10/30 Quiz Flashcards
Name the 3 equations for NZL
(Diameter x Frequency) / 6.16
Radius Squared / wavelength
(Diameter squared x Frequency) / 6
What is the equation for speed of sound
c = f x wavelength
What is the equation for wavelength
Wavelength = c/f
What 2 transducer factors affect NZL
Diameter/Apeture of transducer
Frequency of sound produced by transducer
What 2 things create a beam with a deeper foci
Large crystal, high frequency sound
Smaller diameter crystals produce beams that
Diverge more into the far zone
Which of the folling probes create beams with shallow focus
A) Small dia, high f
B) Small dia, low f
C) Large dia, high f
D) Large dia, low f
B) Small dia, low f
Which of the following probes creates beams with deepest focus
A) 4 mm dia, 4 MHz
B) 5 mm dia, 8 MHz
C) 6 mm dia, 2 MHz
D) 6 mm dia, 8 MHz
D) 6 mm dia, 8 MHz
The lower the frequency of the beam used, the greated the
Expansion of the beam into the far field region
What is the far field divergence angle
Angle between beam axis and the boundary of the beam in the far field
What is the 2 equations for far field divergence angle
Sin0 = (1.2 x wavlength) / Dia
Sin0 = (1.2 x Prop speed) / (Dia x f)
If you have a large diameter you will have a ___ angle
Smaller angle
Which of the following probes create a beam with most divergence
A) Small dia, high f
B) Small dia, low f
C) Large dia, high f
D) Large dia, low f
B) Small dia, low f
What is the range of the sine of an angle
0-1
As the sine of an angle increases what will happen to the actual angle
Increase
What are the 3 forms of flows
Pulsatile
Phasic
Steady
Definition of pulsatile flow
Variable velocity flow due to cardiac contraction
What is an example of pulsatile flow
Arterial circulation
Definition of phasic
Variable velocity due to respiration
What is an example of phasic flow
Venous circulation
Definition of steady flow
Contrast velocity flow
What is an example of steady flow
When holding one’s breathe
What is laminar flow
Layered flow-liquid at different speeds as we move from vessel wall
As part of a boundary condition flow must = 0 at
Vessel wall
What are the 2 types of laminar flow
Parabolic
Plug flow
Define parabolic flow
Avg. flow speed = 1/2 max slow speed at center
Define plug flow
All layers flow at same speed
What is disturbent/turbulent flow
Randome or chaotic circles or eddies
What are the typical regions for disturbing/turbulent
Stenoses
What is stenosis
Narrowing of a vessel or at bifurcation a vessel that splits into 2 regions
What is blood flow is stenosis
Blood flow is changed and can be described by Bernoulli’s equation
What is Bernoulli’s equation for stenosis
P + 1/2pv^2 + pgh = Constant
What is the P stand for in Bernoulli’s equation
What is the equation for this
What are the units
Pressure
P = F/a
Pascals
What does the p stand for in Bernoulli’s equation
What are the units
Density
kg/m^3
What does the pv^2 for in Bernoulli’s equation
Kinetic Energy
What does the pgh stand for in Bernoulli’s equation
Potential energy
In the 1st equation if the P is high and kinetic energy is low then what should the P and kinetic energy be in the second equation
P should be low and kinetic energy should be high
P(1) + pv^2(1) + pgh =
P(2) +pv^2(2) +pgh
What is continuity flow
Volume flow rate must be constant in the before, at and after constriction regions
What does continuity of flow mean
Blood is not created or destroyed as it moves through the vessel
Equation of pressure gradient
PG = Flow x Resistance
T or F:
A) PI has units
B) RI has not units
A) F - PI has no units
B) T
What does PI stand for
What is the equation
Pulsatility index
PI = (Max-Min) / Ave
Pulsatility index is where the max and min are the peak _____ and minimum ____ velocities and average _____
Peak systolic, minimum diastolic, average flow
Max velocity is 60 cm/s, Min velocity is 20 cm/s, Average flow is 40 cm/s
What is the PI?
(60 cm/s - 20 cm/s) / 40 cm/s = 1
What does RI stand for
What is the equation
Resistivity index
RI = (Max-Min) / Max
RI is a useful parameter in diagnosis of
Arterial seconds
Max velocity is 60 cm/s, Min is 20 cm/s
What is the RI
(60 cm/s - 20 cm/s) / 60 cm/s
2/3 or 0.666666666
Technique used to quantify and image blood flow, turn would mean we’re checking heart motion
Doppler
What is the basic premise of Doppler
Relative motion between sound source and observer
What are the 3 ways to produce Doppler
- Source moves and listener is stationary
- Listener is moving but the source is stationary
- Source moves and listener moves
What is the equation for Doppler shift
Doppler shift (Hz) = Reflected frequency - Transmitted frequency
Doppler effect is a smaller ____ riding along with transducers main ______. And we decouple them by
Smaller signal, transducers main frequency, decouple them by demodulation
Reflected frequency is 2.02 MHz, transmitted frequency is 2.00 MHz.
What is the Doppler shift
2.02 (MHz) - 2.00 (MHz) = -0.02 MHz
In a positive Doppler shift what will happen to the following:
Frequency - Increases or Decreases
Wavelength - Increases or Decreases
f - Increase
Wavelength - Decrease
In a negative Doppler shift what will happen to the following:
Frequency - Increases or Decreases
Wavelength - Increases or Decreases
f - Decrease
Wavelength - Increase
What is the other equation for Doppler
f(D) = 2f(o)vcos0 / c
fo in Doppler equation stands for
Original frequency
What does the v in the Doppler equation stand for
Speed of RBC’s
What does cos0 stand for in the Doppler equation
Cosine of angle
What does the c stand for in the Doppler equation
Speed of sound
If the original frequency is high then the Doppler freqeuncy will be (High or Low)
High
If the cosine angle is 0 degress it will =
It is the (Max or Min)
And the view is right at the ______
What color does this show on U/S
Will = 1
Max
Transducer
Red
If the cosine angle is 90 degress it will =
It is the (Max or Min)
The view is ____ to flow
In this degree you can’t see
0
Min
View is perpendicular to flow
Direction of flow
If the cosine angle is 180 degrees it will =
It is the (Max or Min)
What color does this show on U/S
-1
Max
Blue
If the cosine angle is 60 degress it will =
1/2
You should always assume the cosine angle is
60 degrees
