Ultrasound physics 2 Flashcards

Terms Definitions
million
mega
Binary digit
Bit
Far zone
Fraunhofer Zone
less than 20 Hz
infrasound
Cycle
a period or repetition
T/F
PERCENT IS A UNIT
FALSE
source
Period is determined by what?
23. Attenuation coefficient for soft tissue @ 10MHz is
a. 5dB/cm
b. 5dB/mm
c. 5dB
d. 10dB/cm
Image processing done after memory
Postprocessing
PRF DEPENDS ONLY UPON:
IMAGING DEPTH
ATTENUATION IS __________ TO PROPAGATION SPEED.
UNRELATED
Parameters
Describe features of a sound wave
What type of transducers contain numerous elements that have a rectangular shape?
Linear-Array
What does snells law relate to?
Refraction
Define: Rayleigh's principle.
Scattering caused by RBC
What are the units for: PRF
(KHz)
What are the units for wavelength?
mm
30. The following are acoustic variables, except
a. temperature
b. density
c. particle motion
d. particle speed
Wavelength
the physical distance between cyclical wave peaks within a medium. The wave length is determined by the propagation velocity divided by the operating frequency. The wavelength is one of the most critical parameters in ultrasound since the wave length partially determines the axially resolution as well a s affects the type of reflection that occurs
What interaction of ultrasound and tissue is primarily respnsible for imaging the internal structure of organs?
Scattering
Metallic electrodes are components of a:
hydrophone
Continuous wave doppler utilizes ______ elements.

a. one
b. two
b. two
What system control equalizes the differences in echo amplitudes received from similar structures situated at different depths?
TGC/DGC
Electric filter that passes frequencies above a set level and elininates strong, low-frequency doppler shifts from pulsing heart or vessel walls
Wall filter
An electric circuit that passes frequencies within a certain range
Filter
T/F
LATERAL RESOLUTION IS BETTER WITH PHASED ARRAY.
TRUE
Amplitude
the "bigness" of a wave
 It is the difference between the maximum value and the average or undisturbed value of an acoustic variable
B-mode
In this display mode, the x-axis represents depth and the z-axis represents amplitude.
What converts electric energy into ultrasound energy, and vice versa?
Ultrasound Transducers
Define: Poiseulles law.
Mathematical description of the dependence of volume flow rate on pressure, vessel length and radius, and fluid viscoscity
Snells law is a declaration concerning the behavior of waves during a particular physical process or event. what event is this?
Refraction
Impedance increases when:
density increases or
propagation speed increases
Anechoic
Without echoes, echo free, black means fluid.
Which of the following terms denotes the time it takes for one cycle to occur? Frequency, Amplitude, Wavelength, Period, or Pressure?
Period
During abdominal US, you image the following structures: Blood bile, Liver parenchyma, Gallstone, Spleen, which is most attenuating?
Gallstone
The ability of a diagnostic technique to identify true disease is termed:
sensitivity
The ability to distinguish between adjacent structures that produce echoes of similar amplitude is termed what?
Contrast resolution
What information does the z axis (brightness) on the doppler spectrum provide?
Amplitude
If sound sis not attenuate with increasing depth, what system control would no longer be needed?
TGC/DGC
Several reflections produced by a pulse encountering a pair of reflectors;reverberation
Multiple reflection
Artifact produced when echoes are placed too close to the transducer because a second pulse was emitted before they were recieved
Range ambiguity
Nonuniform driving of elements in an array to reduce grating lobes
Adopization
BULK MODULUS IS ________ AS STIFFNESS.
THE SAME
WHAT IS THE RELATIONSHIP BETWEEN PRF AND PRP?
INVERSE
0.01 - 300 W/cm²
In clinical imaging, intensity ranges
 from what?
fixed/conventional/mechanical focusing
Which type of focusing produces poorer transverse resolution?
20. Which of the following is the least obstacle to the transmission of U/S
a. muscleb. fatc. bone d. blood
At what angle between the sound beam and the direction of motion will the Doppler shift be absent?
90degrees
Define M mode.
B mode presentation of changing reflector position, time, motion, and amplitude
Which of the following artifacts commonly fills in small linear vessels: Refraction, Partial volume, Mirror image, Range ambiguity, or multipath artifact?
Partial volume artifact
29. If the wavelength is 8mm, the SPL for a 2 cycle pulse is,
a. 4mm
b. 6mm
c. 8mm
d. 16mm
e. 24mm
Hyperechoic
Portions of an image that are brighter than surrounding tissues, or tissues that appear brighter than normal
Particle motion
one of the 4 acoustic variables, occurs when particles oscillate back and forth about their original location, allowing the concentration of energy to propagate along the wave path.
A 6dB gain would indicate an increase in intensity of
a. 2
b. 4
c. 8
d. 10
B
The change in frequency resulting from motion is termed:
Doppler shift
You are reviewing an ultrasound image that has a sector display format with a pointed top. What kind of transducer produced this image?
Phased array
What aspect of the doppler spectrum is color encoded with power doppler?
Amplitude
the principle of reflection is known?
a. Snell's law
b. Bernoulli's equation
c. Ohm;s Law
d. Pouiselle's Law
a. Snell's Law
Incident is the product of the density and propagation speed.
True or False?
true
Which scanninc mode does not rely on the principle of echo ranging to determine the interface location?
A-Mode
Flow with all fluid portions traveling with the same flow speed and direction
Plug flow
Combination of a PZT ceramic and a nonPZT polmer
Composite
Part of an instrument that accompishes electronic beam scanning, apodization,steering,focusing,and aperture with arrays
Beam former
Flow that cannot be described by straight, parrallel stremlines
Disturbed flow
Region of a medium that contains virtually all of the sound produced by a transducer
Sound beam
DEFINED AS " THE TIME REQUIRED TO COMPLETE ONE CYCLE "
PERIOD
Both the source and medium
What is wavelength determined by?
What is it called when bandwidth is divided by the operating frequency?
Fractional Bandwidth
Define: PRP.
Time from the beginning of one pulse to the next
Define duty factor?
The fraction of time the pulsed ultrasound is on
What is determined by the sound source and the medium?
the wavelength
Refraction
the bending of a beam at an interface of two media. For refraction to occur, there must be a change in propagation speed and a incident angle other than 0 degrees (other than normal)
The percentage of time the sound is on is referred to as the
a. intensity
b. amplitude
c. period
d. duty Factor
D
Increasing the frame rate will:
decrease the maximum imaging depth
Describe a phased array transducer.
Electronically focused along the length os the array mechanically focused along the width, and electronically steered
All of the following are true regarding power doppler except which: Greater sensitivity than color doppler, Doppler angle has little effect on flow detection, slower image rates, or less flash artifact?
Less flash artifacts
if the amplitude of the signal is halved, what is the effect on intensity?

