Ultrasound physics Flashcards

Terms Definitions
hundred
hecto
y-axis
vertical axis
One thousand hertz
Kilohertz
Distance
Measure of particle motion
cm,feet,mile
Ultrasound transducers operate according to the principle of what?
Piezoelectricity
Power divided by area
Intensity
no
Can the frequency be adjusted?
25. B-mode display denotes:
a. basic motion
b. beam motion
c. brightness modulation
d. basic reflection
Refraction occurs with perpendicular incident and speed differences.

True or False?
False
Equalization of recieved echo amplitude differences caused by differnet attenuation for different reflector depths;also called depth gain compensation or TGC
Compensation
AS IMAGING DEPTH INCREASES, PRP_____.
INCREASES
Mechanical & longitudinal
Sound waves are what?
3. As frequency increases, backscatter
a. decreasesb. is not changedc. increasedd. is refracted
Is the following operator adjustable: rejection and amplification?
yes
Define: duplex.
Something that combines 2 things
Define: Doppler phantom.
Used to measure doppler
15. Attenuation__________ , W/ increased path length
a. increases
b. remains the same
c. decreases
d. disappears
Isoechoic
Describes structures with equal echo brightness.
What sound interaction would produce shadows posterior to a fetal head?
Refraction
Which material demonstrates natural piezoelectric properties:
A. lead
B. silver
C. quartz
D. copper
E. barium
C. quartz
What angle provides the maximum doppler shift angle?
Zero
Are the following pre or post-processing procedures: Read zoom?
Post
Maxium variation of an acoustic variable or voltage
Amplitude
Aperature that increases with increasing focal length
Dynamic aperature
Mathematical description of the relationship bewteen doppler shift,frequency,doppler angle prop. speed, and reflector speed
Doppler equation
T/F
SOUND MUST TRAVEL THROUGH A MEDIUM, IT CAN NOT TRAVEL THROUGH A VACUUM.
TRUE
Out-of-phase waves
Two waves that peaks occur at
different times
A-mode
In this display mode, the x-axis represents depth and the y-axis represents amplitude.
How many longer driving voltage cycles are used for doppler techniques?
5-15 cycles
All of the following are determined solely by the ultrasound machine except which: PD, freq, SPL, or Period?
SPL
Propagation speed formula:
frequency (hz) x wavelength (meters)
Lobe artifact degrades which resolution?
Degrades lateral resolution
What property would result in increased propigation speed of a medium?
Increased stiffness
Which of the following adjustments would reduce sound attenuation in the body most? Increasing receiver gain, Decreasing transmit power, Increasing dynamic range, Decreasing frequency, or Decreasing focus?
Decreasing frequency
The mechanical index is proportional to the:
system output
A linear array transducer with 4 transmit focal sones selected requires how many pulses on each vector to create the image?
4
You are scanning a phantom containing many small spherical cystic structures imbedded in a tissue mimmicking material, what type of resolution is best evaluated with this phantom?
Elevational
What color assignment to flow towards the transduce?
Red
Is the following form of information Digital or Analog: Output signal from the digital to analog converter?
Analog
Sound having a frequency greater than 20kHz
Ultrasound
Angle between the reflected sound direction and line perpindicular to the media boundry
Reflection angle
Unit of frequency, one cycle per second; unit of pulse repition frequency, one pulse per second
Hertz
WHAT ARE THE UNITS OF ATTENUATION COEFFICIENT?
dB/cm
ACOUSTIC IMPEDANCE=
DENSITY (kg/m^3) X propagation speed (m/s)
Intensity
The concentration of energy in a sound beam.
Also describes the "bigness" of a wave.
bandwidth(Hz) = maximum frequency - minimum frequency
equation for bandwidth
13. If a wavelength is 4mm and the frequency is doubled, the wavelength becomes:
a. 1mmb. 2mmc. 3mmd. 2cme. 8mm
What is the typical duty factor in continuous wave?
100%
At what velocity is the Doppler shift equal to zero?
<10(cm/sec)
What is the acoustic velocity in soft tissue?
1540m/s
Impedance formula:
impedance (rayls) = density (kg/m3) x propagation speed (m/s)
Mirror Image
Sound may bounce off a strong reflector, called a mirror, in its path and be redirected.

