chapter 4-5 Flashcards
pulsed wave ultrasound
Group : cycle make up 1 pulse
2 component : pulsed ultrasound
- transmits time ( talking / on time )
- receive time ( listening to/ off time )
pulsed repetition frequency
: pulses > U/S system transmit > body in 1 sec
PRF determined by …. but ….. & how ?
sound source
can be changed by sonographer
how can sonographers change PRF
by adjusting depth : view scan
New pulse isn’t sent out until ..
last one has been received
PRF / depth …. related
inversely
depth ⬆️,PRF ⬇️
Units : PRF
hertz
Pulse repetition pulse
time from start : 1 pulse > start : next pulse
- 1 pulse, 1 listening Time
PRP / PRF …. relationship
Reciprocal
PRP determined by …
sound source
how can PRP be changed by sonographers
adjusting depth : view
units : PRP
time ( ms)
PRP / imaging depth …. related
directly
depth ⬆️,PRP⬆️
pulse duration
actual time > start : pulse to end : that pulse
1 talk, transmit on time
PD determined by
sound source
can PD be adjusted
NO
units : PD
time ( ms)
PD / period …. related
directly proportional
PD / frequency …. related
inversely proportional
PRP ……. than PD
longer
Spatial pulse length
distance > pulse occupies > start - end : pulse
SPL determined by
both sound source / medium
units : SPL
distance ( mm)
can SPL be adjusted
NO
duty factor
Fraction / % : time > system pulse
DF determined by
sound source
can DF be adjusted & how
YES
adjust depth
DF / Imaging depth …. related
inversely
⬆️,⬇️
shallow imaging
- less listening
- shorter PRP
- higher PRF
- higher DF
deep imaging
-more listening
- longer PRP
- lower PRF
- lower DF
continuous wave 2 transducer elements
- Continuously sends
- continuously receive
intensities
beam power divide by it area
Units : intensities
w/
5 key words > related to intensities : pulsed wave
- spatial distance / space
- peak - max value
- average - mean value
- temporal time
- pulsed transmit time only
different measurement : intensities
- SPTP - Spatial Peak/ Temporal peak
- SATP - Spatial Average /Temporal peak
- SPTA - Spatial Peak /Temporal average
- SATA - Spatial Average/ Temporal average
- SPPA - Spatial Peak /Pulse average
- SAPA - Spatial Average/ pulse average
SPTA …. bc
most relevant intensity w/ respect to tissue heating
peak measurement > larger than average measurements
SPTP intensity
highest value
SATA intensity
lower value
Spatial peak intensity > …. than spatial average intensity
higher
logarithms / log
: time that 10 is multiple by itself to create original #
decibels
relationship b/w 2 #
units : decibels
amplitude / attenuation
when comparing 2 intensities, power, amplitude, what can be use to describe their relationship
decibels
positive decibels
Represents : increase / strengthening : intensity
negative decibels
Represents : decrease / weakening : intensity