a. quartered
b. quadrupled
c. halved
d. no change
a. quartered
Increasing the dynamic range setting will affect the US image how?
Decreasing the image contrast
Interval of time from beginning to end of a pulse
Pulse duration
The angle bewteen the sound beam and the flow direction
Doppler angle
THE NUMBER OF PULSES THAT OCCUR IN ONE SECOND:
PRF
Increase dampening, which lessens ringing and produces fewer cycles in a pulse; increase frequency, which shortens the wavelength.
Axial resolution is determined by spatial pulse length. How can you create short pulses?
22. For soft tissue, there is approximately_________ of attenuation per____________ for each MHz
a. 0.5dm, mmb. 0.5dB, cmc. 1.0 dB, mmd. 1.0 dB, cm
Define damping material.
Material attached to the rear of the transducer to reduce the pulse duration
The operator can change the:
amplitude, power and intensity. The values of these parameters decrease as sound propagates through the body.
Side lobes and Grating lobes
Extra acoustic energy may be transmitted in directions other than the beam's main axis.

1. Duplicate image of reflector (too much information on a scan)

2. Side by side with the true reflector

Assumption #4 Reflections arise from the structures positioned along the beam's main axis
The Bernoulli effect describes the:
decrease in pressure prior to stenosis

(pressure decreases before stenosis allows fluid to accelerate into the stenosis and decelerate out of it as described by Bernoulli effect)
What is the purpose of the radiofrequency shield that is placed around the crystal and backing material of the ultrasound probe?
It reduces electromagnetic interference
While performing a color doppler exam in the abdomen you have adjusted several system controls and notice that the frame rate has decreased, which of the following adjustments can you make to improve the color frame rate: Increase the packet size, Decreas
Decrease the color box
The ratio between the smallest to the largest amplitude difference is called:

