Axial resolution is determined by
spatial pulse length
Sonographer cannot adjust axial resolution
Typical values of axial resolution:
0.1 to 1.0 mm lower numerical values indicate shorter pulses and improved image accuracy
Axial Resolution Formula:
Axial Resolution (mm) = spatial pulse length (mm) / 2
Better axial resolution is associated with:
- shorter spatial pulse length
- shorter pulse duration
- higher frequencies (shorter wavelength)
- fewer cycles per pulse (less ringing)
- lower numerical values
What is the ability to accurately distinguish two structures lying close together called?
Resolution
Lateral Resolution is determined by:
width of the sound beam
For lateral resolution the mnemonic LATA stands for?
Lateral
Angular
Transverse
Azimuthal
Lateral Resolution (mm) =
beam diameter (mm)
Lateral Resolution is better with the following:
narrowest beam (focus)
Fixed focusing
Also called conventional or mechanical focusing includes both external and internal focusing (determined by the transducer and cannot be changed)
The three methods of focusing are:
- external focusing - with a lens
- internal focusing - with a curved active element
- phased array focusing - with the electronics of the ultrasound system.
