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Questions and Answers
If a reflector is 5cm deep in the body, approximately how long does it take for sound to reach it and return?
If a reflector is 5cm deep in the body, approximately how long does it take for sound to reach it and return?
- 32.5 ms
- 195 ms
- 130 ms
- 65 ms (correct)
Bandwidth is best described as the:
Bandwidth is best described as the:
- Range of harmonics in a pulse
- Average frequency in a pulse
- Range of frequencies within a pulse (correct)
- Lowest frequency in a pulse
Which characteristic of the medium primarily determines the velocity of an ultrasound wave?
Which characteristic of the medium primarily determines the velocity of an ultrasound wave?
- Density
- Stiffness (correct)
- Temperature
- Viscosity
An increase in which of the following parameters would increase volume flow?
An increase in which of the following parameters would increase volume flow?
Which of the following is NOT typically performed by the receiver?
Which of the following is NOT typically performed by the receiver?
Which intensity value would have the highest numerical value?
Which intensity value would have the highest numerical value?
To avoid flicker in an ultrasound image, the frame rate should be at least how many frames per second?
To avoid flicker in an ultrasound image, the frame rate should be at least how many frames per second?
What is the process of converting a voltage from one form to another within the receiver?
What is the process of converting a voltage from one form to another within the receiver?
Determining Doppler shift to provide accurate velocity information requires which technique?
Determining Doppler shift to provide accurate velocity information requires which technique?
The distance between two consecutive points in a wave is called:
The distance between two consecutive points in a wave is called:
The creation of microbubbles due to ultrasound is known as what?
The creation of microbubbles due to ultrasound is known as what?
Which type of resolution varies most with distance from the transducer?
Which type of resolution varies most with distance from the transducer?
What is the function of 'threshold' or 'rejection'?
What is the function of 'threshold' or 'rejection'?
Which statement about bioeffects of ultrasound is most accurate?
Which statement about bioeffects of ultrasound is most accurate?
Which receiver function do we NOT have direct control over?
Which receiver function do we NOT have direct control over?
In ultrasound imaging, what does 'B-mode' stand for?
In ultrasound imaging, what does 'B-mode' stand for?
Which of the following best describes reverberation?
Which of the following best describes reverberation?
What does DF stand for?
What does DF stand for?
In which area does the ultrasound beam diverge the most?
In which area does the ultrasound beam diverge the most?
What is the approximate wavelength ($\lambda$) of a 5 MHz transducer in soft tissue?
What is the approximate wavelength ($\lambda$) of a 5 MHz transducer in soft tissue?
Flashcards
Bandwidth
Bandwidth
The range of frequencies within a pulse.
Ultrasound velocity determinant
Ultrasound velocity determinant
The velocity of an ultrasound wave is determined by the medium through which it travels.
Receiver functions
Receiver functions
A receiver function performed by the receiver which includes amplification, compensation, compression, demodulation and rejection.
Highest intensity value
Highest intensity value
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Flicker-free image
Flicker-free image
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Demodulation
Demodulation
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Doppler shift analysis
Doppler shift analysis
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Wavelength
Wavelength
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Cavitation
Cavitation
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Lateral resolution variance
Lateral resolution variance
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B Mode
B Mode
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Reverberation
Reverberation
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Duty Factor (DF)
Duty Factor (DF)
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Far zone
Far zone
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Impedance (Z) formula
Impedance (Z) formula
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Nyquist Limit
Nyquist Limit
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Propagation Speed
Propagation Speed
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Duty factor
Duty factor
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Axial Resolution
Axial Resolution
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Compression
Compression
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Study Notes
- If a reflector is 5cm deep, sound takes 65 ms to reach it and return.
- Bandwidth is the range of frequencies within a pulse.
- The velocity of an ultrasound wave is determined by the medium.
- An increase in radius would increase volume flow.
- Amplification, compensation, compression, demodulation, and rejection are performed by the receiver.
- SPTP (Spatial Peak, Temporal Peak) has the highest intensity.
- At least 16 frames per second are needed to avoid flicker in an image.
- Demodulation converts a voltage from one form to another within the receiver.
- Determining Doppler shift for accurate velocity information needs Fast Fourier Transform (FFT).
- Wavelength is the distance between two consecutive points in a wave.
- Cavitation is the creation of microbubbles due to ultrasound.
- Lateral resolution varies most with distance from the transducer.
- Threshold or rejection is a level below which signals are not detected.
- Bioeffects are not confirmed below 100 mW/cm².
- Demodulation is a receiver function that is not operator-controllable.
- B-mode stands for Brightness mode.
- Reverberation is an artifact from highly reflective structures, appearing as equally spaced lines.
- Duty factor (DF) is the fraction of time the ultrasound transducer emits a pulse.
- The ultrasound beam diverges in the far zone.
- The wavelength of a 5 MHz transducer in soft tissue is 0.31 mm.
- Impedance (Z) equals density multiplied by propagation speed.
- Propagation speed artifacts include all but aliasing.
- The strength of an echo related to the height of the vertical deflection on the monitor is A-mode.
- Duty factor with diagnostic ultrasound machines is typically <1%.
- All elements, including TGCs, the transducer, and power, should be kept constant when using the AIUM phantom for comparison.
- Pulse duration (PD) equals the number of cycles multiplied by the period.
- Attenuation is a reduction of amplitude and intensity as sound passes through a medium.
- No injuries to humans from diagnostic ultrasound exposure have been reported.
- The compression button controls the number of shades of gray displayed by a system.
- Reducing beam diameter does not improve axial resolution.
- The Piezoelectric Effect is the conversion of sound to electricity, done by the transducer.
