Physics Soundwaves Test Study Guide Flashcards
_______ _______ = The measure of resistance to sound traveling through a medium
Acoustic impedance
_______ of _______ = The angle from normal at which the sound beam strikes and interface
Angle of incidence
_______ = Encompasses absorption, scattering, divergence and reflection
Attenuation
_______ = Units of measure are w/cm^2
Intensity
_______ = Normally the dominant contribution to attentuation
Absorption
_______ = The concentration of energy in a sound beam
Intensity
_______ or _______ = Relates to the strength of the sound beam
Amplitude/Power
_______ = The junction of two media with different acoustic properties
Interface
_______ = The conversion of sound to heat
Absorption
_______ = Units of measure are Watts or milliwatts
Power
_______ = Equals the maximum variation of an acoustic variable
Amplitude
_______ _______ = A sound beam intersects a smooth surface larger than the width of the beam at < 90
Oblique incidence
_______ = Limits imaging depth and must be compensated for
Attenuation
_______ = Rate at which energy is transmitted
Power
_______ = The spreading out of a beam that results from a source of small physical dimensions
Divergence
_______ = The decrease in strength/intensity as a beam traverses a medium
Attenuation
Frequency is a measure of how many _______ an acoustic variable goes through in a second.
cycles
The unit of frequency is the _______, which is abbreviated _______
Hertz
Hz
Period is the _______ that it takes for one cycle to occur
time
Period is one divided by _______
frequency
Wavelength is the _______ over which one cycle occurs
space
Wavelength is equal to _______ _______ divided by _______
Propagation speed
frequency
The average propagation speed in soft tissues is _______ m/s or _______ mm/microseconds
1,540
1.54
Propagation speed is determined by _______
medium
Length of time to complete one cycle
period
Time of the start of one cycle to the start of the next cycle.
period
Attenuation is the reduction of _______/_______ as the wave travels through a medium.
Strength
Intensity
If power is doubled, and area remains unchanged, Intensity is _______
doubled
If amplitude is doubled, and area remains unchanged, power is _______
quadrupled
BONUS: What is the formula describing temporal resolution and its relationship with the depth and other factors that effect the pulse repetition frequency.
P x LPF x FR x NF < (line below less then sign because its less than or equal to) 77,000
List four factors affecting the strength of a reflected echo
1) The degree of acoustic impedance mismatch
2) Inherent strength of the incident ultrasound beam
3) The angle at which the US beam strikes a reflecting surface
4) Size of the reflector
_______ _______ = The measure of resistance to sound traveling through a medium
Acoustic Impedance
BONUS: In oblique incidence, the angle of reflection _______ the angle of incidence
Equals
As density increases, impedance _______
increases
Bone = _______ Rayls
Soft Tissue = _______ Rayls
Fat = _______ Rayls
Lung = _______ Rayls
- 8
- 63
- 38
- 26
In perpendicular incidence, the angle of reflection _______ the angle of incidence
Equals
A decrease in impedance difference will result in a _______ in transmitted sound
increase
As propagation speed decreases, impedance _______
decreases
To obtain maximum detection of the reflected signal, we must orient the transducer so the generated sound beam will strike a interface _______
perpendicular
Smooth interfaces, larger than the beam width _______ (specular reflector or scatterer)
Specular reflector
Very frequency dependant
scatterer
Tiny, punctate reflectors that scatter a small portion of the beam in almost all directions
scatterer
Produce high-intensity, unidirectional reflections
specular
Provide the US texture within organs
scatterer
Very angle dependant
specular
These are responsible for major organ outline as seen by US; i.e., diaphragm
specular
RBCs are a specific type
scatterer
Transducer type: Mechanical = _______ Image shape
Sector
Transducer Type: Linear Switched/Sequenced = _______ Image shape
Rectangular
Transducer type: Linear Phased = _______ Image shape
sector
Transducer Type: Annular Phased = _______ Image shape
sector
Transducer Type: Convex Sequential = _______ Image shape
Blunted sector
Transducer Type: Convex Phased = _______ Image shape
Blunted sector
Transducer Type: Vector = _______ Image shape
Flat top sector
The imaging depth ______ as frequency increases
decreases
Attenuation consists of _______, _______, and _______
if its a fourth option then it would be ________
absorption
scattering
divergence
reflection
If frequency is doubled and path length is halved, attention __________
remains the same