a. enhancement
b. reject
c. dynamic range
d. compression
c. dynamic range
Which of the following terms describes the rate at which the transmitter applies transmit pulses to the transducer: Period, PRF, DGC, Demodulation, Apodization?
PRF Pulse Repitition Frequnecy
WHAT IS THE EQUATION FOR DUTY FACTOR?
PULSE DURATIN / PRP*100
Two Part Question?What material has impedance of some intermediate value between those of the transducer elements and the tissue? What does it reduce at the transducer element surface thereby improving sound transmission across it?
1. Matching layer2. Reflection of ultrasound
What is variance mode?
Variance adds green to red to blue progressing from RT to LT across the map for detection of turbulent blood flow
Pulse duration:
the time from the start of a pulse to the end of that pulse, only the ACTUAL TIME that pulse is on.
Which of the following statements is true regarding the effect of frequency on Rayleigh scattering; The amount of scattering is not affected by frequency, Scattering intensity doubles if frequency is doubled, Doubling the freq results in halving the scatt
Scattering intensity is proportional to frequency raised to the fourth power
The ratio of the largerst to smallest amplitude a system can handle describes:
compression or dynamic range
If you wish to produce a sonogram in a rectangular format, what transducer should you choose?
Linear array
What do you expect to see with a high reynolds number?
Turbulent flow
What information is present in the M-mode display
Time, Motion pattern, and Amplitude
Region of a sound beam in which the beam diameter increases as the distance from the transducer increases
Far zone/Far field
WHERE DOES HIGH FREQUENCY US IMPROVE LARRD RESOLUTION? LATA RESOLUTION?
LARRD-EVERYWHERE IN THE IMAGE
LATA-FAR FIELD ONLY
What is it called when you are moving the transducer on the tissue where you want to get the cross-section to be imaged? Name all three names?
1. Scanning2. Sweeping3. Steering
What type of format, beam steering, and beam focusing does the following have: Single element.
Pie shape image, Mechanical focusing and steering; Lens mirror
What material is attached to the rear face of the transducer elements to reduce the number of cycles in each pulse? Two Names?
1. Damping material
2. Backing material
The size of the displayed image is directly related to the:
pulse repetition frequency

(field of view or imaging depth is directly related to PRF and inversely related to the frame rate and PRP)
CW ultrasound can: sample specific areas, Sample a range of large areas, Can measure high velocities of blood flow, or has limitation of nyquist limit?
It can measure high velocities of blood flow
On color flow imaging, the best way to overcome aliasing is:

a. increase the transducer's frequency
b. avoid low velocity flow
c. use a high PRF
d. decrease the doppler angle
c. use high PRF
Preprocessing functions may be defined as what?
A function that is performed before the echo data are stored in memory
4. The piezoelectric effect can be described as
a. density of tissue & speed of sound in the tissueb. mechanical deformationc. piezoelectric crystals subjected to pressure resulting in electrical change appearing on their surfaced. having a damaging effect on crystals due to high voltage
You are scanning a large abdominal mass that is comprised primarily of fat. What are you most likely to encounter?
Axial misregistration of the mass on the screen caused by the slower propagation speed through fat
What is the difference between FFT and autocorrelation doppler techniques?
Autocorrelation can olnly provide mean values of doppler shift
Differentation between two very similar reflected signal strengths is most closely associated with which of the following: Number of pixels in the scan converter matrix, Number of raster lines in the scan converter matrix, Dimension of the scan converter
Number of bits per pixel in the scan converter matrix
PRP and depth = directlyPRF and depth = indirectly
PRP and depth are ______ related.PRF and depth are ______ related.
What is better Narrow or broad bandwidth?
Broad due to the larger spectrum of frequencies
What can be done to enhance visibility of a specular reflector?
Acan with an incident angle of 90
Which type of transducer will decrease the slice of thickness of the beam?
A linear array with multiple rows of elements
T/F
WAVELENGTH IS DETERMINED BY BOTH THE SOURCE AND THE MEDIUM.
TRUE. ( ONLY ONE THAT IS DETERMINED BY BOTH )
What should you do to obtain the best lateral resolution for a given transducer?
Use the maximum number of transmit focal zones
Billion
Giga
Imaging depth
Penetration
Time per cycle
Period
No
can wavelength be adjusted?
Speed
the rate of travel
MEASURE OF PARTICLE MOTION?
DISTANCE
Grating lobes
Arrays create grating lobes
Reduction in echo amplitudefrom reflectors that lie behind a strongly reflecting or attenuating structure
Shadowing
T/F
ATTENUATION ULTIMATELY LIMITS THE MAXIMUM DEPTH FROM WHICH MEANINGFUL REFLECTIONS ARE OBTAINED.
TRUE
unrelated
two items that are not associated
5. As frequency increases, backscatter
a. decreasesb. is not affectedc. increasesd. is refracted
Which of the following contributes most to total attenuation in soft tissue: Absorption, Reflection, Scattering?
Absorption
Define Aliasing.
Improper doppler shift information from pulsed wave/color when the doppler shift exceeds the nyquist limit
What is the equation for: Wavelength?
Wavelength=c/f
5. As frequency increases, backscatter
a. decreases
b. is not affected
c. increases
d. is refracted
Medium
the material through which a mechanical wave propagates. During imaging , the medium is the part of the patient being scanned
As acoustic pressure increases, so does what?
Intensity
Utilizing previous echo reflections while adding new echoes to the image along a parallel scanning plane describes:
panoramic imaging
Zero-crossing detectors are useful for providing direction and amplitude of flow.

