Chapter 13 Real-Time Imaging Flashcards
Ability of the system to create numerous frames per second is called?
Frame rate
Images displayed one image at a time in the early days was known as?
Static scanning
Factors affecting frame rate include
- speed of sound in the medium
- imaging depth
What unit is frame rate measured in?
Hertz (images per second)
What does “accuracy in time” (the ability to precisely position moving structures from instant to instant) describe?
Temporal resolution
Temporal resolution is excellent when a system produces __________ frames per second.
Many
Temporal resolution is determined by?
Frame rate
High frame rate will ________ temporal resolution.
Improve
What are the units for temporal resolution?
Hertz (per second)
What is the relationship between frame rate and the time required to make a single image?
Inversely related and reciprocals
Two sonographer-controlled settings of an ultrasound system determine frame rate:
- Imaging depth
2. Number of pulses per frame
Imaging depth and frame rate are directly or inversely related?
Inversely related
Shallow imaging increases frame rate and does what to temporal resolution?
Improves
Deeper imaging decreases frame rate and does what to temporal resolution?
Degrades
High frame rate equals _________ depth
Shallow
Low frame rate equals _______ depth
Deep
The following describes what type of imaging:
- short go-return time
- shorter Tframe
- higher frame rate
- superior temporal resolution
Shallow imaging
The following describes what type of imaging depth:
- long go-return time
- longer Tframe
- lower frame rate
- inferior temporal resolution
Deep imaging
What’s the equation for time needed to make a single frame?
Tframe = # pulses x PRP
Pulses per frame and frame rate are directly or inversely related?
Inversely related
What is needed to give the illusion of moving pictures?
High frame rate
What factors affect the number of pulses needed to create an image?
- number of focal points
- sector size
- line density
What type of focus is describe below:
- one pulse per scan line
- shorter Tframe
- higher frame rate
- better temporal resolution
- poorer lateral resolution
Single focus
What type of focus is described below:
- many pulses per scan line
- longer Tframe
- lower frame rate
- diminished temporal resolution
- improved lateral resolution
Multi-focus
What is the main advantage of multiple focal zones?
It improves accuracy in the individual images, each scan line has better lateral resolution because it is narrow over a wide range if depths
Field of view (sector size) and frame rate are directly or inversely related?
Inversely related
Narrower images result in ______ frame rates. Wider images result in _______ frame rate.
Higher; lower
- fewer pulses per frame
- shorter Tframe
- higher frame rate
- superior temporal resolution
These describe what type of sector?
Narrow sector
- more pulses per frame
- longer Tframe
- lower frame rate
- inferior temporal resolution
These describe what type of sector?
Wide sector
Ultrasound systems can alter the spacing between sounds beams and this is known as?
Line density
Lines that are spaced far apart is?
Low line density
Lines closely packed is called?
High line density
Line density and frame rate are directly or inversely related?
Inversely related
- widely spaced lines
- fewer pulses per frame
- shorter Tframe
- higher frame rate
- high temporal resolution
- poor spatial resolution
This describes what type of line density?
Low line density
- tightly packed lines
- more pulses per frame
- longer Tframe
- lower frame rate
- low temporal resolution
- excellent spatial resolution
Describes what type of line density?
High line density
What is the main advantage of high line density?
Improved spatial (detail) resolution
Lateral resolution improves with _________ focusing.
Multi
Spatial resolution improves with _______ line density
Higher
- shallower imaging
- single focus
- narrow sector
- low line density
Describes what type of frame rate?
Better-higher frame rate
- deeper imaging
- multiple focal points (improves lateral resolution)
- wide sector
- high line density (improves spatial resolution)
Describes what type of frame rate
Worse-lower Frame rate
Temporal resolution is directly or inversely related to frame rate?
Directly related