1. Second copy of a reflector (duplicates) (extra reflections on the scan)

2. Artifact (A) located deeper than the true reflector (R)

3. Mirror lies on the straight line between the artifact and transducer

4. True reflector and artifact are equal distances from mirror.
Assumption #2 Sound travels directly to a reflector and back to the transducer.
Power
the rate at which work is being preformed. The unit for power is watts
What term is used to describe the reduction in the intensity of sound as it propagates through tissue?
Attenuation
Even and odd multiples of the fundamental frequency describes:
harmonic frequencies
When the operating frequency increases, the:
A. flow speed decreases
B. Doppler shift increases
C. pressure energy increases
D. detail resolution decreases
E. penetration depth increases
B. Doppler shift increases
Which of the following transducers is electronically focused but mechanically steered: Segmental linear array, Switched linear array, Phased linear array, Single element mechanical sector, or Annular array?
Annular array
While evaluating the liver vasculature with color doppler, you are unable to obtain signals from the deeper vessels, what should you do to enhance your ability to demonstrate flow in the deeper vessels?
Decrease doppler frequency
Which technique allows the display of amplitude signals from the blood cells?
Power doppler
the angle of reflection is equal to angle of incident

True or False?
True
What number system is employed by computers to carry out mathmatical operations and represent numbers?
Binary system
A rapid technique, used in most color doppler-shift frequency
Autocorrelation
Range of brightness between white and black
Gray scale
Ability of an imaging system to detect weak echoes
Sensitivity
WHAT IS USED FOR 4D IMAGING ?
2D ARRAY
A COLLECTION OF CYCLES THAT TRAVEL TOGETHER IS KNOWN AS:
A PULSE
IN SOFT TISSUE THE ATTENUATION COEFF. IS APROX. __________ OF THE FREQUENCY.
ONE HALF
IRC(%) = [(Zˇ2-Zˇ1)/(Zˇ2+Zˇ1)]^2 x 100ITC(%) = 100% - IRC
equations for IRC and ITC
24. Under what conditions does refraction occur
a. unequal propagation speed on either side of the boundaryb. unequal impedances of 2 mediumsc. equal propagation speed on either side of the boundaryd. equal impedances of 2 mediums
Define: Fast Fourier Transform.
Digital computer implementation of a mathematical technique for obtaining a doppler frequency spectrum
Reflection occurs when:
some of the propagating sound energy strikes a boundary between 2 media and is returned toward the transducer.
Refraction artifact degrades what resolution?
It degrades the lateral resolution.
The log of 10,000 is equal to:
a. 2
b. 3
c. 4
d. 5
C
Which of the following remains constant throughout the vessel:
A. velocity
B. pressure
C. direction
D. resistance
E. volumetric flow rate
E. volumetric flow rate
An internal method of focusing is what?
Curved piezoelectric element
True or False: A minimum of 3 pulses per scan line is required to assign color?
True
Color flow doppler provides ______ velocity information.

a. peak
b. mean
b. mean velocity information
Pulse repition period is the inverse of what?
Pulse repitition frequency
A doppler device or procedure that uses continuous wave ultrasound
Continuous Wave Doppler
Flow in which fluid layers slide over each other in a smooth, orderly manner, with no mixing between layers
Laminar flow
THE TIME FROM THE START OF ONE PULSE TO THE START OF THE NEXT PULSE IS KNOWN AS:
PRP
MATERIALS DEFORM OR CHANGE SHAPE WHEN A VOLTAGE IS APPLIED TO THEM.
REVERSE PIEZOELECTRIC EFFECT.
2 MHz - 10 MHz
In clinical imaging, frequency ranges approximately what?
26. Which of the following are most commonly used in U/S
a. lead zirconate titanateb. barium sulfatec. metaniobated. quartz
What is the location where the sound beam reaches its narrowest diameter known as?
The focal zone
______ intensity has the highest value.
Spatial peak temporal peak (SPTP)
When the propagation speed is greater than 1,540 m/s The reflector speed will be placed too....
shallow on the display
If the initail is 40 and there is a 3dB gain the final intensity is:
a. 80
b. 60
c. 40
d. 20
A
Increasing the transducer diameter has which of the following effects: Increased near zone length, Increases the frequency, Increases the beam diameter in the far field?
Increases the near zone length
The ensamble lenght in color doppler refers to the number of what?
Pulses per scan line
The color map represents the:

a. maximum color flow velocities on the vessel
b. an array of different flow velocities, including the peak velocities
c. mean doppler shift only
d. amplitude information of the blood flow
c. mean doppler shift only
What are the 5 functions of the receiver?
Amplification, Attenuation, Compensation, Compression, Demodulation
AN EASY WAY TO REMEMBER THE LOGARITHM OF A SPECIFIC NUMBER IS TO:
COUNT THE ZEROS
axial resolution(mm) = SPL(mm) / 2 axial resolution(mm) = wavelength x # of cycles in pulse / 2
equations for axial resolution?
What are the 3 types of mechanical bioeffects?
radation force, steaming, cavitation
_____ Intensity is the most relevant to tissue heating.
Spatial peak Temporal Average (SPTA)
Mirror and refraction are both reflector artifacts the difference in the two is?
Mirror is deeper

