Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/151

Click to flip

151 Cards in this Set

  • Front
  • Back
define unrelated?
two items that are not associated.
ex: hair color & shoe size
define directly related or directly proportional?
two items that are associated such that when one item increases the other increases.
ex: clothing size to one's weight
define related or proportional?
two items that are associated oor affiliated. relationship does not have to be specific.
ex: Santa to Christmas
define inversely related or inversely proportional?
two items are associated such that when one increases, the other decreases.
ex: car's gas mileage to engine size
define reciprocal relationship?
when two numbers with a reciprocal relationship are multiplied together the result is one.
ex: 2 and 1/2
what does increase by a factor imply?
multiplication
what does decrease by a factor imply?
division
what is the unit for a number followed by a percent sign?
unitless
what are the units associated with length?
meter, centimeter, feet etc
what are the units associated with area?
cm2, ft2,
what are the units of volume?
cm3, ft3
what does 10^9 or giga stand for?
G or a billion
what does 10^6 or mega stand for?
M or a million
what does 10^3 or kilo stand for?
k or a thousand
what does 10^2 or hecto stand for?
h or a hundred
what does 10^1 or deca stand for?
da or ten
what does 10^-1 or deci stand for?
d or tenth
what does 10^-2 or centi stand for?
c or hundredth
what does 10^-3 or milli stand for?
m or thousandth
what does 10^-6 or micro stand for?
u or a millionth
what does 10^-9 or nano stand for?
n or billionth
sound is considered what kind of wave in whih particles in the medium move?
mechanical
all waves carry what?
energy
in ultrasound, sound pulses travel through biologic tissue or?
media
sound cannot travel through what?
a vacuum.
the squeezing together of molecules is called?
compression
the stretching of molecules is called?
rarefaction
compression and rarefaction are necessary for sound to do what?
move through a medium
in what direction does sound travel?
a straight line
what kind of waves are sound waves?
longitudinal
what are the three acoustic variables? and what are they used for?
pressure, density and distance. they are used to distinguish between sound waves and ther types of waves.
what are the units for pressure?
pascals Pa
what are the units for density?
kg/cm^3
what are the seven acoustic parameters?
period
frequency
amplitude
power
intensity
wavelength
propagation speed
how do particles move in a transverse wave?
they move in a direction that is perpendicular to the direction that the wave propagates.
how do particles move in a longitudinal wave?
in the same direction that the wave propagates.
what are in phase waves?
waves that have their peaks at the same time and the same location. aka in step
what are out of phase waves?
two waves that have their peaks occurring at different times and so do their troughs. aka out of step
what is interference??
when more than one wave arrives at an identical location at the exact same time and they combine to form a single wave.
what is constructive interference?
a pair of in phase waves resulting in the formation of a single wave of greater amplitude than either of its components.
what is destructive interference?
the resultant wave is small than one of its components. caused by out of phased wave.
what are parameters?
they describe features of a sound wave
tissue is also called?
the medium
what is period?
the time it takes a wave to vibrate a single cycle, or the time from the start of a cycle to the start of the next cycle.
what units is period reported in?
seconds
what determines period?
the sound source only and cannot be changed by the sonographer
what is frequency?
the number of particular events that occurs in a specific duration of time.
what units are frequency reported in?
herz (Hz) = 1cycle/second
what determines the frequency of a sound wave?
sound source only and is not adjustable.
when the frequency of a sound wave is less than 20Hz it is considered?
infrasound
what is the range for audible sound?
between 20 Hz and 20kHz
what is the range for ultrasound?
greater than 20 kHz.
how does frequency effect diagnostic sonography?
it affects the penetration and image quality.
how are period and frequency related?
inversely
as frequency increases what happens to period?
it decreases
as period increases what happens to frequency?
it decreases
if period remains unchanged what happens to frequency?
it remains unchanged
what kind of other relationship does frequency and period have?
reciprocal.
period x frequency = 1
what are the three parameters that describe the bigness of the wave?
amplitude
power
intensity
what is amplitude?
the bigness of a wave. it is the difference between the maximum value and the average value.
what are the units of amplitude?
can assume any unit of any of the acoustic variable. pa, g/cm^3, m, etc
what determines amplitude?
the sound source controls amplitude, but it can be adjusted by the sonographer.
what is the formula for amplitude?
maximum value - average value or
minimum value - average value
what is power?
the rate of energy transfer or rate at which work is performed.
what are the units for power?
watts
what determines power?
the sound source determines the power, but it can be adjusted by the sonographer.
how are power and amplitude related?
power is proportional to the amplitude.
power = amplitude^2
what is the formula for power?
power=amplitude^2
what is the formula for frequency?
1/period
what is the formula for period?
1/frequency
what is intensity?
the concentration of energy in a sound beam.
what are the units associated with intensity?
watts/square centimeter
W/cm^2
what is the formula for intensity?
power/area or amplitude^2/area
what determines intensity?
initially the sound source, but intensity changes as it propagates through a medium. it is adjustable by the sonographer.
how is intensity related to power?
intensity is proportional 'to power
ex: if a wave's power is doubled , the intensity is doubled.
how is intensity related to amplitude?
intensity is proportional to amplitude squared.
intensity=amplitude^2
what is wavelength?
the distance or length of on complete cycle.
ex: a train, wavelength is the length of one boxcar in a train.
what is wavelength measured in?
meters
what determines wavelength?
the source and the medium
Is wavelength adjustable?
no
what is the formula for wavelength?
velocity/frequency
what is the relationship between wavelength and frequency?
inversely related as long as the wave remains in one medium.
what is the speed of sound in soft tissue?
1540 m/s
why is wavelength important in ultrasound?
shorter wavelengths produce higher quality images with greater detail
what produces a shorter wavelength?
higher frequency probes
what is propagation speed?
the distance that a sound wave travels through a medium in one second
what are the units associated with propagation speed?
m/s
what determines propagation speed?
the medium and it can not be adjusted by the sonographer.
what is the speed of sound through air?
330 m/s
what is the speed of sound in fat, liver, blood, muscle, tendon and bone?
1450 m/s, 1560 m/s, 1560 m/s, 1600 m/s, 1700 m/s, 3500 m/s
sound travels faster in what substance?
sound travels the fastest through a solid substance, slower in liquids, and the slowest through gases.
what is the formula for velocity?
speed (m/s) = frequency x wavelength
what are the two characteristics of a medium that affect the speed of sound?
stiffness and density
what is stiffness?
it described the ability of an object to resist compression.
how does stiffness affect speed?
they are directly related. as materials become more stiff, the speed of sound in the material increases.
the degree of stiffness may also be described with the terms?
elasticity or compressibility which are the opposite of stiff
what is density?
the relative weight of a material.
how does density affect speed?
they are inversely related. as materials become more dense (heavier), the speed of sound in the material decreases.
if two media are equally stiff which one will have a lower speed?
the denser medium will have a lower speed
what is the rule of thumb for remembering stiffness and density?
stiffness and speed both start with "S". Stiffness increases, speed increases.
Density increases, speed decreases
what are the parameters that can be adjusted by the sonographer?
amplitude, power and intensity
what are the parameters that cannot be adjusted by the sonographer?
period, frequency, wavelength, speed
what parameter is determined strictly by the medium?
speed
which parameter is determined by the medium and the source?
wavelength
which parameters are determined by the source?
period, frequency, amplitude, power and intensity
what are bioeffects?
the effects of the sound wave on tissue in the body
what are acoustic propagation properties?
the effects of tissue unsound waves.
what is pulsed sound?
a collection of cycles that travel together. they must have a beginning and an end. it moves as a single unit.
what are the two components of pulsed ultrasound?
transmit or "on" time
receive or "off" time
what is the percentage of time that the pulsed sound is talking?
99.9%
what is pulse duration?
the actual time from the start of a pulse to the end of that pulse. it is a single transmit, talking or "on" time
what are the units of pulse duration?
time: seconds
what determines pulse duration?
the sound source only and is not adjusted by the sonographer
what is the formula for pulse duration?
# of cycles x period

