Pulsed US Flashcards
Pulse Duration
Define:
Units:
Determined by:
Changed by Sonographer?
Define: the time from the START of a pulse to the END of that pulse (actual time that the pulse is “on”)
Units: seconds
Determined by: sound source
Changed by Sonographer? no it is a characteristic of the transducer
Pulse duration is determined by the ____________ in each pulse and the _________ of each cycle
number of cycles
period`
Pulse Repetition Period
duration of time form the START of one pulse to the START of the next pulse (“on” time plus “listening” time)
What is the only thing the sonographer changes in pulsed ultrasound?
the listening time between pulses
As depth increases, PRP ___
as depth decreases, PRP ___
increases; decreases
PRF
The # of pulses that occur in one second - also, how frequently the pulses are generated
The PRF depends on _________
imaging depth
shallowing images have a ______ PRF
higher
deeper images have a ________ PRF
lower
standard unit for PRF?
standard unit for PRP?
Hz
seconds
If PRF is given in KHz, what will PRP be changed to?
miliseconds
Duty Factor
the PERCENTAGE or FRACTION of time that the pulse is transmitted
*important for intensity
Duty Factor increases when (3 things):
- imaging depth decreases
- PRP decreases
- PRF increases
Axial Res =
image quality
SPL
The distance from the start of a pulse to the end of that pulse
SPL determines _____ resolution
axial
Imaging depth effects with 3 factors?
- Duty factor
- PRP
- PRF
Intensity
concentration of the power in a beam
What are 5 key words that relate to Intensity and what to do they mean?
- peak - max value
- average - mean value
- spatial - distance/space
- temporal - time (transmit & recieve)
- pulse - only the time the pulse exists (transmit only)
What are 6 intensity descriptors?
- SPTP (spatial peak, temporal peak)
- SATP (spatial average, temporal peak)
- SPTA (spatial peak, temporal average) *Bioeffects
- SATA (spatial average, temporal average)
- SPPA (spatial peak, pulse average)
- SAPA (spatial average, peak average)