Refraction has the duplicate side by side
The five major components of a pulse-echo US system are:
pulser, transducer, receiver, image memory, display
How is beam focused with a single element transducer?
With a curved element
You have obtained a color doppler image of the common carotid artery after employing a red/blue map. WITHOUT using invert, if the frequency is greater than the transmitted frequency, which of the following would be correct: Color encoding red/negative dop
Color encoding red/positive doppler shift
What is a typical value for the Duty factor in doagnostic US imaging?
0.1 - 1.0%
THE TIME FROM THE START OF A PULSE TO THE END OF THAT PULSE , THE ACTUAL TIME THE PULSE IS ON:
PULSE DURATION
If the diameter increases or the frequency increases, the focal depth increases.
If the transducer diameter increases, what happens to the focal depth? If the frequency increases?
What is a calorimeter?
A device used to measure the amount of conversion of heat
What is constructed as a curved line of elements rather than a straight one? Two names?
1. Convex array
2. Curved array
Which of the following is a function of the power control:
A. filters out weak reflections
B. levels out the returning signals
C. improves the signal-to-noise ratio
D. amplifies returning reflections
E. changes the gray scale of the returning echoes
C. improves the signal-to-noise ratio
What is the optimal thickness for the matching layer?
one fourth of a wavelength
The method used by CW doppler to discriminate valuable signals is the:

a. target-to-flow ratio
b. resistive index
c. zero- crossing detector
d. FFT
c. Zero - crossing detector
The computer parameter that limits the number of brightness levels (shades of gray) available for display of the image matrix is what?
The number of bits per pixel
near zone, near field, or Fresnel zone
the region between the transducer and the focus
you are imaging the interface between two abdominal structures at normal incidence. They have the same acoustic impedance. What will occur at the boundary of the two structures?
All of the sound will be transmitted
What is the matching layer between the piezoelectric element and the tissue designed to do?
Reduce the acoustic impedance mismatch between the element and tissue
In the scan converter, interpolation is performed to do what?
Fill in the empty pixels that occur between scan lines
WHAT TYPE OF RELATIONSHIP DO IMAGING DEPTH AND PRF HAVE?
INVERSE (WHEN ONE INCREASES THE OTHER DECREASES)
Why do we use coupling gel?
To provide a good sound path from the transducer to the skin, eliminating the thin layer of air that would reflect the sound
What is the assumption # for Mirror image?
Assumption # 2 Sound travels directly to a reflector and back to the transducer.
If you want to use an array transducer that allows you to control transmit focal depth, what type would you select?
Linear array, Convex array, Phased array, Annualar array
Without interpolation, which of the following would best describe the resultant B mode image: Very weak echoes in the far field compared to the near field, Poor differentiation between the US signal and the noise floor, Saturation of the white shades on t
A series of scan lines with blank data between the lines
What is the sped of sound defined as?
The Speer at which the sound wave propagates through the medium
thousand
kilo
Multiple reflection
Reverberation
Resistance to acceleration
Inertia
Yes
Can amplitude be adjusted?
Temporal
the measure of time
"A-MODE" STANDS FOR?
AMPLITUDE MODE
Density
Concentration of mass in a volume
kg/cm³
21. Period is inversely proportional to:
a. velocity
b. watts
c. hertz
d. frequency
Regarless of frequency, the propagation speed will remain the same providing the medium doesnot change

True or False
True
Conversion of sound to heat
Absorption
ALL INTENSITIES HAVE UNITS OF___________.
WATTS/CM^2
sound source
Powere is determined by what?
Because wavelength decreases as frequency increases what type of element yields higher frequencies?
Thinner elements
What does lateral resolution equal?
Beam diameter
What are the ranges for PRF?
1000-10,000Hz
Because wavelength decreases as frequency increases what type of element yields higher frequencies?
Thinner elements
Period
the reciprocal of the frequency representing the amount of time it takes for one full cycle to occur
Bulk modulus refers to what quality?
Stiffness
Which testing devices measures the duration of a pulse:
hydrophone
The ________ impedence difference between two media interfaces, the greater the amount of ultrasound reflected back to the transducer.

