Questions and Answers
What is dynamic aperture?
To which acoustic variable is penetration depth inversely related?
Which imaging mode requires a broadband transducer?
What is the Doppler shift frequency?
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What is the potential effect of increasing the pulse repetition frequency (PRF)?
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What is an advantage of using pulsed wave Doppler compared to continuous wave Doppler?
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What affects the beam width in the near field?
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What is the advantage of using pulsed-wave Doppler versus continuous-wave Doppler?
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Which parameter is target group C evaluating based on the image?
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In this image, which target group is used to evaluate dead zone?
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Which ultrasound parameter directly affects an ultrasound beam's intensity?
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The center frequency of a transducer depends primarily upon which characteristics of the crystal?
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Which factor limits image frame rate?
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When using a 5 MHz transducer, in which tissue is the ultrasound wavelength shortest?
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Which term describes the averaging together of scan lines from multiple angles to create one image?
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Which variable can cause an acoustic shadow artifact?
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What does coded excitation improve in addition to penetration?
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How is lateral resolution determined for a pulsed-echo system using a tissue-mimicking test object?
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Which variable caused the color change from blue to red of the vessel in this image?
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Which artifact is indicated by the arrows in this image?
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Which control improves the effects of attenuation?
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Which Doppler angle to flow results in the greatest absolute Doppler shift?
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What term describes blood flow changes in response to respiration?
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An increase in which parameter will improve the accuracy of velocity measurements with autocorrelation?
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Which harmonic imaging, how does echo frequency relate to transmitted frequency?
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Which change would minimize the artifact observed in this image, assuming the pulse repetition frequency is at its maximum limit?
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Which parameter is most likely to affect spatial resolution?
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Which imaging modality can provide the most accurate measurement of tumor volume?
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According to ALARA (as low as reasonably achievable) guidelines, which parameter should be minimized?
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What is an advantage of using pulsed-wave Doppler versus continuous wave Doppler?
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What is demonstrated in this image produced by a linear array transducer placed on a uniform tissue-mimicking phantom?
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What is the distance to the interface if the round trip time for a sound wave is 39 microseconds?
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Which signals are eliminated by the wall filter in a spectral Doppler display?
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At minimum, what is required when documenting a pathology discovered during an examination?
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If the diameter of the sound beam is halved by focusing, what happens to the intensity?
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Which parameter would change on a phantom test if the spatial pulse length were made longer?
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If the ultrasound machine comes in contact with a patient's body fluids, what should be done?
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Which parameter is most related to cavitation tissue?
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Which interface will cause the maximum reflection of the incident sound beam?
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Acoustic enhancement occurs distal to what?
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As the pressure amplitude of ultrasound doubles, what happens to the wavelength?
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What is the period of a 5 MHz ultrasound wave?
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What limits diagnostic application at higher frequencies?
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What is the function of a lens on a transducer?
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What would improve axial resolution?
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What is true of the far field?
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What improves lateral resolution?
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Which statement is true for a linear phased array transducer?
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Which artifact is commonly seen within cystic masses due to the finite dimensions of the ultrasound beam?
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Which technique utilizes frequency modulation of the transmitted pulse to improve signal to noise ratio?
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What is varied to implement apodization?
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What will produce no Doppler shift at a receiver?
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Which mode requires two elements mounted side by side?
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When employing a tissue mimicking phantom, the depth at which echoes are no longer detected is an indicator of what?
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What enhances the transmission of ultrasound energy between the transducer and the skin?
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Which technique increases the sharpness of high contrast boundaries?
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What is the most appropriate action for the sonographer to take when receiving a verbal order for an exam?
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Which setting of an ultrasound system gives the sonographer the ability to display both strong and weak echoes?
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What is a benefit of using contrast agents?
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A sound wave propagates fastest through which substance?
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When the focal point in a B-mode image is electronically changed, which type of focusing is in use?
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When a fluid is flowing at a slow and constant rate within a long tube having a uniform diameter, what is the nature of the flow?
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What causes range ambiguity artifacts?
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What is the round trip time in soft tissue for an echo from a reflector at a depth of 1 cm?