#cycles/frequency (MHz)
what is the relationship of pulse duration and #of cycles, period and frequency?
directly proportional to the # of cycles in the pulse.
directly proportional to the period
inversely related to the frequency
what are the two characteristics that create pulses of long duration?
many cycles in the pulse or
individual cycles with short periods
what are the two characteristics that create pulses of short duration?
few cycles in the pulse or
individual cycles with short periods
what is spatial pulse length?
the distance that a pulse occupies in space from the start to the end of a pulse.
what are the units associated with spatial pulse length?
meters
what determines spatial pulse length?
the source and the medium. it is not adjustable by the sonographer.
what is the formula for spatial pulse length?
# of cycles x wavelength
what is the difference between pulse duration and pulse length?
pulse duration is the time a pulse is on. pulse length is the distance of the pulse end to end
what is pulse repetition period?
the time from start of one pulse to the start of the next pulse. it includes one pulse duration plus one listening time.
what are the units associated with pulse repetition period?
seconds
what determines pulse repetition period?
sound source only and is adjustable by the sonographer
Is PRP related to period??
No! PRP is unrelated to period.It is related only to depth of view.
what is depth of view?
it describes the maximum distance into the body that an ultrasound system is imaging.
how are pulse repetition period and depth of view related?
as depth of view increases, pulse repetition period increases.
as depth of view decreases, pulse repetition period decreases.
THEY ARE DIRECTLY RELATED
transmit time is also called
pulse duration
what happens to the listening time with deeper imaging?
the listening time and the pulse repetition period lengthen
what is the formula for pulse repetition period?
1/pulse repetition frequency
when the sonographer alters imaging depth what part is changed?
only the listening time portion of the pulse repetition period
what is pulse repetition frequency?
is the number of pulses that an ultrasound system transmits into the body each second.
what is the formula for pulse repetition frequency?
1/pulse repetition period
what are the units associated with pulse repetition frequency?
Hertz (Hz)
what determines PRF?
the sound source only and it is adjustable by the sonographer
how are pulse repetition frequency and depth of view related?
they are inversely related.
as depth of view increases, pulse repetition decreases.
as depth of view decreases, pulse repetition increases.
what is the relationship between pulse repetition period and pulse repetition frequency?
they are inversely related.
what is duty factor?
is the percentage or fraction of time that the system is transmitting a pulse.
what are the units associated with duty factor?
none
what determines duty factor?
source only and it is adjustable by the sonographer.
how is duty factor and imaging depth related?
inversely. duty factor is higher when the system is imaging at shallow depths, and lower when imaging to greater depths.
what is the formula for duty factor?
(%) = pulse duration/prp x 100
what are the maximum and minimum values for duty factor?
max is 1 or 100% and the minimum is 0% or 0.2%
shallow imaging produces?
less listening
shorter PRP
higher PRF
higher duty factor
deeper imaging produces?
more listening
longer PRP
lower PRF
lower duty factor
by changing imaging depth, the operator changes?
prp, prf, duty factor,
what parameters are adjustable by the sonographer?
prp, prf, duty factor
what parameters are not adjustable?
pulse duration, spatial pulse length
which parameters are determined by source?
pulse duration, spatial pulse length, duty factor, PRP, PRF
what parameter is determined by both source and medium??
spatial pulse length