3 Pulsed Sound Flashcards
What are the 2 components of pulsed ultrasound?
The CYCLES or “on” or “transmit” time and
The DEAD TIME or “off” or “receive” time.
What is a pulse?
A collection of cycles that travel together and must have a beginning and an end.
What are the 5 parameters that describe pulsed sound?
Pulse duration Pulse repetition period PRF Duty factor Spatial pulse length
What is pulse duration?
The time from the start of a pulse to the end of hyphae pulse, ie the actual time that the pulse is “on”.
Typical values: 0.5-3 microsec
Determined by sound source
NOT changed by sonographer
What is the equation for pulse duration?
Pulse duration (microsec) = # cycles in pulse x period (microsec)
What type of pulses are used in diagnostic imaging?
Short pulses of acoustic energy
What is a pulse?
A collection of cycles that travel together
What must a pulse contain?
A beginning and an end
What are 2 compartments of pulsed ultrasound?
- The cycles
2. The dead time
What are 5 additional parameters that describe pulsed sound?
Pulse Duration Pulse Repetition Period PRF Duty Factor Spatial Pulse Length
What is pulse duration?
Time from the start of a pulse to the end of that pulse, the actual time that the pulse is “on”.
What are the units of pulse duration?
Microsec (or any unit of time)
What determines pulse duration?
Sound source
What are typical values of pulse duration?
0.5 - 3 microsec
2-4 cycles
What is the equation for pulse duration?
Pulse duration (us) = # cycles in pulse x period (us)
What is the spatial pulse length?
Length or distance that an entire pulse occupies in space
What are units of spatial pulse length?
mm
What determines spatial pulse length?
Both source and medium
Can spatial pulse length be changed by the sonographer?
NO
What is the equation for spatial pulse length?
Spatial pulse length (mm) = # of cycles x wavelength (mm)
What is the pulse repetition period?
Time from the start of one pulse to the start of the next pulse
Includes 1 pulse duration and 1 “listening time”
What are units of the pulse repetition period?
msec
What is pulse repetition period determined by?
Sound source
Imaging depth
Can pulse repetition period be changed by sonographer?
YES