a. Larger
b. Smaller
a. Larger
Indicator of thermal mechanism activity; a value equal to transducer acoustic output power divided by the estimated power required to raise tissue temperature
Thermal index
Range of doppler-dhift frequencies present in the returning echos
Frequency spectrum
L=C/F <--------- WHAT DOES THIS FORMULA REFER TO?
WAVELENGTH
T/F
INTENSITIES MAY BE REPORTED IN VARIOUS WAYS, WITH RESPECT TO TIME AND SPACE.
TRUE
watts/square centimeter
W/cm²
What is the units for intensity?
M-mode
the only display mode that provides information regarding reflector motion with respect to time
Transducers are typically driven by how many cycles of alternating voltage for sonographic imaging?
1-3 cycles
Define PRF.
Number of electrical pulses per second
Define pixel.
Unit which imaging information is divided for storage and display in a digital instrument
What is the equation for: Pulse Duration?
pd=n*t
What is determined by the medium:
propagation speed
Hetrogenous
Displaying a variety of different echo charatersitic within the tissue
Which of the following frequencies is considered to be ultrasound? 2,000Hz, 20Hz, 2MHz, 200Hz, or 2Hz?
2MHz
What system control should you adjust to account for sound attenuation with depth?
TGC
The electronic transfer of images from the US system to another location is called:
PACS
Increasing scan line density will improve what?
Lateral resolution
Resolution of the two structures parallel to the path of the sound beam is termed what?
Axial resolution
True or False: Vascular resistance is determined by the radius of the blood vessel?
True
What type of resolution is demonstrated by the number of pixels in the scan converter?
Spatial resolution
Linear sequenced array that emits pulses from different starting points and different directions
vector array
Angle between the transmittted sound direction and a line perpendicular to the media boundry
Transmission angle
Attenuation per cm of wave travel
Attenuation Coefficient
Frequencies that are even and odd multiples of another, commonly called the fundamental or operating frequency
Harmonics
WHAT ARE THE UNITS OF VOLUME?
cm3, ft3,
IN DIAGNOSTIC ULTRASOOUND IMAGING, SHORT BURSTS, OR _____ , OF ____ ______ ARE USED TO CREATE ANATOMIC IMAGES.
PULSES; ACOUSTIC ENERGY.
lateral resolution(mm) = beam diameter(mm)
equation for LATA resolution
18. Which of the following is the most dominant factor that contribute to attenuation
a. propagation speedb. reflectionc. absorptiond. scattering
Define: Attenuation.
Reductin of power or intensity as sound travels through a medium
How are the maximum imaging depth and spatial pulse lenght related?
Unrelated
Define Linear array.
Array made of rectangular elements arranged in a line
If the boundary between 2 media has irregularities (with a size similiar to or a bit smaller than pulse's wavelength) then the wave maybe redirected into a number of different directions.
scattering
The casuses of artifacts
-Violation of assumptions (acoustic artifacts)
-Equipment malfunction or design
-physics of ultrasound
-Interpreter error (anatomic pitfalls)
-Operator error
Perpendicular
- meaning at a right angle (90 degrees)
Which of the following factor does not affect impedance: Stiffness, Density Prop speed, Frequency or all of the above?
Frequency
Multihertz transducers utilize:
A. the bandwidth
B. wider crystals
C. thicker elements
D. pixel interpolation
E. spatial compounding
A. the bandwidth

(multihertz transducers utilize the range of frequencies found in a pulse or bandwidth)
You must obtain intercostals views to image a liver mass on a small elderly woman, but the large probe you are using does not provide sufficient contact. What probe would be most helpful in this situation?
Phased array
There is no turbulence of blood whan the Reynolds number is less than what?
2000
What portion of the ultrasound system drives the transducer?

a. pulser
b. receiver
c. scan converter
d. TGC controls
a. pulser
Which electronic component is required for gray scale imaging?
The scan converter
Force divided by the area in a fluid
Pressure
NAME THE 7 TYPES OF TRANSDUCERS:
MECHANICAL
LINEAR SWITCHED
LINEAR PHASED ARRAY
ANNULAR PHASED
CONVEX SEQUENTIAL
CONVEX PHASED
VECTOR
directly related to frequencyunrelated to path length
Attenuation coefficient is _______ related to frequency and ________ to path length.
What reduces pulse duration and spatial pulse length and improves resolution?
Damping or backing material
How are the spatial pulse length and the number of cycles in the pulse related?
Directly related
With oblique incidence:
1) reflection angle = incident angle and

2) % transmission + % reflection = 100%
Angle of incidence
the angle formed between a wavefront and the acoustic interface between two structures. The angle of incidence can also be measured as the angle between the wave direction and the line perpendicular (normal) to the acoustic interface
The trm used to describe the number of cycles that occur in a one-second time period is:
a. lambda
b. frequency
c. wavelength
d. period
B
The time for a wave to complete one cycle is termed the:
period
Which of the following is not associated with a low Q transducer: wide bandwith, multifrequency selection, long pulse length, diagnostic pulsed waved ultrasound, loss of most energy in first few vibrations?
Long pulse length
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
the factors that contribute to attenuation are:

a. Scattering
b. Reflection
c. Absorption
d. All the above
d. all the above
Which of the following is constant with increased or improved temporal reso: More gray shades, more detal in each image, color Doppler, or Higher frame rate?
Higher frame rate
Part of the image processor where echo information is stored in image format
Image memory
THE PROP SPEED FOR PZT IS APROX:
4-6mm PER SECOND
1.54 mm
In soft tissue, frequency of 1 MHz has a wavelength of what?
6. PRF is the # of pulses occurring per
a. timeb. secondc. pulsed. none of the above
Define matching layer.
Material attached to the front of a transducer to reduce the reflections at the transducer element
Units for attenuation is:
dB (must be negative, since the attenuation causes intensity to decrease)
Synonyms for propagation
speed errors....
1. Range error artifact

