Chapter 13 Flashcards
what was the process were images were displayed one frame at a time?
static scanning
what is the systems ability to create numerous frames each second?
frame rate
what is the speed of soft tissue?
1.54 km/s
what are the units for frame rate?
hertz (Hz) per second or images per second
what are the factors affecting frame rate?
speed of sound in the medium and imaging depth
______ (pertains to accuracy in time) describes the ability to precisely position moving structures from instant to instant
temporal resolution
temporal is ______ when a system produces many frames per second, and ______ when it produces few frames per second
excellent, substandard
what is temporal resolution determined by and what are its units?
frame rate and hertz or per second
what is the relationship between frame rate and time required to make a single image?
inversely related and reciprocals
the time need to create each image increases then the frame rate decreases
what are the system settings affecting frame rate?
imaging depth and number of pulses per frame
shallowing imaging ______ frame rate and improves temporal resolution, deeper imaging ______ frame rate and degrades temporal resolution
increase, decrease
imagine depth and frame rate are directly related
short go-return time, shorter time frame, higher frame rate, and superior temporal resolution is?
shallow imaging
long go-return time, longer time frame, lower frame rate, and inferior temporal resolution is?
deep imaging
how does the number of pulses in each image affect temporal resolution?
hight frame rates are possible when each individual image is made with fewer pulses, lower frame rates occur when each image is made with more pulses, pulses per frame and frame rate are inversely related
what 3 factors affect the number of pulses per frame?
number of focal points, sector size, and line density
muti-focusing ______ the frame rate, and diminishes temporal resolution
decreases
one pulse per scan line, shorter time frame, higher frame rate, better temporal resolution, poorer lateral resolution is?
single focus
many pulses per scan line, longer time frame, lower frame rate, diminished temporal resolution, improved lateral resolution is?
multi-focus
what is the main advantage of multiple focal zones?
improves accuracy of the individual images, each scan has better lateral resolution
how do you determine the time needed to make a single frame
T frame= # pulses x PRF
when the sonographer expands the sector size ______ pulses are required to create an image
more- temporal resolution decreases
fewer pulses per frame, shorter frame time, higher frame rate, and superior temporal resolution is?
narrow sector
more pulses per frame, longer frame time, lower frame rate, and inferior temporal resolution is?
wider sector
when the US system alters the spacing between sound beams
line density
when lines are spaced far apart
low line density
when lines are closely packed
high line density
when line density is ______ few pulses create each image, the frame rate is high, temporal resolution is high
low
when line density is ______ the number of pulses per image increases, the frame rate drops and the temporal resolution decreases
high
what is the main advantage of high line density?
improve the accuracy of each individual image, each image contains more detail aka improves spatial resolution
widely spaced lines, fewer pulses per frame, shorter frame time, higher frame rate, high temporal resolution, and poor spatial resolution is?
low line density
tightly packed lines, more pulses per frame, longer frame time, lower frame rate, low temporal resolution, and excellent spatial resolution is?
high line density
______ resolution improves with multi-focusing, ______ resolution improves with higher line density
lateral, spatial
shallower imaging, single focus, narrow sector, and low line density is?
better temporal- higher frame rate
deeper imaging, multiple focal points, wider sector, high line density is?
worse temporal- lower frame rate
