11 Contrast, Spatial + Temporal Resolution Flashcards
What is contrast resolution?
Visualizing a variety of gray shades in an image
Few grade shades = poor contrast resolution
What is spatial resolution?
Visualizing detail in an image
Limited detail = poor spatial resolution
What is real-time imaging?
The production of a motion picture
What is temporal resolution?
The ability to accurately locate moving structures at any particular instant of time
What is temporal resolution determined by?
Frame rate
More images/sec improves temporal resolution
What is the typical value of temporal resolution?
20–100 Hz
What are the two factors that determine frame rate?
Imaging depth # of pulses per image
What are two factors that limit frame rate?
The speed of sound in medium
Imaging depth
What is a fundamental limitation of temporal resolution?
Speed
What are four settings that a sonagrapher controls that affect temporal resolution?
Maximum imaging depth
# of pulses per scanline
Sector size
Line density
List 2 questions to determine the effect on temporal resolution.
Is the image shallower?
Is the image comprised of fewer pulses?
With regard to maximum imaging depth, what will create a frame in less time?
Shallow depth of view makes a frame faster
With regard to pulses per scan line, which will create a frame with fewer pulses?
Single focus systems use fewer pulses
What will create the best temporal resolution?
Single focusing Narrow sector Low line density Higher frame rate Shallow imaging Fewer pulses per image
How does multi-focus affect lateral and temporal resolution?
Improves lateral resolution
Reduces frame rate and degrades temporal resolution
With regard to sector size, what will create a frame with fewer pulses?
Smaller sector angle creates images with fewer pulses
With regard to line density, what will create a frame with fewer pulses?
Low line density images use fewer pulses
What does lower line density degrade?
Spatial resolution
What is line density in a sector image?
Number of scan lines per degree of sector
What does improved temporal resolution degrade?
Image quality
What is Tf?
Time required to make a frame
What is the relationship between Tf and frame rate?
They are reciprocals
Tf x FR = 1
