US - Understanding US Physics - 4 Flashcards by Mai Trnhv

5 parameters of pulse sound

SP3D

Spatial pulse length
Pulse duration
Pulse repetition period
Pulse repetition frequency
Duty factor

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def PULSE ULTRASOUND

= imaging systems produce short burst of acoustic energy to create anatomical picture

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def PULSE SOUND

= collection of wave cycles that propagates as 1 unit
. has an “end” & a “begining”

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2 components of pulse sound

. ON time - transmit, talking
. OFF time - receive, listening

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def PULSE DURATION

= 1 ON time
. actual time from start-end of a pulse

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pulse duration - US range

0.3 - 2 micro.s

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pulse duration - adjustable??

NO, fixed on each transducer

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pulse duration - determined by??

sound source

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pulse duration - equations (2)

pulse duration(micro.s) = #cycles x period(micro.s)

pulse duration(micro.s) = #cycles / f(MHz)

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pulse duration r/t f

inverse r/t

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pulse duration r/t #cycle

direct r/t

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pulse duration r/t period

direct r/t

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in US, # of cycles in 1 pulse?

1 pulse = 2-4 cycles

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short pulse r/t accuracy & pulse duration

short pulse =
UP accuracy
DOWN pulse duration

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long pulse r/t accuracy & pulse duration

long pulse =
DOWN accuracy
UP pulse duration

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def spatial pulse length

= distance of a pulse from start-end

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spatial pulse length, US range

soft tissues = 0.1 - 1mm

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spatial pulse length equation

spatial pulse length(mm) = #cycle x wavelength(mm)

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spatial pulse length - determined by?

.sound source
.medium

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spatial pulse length - adjustable??

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pulse DURATION vs. spatial pulse LENGTH

.duration - ON time, micro.s
.length - ON distance, mm

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SHORT spatial pulse length r/t accuracy, #cycle, wave.l

SHORT spatial pulse length
-UP accuracy
.UP f
.DOWN #cycle
.DOWN wave.l

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LONG spatial pulse length r/t accuracy, #cycle, wave.l

LONG spatial pulse length
-DOWN accuracy
.DOWN f
.UP #cycle
.UP wave.l

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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 duration*not 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