Radar Aliasing and Avoidance Techniques

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Questions and Answers

What is the primary cause of aliasing in pulsed Doppler systems?

  • Undersampling (correct)
  • Insufficient PRF
  • Inadequate baseline shifting
  • Improper Doppler shift frequency

What is the effect of increasing the Pulse Repetition Frequency (PRF) on aliasing?

  • It reduces the range of detectable velocities
  • It increases the likelihood of aliasing
  • It helps to avoid aliasing (correct)
  • It has no impact on aliasing

What is the definition of the Nyquist Limit (NL)?

  • The lower limit of Doppler shift detectable by pulsed instruments
  • The minimum baseline shift required to avoid aliasing
  • The maximum PRF value for pulsed Doppler systems
  • The upper limit of Doppler shift detectable by pulsed instruments (correct)

What is the result of temporal aliasing in Doppler systems?

<p>Improper Doppler shift information (direction and value) (B)</p> Signup and view all the answers

What is the typical range of PRF for pulsed Doppler instruments?

<p>5-30 kHz (C)</p> Signup and view all the answers

What is the purpose of baseline shifting in correcting aliasing?

<p>To electronically adjust the baseline (B)</p> Signup and view all the answers

What is the term for the region of the ultrasound beam close to the transducer?

<p>Near Zone (D)</p> Signup and view all the answers

What is the purpose of the Matching Layer in a transducer?

<p>To maximize acoustic energy transfer (B)</p> Signup and view all the answers

What is the term for the ability to distinguish structures perpendicular to the ultrasound beam?

<p>Lateral Resolution (C)</p> Signup and view all the answers

What is the primary factor that determines the ability to resolve features in the lateral dimension of an ultrasound image?

<p>Beam width (A)</p> Signup and view all the answers

What is the arrangement of elements in a Linear Array transducer?

<p>In a linear arrangement (C)</p> Signup and view all the answers

Which technique is used to enhance spatial resolution and contrast in ultrasound images?

<p>Virtual beamforming (C)</p> Signup and view all the answers

What is the term for the effective size or opening of the transducer that determines the width of the ultrasound beam?

<p>Aperture (B)</p> Signup and view all the answers

What is the term for the inherent focusing of certain transducer designs?

<p>Natural Focus (A)</p> Signup and view all the answers

What is the primary factor that influences the ability to resolve features in the elevation plane of an ultrasound image?

<p>Beam thickness (A)</p> Signup and view all the answers

What is the term for the secondary lobes that appear in phased array imaging?

<p>Grating Lobes (D)</p> Signup and view all the answers

What is the term for the range of frequencies that a transducer can effectively use for imaging?

<p>Useful frequency range (D)</p> Signup and view all the answers

What is the technique used to adjust the intensity of the ultrasound beam across its aperture to improve image quality?

<p>Apodization (A)</p> Signup and view all the answers

What is the primary purpose of the Mechanical Index (MI)?

<p>To indicate possible non-thermal bioeffects of the acoustic field (C)</p> Signup and view all the answers

What is the main function of Hydrofoam Measurement Devices?

<p>To measure the acoustic output of an ultrasound instrument (A)</p> Signup and view all the answers

What is the primary characteristic of a device that measures imaging performance?

<p>It takes into account the operation of the entire instrument (D)</p> Signup and view all the answers

What is typically used to assess the dynamic range of an ultrasound instrument?

<p>Echo free regions (A)</p> Signup and view all the answers

What is the primary factor in determining the reproducibility of an ultrasound instrument?

<p>The sonographer's ability (D)</p> Signup and view all the answers

What is the purpose of calculating the thermal indices (TIS, TIB, TIC) of an ultrasound beam?

<p>To display voluntary output standards (A)</p> Signup and view all the answers

What is the term for combining multiple images from different angles to improve image quality?

<p>Spatial compounding (C)</p> Signup and view all the answers

What is the measure of tissue stiffness in elastography?

<p>Young's modulus (B)</p> Signup and view all the answers

What is the purpose of time gain compensation?

<p>To adjust signal strength with increasing depth to compensate for attenuation (C)</p> Signup and view all the answers

What is the ability to distinguish structures in motion over time?

<p>Temporal resolution (A)</p> Signup and view all the answers

What is the term for the deformation or change in shape of tissues?

<p>Strain (D)</p> Signup and view all the answers

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