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Which variable decreases when the number of acoustic lines per frame is increased without changing its maximum depth?
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Frequency compounding improves image quality by doing what?
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What is the most common cause of localized vertical nonuniformity in a real-time B-mode image?
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What is the cause of the black region in the center of the vessel seen in this image?
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What is increased if the pulse duration is decreased?
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What is the Nyquist limit if a pulsed wave Doppler instrument has a pulse repetition frequency of 16 kHz?
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What caused the color pattern demonstrated in the artery indicated by the arrow in this image?
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Which adjustment should be made to avoid the aliasing displayed on this spectral Doppler image seen on spectral analysis?
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If red blood cells are approaching a 5 MHz Doppler transducer at a speed of 75 cm/s, what is the approximate received ultrasound frequency?
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Which condition must be present for refraction to occur?
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The thermal index (TI) is most affected by which type of interaction between sound and tissue?
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In an unfocused transducer, what is the region between the transducer face and the point where the beam diverges?
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What is this artifact?
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How do you fix this?
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Which way is the blood flowing?
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Study Notes
Dynamic Aperture and Imaging Modes
- Dynamic aperture varies with transmit frequency, affecting imaging quality as focal length changes.
- Penetration depth is inversely related to frequency; higher frequencies result in lower penetration.
- Pulsed wave Doppler requires broadband transducers, essential for capturing detailed blood flow information.
Doppler Shift and Pulse Repetition Frequency
- Doppler shift frequency is the difference between transmitted and received ultrasound frequencies, critical for measuring flow velocities.
- Increasing pulse repetition frequency (PRF) can lead to depth ambiguity, complicating signal interpretation, while also affecting frame rate.
Imaging Parameters and Artifacts
- Near field beam width is influenced by transducer aperture, impacting image resolution.
- Dead zone evaluation is crucial for diagnostic accuracy; it determines areas where no echoes are received, leading to potential interpretation errors.
- Coded excitation enhances penetration and improves the signal-to-noise ratio in Doppler imaging.
Resolution and Acoustic Variables
- Axial resolution is determined by pulse length; shorter pulses yield better resolution.
- Lateral resolution is improved by decreasing beam width, enhancing the clarity of structures in the imaging plane.
- The acoustic shadow artifact occurs due to high acoustic impedance mismatches, while acoustic enhancement occurs distal to weakly attenuating structures.
Transducer Characteristics and Frequency Relationships
- Transducer center frequency primarily depends on crystal thickness, influencing image quality and depth of visualization.
- Higher frequencies offer better resolution but are limited by penetration capabilities in soft tissue.
- Frequency modulation techniques like coded excitation can augment imaging quality through enhanced signal capture.
Doppler Characteristics and Blood Flow
- The greatest absolute Doppler shift occurs at a 0-degree angle to flow, essential for accurate velocity measurements.
- Phasic blood flow changes occur in response to respiration, impacting the interpretation of Doppler signals.
- Increased packet size improves velocity measurement accuracy, particularly in power Doppler imaging.
Artifacts and Image Interpretation
- Range ambiguity artifacts result from overly high PRF, leading to confusion in depth interpretation.
- Specific artifacts like mirror image and reverberation can confuse diagnosis and must be recognized for proper image assessment.
- Resolving color aliasing involves adjustments such as decreasing transducer frequency or repositioning sample volumes.
Safety and Operational Practices
- ALARA principles recommend minimizing transmit power to reduce patient exposure while maintaining image quality.
- Infectious protocols must be adhered to when ultrasound machines come into contact with bodily fluids to ensure safety and reliability.
Practical Applications and Technical Knowledge
- Understanding the behavior of sound waves in different mediums, such as bone and fat, is essential for accurate imaging and diagnosis.
- Training and experience contribute significantly to recognizing and correcting parameters affecting image quality, like dynamic range and gain settings.
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Description
Test your knowledge with SPI practice flashcards focusing on ARDMS A & B topics. Dive into key concepts like dynamic aperture and acoustic variable relations. Perfect for students preparing for their SPI certification.