True or False
True
What receiver function is responsible for decreasing the difference between the smallest and the largest reveived signal amplitudes?
Compression
Gray-scale echo strength below which color doppler information is shown preferentailly on a display
Priority
NEGATIVE dB MEANS GETTING SMALLER, THUS INTENSITY WILL:
DECREASE
stiffness
density
What two characteristics of a medium affect the speed of sound?
axial resolution
the ability to distinguish two structures that are close to each other along/parallel to the beam's main axis
2. If frequency in soft tissues is doubled, propagation speed is
a. halvedb. doubledc. decreasedd. unchanged
Which of the following parameters is affected by the medium: PRP, SPL, DF, or PD
SPL
What is the formula for pulsed duration?
pd=n*t
What converts electric energy into ultrasound energy, and vice versa?
Ultrasound Transducers
Apodization
Grating lobes are further reduced by exciting the subdiced elements with different voltages. Subelembets closer to the center of the sound beam are excited with the higher voltages, while the outermost sublelements, further away from the center, are excited with lower voltages. This is called apodization.
If the propgation speed is unchanged at the interface, which most correctly describes the sound tissue interaction that will take place when the ultrasound wave strikes the interface? Specular reflection, Dcattering, Diffraction, Refraction, or None
Scattering
What is another term for nonspecular reflection?
Scattering
Flow rate is proportional to the:
pressure gradient
What transducer component is designed to control piezoelectric element ringing?
Backing material
The Nyquist limit describes what?
The aliasing frequency
True or False: Power doppler can detect flow direction?
False
What control should you adjust to modify the image if the attenuation coefficient of the tissue is very high: Dynamic range, Rejection, Threshold, Compensation, Compression
Compensation
Is the following form of information Digital or Analog:Output signal from the analog to digital converter?
Digital
Number of pulses per second;
Pulse repetition frequency
Flow that accelerated and decelerates with each cardiac cycle
Pulsatile flow
One complete variation of an acoutic variable
Cycle
THE AMOUNT OF ATTENUATION PER CENTIMETER IS KNOWN AS THE:
ATTENUATION COEFFICIENT
LIST THE THREE "BIGGNESS PARAMETERS"
AMPLITUDE, POWER, INTENSITY.
ADJUSTABLE FOCUS OR MULTI-FOCUS; THESE ARE ACHIEVED ELECTRONICALLY:
PHASED ARRAYS
intensity = power
(proportional)
how is intensity and power related?
LateralAngularTransverseAzimuthal
What are the other names for lateral resolution?
Define: Tissue equivalent phantom.
Device for testing ultrasound characteristics of tissue. Simulates soft tissue
How lung is the typical pulsed duration?
.5-3 microseconds
What are the 2 types of color doppler?
B-Dmode
10. How many cycles are their in a 2seconds of continuous-wave 5MHz U/S
a. 5
b. 10
c. 5,000
d. 5,000,000
e. 10,000,000
Homongeneous
A portion of tissue or a structure that has similar echo characterstics throughout.
Transmit
refers to the process of driving a transducer with an electropotentional (voltage) to produce energy to propagate into the patient most direct consequence on signal strength as well as a significant impact on the risk of bioeffects
The speed of sound in tissue is:
a. 1.54 mm/us
b. 1540 mm/sec
c. 1.54 kilo/sec
d. all of the above
A
3D imaging acquires volume data at rates up to:
30 volumes/second
A transducer is a component of which testing device:
hydrophone
Which transducer has the same line density in both the near and far fields?
Linear array
What term describes the number of pulses that are used to determine the velocity along a color line of sight?
Packet size
PWD instruments are charecterised because of their ability to do all of the following except:

