Test Questions Flashcards
Sound waves are…
Longitudinal and mechanical
The speed of ultrasound in soft tissue is closest to
1,500 m/s
The frequency closest to the lower limit of Ultrasound is
15,000 hz
Which is not an acoustic variable?
Density
pressure
distance
intensity
Intensity
The effects of soft tissue and Ultrasound are called
Acoustic propagational properties
Two waves with identical frequencies must interfere constructively.
True or False
True
Put in decreasing order..
Deca
Deci
Micro
Centi
Deca
Deci
Centi
Micro
________ is the time to complete one cycle.
Period
Which of the following sound waves is ultrasonic and least useful in diagnostic imaging?
30 khz
8mhz
8,000hz
15hz
30 khz
What is the frequency of a wave with 1 msec period?
10,000 hz
1,000 hz
1 khz
1 mhz
1 khz
______ is the distance covered by one cycle
Wavelength
Which of the following is determined by the source and a medium?
Frequency
Period
Propagation speed
Range resolution
Range resolution
Propagation speed = ______ x wavelength
Frequency
As a result of______ the propagation speed increases
Decreasing compressibility and decreasing density
Put in decreasing order of propagation speed
Gas
Liquid
Solid
Solid
Liquid
Gas
In the same medium, if the frequency of ultrasound is increased from 0.77 mhz to 1.54 mhz, what happens to the wavelength?
Halved
A sound waves frequency is 10 mhz. The waves traveling in soft tissue. What is it’s wavelength?
0.15 mm
1.54 mm
15.4 mm
10mhz
0.15 mm
If the frequency of an ultrasound wave is doubled, what happens to the period?
Halved
If the frequency of ultrasound is increase from 0.77 mhz to 1.54 mhz, what happens to the propagation speed?
Remains the same
The units of pulse repetition frequency are
Per minute
The time from the beginning of a pulse until its end is _______?
Pulse duration
What happens to the speed of sound in a medium when the bulk modulus of the medium increases?
Faster
_____ resolution is determined by the spacial pulse length
Radial or axial
If a wavelength amplitude is doubled, what happens to the power?
Nothing
Halved
Doubled
Quadrupled
Quadrupled
Power of sound has units of
Watts
If the intensity of a sound beam remains unchanged while the beam area is reduced in half, what has happened to the power?
Quadrupled
Doubled
Halved
Unchanged
Halved
Which of these intensities is smallest
SATP
SPTP
SATA
SATA
The duty factor for continuous wave ultrasound is
10.0
1%
1.0
0.0%.
1.0
What is the minimum value of the duty factor?
10.0
1 %
1.0.
0.0%.
0.0%.
What are the units of intensity?
Watts
DB
Watts/cm squared
DB
Watts/ cm squared
What happens to the speed of sound in a medium when the bulk modulus of the median decreases?
Faster
Slower
Unchanged
Slower
The units of attenuation are_____, this is a______ scale
dB, logarithmic
Sound intensity is decreased by 75%. How many decibels of attenuation is this?
6db
9DB
5 DB
10 Db
6DB
The fundamental frequency of a transducer is 2.5 MHz what is the second harmonic frequency?
1.25 MHz.
4.5 MHz.
5 MHz
5 cm
5 MHz
A pulse is emitted by a transducer and is traveling in soft tissue. The go return time, or time of flight, of a sound pulse is 130 µs. What is the reflector depth?
10 cm
10 mm
10 m
130 mm
13 cm
10 cm
If a 5 MHz sound wave is traveling in the tissues, listed below, which will have the shortest wave length?
Fat
Air
Muscle
Bone
Air
If a 5 MHz sound wave is traveling in the tissues, listed below, which will have the longest wavelength ?
Fat
Air
Muscle
Bone
Bone
What is the approximate attenuation coefficient of 1 MHz ultrasound in soft tissue?
0.5 dB/centimeters.
1 cm
3 dB/centimeters
1 dB
0.5 dB/centimeters.
