2 Ch 13: Real-Time Imaging Flashcards
This is a process of scanning one frame at a time.
static scanning
This is the most important operational parameter associated with an u/s movie.
frame rate
This is the system’s ablity to create numerous frames each second.
frame rate
What two factors determine frame rate?
- sound’s speed in the medium
2. the depth of imaging
Frame rate is measured in units of…
hertz (Hz).
This describes the ability to precisely position moving structures from instant to instant.
temporal resolution
Temporal resolution is determined by…
frame rate.
___ is determined by frame rate.
Temporal resolution
What is the relationship between frame rate and the time required to make a single image?
They are inversely related and reciprocals.
T x frame rate =
1
When an u/s system creates an image in 1/10 of a second, the frame rate is…
10 Hz.
When a system creates an image in 1/50 of a second, the frame rate is…
50 Hz.
What two sonographer-controlled settings of a system determine frame rate?
- imaging depth
2. # of pulses in each picture
How does imaging depth affect temporal resolution?
They are directly related.
Shallow imaging involves ___ go-return time, ___ T, ___ frame rate, and ___ temporal resolution.
short, shorter, higher, superior
Deep imaging involves __ go-return time, __ T, __ frame rate, and __ temporal resolution.
long, longer, lower, inferior
pulses x PRP =
T
How are # of pulses and temporal resolution related?
They are inversely related.
What factors affect the # of pulses needed to create an image?
- # of focal points
- sector size
- line density
When the sonographer activates multiple focal zones, the frame rate and the temporal resolution ___.
decrease.
What is the main advantage of multiple focal zones?
Improved accuracy of individual images
With multi-focus, each scan line has better…
lateral resolution.
When the sonographer expands the sector size (field of view) the temporal resolution…
decreases.
A narrow sector involves ___ pulses per frame, __ T, __ frame rate, and __ temporal resolution.
fewer, shorter, higher, superior