a. real time and spectral dopppler
b. gate position
c. velocity estimation
d. velocity limits unrestricted
d. velocity limits unrestricted
When you adjust the TGC, what component of the US system implements the changes?
The receiver
Mode of operation in which the display presents a spot approriate brightness for each echo recieved by the transducer
B-mode
Linear array operated by applying voltage pulses to groups of elements sequentially
Lenear sequenced array
Single one or two way path for tranmitting electric signals, in distinction from other parrallel paths
Channel
Region of low density and pressure in a compressional wave
Rarefaction
WHAT IS THE DIFFERENCE BETWEEN THE MAXIMUM AND MINIMUM VALUES OF AN ACCOUSTIC VARIABLE KNOWN AS?
PEAK-TO-PEAK AMPLITUDE
IS A CHARECTERISTIC OF THE MEDIUM ONLY AND IS CALCULATED, NOT MEASURED.
IMPEDANCE
WHAT DOES SATA STAND FOR?
SPATIAL AVERAGE, TEMPORAL AVERAGE
Constructive Interference
The interference of a pair of in-phase waves results in the formation of a single wave of greater amplitude than either of its components
Arrays are operated in which two ways?
1. Sequencing2. Phasing
What 2 things determine a wavelength?
Frequency and propagation speed
What is the equation for: spatial pulse length?
spl=number of cycles*wavelength
Which of the following artifcat is associated with resonance of a gas bubble: Grating lobes, Comet tail, Acoustic speckle, Ring down, or Refraction?
Ring down ie.-bowel
__ intensity is averaged during the pulse repetition period (both on and off times)
temporal average (TA)
Obtuse angle
an angle that is greater than 90 degrees but less than 180 degrees
what 2 characteristics of a medium dtermine it's propagation speed?
a. density & temp
b. stiffness & pressure
c. density & stiffness
d. prop speed is not affected by the medium
A, C, D
The amount of time pulse US is transmitting is termed:
duty factor
The conversion of an incident pressure wave to an electrical signal is what?
The piezoelectric effect
You have increased the packet size while using color doppler to evaluate flow in the thyroid gland, what negative result will occur from this action?
Decreased frame rate
A 3dB gain would indicate an increase in intensity of
________ times

a. 2
b. 4
c. 8
d. 10
a. 2
Which of the following is not a function of the receiver?
Dynamic aperature
Wave in which the particle motion is parrallel to the direction of the wave travel
Longitudinal wave
SOUND WAVE'S FREQUENCY = THE FREQUENCY OF THE VOLTAGE APPLIED TO THE PZT BY THE MACHINE'S ELECTRONICS. IS A CHARECTERISTIC OF:
CONTINUOUS WAVE TRANSDUCERS
WHAT IS THE FORMULA FOR WAVELENGTH?
=PROPAGATION SPEED / INTENSITY
ATTENUATION OF SOUND IN SOFT TISSUE DEPENDS UPON THE WAVE'S : (2 THINGS)
1. DISTANCE
2. FREQUENCY
external focusing
This type of focusing is a result of using a lens.
14. If the incidence angle is 20 degrees in oblique incidence & the propagation speed of medium 1 is 1.7mm/us & the propagation speed of medium 2 is 1.6mm/us, calculate the reflection angle
a. 10 degreesb. 18.8 degreesc. 20 degreesd. 22.5 degrees
______ intensity has the lowest value.
Spatial average Temporal average (SATA)
When the propagation speed is less than soft tissue's the reflector will be placed too....
deep on the display
The ability of a test to determine abnormal findings defines:
positive predictive value
What is a method used to improve frame rates with multizone electronic focusing termed?
Aperature focusing
According to the doppler equation which of the following is not true: Increasing doppler frequency will increase the frequency shift, Increasing doppler interrogation angle will increase the frequency shift, Decreasing the reflector speed will decrease th
Increasing doppler interrogation angle will increase the frequency shift is false.
Which is not an example of pre-processing?

