Mag
Selected part of an image for zoom
Why was coded excitation developed
What was taken into consideration
FDA established maximum peak intensity levels
Bioeffects on patients
Averaging information from several different directions and angles to create one image
_____ Compounding
Spatial Compounding
Continues to display information from older images and superimposes them on the current frame to create a smoother image
Temporal Compounding
Function of dynamic range
Method of reporting the extent to which a signal can vary and be accurately measured
It’s the “number of available choices”
Occurs after the image is stored in scan converter
Read Magnification
Coded excitation creates very ____ pulses containing a wide range of _____
long, frequencies
___ Speckle Artifact
___ Shadowing Artifact
___ Image Quality
___ Frame Rate
___ Temporal Resolution
Reduces speckle artifact
Reduces shadowing artifact
Improves image quality
Low frame rate
Poor temporal resolution
Other names for Temporal Compounding
Persistence or Temporal averaging
Measured in
dB
Occurs during acquisition, before storage in the scan converter
Write Magnification
Occurs in the ____
Pulser
The reflected signal is divided into sub-bands of limited frequencies
Frequency Compounding
"fills in the gaps" between the scan lines by looking at the nearby grey levels and predicting the pixelation of the "missing" information
Fill-in Interpolation
Narrow Dynamic Range Wide Dynamic Range
___ gray shades. ___ gray shades
___ contrast ___ contrast
Narrow Dynamic Range Wide Dynamic Range
Less gray shades. More gray shades
High contrast Low contrast
Identical pixel size
Improved spatial resolution
Improved temporal resolution possible
Write Magnification
The coding schemes are called
Barker Codes or Golay Codes
Frequency Compounding
___ Speckle Artifacts
____ Noise
Reduces Speckle Artifact
Reduces Noise
Color overlay on top of the gray-scale image to estimate tissue stiffness
____ Wave applies compressive force
____ Wave produces acoustic frequency
Elastography
Strain
Shear
Can the sonographer adjust compression
Dynamic range compressed: _____ the decibels
Dynamic range original uncompressed: ____ the dBs
Yes. Largest signal remains the largest, smallest signal remains the smallest, range of signal is reduced
Dynamic range compressed: subtract the decibels
Dynamic range original uncompressed: add the dBs
Changes the pixel size
Spatial Resolution remains same
Temporal Resolution remains same
Read Magnification
Coded excitation provides:
_____ SNR
_____ Noise
_____ Axial Resolution
_____ Spatial Resolution
_____ Contrast Resolution
_____ Penetration
Higher SNR
Less Noise
Improved Axial Resolution
Improved Spatial Resolution
Improved Contrast Resolution
Deeper Penetration
Computer identifies and emphasizes sharp edge boundaries in the image by increasing contrast
Edge Enhancement
PACS:
DICOM:
Picture Archiving and Communications System
Digital Imaging and Computers in Medicine
Transducer
Receiver
Scan converter
Display
Archive
Transducer 120 dB
Receiver 100 - 120 dB
Scan Converter 40 - 50 dB
Display 20 - 30 dB
Archive 10 - 30 dB