physics 2

what are the 5 parameters for pulsed waves

pulse duration, spatial pulse length, pulse repetition period, pulse repetition frequency, duty factor

define pulse ultrasound

pulses of acoustic energy to create every picture of anatomy

pulse ultrasound is how many units

single unit

define pulse sound

collection of cycles that travel together

what are the 2 components of pulse ultrasound

on time and off time

what is pulse duration pd

actual time from the start of a pulse to the end of a pulse

what is the unit of pd

microseconds

what is pd determined by

sound source only

can pd change

no

what is pd equal to

#cycles x period

what is pd inverse to

#cycles/ frequency

pd is what to number of cycles

directly

pd is what to period

directly

pd is what ti frequency

inverse

2 characteristics of long duration

many cycles in pulse or individual cycles with long periods

characteristics of short duration of pd

few cycles in the pulse or individual short periods

which type of pulse is more desirable in imaging long or short duration?

short duration for higher accuracuy

define spatial pulse length (spl)

distance that a pulse occupies in the space from the start to the end of a pulse

units of spl

mm

spl is determined by

sound source and medium

spl adjustable

no

formula for spl

#cycles x mm

spl to #cycles in pules

direct

spl to wavelength

direct

spl to frequency

inverse

what is the difference between pd and spl

pd is time and spl is distance

long pulse length spl

many cycle in the pulse; cycles with longer wavelengths

short pulse length spl

fewer cycles in the pulse; cycles with short wavelength

what type of pulse do you want for imaging in spl

pulse of shorter length

pulse repetition period prp

time from the start of one pulse to the start of the next pulse

units of prp

time

determined by prp

sound source only

what else can prp determined by

imaging depth

prp adjustable

yes

prp is to period

unrelated

prp to depth of view

related

when the system is imagine at shallow depths, the time from one pulse to the next is

short

when the system is imaging more deeply, the time from one pulse to the next is

longer

what is the depth of view

maximum distance into the body that is imaging

what are the 2 components of prp

transmit time and receive time

transmit time is called

pulse duration

with deeper imaging, the listening time and prp _

lengthen

with shallower imaging, the listening time and prp _

shorten

Pulse repetition frequency prf

number of pulses than an ultrasound system transmits into the body each seconds

units prf

hertz

prf determined

sound source

what else can prf determined by

maximum imaging depth of system

prf adjustable

yes

when the system is imagine shallow the prf is

higher

when the system is imaging deep the prf is

lower

prf to frequency

unrelated

prf to depth of view

inverse

an ultrasound machine is imaging to a depth of 2cm. would the pulse repetition frequency be described as high or low.

high

prp to prf

inverse

prp to prf

proportional

which of these values for prf would have the longest prp

6Hz

four pulses have prp as listed below. which of the following 4 waves has the highest prf.

5ms

which of these 4 pulses with prf listed below has the shortest prp

20kHz

4 waves have prp as listed below. which of the following 4 waves has the lowest prf.

8s

TRUE OR FALSE; 2 waves can have identical prf, even if their prp are different

false

TRUE OR FALSE; 2 waves can have identical prf even if their periods are different

true

TRUE OR FALSE; 2 waves can have identical prfs even if their frequencies are different

true

TRUE OR FALSE; prf and prp are determined by only imaging depth

true

duty factor

percentage that the system transmits a pulse

units of duty factor

%

typical values of duty factor

0.2% -0.5%

determined duty factor

sound source

adjustable duty factor

yes

duty factor to imagine depth

inverse

min duty factor

0%

max duty factor

100%

if all other factors remain unchanged what happens to the duty factor when the prf increases?

increases

if all other factors remain unchanged what happens to the other duty factors when imaging depth increases

decreases

if all other factors remain unchanged what happens to the duty factor when the prp increases

decreases

if all other factors remain unchanged what happens to the duty fact when thes sonographer uses a new transducer with a longer pd

increases

what is the duty factor if the pd is 1 and the prp is 1ms

0.001

which term does not belong with the rest

low prf

which of the following terns does not belong with the others

shallow imaging

_ is the time from the start of a pulse to the end of that pulse

pulse duration

_ is the time from the start of a pulse to the start of the next pulse

prp

prf is the reciprocal of _

prp

the speed of a 5 MHz continuous wave is 1.8km/sec. the wave is the pulsed with a duty factor of 0.5. calculate the new propagation speed.

1.8km/sec

what is the duty factory if the pd is 1 microsecond and the prp is 1 ms 

0.001

TRUE OR FALSE; spl changes when a sonographer changes their depth

false

TRUE OR FAlSE; two waves can have identical prf even if their periods are different

true

shallow imaging is associated with all except

lower duty factor 

if all the other factors remained unchanged what happened to the duty factor when the prf increases 

increases 

when changing imaging depth which of the following parameters does the operator also change. prf prp duty factor propagation speed amplitude spl 

prf, prp, duty factor

in clinical ultrasound what type of pulse is the most diserable

short duration pulses

what parameters of pulsed ultrasound is defined as the time form the start of one pulse to the start of the next one

prp

how are the depth view and prf related

inverse

what is the equation for duty factor 

pd/prp x100

spatial 

refers to distance or space

peak

the max value

average

the middle value 

temporal

all time, transmit, and receive

pulsed

only to the transmit time 

spatial peak intensity Isp

the beams intensity at the location where its maximum

spatial average intensity Isa

the average intensity across the beams entire cross-sectional area

which is always higher Isp or Isa

Isp