Flashcards in Chapters 1-5 Deck (121):
What does the horizontal axis represent?
What does the vertical axis represent?
what are some units for area?
What are some units for volume?
What is the reciprocal of giga?
What is the reciprocal of hecto?
What is the reciprocal of deca
What do all waves have in common?
all waves carry energy from one location to another.
What is a sound wave?
mechanical and longitudinal
What is defined as the effects of the medium upon the sound wave?
acoustic propagation properties
What is defined as the effects of the sound waves upon the tissue through which it passes?
What are the acoustic variables?
pressure, distance (particle motion), density
What are the acoustic parameters?
What is it called when the peaks occur at the same time and location?
in phase waves
what is it called when the peaks occur at different times?
out of phase waves
What is interference?
the combo when multiply beams arrive at the same time and location but they lose their individual characteristics at the moment and combine to make a single wave
What are constructive interference?
in phase and the formation of a single wave of greater amplitude than either of the components
the resulting wave is larger
What are destructive interference?
out of phase and the single wave is lesser amplitude and the resultant wave is smaller
What happens when interference of waves with different freq occurs?
when freq differs, both constructive and destructive interference occurs.
the time it takes to complete a cycle units of time
What are typical values for period?
What is the source of sound determined by?
transducer and ultrasound system
What is the medium determined by?
Can you adjust period?
the number of cycles that occur in one sec units hertz
cycle/sec per sec
Is frequency adjustable?
what are freq ranges in imaging?
What parameters are determined by the sound source?
period, freq, amplitude, intensity, power
What is considered infrasound?
less than 20hz
what is considered audible sound?
what is considered ultrasound?
greater than 20,000hz
What is the relationship between freq and period?
What are the bigness parameters?
amplitude, intensity, power
What is amplitude?
the difference between the min value and the average value of the acoustic variable
What are units for amplitude?
particle motion (distance)- cm, inches
What are typical pressure amplitude?
Is amplitude adjustable?
the rate at which work is performed
is power adjustable?
True or false: amplitude decreases as sound propagates through the body
How are power and amplitude related?
concentration of energy in a sound beam
What is the formula for intensity?
Is intensity adjustable?
how is power and intensity related?
How are amplitude and intensity related?
the distance or length of one complete cycle
units length- mm
how is wavelength determined?
sound source and medium
is wavelength adjustable?
what is the typical value for wavelength?
how are wavelength and frequency related?
What is the formula for wavelength?
What is the formula for frequency?
Shorter wavelengths are created with higher frequency which produces ____ images.
true or false: higher frequency transducer produce better quality images
Define propagation speed
the rate at which a sound waves travels through a medium
units meters per second
What is propagation speed determined by?
Is propagation speed adjustable?
what is the propagation speed in soft tissue?
1,540 m/s or 1.54 mm/microsecond or 1.54 km/s
Arrange these tissue types in increasing order:
gas, solid, liquid
gas, liquid, solid or
air, lung, fat, soft tissue, liver, blood, muscle, tendon, bone
what is the formula for propagation speed?
=freq (Hz) x wavelength (m)
What characteristics determine the speed of sound?
stiffness and density
How are stiffness and speed related?
How are density and speed related?
What are some words to describe opposite of stiff?
elasticity and compressibility
What factors will affect a medium to travel fast?
more stiff, less dense
What factors will affect a medium to travel slow?
less stiff, more dense
What has the greatest influence of speed?
five parameters that describe pulsed sound
What is pulse duration?
the actual on time from the start of that pulse to the end of that pulse
"on" time, talking or transmit
units of time
What are typical values for pulse duration?
what is pulse duration determined by?
is pulse duration adjustable?
What are the two formulas for pulse duration?
=#cycles x period or
how are period and pulse duration related?
how are pulse duration of freq related?
What type of pulses are more desirable for imaging and why?
shorter duration pulses b/c they create images of greater accuracy
define spatial pulse length
the distance that a pulse occupies in space from the start to the end of a pulse
What are typical values for SPL?
What is SPL determined by?
source and medium
is SPL adjustable?
What is the formula for SPL?
=#cycles x wavelength
How are wavelength and SPL related?
How are freq and SPL related?
Which type of pulses is more desirable in imaging?
pulses of shorter length are desirable because they create more accurate images.
the time from the start of one pulse to the start of the next pulse. includes pulse duration plus listening time
What is PRP determined by?
sound source and imaging depth
is PRP adjustable?
how is PRP and imaging depth related?
What are the two components of PRP?
the transmit time and receive time or on and off time
true or false: transmit time is also called pulse duration
When is listening time longer?
with deep imaging
When is listening time shorter?
with shallow imaging
the number of pulse that is transmitted into the body each second
typical value for PRF?
1,000 to 10,000 hertz
What is PRF determined by?
sound source and maximum imaging depth
is PRF adjustable?
When imaging shallow, the PRF will be ____
When imaging deep, the PRF will be ____
what is the relationship between PRF and frequency?
PRF is only related to depth of view
What is the relationship between PRF and depth of view?
What is the relationship between PRF and PRP?
inverse or reciprocals
Define duty factor
the percentage or fraction of time that the system transmits a pulse
what are the typical values for duty factor?
What is the duty factor for CW?
1.0 or 100%
What is duty factor determined by?
sound source only
is duty factor adjustable?
what is the formula for duty factor?
=pulse duration/PRP x 100
How is duty factor altered?
by changing imaging depth
What is the relationship between duty factor and depth?
What happens with shallow imaging?
less listening, shorter PRP, higher PRF. and higher duty factor
What happens with deep imaging?
more listening, longer PRP, lower PRF. and lower duty factor
What are key words related to intensity?
spatial, peak, average, temporal, and pulsed
Which is higher? spatial peak intensity or spatial average intensity?
spatial peak intensity
What are the temporal intensities from largest to smallest?
Itp, Imax, Ipa, Ita
What is the most relevant intensity with respect to tissue heating?
What is another name for beam uniformity coefficient?
SP/SA factor which describes the beam in space
For CW, which intensities are always equal to one another?
SPTA=SPPA and SATA=SAPA
When CW and pulsed have the same SPTP intensities, then CW has the higher _____intensity?
When CW and pulsed have the same SATP, then CW has the higher ____intensity