2. Range ambiguity artifact
The ability of a test to establish normal findings defines:
negative predictive value
The sound beam can be focused by all of the following except which: Acoustic mirror, Acoustic lens, Curved crystal, Matching layer, or Electronic phasing?
Matching layer
Color frame rate is affected by all of the following except what: Sector size, Color box size, Color gain, or PRF
Colro gain
In laminar flow, blood is seen to move:

a. in layers
b. in a turbulant way
c. high peak velocity
d. close to vessel walls
a. in layers
What system function is limited by the speed of sound in tissue: Demodulation, Pulse Repitition Frequency, Voltage amplitude, Rectification, or TGC?
Pulse repitition frequency
A # CALLED THE ____ ______ ______ (ALSO CALLED SP/SA FACTOR) DESCRIBES THE SREAD OF A BEAM IN SPACE. IT IS A UNITLESS NUMBER WITH A VALUE OF 1 OR GREATER.
BEAM UNIFORMITY COEFFICIENT
phased array focusing
This type of focusing is a result of electronic manipulation from the ultrasound machine.
You have obtained an ultrasound image that demonstrates refraction of the sound beam, this artifact might be manifested as what?
Lateral displacement of a reflector
6 dB means ______
two times, two times.
The final is 4 times bigger than the original
With specular reflection the strength of the received signal depends on what 2 factors?
Difference in acoustic impedance and angle of incidence
Which of the following intensity values describes the average intensity within the beam during the highest intensity in time:
A. SATA
B. SPTP
C. SATP
D. SPPA
E. SPTA
C. SATP
(the average intensity within the beam=SA. The highest intensity in time=TP.)
Which of the following can best improve lateral resolution: Increase damping, Decreased frequency, Increased bandwith, Use of a curved crystal, or Decreased aperature?
Use of a curved crystal
What are the two catagories of energy that make up total fluid energy?
Potential and kinetic energy
While performing an OB US exam, you wish yo increase the frame rate to evaluate the fetal heart. What should u do: Increase scan line density, Increase the number of focal zones, Decrease the sector width, Decrease the system PRF?
Decrease the sector width
Device that converts a number to a proportional voltage amplitude
Digital to Analog converter
WHAT ARE THE UNITS OF WAVELENGTH?
ANY UNIT OF LENGTH (METERS, mm)
transducer diameter and frequency of the sound wave
What determines the divergence in the Fraunhoffer zone?
At what point does ailiasing occur?
When the frequency exceeds 1/2 the PRF
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. Scanning
2. Sweeping
3. Steering
If the frame rate increases and the PRF is unchanged, the:
A. line density will decrease
B. pulse duration will increase
C. temporal resolution is reduced
D. operating frequency will increase
E. number of scan lines will increase
A. line density will decrease
What is the purpose of applying multiple matching layers to the transducer face?
Each matching layer thickness is optimized for a different frequency of the transmitted bandwith which improves sound transmission at the element-tissue interface
Line density for a given transducer is determined by:

a. number of elements
b. number of channels
c. footprint of the transducer
d. all of the above
d. all of the above
What is the purpose of preamplification of the incoming signal that occurs in the transducer assembly?
To increase echo voltage before noise is induced through the cable.
the temperature at which a PZT is polarized; 360ºC/680ºF
What is the Curie Point?What temperature is it at?
If sound waves of 3Mhz, 5Mhz, and 10Mhz are transmitted through the same section of liver, which frequency would reach the transducer first?
Reflections from all three frequencies would have identical transmit times
You are performing a carotid duplex examination with the following: 5MHz doppler freq, 6KHz, 4cm depth, and a 1.5mm sample volume length, what is the aliasing frequency?
3KHz, One half the PRF (OPERATING FREQUENCY 6KHz)
Which of the following is the most reaspnable action to take when the image on your US system displays only bright reflections at all locations on the image, that arise from both strong and weak reflectors in the body: adjust the systems compensation, Dec
Decrease the overall amplification or gain
WHAT ARE THE TWO COMPONETS OF PULSED ULTRASOUND?
THE CYCLES (ON, TRANSMIT TIME)