The rayl is the unit of______
Intensity
Reflectance
Density
Impedance
Impedance
Impedance is the ______ of______ and_________.
Product, propagation, speed, density
What are attenuations three components
Scattering, reflection, absorption
For soft tissue, the approximate attenuation coefficient in dB/centimeters is equal to 1/2_______ in ______.
Wave length, MM
Frequency, HZ
Frequency, MHZ
Impedance, rayls
Frequency, MHZ
As the impedances of two media become vastly different, the_________ increases.
Reflection
Transmission
Refraction
Absorption
Reflection increases
The angle between an ultrasound pulse and the boundary between two media is 90°. What is this called?
Direct incidence
Oblique incidence
Indirect incidence
Orthogonal incidence
Orthogonal incidence
The angle between an ultrasound pulse and the boundary between two media is 56°. This is called ________
Direct incidence
Oblique incidence
Indirect incidence
Orthogonal incidence
Oblique incidence
Refraction only occurs if there are___________.
Oblique incidence, and different propagation speeds
With normal incidence, what factors affect refraction of ultrasound?
Propagation speed
Frequencies
Attenuation coefficients
None of the above
None of the above
With right angle, incidence, reflections are always generated at a boundary if the propagation speeds of the media are different.
True or false
False
_________ as a redirection of Ultrasound in many directions as a result of a rough boundaries between two media.
refraction.
Rayleigh scattering
Scattering
Reflection
Scattering
Which of the following tissues is most likely to create Rayleigh scattering?
Red blood cells
Muscle
Fat
Bone
Red blood cells
With normal incidents, the angle is 180°
True or false
False
Under which of the following conditions is axial resolution improved?
Decreased special pulse length
Decreased pulse amplitude
Decreased Imaging depth
Decreased pixel size
Decreased beam diameter
Decreased spacial pulse length
Snells law describes physics of______
Ultrasound
Reflection
Refraction
Transmission
Refraction
Most likely amount of reflection at a boundary between soft tissue is______
1%
22%
34%
99%
1%
The most typical amount of transmission at a boundary in biologic media is:
1 %
22%
34%
99%
99%
Sound is traveling from medium 1 to medium 2 . Propagation speeds of M1 and M2 are 1,600 m/s 1,500 m/s respectively. Three is normal incidence.
Angle of incidence > angle of reflection
Angle of incidence = angle of reflection
Angle of incidence < angle of reflection
Angle of incidence = angle of reflection
Doppler shifts always occur if the sound source and receiver are in motion
True or false
False
Which of the following is associated with power mode Doppler?
-Poor temporal resolution, and flash artifact
-lower sensitivity and good temporal resolution
-High sensitivity and high frame rates
-Flash artifact and reduce sensitivity
-Good temporal resolution and flash artifact
-Poor temporal resolution, and flash artifact
The Doppler shift is a measure of_______
-Ratio of incident frequency, to reflector frequency
-sum of incident frequency and reflective frequency
-difference between incident and reflect it frequency
-Product of incident and reflective frequencies
Difference between incident and reflected frequency
The sonographer cannot change directly or indirectly the duty factor of an ultrasound machine
True or false
False
Depth calibration of a machine measures 100 mm spaced wires to be 90 mm apart. Scanning reflectors 50 mm apart, what will the machine calculate the distance to be?
40 mm
45 mm
60 mm
65 mm
45 mm
There have not been biological effects from Ultrasound found in the laboratory
True or false
False
Which of the following is most relevant with regard to bioeffects?
Mechanical index
Overall gain
Output intensity
Thermal index
Output intensity
How many centimeters are 60 mm?
600
6
0.6.
0.06.
6
Lateral resolution is also called
Azimuthal
Which has the correct units?
Hz mm/s joules db/cm
MHz m/sec w/cm2 db
MHz m/sec w/cm2 db
What increases patient exposure?
Exam time
Frequency
Videotaping
Wave length
Exam time
Shadowing may result from higher amounts of reflection of ultrasound energy
True or false
True
Where are harmonics created?
