ARDMS SPI - Sonography Principles and Instrumentation

Comprehensive and Detailed Explanation From Exact Extract:

Output power directly affects the intensity of the ultrasound beam transmitted into the patient. Reducing output power lowers the risk of both thermal and mechanical bioeffects.

According to sonography instrumentation reference:

“Output power should be minimized following the ALARA (As Low As Reasonably Achievable) principle to reduce potential bioeffects while still obtaining diagnostic-quality images.”

Therefore, the correct answer is B: Output power.

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In this image, which characteristics of flow are represented by the upper right side of a variance mode color map?

A close-up of a screen Description automatically generated

A. Higher velocity, laminar with a positive Doppler shift

B. Higher velocity, laminar with a negative Doppler shift

C. Higher velocity, turbulent with a positive Doppler shift

D. Higher velocity, turbulent with a negative Doppler shift

Answer: C

Comprehensive and Detailed Explanation From Exact Extract:

In variance mode color Doppler, colors are assigned based on both flow direction (Doppler shift polarity) and flow character (laminar vs turbulent). In the image:

The vertical color bar shows standard Doppler shifts: positive shifts (toward the transducer) are displayed at the top, and negative shifts (away from the transducer) at the bottom.

The variance mode adds horizontal color variation (from left to right), where the right side indicates increasing turbulence.

Thus, the upper right portion of the color bar indicates:

Positive Doppler shift (flow toward the transducer)

High velocity

Turbulent flow

According to sonography instrumentation reference:

“In variance mode, the vertical axis represents flow direction and velocity, while the horizontal axis represents flow variance (turbulence). The upper right corner indicates high-velocity turbulent flow toward the transducer.”

Therefore, the correct answer is C: Higher velocity, turbulent with a positive Doppler shift.

Comprehensive and Detailed Explanation From Exact Extract:

The wall filter in Doppler ultrasound is designed to eliminate low-frequency signals, typically associated with motion artifacts such as vessel wall or tissue motion. These low-frequency signals are not part of the desired blood flow signal and can interfere with accurate Doppler display.

When the wall filter setting is increased, it removes these low-frequency signals from the Doppler spectrum. However, increasing the wall filter too much can also eliminate true low-velocity flow information, leading to a loss of clinically relevant data.

This principle is described in official sonography Principles and Instrumentation references:

"Increasing the wall filter will reduce the display of low-frequency Doppler shifts, which are typically associated with slow-moving structures. These low-frequency signals can represent either slow blood flow or tissue motion artifacts."

Therefore, the correct answer isD: Reduced display of low-frequency shifts.

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 calipers shown in the image are used to measure the depth of structures within the ultrasound image. This performance characteristic, known as depth measurement accuracy, assesses how accurately the ultrasound system can measure the distance from the transducer to a specific point within the body. Accurate depth measurements are crucial for diagnostic purposes, ensuring that anatomical and pathological structures are correctly identified and evaluated.

American Registry for Diagnostic Medical Sonography (ARDMS) Sonography Principles and Instrumentation study materials.

Textbook of Diagnostic Sonography by Hagen-Ansert, S. L. (latest edition).

Comprehensive and Detailed Explanation From Exact Extract:

Higher frequency transducers provide better axial resolution due to their shorter wavelengths and spatial pulse lengths. This allows finer detail when imaging superficial structures where penetration is not a concern.

According to sonography instrumentation reference:

“Higher frequencies result in shorter pulse lengths, improving axial resolution and making them ideal for superficial imaging.”

Therefore, the correct answer is D: Improved axial resolution.

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Comprehensive and Detailed Explanation From Exact Extract:

In color Doppler imaging, the default color map assigns red and blue to represent flow direction relative to the transducer (usually red toward, blue away). The color invert control reverses this assignment.

According to sonography Principles and Instrumentation:

"The color invert control reverses the baseline of the color map, swapping red and blue assignments for flow direction."

Color priority adjusts the overlay of color vs grayscale.

Color gain controls amplification of the Doppler signal.

Color threshold sets minimum amplitude to display color.

Therefore, the correct answer is D: Color invert.

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Comprehensive and Detailed Explanation From Exact Extract:

Acoustic impedance (Z) is determined by the product of tissue density (ρ) and propagation speed (c), expressed as:

Z = ρ × c

According to Principles and Instrumentation:

"Acoustic impedance is a property of the tissue, determined by its density and the speed of sound through it."

Penetration depth (A) does not affect impedance directly.

Attenuation coefficient (B) affects signal loss, not impedance.

Transducer frequency (D) is independent of tissue impedance.

Therefore, the correct answer is C: Tissue density.

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Persistence is a technique used in ultrasound imaging that averages individual frames together to improve the overall image quality. This process helps to reduce noise and improve the signal-to-noise ratio, leading to clearer and more stable images. By averaging multiple frames, transient artifacts are minimized, and the continuity of structures is better visualized. Persistence is particularly useful in imaging static or slow-moving structures.References:

ARDMS Sonography Principles and Instrumentation guidelines

"Ultrasound Physics and Technology: How, Why and When" by M. Evans, C. Archer, and K. Weston

During 3-D volume acquisition in ultrasound, the quality of the images is most dependent on the number of slices acquired. This is because the more slices (or planes) that are captured, the more detailed and accurate the reconstruction of the 3-D volume will be. This allows for better spatial resolution and more precise visualization of anatomical structures. Other factors, such as power output, rendering methods, and speed of post-processing, also affect image quality but are secondary to the number of slices in terms of fundamental image acquisition quality.

Lateral resolution refers to the ability to distinguish two structures that are side by side. It is dependent on the width of the ultrasound beam. By decreasing the depth of field, the beam width is reduced at any given point along the depth, which improves the lateral resolution. This is because a narrower beam can better distinguish between objects that are close together laterally.

ARDMS Sonography Principles and Instrumentation guidelines

Kremkau, F. W. (2015). Diagnostic Ultrasound: Principles and Instruments.