THE DEAD TIME (OFF OR RECEIVE TIME)
What is the AIUM 100mm test object?
A device that contains rod groups to measure axial and lateral resolution, range accuracy, receiver compensation, dead zone, and thurough registration accuracy
What is the assumption # for slice thickness?
Assumption #6 The imaging plane is extremely thin
You have been asked to perform an endovaginal examination of a patient postmenopausal bleeding to evaluate the endometrial thickness. What is the main advantage of scanning endovaginally compared to scanning with a conventional curved linear array through
Since the endovaginal probe is closer to the area of interest, a higher frequency transducer can be used, resulting in superior spatial resolution
FOCUSING ALTERS BEAMS IN WHAT THREE WAYS?
1. NARROWER WAIST IN THE US BEAM
2. SHALLOWER FOCUS
3. SMALLER FOCAL ZONE
A transducer with a small foot print has which of the following disadvantages: Its too large to use for intercostals scanning, The far field of view is only 1/4 the diameter of the transducer, The Q value is very high, or Focusing degrades at a depth of t
Focusing degrades at a depth of twice the transducer aperature
echo-free
Anechoic
Define: reverberation.
Myltiple reflections
Reflection angle =
incident angle
Having revatively weak echos.
Hypoechoic
watts
Power has units of what?
____________ ___________

does not change when path length changes.
attenuation coefficient.
Is Vascular resistance: Directly, Inversely, Logithimically, or not proportional to the radius of the vessel?
Directly
continuously variable reception focusing that follows the increasing depth of the transmitted pulse as it travels
Dynamic focusing
*STUDY TANSDUCER CHART*!!!!!!
*STUDY TRNSDUCER CHART*!!!
Pressure
Concentration of force in an area
pascals(Pa)
 
B-mode
The first form of grayscale imaging.
Negative decibles means the intensity is doing waht?
Decreasing
What information does the Doppler shift furnish concerning the blood cells that produce it?
Velocity
What are the units for Doppler?
(KHz)
What type of transducers contain numerous elements that have a rectangular shape?
Linear-Array
Slice Thickness
Ultrasound beams have measurable thickness. However we asume that the imaging plane is razor thin. Occurs when beam has a greater width or size than the reflector.
Therefore the reflections produced by structures above or below the ideal imaging plane appears in the image. This may act to fill in hollow structures such as cysts.

Assumption #6 The imaging plane is extremly thin.

1. True reflector located outside of the idealized imaging plane appear on the image.

This artifact is cured with the 1 1/2 dimentional array transducer
For distance measurement to be accurate in an ultrasound tissue phantom, the phantom sound propagation speed must be waht?
1540m/s
An one dimensional display presenting the depth of a reflection in the vertical axis and the strength of the returning signal in the horizontal axis is termed:
A-mode
CW doppler utilizes how many elements?
Two
Which of the following corectly describes a typical CRT: Interlaced, progressice scan, bistable, or non-interlaced?
Interlaced
Artifactual gray-scale,color flow, or doppler signal appearing on the oppisite side of a strong reflector
Mirror image
Conversion of pressure to electric voltage
Piezoelectricity
Bandwidth divided by operating frequency
Fractional Bandwidth
WHAT ARE THE UNITS OF INTENSITY?
W/CM^2
LATERAL RESOLUTIN IS APPROXIMATELY EQUAL TO:
BEAM DIAMETER
attenuation coefficient(dB/cm) = frequency(MHz)/2
equation for attenuation coefficient
Inversely related
How are density and speed related?
What is the range of frequencies involved in a pulse?
Bandwidth
What is the formula for propagation speed?
C=wavelength*Freq
What is the formula for impedance?
Density*Prop Speed
Sounds waves are comprised of:
rarefactions and compressions
What elements convert electric voltage into ultrasound pulses and convert returning echoes back into voltages?
Piezoelectric Elements
What is the period of 5MHz frequency?
.0000002s
What sound parameter is determined only by the medium?
Propagation speed
Which resolution diminishes with pulse inversion:
A. axial
B. detail
C. lateral
D. contrast
E. temporal
E. temporal
Spatial pulse length is inversely proportional to the:
operating frequency
For linear array transducer, which method of focusing is used to focus the beam in the elevational direction?
Mechanical focusing
Which of the following methods will help you to demonstrate flow turbulence with color doppler: Autocorrelation, Variance, FFT, Zero crossing detection, or Phase quadrate detection?
Variance
Approximately what percent of the incident intensity is reflected at a soft tisue-air interface?