In the receiver
In the transducer
In the tissues
In the beam former
In the tissues
How is range ambiguity Artifact eliminated?
Lower the PRF
Raise the PRF
Increase the gain
Use a lower frequency transducer
Lower the PRF
For Doppler, which incident, angle results, and no shift?
180°
90°
0°
45°
90°
Which transducer would be best to image superficial structures?
Small diameter, high frequency
Small diameter, low frequency
Large diameter, high frequency
Large diameter, low frequency
Small diameter, high frequency
A transducer with more than one active element is called-
Multipurpose
Annular
Mechanical
Array
Array
How many bits are needed to represent 16 shades of gray?
2
3
4
5
4
What information does Doppler shift provide?
Flow
Cardiac output
Velocity
Speed
Velocity
A sound wave is a pressure wave made of compressions and rarefactions.
True or false
True
A hydrophone is used to measure
Velocity
Frequency
Intensity
Phase
Frequency or intensity
Images on video tape are stored using-
Magic
Magnetism
Paper
computer memory
Magnetism
Circumferences may be measured in unit of
CM
CM squared
Cubic CM
Cubits
CM
Decimal uses a base of 10, binary uses a base of
1
2
5
10
2
If the frame rate increases and the lines per frame is unchanged, what else must happen?
Ultrasound speed increases
Frequency increases
Depth increases
Depth decreases
Depth decreases
Which of these cannot be performed by a Sonographer?
Adjust gain
Alter grayscale
Clean pixels
Adjust time gain compensation
Clean pixels
Which of the following is not a beam steering technique for a mechanical scan head?
Rotating wheel
Phased beam
Oscillating disc
Oscillating mirror
Phased beam
Which has the greatest amount of attenuation?
Bone
Fat
Water
Muscle
Bone
Which of the following will result in the greatest number of shades of gray in a digital image display?
Large pixels with many bits/pixel
Small pixels with few bits/pixel
Many TV lines per frame
High contrast
Narrow, dynamic range
Large pixels with many bits/pixel
What is not the responsibility of a sonographer?
Clean the filters
Adjust the recorder
Adjust converter matrix
Change paper
Adjust converter matrix
With good images on the display, but not on the printer, one should
Increase the gain
Check the scan head
Check scan converter
Adjust the recorder
Adjust the recorder
To measure the ultrasound beam, intensity, use a
Calibrated hydrophone
Lateral oscilloscope
Water filled phantom
Tissue equivalent phantom
Calibrated hydrophone
When the ultrasound machine displays only strong, reflecting objects, and nothing else, that sonographer should
Adjusted far gain
Increase output power
Increase lateral resolution
Adjust TGC
Increases output power
Dynamic range is used to
Decrease the amplitude
Altar grayscale
Reduce speckle
Altar grayscale
Reject is used to
Alter the appearance of highly reflective objects
Alter the appearance of Lowly reflective objects
Improve axial resolution
Improve digital scan converter sensitivity
Alter the appearance of Lowly reflective objects
If a reflector is moved twice as far away from the transducer, how will this affect the time of flight of a sound pulse?
Quadruple it
Double it
No change
Halve it
Double it
A single element transducer is focused
By the manufacturer
Cannot be focused
By increasing output power
By the sonographer
By the manufacturer
An ultrasound machine has a digital scan converter, but has an analog input signal. The machine needs to have a
Hybrid multiplexer
Modem
Analog to digital converter
Digital monitor
Analog to digital converter
Under which of the following conditions is lateral resolution improved?
Decreased beam diameter
Decreased pulse duration
Decreased Imaging depth
Decreased pixel size
Decreased beam diameter
In which way is an annular phase array, transducer different than a linear phased array transducer?
The linear is steered mechanically
The linear can have multiple focal zones
The annular can create a rectangular shaped image
The linear has higher pulse, repetition frequency
The annular is steered mechanically
The annular is steered mechanically