SPI Leak Questions

Refraction is the change in direction of a sound wave as it crosses a boundary between two different tissues at an oblique angle, where there is a difference in propagation speeds between the tissues. This bending of the sound wave path occurs due to the change in speed, causing the wave to change direction according to Snell's law. Refraction can result in artifacts such as edge shadowing and displacement of structures in an ultrasound image.

Gray-scale evaluation in a tissue-mimicking phantom involves assessing the uniformity and accuracy of the gray-scale representation of the tissues.

Option C typically contains structures designed to test the machine's ability to accurately depict varying levels of echogenicity, which is essential for proper gray-scale evaluation.

This area will have a range of echo intensities that help in determining the contrast resolution and the ability of the system to distinguish between different tissue types based on their gray-scale values.References:

ARDMS Sonography Principles and Instrumentation guidelines on tissue-mimicking phantoms and image quality evaluation.

The ALARA principle stands for "As Low As Reasonably Achievable" and aims to minimize patient exposure to ultrasound energy. Decreasing the output power reduces the intensity of the ultrasound waves, thereby reducing the potential for tissue heating and mechanical effects, which aligns with the ALARA principle of minimizing exposure while still obtaining necessary diagnostic information.

ARDMS Sonography Principles and Instrumentation guidelines

Hangiandreou, N. J. (2003). "Physics Tutorial for Residents: Topics in US: B-Mode US: Basic Concepts and New Technology." Radiographics.

Comprehensive and Detailed Explanation From Exact Extract:

Continuous wave (CW) Doppler utilizes two separate crystals: one constantly transmitting and one constantly receiving. This setup allows CW Doppler to measure very high velocities without aliasing, but at the cost of losing range specificity (no depth resolution).

According to sonography instrumentation reference:

“Continuous wave Doppler uses two separate elements for continuous transmission and reception of sound waves, allowing for detection of very high velocities but without depth specificity.”

Therefore, the correct answer is D: Dedicated transmit and receive crysta

82

What artifact is indicated by the arrows in the image below?

An ultrasound image of a fetus Description automatically generated

A. Ring down

B. Grating lobe

C. Enhancement

D. Refraction

Answer: A

Comprehensive and Detailed Explanation From Exact Extract:

The image shows a bright, continuous, vertical band extending from a gas-containing structure (seen at the top). This is characteristic of ring down artifact, which occurs when multiple small gas bubbles resonate and create continuous echoes below the structure.

According to sonography instrumentation reference:

“Ring down artifact results from resonance of gas bubbles, producing a continuous series of echoes distal to the source. It appears as a bright, vertical band that does not fade with depth.”

Therefore, the correct answer is A: Ring down.

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