a. 100%
b. between 10% and 60%
c. 2% or less
d. 200%
a. 100%
Television frames are displayed at a rate of how many frames per second?
30
Sound propagation in which the propagation speed depends on pressure causing the wave shape to change and harmonics to be generated
Nonlinear propagation
Combination of positive or negative pressure
Constructive interference
Sophisticated form of transmission in which the driving voltage pulses have intrapulse variation in amplitude, frequency,and/or pulse
Coded excitation
The concentration of the sound beam into a smaller beam area than would exist otherwise
Focus
Fraction of time that pulsed ultrasound is on
Duty factor
Electronic device that manipulated and prepares images for visual presentation
Image processor
T/F
SOUND DOES NOT TRAVEL IN A STRAIGHT LINE.
FALSE
WHAT ARE THE TYPICAL VALUES OF FREQUENCY?
2MHz-10MHz
CONCENTRATION OF MASS WITH IN AN OBJECT?
DENSITY
true
A number followed by the word percent is unitlesss
LongitudinalAxialRangeRadialDepth
What are the other names for axial resolution?
What is the distance from the transducer to the center of the focal region?
Focal Length
Define: refraction.
Change of sound direction on passing from one medium to another
What are the effects of ultrasound on tissue termed?
Bioeffects
Refraction occurs when:
there are different propagation speeds and oblique incidence.
When you have additional beams of significant intensity that travels out in some direction not included in the main beam, they are a source of artifacts?
Side lobes
Unit
reference for how a measurement of a physical quanity is made
An echo from which of the following sound reflectors is most dependent on the angle of incidence: Rayleigh, Diffuse, Specular, Acoustic, or Nonspecular?
Specular
Which portion of the transducer increases the transmission of sound across the element-tissue boundary:
A. focus
B. aperture
C. damping
D. acoustic gel
E. matching layer
E. matching layer
Electronic beam steering in an array assembly is accomplished by the:
beam former
Where is the point of maximum intensity in a sound beam called?
Focal point
What is the minimum number of pulses required for color to be displayed using autocorrelation technique?
3
The units for impedence are:

a. dB
b. mm/microseconds
c. rayls
d. no units
c. Rayls
What is the maximum number of shades of gray in an 8-bit digital scan converter?
256
Region of minium beam diameter and area
Focal region
Size of a transducer element or group of elements
Aperature
Display that, with a sufficient frame rate, appears to image moving structures or a changing scan plane continuously
Real-time display
ARRAY LOOKS LIKE A "BULL'S EYE" TARGET
ANNULAR PHASED ARRAY
frequency and path lengthdirectly
Attenuation is determined by ______ and ______. It is ______ related to both.
reverse piezoelectric effect
the ability of certain materials to change shape when voltage is applied
What happens to duty factor when PRF increases?
DF increases
In order for reflection to occur when sound strikes a border between 2 media, what must be different for the reflection to take place?
Different Impedances
If the reflector is much smaller than the wavelength of sound, the ultrasounic energy is uniformly diverted in all directions. Higher frequency sound undergoes more of this. A rbc is this.
Rayleigh scattering
Shadowing
On occasions the US beam is unable to pass through a structure has a higher than usual attenuation.
1. shadow same as backround color
2.A result of too much attenuation
3. Abscence of true anatomy on scan
4.Parallel to the sound beam
Assumption # 5 Intensity of the reflections is related to the scattering characteristics of the tissue.
Attenuation increases with increasing what?
Path lenght, absorption, frequency, acoustic impedance
Which of the following frequencies is above human hearing:
A. 5 Hz
B. 20 Hz
C. 20 kHz
D. 20,000 Hz
E. 25,000 kHz
E. 25,000 kHz
You are using a linear array transducer to evaluate the thyroid gland, for standard B mode imaging, this modern day transducer most likely produces pulses of how many cycles?
One to three
The Nyquist limit is equal to what?
1/2 the PRF
In doppler systems, changing the PRF is equal to changing the:

