US - Understanding US Physics - 4 Flashcards
5 parameters of pulse sound
SP3D
Spatial pulse length
Pulse duration
Pulse repetition period
Pulse repetition frequency
Duty factor
def PULSE ULTRASOUND
= imaging systems produce short burst of acoustic energy to create anatomical picture
def PULSE SOUND
= collection of wave cycles that propagates as 1 unit
. has an “end” & a “begining”
2 components of pulse sound
. ON time - transmit, talking
. OFF time - receive, listening
def PULSE DURATION
= 1 ON time
. actual time from start-end of a pulse
pulse duration - US range
0.3 - 2 micro.s
pulse duration - adjustable??
NO, fixed on each transducer
pulse duration - determined by??
sound source
pulse duration - equations (2)
pulse duration(micro.s) = #cycles x period(micro.s)
pulse duration(micro.s) = #cycles / f(MHz)
pulse duration r/t f
inverse r/t
pulse duration r/t #cycle
direct r/t
pulse duration r/t period
direct r/t
in US, # of cycles in 1 pulse?
1 pulse = 2-4 cycles
short pulse r/t accuracy & pulse duration
short pulse =
UP accuracy
DOWN pulse duration
long pulse r/t accuracy & pulse duration
long pulse =
DOWN accuracy
UP pulse duration
def spatial pulse length
= distance of a pulse from start-end
spatial pulse length, US range
soft tissues = 0.1 - 1mm
spatial pulse length equation
spatial pulse length(mm) = #cycle x wavelength(mm)
spatial pulse length - determined by?
.sound source
.medium
spatial pulse length - adjustable??
NO
pulse DURATION vs. spatial pulse LENGTH
.duration - ON time, micro.s
.length - ON distance, mm
SHORT spatial pulse length r/t accuracy, #cycle, wave.l
SHORT spatial pulse length
-UP accuracy
.UP f
.DOWN #cycle
.DOWN wave.l
LONG spatial pulse length r/t accuracy, #cycle, wave.l
LONG spatial pulse length
-DOWN accuracy
.DOWN f
.UP #cycle
.UP wave.l
def PULSE REPETITION PERIOD
= 1 ON time + 1 OFF time
= the start of one pulse to the start of the next pulse
PULSE REPETITION PERIOD - US range
100 micro.s – 1m.s
PULSE REPETITION PERIOD (PRP) - equation
PRP = 1 ON time + 1 OFF time
PULSE REPETITION PERIOD - determined by?
sound source
PULSE REPETITION PERIOD - adjustable?
YES
PULSE REPETITION PERIOD r/t depth.shallow
shallow depth - short PRP
PULSE REPETITION PERIOD r/t depth.deep
deep depth - long PRP
PULSE REPETITION PERIOD r/t period
PRP NOT r/t period
PULSE REPETITION PERIOD r/t depth?
direct
2 components of PULSE REPETITION PERIOD
.OFF time
.ON time
while PULSE REPETITION PERIOD is adjustable, which component of PRP is not adjustable?
ON time (pulse duration) is NOT adjustable
when adjusting PULSE REPETITION PERIOD, which component of PRP change? remain the same?
change PRP, change depth
.change OFF time
.same ON time pulse durationnot adjustable
def PULSE REPETITION FREQUENCY (PRF)
= # of pulses transmit per second
PULSE REPETITION FREQUENCY (PRF) - US range
1,000 - 10,000 Hz/second
PULSE REPETITION FREQUENCY (PRF) determined by
sound source
PULSE REPETITION FREQUENCY (PRF) - adjustable?
YES
PULSE REPETITION FREQUENCY (PRF) r/t max image depth
inverse
PULSE REPETITION FREQUENCY (PRF) r/t frequency
PULSE REPETITION FREQUENCY (PRF) is NOT r/t f
PULSE REPETITION FREQUENCY (PRF) r/t PRP
inverse
PULSE REPETITION FREQUENCY (PRF) - equation
PULSE REPETITION FREQUENCY (PRF) = 1 / PRP
1 = PRF x PRP
def DUTY FACTOR
= percentage or fraction of time that the system transmit a pulse
DUTY FACTOR - US range
0.2 - 0.5%
0.002 - 0.005
DUTY FACTOR determined by?
sound source
DUTY FACTOR - adjustable?
YES
changes DUTY FACTOR, also changes…..?
change DUTY FACTOR
change depth
inverse r/t
DUTY FACTOR r/t depth
inverse
DUTY FACTOR equation
DUTY FACTOR (%) = pulse duration / PRP x (100)
DUTY FACTOR - 0%
silent transducer
DUTY FACTOR - 100%
continuous sound wave
NO image
shallow image r/t listening time, PRP, PRF, duty factor
shallow image =
.LESS listening
.SHORT PRP
.HI PRF
.HI duty factor
deep image r/t listening time, PRP, PRF, duty factor
deep image =
.MORE listening
.longer PRP
.LOW PRF
.LOW duty factor
SHALLOW vs. DEEP imaging r/t listening time, PRP, PRF, duty factor
shallow image =
.LESS listening
.SHORT PRP
.HI PRF
.HI duty factor
deep image =
.MORE listening
.longer PRP
.LOW PRF
.LOW duty factor
which parameters of sound pulse are adjustable?
ADJUSTABLE
.PRP
.PRF
.duty factor
which parameters of sound pulse are NOT adjustable?
NOT adjustable
.spatial pulse length
.pulse duration
5 parameters of sound pulse - US range?
pulse duration = 0.5 - 3.0 micro.s
spatial pulse.l = 0.1 - 1mm
PRP = 0.1 - 1m.s
PRF = 1,000 - 10,000 Hz
duty factor = 0.2 - 0.5%
draw info graph for 5 parameters of sound pulse
check CH 4 notes
