Part 2 - important (notes) Flashcards
-front t back, parallel to sound beam
-determined by SPL
-same at all depths, does not change
-best with short pulses, less cycles, high frequency
-LAARD
longitudinal, axial,radial,depth
axial resolution
- Side by side, perpendicular to beam
- Determined by beam width
- Best with narrowest beams
- Changes w/ Depth
- LATA – Lateral, angular, transverse, azimuthal
- Large Beam diameter , High Frequency – LESS divergence in far field
Lateral resolution
Determined by
thickness of PZT
propagation speed of PZT
Pulsed transducers
Thinner PZT
High frequency
Thick PZT
Low frequency
1/2 wavelength thick
PZT
1/4 wavelength thick
Matching layer
increases efficiency of sound transmission w/ impedance between skin & active element
Matching layer
Reduces ringing, shortens pulse duration & SPL
Damping material
Maximum Frequency - Minimum frequency equals ?
Bandwidth
- Pulses w/ short duration
- uses backing material
- reduced sensitivity
- wide bandwidth
- Low Q factor
- Improved axial resolution
Imaging transducer
- Continous wave
- no backing material
- increased sensitive
- narrow bandwidth
- high Q factor
- no image
Non - imaging transducer
- Small diameter
- lower frequency
- more divergence
Shallow focus
- large diameter
- higher frequency
- less divergence
Deep focus ( better lateral resolution in far field)
Determined by frame rate
Temporal resolution
Frame is determined by
Image depth # of pulses , focus, sector size, line density
Short go return time
Short Tframe
Higher frame rate
superior temporal resolution
Shallow imaging
Long go return time
Longer Frame
Low frame rate
Inferior temporal resolution
Deep imaging
Single focus
Narrow setor
Low line density
More pulses per frame
SUPERIOR TEMP RESOLUTION
High line density improves
Spatial resolution
Uses old data post processing larger pixel size same # of pixels as the original ROI unchanged temporal resolution
Read magnification
Aquires new data preprocessing smaller pixel size more pixels than original ROI improved spatial resolution May improve temporal resolution
Write magnification
Improves higher signal to noise ration
improved axial, spatial, contrast resolution
-deeper penetration
Coded excitation does this
A Mode
X -
Y -
X - depth
Y - amplitude