a. "write" zoom magnification
b. "read" zoom magnification
c. persistance
d. changing 2D maps (compression)
b. "read" zoom magnification
What part of the US instrument is responsible for apodization, beam stearing, focusing, and aperature control?
The beam former
WHEN THE AMPLITUDE OF THE NEW WAVE IS LESS THAN ONE OF THE ORIGINAL WAVES, THIS IS KNOWN AS:
DESTRUCTIVE INTERFERENCE
soft tissue 1%bone-tissue 50%air-tissue 99%
IRC is ____% at soft tissue boundary, ____% at a bone-tissue boundary, and ______% at an air-tissue boundary.
Operating frequency is determined by what two things?
1. Propagation speed of the transducer material2. Element thickness of the transducer element
What factors will eliminate ailiasing in Doppler instruments?
Change angle, Shift the baseline, Lower the frequency, Increase PRF, Use CW Doppler
What is determined by the sound source?
period, frequency, amplitude, power, intensity
As you perform an abdominal ultrasound exam, you switch from a 3.5 to 7.0 MHz transducer to image a pancreatic mass. Compared to those of the previous transducer, what will the new attenuation rate and the wavelength be?
Double attenuation rate, on-half wavelength
Which of the following statements accurately describes harmonic frequencies:
A. demonstrates wide beam widths
B. Grating lobes are increased
C. Harmonic frequencies are generated in superficial structures
D. Lateral resolution is reduced
E. generate in t
E. Harmonic frequencies generate in the highest intensity of the sound beam
What is another name for axial resolution?
Range (L.A.R.R.D Longitudinal axial range radial depth)
Ailiasing is a potential problem in PW doppler, why?
Because of intermittent sampling
Where are images stored in the US system?
in the Scan converter
WHAT ARE THE UNITS OF AMPLITUDE?
THOSE OF THE ACOUSTIC VARIABLES. (PRESSURE, DENSITY, PARTICLE MOTION)
What do you get when operating frequency is divided by the bandwidth or 1/fractional bandwidth? What is the unit of it?
1. Quality factor (Q factor)2. Unitless
You are imaging a patient with a thickened gallbladder wall. In what direction can the the wall thickness be measured most accurately?
Perpendicular to the beam axis
What do you get when operating frequency is divided by the bandwidth or 1/fractional bandwidth? What is the unit of it?
1. Quality factor (Q factor)2. Unitless
The diameter of the beam determines the:
near zone length and lateral resolution
All are true regarding amplitude imaging except: It is a quantitative technique, it has good sensitivity to slow flow, it is not angle dependent, or it can not display direction of flow?
It is a quantitavie technique is false
All of the following are characterisitcs of write zoom magnification except which: Preprocessing function, more pixels in the region of interest, identical regions stored in the scan converter before and after zoom is enabled, or the preferred method of i
Identical regions stored in the scan converter before and after zoom is enabled
T or FDo thinner elements operate at lower frequencies?
False, they operate at higher frequencies
What must be present for sound reflection to occur at the interface of two structures?
A difference in the acoustic impedance of the media
What is the maximum velocity limit for a 3MHz CW Doppler unit operating at a depth of 4cm: 40cm/s,200cm/s, 2.5m/s, 4m/s, none
CW has range ambiguity so none
Which of the following is associated with improper adjustment of the brightness and contrast on the video monitor: Spatial resolution of the resultant image will be degraded, The operator will likely overgain or undergain the image, The temporal resolutio
The operator will likely overgain or undergain the image.
3dB = 2x bigger6dB = 4x bigger (2 x 2)9dB = 8x bigger (2 x 2 x 2)
3dB rule for positive numbers
Period, frequency and wavelength are changed when:
a new transducer with a diff freq is used.
While imaginag a breast cyst, you notice shadowing posterior to each lateral border of the cyst. Wjat is the source of the shadow?
Redirection of the sound beam at an interface with diefferent propagation speeds and a curved surface
Will Aliasing occur in: PW doppler, CW doppler, or Color doppler?
PW and Color doppler, not CW doppler
WHEN PRODUCED BY A TINY SOURCE, WITH A SIZE NEAR THE WAVELENGTH OF THE SOUND, WAVES WILL MAKE THIS SHAPE AS THEY PROPAGATE.
V-SHAPED WAVE, ALSO CALLED HUYGEN'S WAVELET.
All of the following are true of ordinary cathode ray tubes except which statement: They are large vacuum tubes with a phosphor coated screen, Electrons are emitted by a gun ans swept across the front, There are 600 horizontal lines from top to bottom, pa
Ther are 600 horizontal scan line from top to bottom, painted in order is incorrect. Lines are painetd with the Odd numers first then the even numbers and there are only 500 ish horizintal scan lines
/ 237
Term:
Definition:
Definition:

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