- Diagnostic ultrasound uses frequencies All of these: above the range of human hearing, determine the spatial resolution, that influence the penetration depth of the image
- A 4-bit system display can show 16 shades of gray.
- Lateral resolution is mostly dependent on beam diameter.
- A CRT (cathode ray tube) is used for display.
- A 9MHz transducer is best for superficial structures such as the thyroid, while a 3 MHz transducer is best for deeper structures like the abdomen.
- Period is the time it takes for a single cycle to occur.
- Ultrasound is defined as a sound wave above 20 kilohertz (>20kHz) and is inaudible.
- Wavelength (λ) equals propagation speed (c) divided by frequency (f): λ = c/f
- Q factor consists of all of these: operating frequency divided by bandwidth, is very low in ultrasound, and the ability for an US machine to operate at its center f
- The dead zone is an area where imaging cannot be performed.
- No harmful bioeffects of ultrasound have been confirmed in labs.
- LATA (lateral, angular, azimuthal, transverse) is a mnemonic for lateral resolution.
- Shadow can be caused by highly attenuating, highly reflecting, or highly absorptive objects.
- Doppler shift is at a minimum at a 90-degree angle.
- Decreasing the frequency results in better depth penetration.
- Intensity equals amplitude squared.
- A mechanical transducer has only one active element.
- Comet tail is a reverberation artifact.
- "In vitro" means the experiment is done in a test tube.
- Transient cavitation is worse than stable cavitation.
- Pulse Repetition Frequency (PRF) is determined by the number of lines per frame multiplied by the frame rate.
- More bits = better contrast resolution, more pixels = better spatial resolution.
- Piezoelectricity is producing an electrical voltage by applying enough pressure to a crystal to deform it.
- The scan converter is also called memory.
- Dynamic range is the smallest to largest ratio of amplitudes that a system can display.
- 5 cm converts to 50 mm.
- The limit to PRF and frequency to which aliasing will occur is the Nyquist limit.
- Refraction requires oblique incidence and a difference of impedance between two mediums.
- Snell's law applies to refraction.
- "Mega" can be expressed as 10^6.
- The TI (Thermal Index) indicates the potential for tissue heating.
- The compression operator is adjustable.
- The demodulation operator is not adjustable.
- M-mode is related to time and motion.
- The acoustic impedance of a medium equals the product of density and velocity.
- Viscosity is a liquid's resistance to flowing.
- Friction is a force that opposes motion between two surfaces in contact.
- Changing voltages to another form describes the process of demodulation consisting of rectification of negative signals to positive, then smoothing the new signal.
- Frame rate and PRF decrease when image depth increases.
- Higher frequency and more damping material improve axial resolution.
- The wavelength formula is wavelength = velocity/frequency.
- Propagation speed (velocity) is determined by the medium.
- The matching layer is the material in front of the transducer face.
- A 7.5 MHz transducer should image superficial structures.
- The impedance formula is Z=pc.
- Bandwidth is the amount of data transmitted over a network in a given amount of time.
- Inertia is the tendency of an object to resist a change in motion.
- Pulse duration is the product of the period and number of cycles in a pulse.
- The far zone is also known as the Fraunhofer zone.
- Attenuation is the loss of power in a signal as it heads from the sending device to the receiving device.
- The AIUM stated in 2008 that the intensity for mammalian in vivo biological effects should be 100 mW/cm.
- The speed for the medium soft tissue is 1540 m/s.
- The equation for wavelength is wave speed/frequency.
- More bits per pixel makes for better contrast resolution.
- Turbulent flow would show as green when using color Doppler in the variance mode.
- An ultrasound pulse requires 13 µs (microseconds) to travel 1 cm and back in soft tissue.
- A pixel is also known as a picture element.
- Spatial pulse length is the length that a pulse occupies in space from the start to the end of a pulse
- SPTP (Spatial Peak Temporal Peak) is the largest intensity.
- SATA (Spatial Average Temporal Average) is the lowest intensity.
- The frequency for infrasound is less than 20 Hz.
- The frequency for audible sound is 20-20,000 Hz.
- The frequency for ultrasound is > 20,000 Hz (greater than audible range).
- Mirror image is an artifact where sound bounces off a strong reflector, and ultrasound systems assume that sound travels directly to a reflector and back to the transducer.
- A ladder-like appearance is characteristic of reverberation artifacts.
- Propagation speed is the rate at which a sound wave travels through a medium.
- Duty factor is the percentage or fraction of time that the system transmits a pulse.
- Duty factor is unitless.
- Axial resolution is also known as LARRD (Longitudinal, Axial, Range, Radial, Depth).
- Frequency and depth of penetration have an inverse relationship.
- Penetration decreases if frequency is increased.
- Doppler shift always occurs if the source and reflector are in motion to each other and the angle between their motion isn't 90°.
- Intensity and amplitude squared are proportional.
- Lateral resolution can be improved by:
- Narrowing the beam in the proximal field by adding an acoustic lens
- Minimizing gain
- Using a phased array with multiple focal zones
- Increase the line density.
- Compression is a region in a longitudinal wave where particles are closest together.
- An annular array transducer has a sector image format.
- Doppler shift produces velocity information.
- Pulse Repetition Period (PRP) and Pulse Repetition Frequency (PRF) are Inversely and Reciprocals.
- Transient and stable are two types of cavitation.
- The beam of an unfocused transducer diverges most in the far zone.
- "In vivo" refers to animal studies.
- Bandwidth is what ultrasound pulses contain.
- Dynamic range is the ratio of the largest to the smallest amplitude or power that a system can handle.
- Rarefaction is the part of a longitudinal wave where the particles of the medium are far apart.
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