Final Review Flashcards
________ is the percentage of time the system is pulsing.
Duty Factor
__________ _______ have particle disturbance that is _____ to the direction of wave propagation.
Longitudinal Waves
parallel
If the number of scan lines increases, it ________ the frame rate
Slows down
As density increases, the speed of sound ________.
decreases
Color Doppler is processed using a ___________.
Autocorrelation
Sound travels fastest through _____.
Bone
The _________ _______ is a measure of the spread of frequencies in the plot.
Frequency bandwidth
________ _____ is a single gain control that increases amplification at all depths.
Overall gain
Units of frequencies and their prefixes in order of smaller to larger:
Cycle
Hz
kHz
Mhz
The purpose of damping material is to:
Shorten the pulse to improve axial resolution
The time it takes for one disturbance to repeat itself (from the start of one cycle to the start of the next cycle) is called ______.
Period
This parameter it is equal to the acoustical power, W, contained within the beam, divided by the beam area A: is ________.
I(SATA)
Three types of Doppler displays:
Spectral Doppler
color Doppler
power Doppler
Pulsed wave Doppler combined with gray-scale sonography is called ______ _______.
Duplex scanning
Prudent practice of sonography involves application of the ______ ______.
ALARA principle
Ultrasound produces a temperature rise as it ______________.
Propagates through tissues
Another name for the Frauhofer zone is ______.
Far zone
Ring-down artifact is a form of ________.
Reverberation
Beneficial artifacts include:
shadowing
enhancement
_________ demonstrates layers of fluid sliding over each other
Laminar flow
The difference between the emitted frequency and the echo frequency returning from a moving scatterer is known as _________.
Doppler shift
The _______ ________ relates the Doppler shift to the flow speed, frequency, and Doppler angle.
Doppler equation
Shape of the sound beam ________ as it extends into the far field
diverges
two elements are required for ______________________.
continuous wave imaging
An ultrasound transducer element vibrates when…
electricity is applied
As frequency increases, it increases ________.
attenuation
_____ __________ yield the best image on the monitor.
Write magnification
The most commonly used element for ultrasound transducer is:
PZT-lead zirconate titanate
In a single-element transducer, additional beams not included in the ultrasound beam are called _____ ______.
Side lobes
Lateral resolution is equal to _____ ________.
Beam diameter
____ ______ is the minimum separation necessary to resolve reflectors along the scan line.
Axial resolution
Does the near zone length decreases with an increase in frequency?
No
A _________ image display would be seen when using a linear transducer.
Rectangular
20 kHz is equal to _______ Hz.
20,000 Hz
If beam power increases, intensity will ______.
Increase
Attenuation increases with increasing ____.
frequency
Impedance is equal to density multiplied by ____.
Propagation speed
The unit for impedance is _____.
Rayls
Can sound can travel through air, lung, bone, and a vacuum?
NO
A sector scan is shaped like ______.
A slice of pie
msec is a unit of _____.
Time
frequencies higher than the human ear can hear is _________
Ultrasound
factors determine the speed of sound are:
stiffness of the tissue
elasticity of the tissue
compressibility of the tissue
density of the tissue
_____ ______ reduces the spatial pulse length.
Backing material
Is mm a unit for Impedance?
NO
Acoustic output is important when considering ______ & _________.
Bioeffects and safety
_____ _______ is important when considering bioeffects and safety.
Acoustic output
A change in direction of the sound beam at a tissue interface occurs when the following two conditions are present:
different propagation speeds
non-perpendicular angle of incidence
the types of cavitation are:
stable cavitation:
(transient inertial) cavitation
Beam refraction occurs when the following conditions are present:
non-perpendicular incidence
different speed of sound
The Doppler effect is a ________
Change in echo frequency
A sector scan is shaped like a _______.
Slice of pie
Sonography is medical anatomic imaging using a__________.
Pulse echo technique
Frequency is the number of _____________.
Complete cycles per second
Sound requires ___________.
A medium through which to travel
The mechanical index (MI)is an indication for the likelyhood of:
Cavitation
Acoustic impedance values are determined by:
Speed of sound
Density
The speed of sound in a medium is dependent on _______________.
Stiffness and Density
The percentage or fraction of time that the system transmits a pulse is called _______.
Duty factor
Power and intensity are __________ ______ related
Directly proportional
_______ is the unit for Power.
Watts
________ and ________ are descriptions of attenuation artifacts.
Shadowing
Enhancement
Weakening of echoes distal to a strongly attenuating structure describes ________.
Shadowing
_______ is the appearance of Doppler information on the wrong side of the baseline.
Aliasing
Mirror image is commonly seen around ______.
Diaphragm
Mean Doppler shifts are displayed in _____ ______.
Color doppler
______ _____ _____ are displayed in Color Doppler.
Mean Doppler shifts
______ is the time it takes for one cycle to occur.
Period
Sonography is medical anatomic imaging using a _____ _____ ______.
Pulse echo technique
Frequency is ______ proportional to wavelength.
Inversely
Propagation speed is primarily determined by the ____________.
Stiffness of the media
Ultrasound pulses contain a range of frequencies called the _______.
Bandwidth
pressure density particle vibration are _______ ______.
Acoustic variables
The damping material is also known as _____ _____.
Backing material
The following are all ultrasound frequencies:
30,000.0 Hz
250.0 kHz
0.30 MHz
If frequency increases, period will _____.
Decrease
________ is the distance over which one cycle occurs.
Wavelength
______ ______ is the speed at which a wave travels through a medium.
Propagation speed
Matching layers are typically ______ the wavelength of the _______ ______.
1/4
Ultrasound beam
Z = pc is the equation for _______ ______.
Acoustic impedance
If the frequency of the transducer producing the sound wave is 500 Hertz, __________ is being produced.
Audible sound
The fraction of time that pulsed ultrasound is on is called __________.
Duty factor
The rate at which energy passes through a unit area is called ______.
Intensity
As sound travels, the reduction in amplitude and intensity of the wave is called ________.
Attenuation
____ ________ refers to the minimum reflector spacing along the axis of an ultrasound sound beam that results in separate echoes on display.
Axial Resolution
Parameters of pulsed wave doppler are:
pulse duration
pulse repetition period
pulse repetition frequency
Spl?
duty factor
the term that means “bending of the beam” and is the the name of the associated law is refraction is related to _______.
Snell’s law
If density increases impedance ______.
Increases
Absorption relates to ______.
Heating
