Describing pulsed waves Ch 4 Flashcards
Units for pulse duration
us micro seconds
Source of pulse duration
Sound source
of cycles x period or # of cycles/ frequency
pulse duration
The distance that a pulse occupies in space from the start to the end of a pulse
Spatial pulse length
Source of spatial pulse length
source and the medium
Units for spatial pulse length
mm
Is pulse duration adjustable
No
Is spatial pulse length adjustable
No
The time from the start of one pulse to the start of the next pulse (one pulse duration plus one listening time)
Pulse repetition period
Units for Pulse repetition period
ms milli second
Source for pulse repetition period
sound source
Is pulse repetition period adjustable and why
yes; because it is determined by depth
How are pulse repetition period and depth related?
directly
The two components of pulse repitition period
transmitt time and receive time
The number of pulses that an ultrasound system transmits into the body each second
Pulse repetition frequency
Units for pulse repetition frequency
Hz
Source for pulse repetition frequency
sound source
Is pulse repetition frequency adjustable
Yes
Is pulse repetition frequency related to frequency?
No
How are pulse repetition frequency and depth related?
inversely
Is pulse repetition period related to period?
No
How are pulse repetition period and pulse repetition frequency related?
inversely
How are pulse repetition frequency and depth related?
inversely
Is pulse repetition frequency adjustable?
Yes
The percentage or fraction of time that a system transmits a pulse
Duty factor
Source for duty factor
sound source
Is duty factor adjustable?
yes
How are duty factor and depth related?
inversely
Which parameters are determined by sound source?
Pulse duration, pulse repetition period, pulse repetition frequency, and duty factor
Which parameters do not change with depth?
Pulse duration and spatial pulse length
Which parameter is determined by both sound source and medium?
spatial pulse length
Which parameters can be changed with imaging depth?
pulse repetition period, pulse repetition frequency, and duty factor
The actual time from start of a pulse to the end of that pulse. (single trasmit talking time)
Pulse duration
Typical Value for Pulse duration
0.5 to 3.0 us
Typical value for Pulse repetition period
0.1 to 1.0 ms
Typical value for Pulse repetition frequency
1 to 10 kHz
Typical value for Spatial pulse length
0.1 to 1.0 mm
Typical value for Duty Factor
0.2% to 0.5%
Two characteristics of long duration
Many cycles in the pulse or individual cycles wtih long periods
Two characteristics of short duration
Few cycles in the pulse or individual cycles with short periods
Clinical imaging typically contains how many cycles?
2 to 4 cycles
of cycles x period =
Pulse duration
Two characteristics create long pulse
Many cycles in the pulse or cycles with longer wavelengths.
Two characteristics create short pulse length
Fewer cycles in the pulse or cycles with shorter wavelengths
cycles x wavelength
Spatial pulse length
Are pulse repetition period and pulse repetition frequency inversely related?
yes
Pulse duration / pulse repetition period x 100
Duty Factor
