Radar Aliasing and Avoidance Techniques

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?

Improper Doppler shift information (direction and value) (B) Signup and view all the answers

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

5-30 kHz (C) Signup and view all the answers

What is the purpose of baseline shifting in correcting aliasing?

To electronically adjust the baseline (B) Signup and view all the answers

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

Near Zone (D) Signup and view all the answers

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

To maximize acoustic energy transfer (B) Signup and view all the answers

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

Lateral Resolution (C) 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?

Beam width (A) Signup and view all the answers

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

In a linear arrangement (C) Signup and view all the answers

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

Virtual beamforming (C) 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?

Aperture (B) Signup and view all the answers

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

Natural Focus (A) 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?

Beam thickness (A) Signup and view all the answers

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

Grating Lobes (D) Signup and view all the answers

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

Useful frequency range (D) 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?

Apodization (A) Signup and view all the answers

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

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

What is the main function of Hydrofoam Measurement Devices?

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

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

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

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

Echo free regions (A) Signup and view all the answers

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

The sonographer's ability (D) Signup and view all the answers

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

To display voluntary output standards (A) Signup and view all the answers

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

Spatial compounding (C) Signup and view all the answers

What is the measure of tissue stiffness in elastography?

Young's modulus (B) Signup and view all the answers

What is the purpose of time gain compensation?

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

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

Temporal resolution (A) Signup and view all the answers

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

Strain (D) Signup and view all the answers