Quizes from the Fall Flashcards
T or F:
Sound is on the electromagnetic spectrum in between x-rays & ultraviolet
False
Name the 3 acoustic variables:
Particle Motion
Density
Pressure
In a longitudinal wave the sound beam travels _______ to the direction of particle motion
Parallel
2 waves that are in-phase interfere with each other. what happens to the resultant wave?
constructive interferance. the resulting wave is bigger
2 out of phase that have identical amplitudes (heights) interfere with each other. what happens to the resultant wave?
Destructive interferance. they cancel each other out.
The lowest propagation speed is found in _____ and the highest prop speed is found in ____
Air
Bone
what is the range of infrasound?
less than 20 Hz.
what is the range of ultrasound
greater than 20,000 Hz.
what is the range of medical diagnostic ultrasound
2-15 MHz.
Frequency is the number of ______ per ______
cycles
second
how are frequency and wavelength related
indirectly
how are frequency and prop speed related
unrelated
how are frequency and period related
indirectly
how are prop speed and stiffness related
directly
how are duty factor and pulse duration related
directly
how are power and intenstiy related
directly
how are frequency and amplitude related
unrelated
how are PRF and frequency related
unrelated
______ is the time from the start of a poulse to the start of the next pulse
pulse repetition period
what will create the fastest speed of sound?
low density & high stiffness
what can be changed by the operator?
duty factor PRF
Write the right units:
- Distance
- Velocity
- Frequency
- Volume
- meters
- m/s
- Hz.
- cm3
a millionth of something is what is scientific notation
10 to the -6th
if the intensity stays the same despite a power increase, what must have happened?
the area got bigger
what mode is typically used in cardiac US because of the movement of the beating heart?
M-Mode
when pressure is applied to a piezoelectric material, what is generated?
electricity
lead zirconate titanate is what part of the ultrasound transducer?
piezoelectric material
which image shape is considered to be “trapezoidal”?
vector
at what temperature does a man-made piezoelectirc material obtain its awesome properties?
curie point
T or F:
under some circumstances US transducers can be heat sterilized?
false
areas of high pressure in the beam are called ______ and areas of low pressure are called ______
compression
rarefaction
T or F:
sound is created by the probe as one big sound wave at the face of the probe and propagated from there
false
what part of the probe is essential for decreasing the numebr of cycles in the pulse
backing material
Where is backing material in relation to the piezoelectric element?
behind the PEM
CW probe has a _______ quality factor?
high
The shorter the pulse, the ____ the Q-factor, the ___ the bandwidth, and the __ the image resolution
lower
higher
higher(better)
what part of the probe is used to improve the efficiency of sound transmission from the element to the patients skin?
Matching layer
PD equals the number of cycles in a pulse multiplied by the ____
period
duty factor increases as pulse repetition period ____
decreases
if the pulse duration is increased what happens to the spatial pulse length?
increase
if the frequency is increased, what happens to the spatial pulse length?
the SPL decreases because the higher the frequency the shorter the pulse.
sound comes out of the probe witha duty factor of 1. what type of probe is this?
CW transducer
what is the range equation (soft tissue medium)
d= .77(t)
sound travels through a lipoma to reach a reflector. will the reflector be displayed too close or too far away from the probe?
too far away
you buy an US machine but the image is only a series of spikes whereby amplitude is measured on the y-axis. what type of machine did you buy?
A-Mode machine
there is a part of the probe whose job it is to shorten the pulse. this component is made up of an epoxy containing what material?
tungsten
between lateral & axial resolution, which is usually better on msot equipment?
axial
where in the beam is the beam are going to be smallest?
focal zone
T or F:
the slice thickness plane is a fixed focus and does not change with most transducers?
false
assuming a fixed depth and one focal zone, what must change if the sector angle width changes?
frame rate
if the frame rate stays the same and the numebr of line per frame is increased, what must happen to PRF?
the PRF also increases.
FR= PRF/LPF
doubling the frequency causes the axial resolution to be _____
halved.
temporal resolution is another word for what?
frame rate
which factor does not affect axial resolution? damping beam width frequency pulse frequency
beam width
name a disadvantage of using multiple transmit focal zones?
it decreased the frame rate because it takes longer with mult focal zones.
T or F:
smaller axial resolution is better
ture.
name 2 things that will decrease temporal resolution?
- increase in lines per frame
2. decreasing the PRF
which of the following primarily determines longitudinal resolution ? aperture PD probe diameter lines per frame
pulse duration
a 1.5D transducer permits focusing in what plane?
elevational plane
Name the synonyms for lateral resolution
Lateral
angular
transverse
azimuthal
name the synonyms for axial resolution
longitudinal axial radial range depth
you are building a probe and want the best axial resolution you can have. you want a ____ frequency and a _____ pulse
High
Short
to build a transducer with the longest near zone and smallest amount of beam divergence, what combination of frequency and element diameter do you want?
high freq.
wide element diameter
T or F:
the focal zone should be placed so that pertinent anatomy lies within the Fraunhofer zone?
false
T or F
radial resolution varies with distance from the transducer?
false
the Fraunhofer zone is another name for the ____ zone
far
Azimuthal resolution is based upon reflectors that lie ______ to the beam?
perpendicular
lateral resolution is improved by? damping pulsing focusing attenuating
focusing
what happens to attenutaion as the frequency increases?
it increased
does attenuation coefficient change with depth? ___ does total attenuation? ___
NO
Yes
which of the following has the lowest relative attenuation? Air Liver Blood Bone
blood
The gain of a receiver is 70dB. The intensity is decreased by one-fourth. what is the new gain, in dB?
64 dB.
the amplitude of a beam is doubled. what is the change in intensity , in dB.
6 dB.
Attenuation is made up of what 3 components?
Absorption
Reflection
Scattering
What is the most significant contributor to attenuation?
Absorption
What are the units of:
- Attenuation
- Attenuation Coefficient
- Power
- dB
- dB/cm
- watts
what is the average rate of attenuation in soft-tissue?
Anywhere from .5 dM/cm/MHz to 1.0 dB/cm/MHz
what medium has the highest rate of attenuation?
air
is attenuation in bone higher or lower than in soft tissue?
higher in bone
which of the following remain unchanged as the beam travels through a medium? Frequency Intensity Power Amplitude
Frequency