a. color map
b. filter
c. velocity scale
d. color gain
c. velocity scale
You have increased the reject level while performing a thyroid US exam, what effect will you see in the image?
Decreased low-level echoes
Number that depends on flow speed and viscosity to perdict the onset of turbulence
Reynolds number
2 CHARECTERISTICS OF A HIGH FREQUENCY TXR:
-THIN CRYSTAL
-FAST PZT
THESE INFORM US WHICH WAVES ARE SOUND WAVES.
ACOUSTIC VARIABLES
In-phase waves
Two waves that peaks occur at the same time and at the same location
Focusing can only be accomplished in what zone of a transducer?
Near-zone of a transducer
What type of format, beam steering, and beam focusing does the following have: Phased array.
Electronic focusing and steering
What is the more complete name for linear array?
Linear Sequenced Array
Which of the following is true regarding the half value (HVL) thickness for a 10Mhz transducer in soft tissue? It represents a 3dB decrease in signal intensity, it occurs at a shallower dpth than the HVL for a 5Mhz transducer, It represents the point at w
A & B& C
Apodization is a function of which of the following instruments:
A. pulser
B. receiver
C. transducer
D. beam former
E. master synchronizer
D. beam former
An advantage of CW doppler over PW doppler is: Range resolution, Peak nyquist limit, Peak velocity detection, or Aliasing can be detected?
Peak velocity detection
wavelength is determined by:
a. sound source
b. medium
c. power
d. a and c
e. a and b
f. all the above
e. sound source and medium
What is the order in which the signal travels in the US system: Transducer-receiver-display-scan converter, Scan converter-transducer-receiver-display, Scan converter-receiver-transducer-display, Transducer-receiver-scan converter-display, or Receiver-tra
Transducer-receiver-scan converter-display
Length of space over which a pulse occurs
Spatial pulse length
IN MECHANICAL IMAGING, WHAT IS THE IMAGE SHAPE?
FAN OR SECTOR SHAPED
When transducer diameter or frequency increases, divergence decreases.
Does divergence increase or decrease with a larger diameter transducer? With a higher frequency?
What is the rule of thumb regarding propagation speed?
Prop speed increase=Stiffness increase=Density decrease
Prop speed decrease=Stiffness decrease=Density increase
3 DB means _____
2 times, the final intensity is 2 times bigger than the original intensity.
Comet tail or ring down
Appears as a solid line directed downward, merged reverberation.
1. Single, solid hyperechoic line
2.Long echo
3. Parallel to sound beam
4. A reverb with the 'space' squezzed out.

Hint when you have two strong reflectors there is a high differenc in the propagation speeds.
Assumption # 1 sound travels in a straight line
Which material is commonly used when manufacturing imaging transducer elements:
A. ceramic
B. tourmaline
C. Rochelle salt
D. lead zirconate titanate
E. polyvinylidene diflouride
D. lead zirconate titanate (PZT)
What happens when pressure is applied to a piezoelectric crystal?
It emits an electrical signal
What is spectral analysis used to do?
Determine the distribution and magnitude of frequency shifts in the reflected doppler signal
The percentage of time the sound is on is called?

a. PRF
b. PRP
c. Q factor
d. Duty factor
d. Duty factor
When you freeze an image, where is the echo information stored?
The scan converter
WHAT ARE THE UNITS OF THE THREE ACOUSTIC VARIABLES?
PRESSURE- PASCALS
DENSITY- GRAMS/CUBIC cm
PARTICLE MOTION- cm, inches, units of distance
High frequency shortens pulse length, improving axial resolution.
Why does high frequency improve LARRD resolution?
You are performing a venous ultrasound exam with a 5MHz linear array transducer using a single focal zone. Where is the thinnest width of the beam in the z-axis
At the point of mechanical focusing
Operating frequency is determined by what two things?
1. Propagation speed of the transducer material
2. Element thickness of the transducer element
How is a longitudinal wave characterized?
Particle motion occurring in the same direction as propagation
What determines the frequency of the transducer
The thickness of the transducers element and the propagation speed of the transducer material
The depth of a reflector from a 10 MHz probe is _____ if it was detected @ 1.54 microsecs:

a. 1.54 mm
b. 1.19 mm
c. 7.7 mm
d. 1.19 cm
b. 1.19 mm
What determines the acoustic power of a sound beam emitted from a transducer?
The voltage of the pulsers signal
focal depth, focal length, or near zone length
the distance from the transducer face to the focus
What is the assumption # for reverberations?
Assumption #1 Sound travels in a straight line
Convert the binary number 0101001 to decimal equivalent:
A. 17
B. 21
C. 41
D. 60
E. 82
C. 41

(Binary number 0101001=
0 + 32 + 0 + 8 + 0 + 0 + 1 = 41)
The color priority on color flow instruments is used to:

a. eliminate unwanted echoes
b. increase the brightness of white in the gray scale
c. compensate for weak echoes arriving to the transducer.
d. decide the relative contribution of color/echoes on
d. decide the relative contribution of color/echoes on the image
WHAT IS THE RELATIONSHIP BETWEEN POWER AND AMPLITUDE?
POWER IS PROPORTIONAL TO THE WAVE'S AMPLITUDE SQUARED
What does the dynamic range of the receiver of an ultrasound instrument refer to?
The range of echo signal amplitudes that can be processed without distortion
What is the assumption # for refraction?
Assumption # 1 sound travels in a straight line
Analog to digital conversion of the US signal must occur at what part of the imaging process?
Between the transducer and the scan converter
Beam diameter in the near field and focal zone narrowsFocal depth decreasesBeam diameter in the far zone increasesFocal zone is smaller
What are the four results from using focusing?
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