SPI Exam Dumps - ARDMS SPI Questions and Answers

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:

The matching layer is placed in front of the piezoelectric element and serves to reduce the difference in acoustic impedance between the transducer and human tissue, thereby improving sound transmission and minimizing reflection at the interface.

According to sonography instrumentation reference:

“The matching layer minimizes impedance mismatch between the transducer and soft tissue, allowing more efficient transmission of ultrasound energy into the patient.”

Therefore, the correct answer is D: Matching Layer.

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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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Autoclaving involves high-pressure steam at high temperatures, which can damage the delicate piezoelectric crystals within the ultrasound transducer. These crystals are responsible for converting electrical energy into sound waves and vice versa. Exposure to the extreme conditions of an autoclave can cause thermal and mechanical damage to the crystals, rendering the transducer ineffective.

ARDMS Sonography Principles and Instrumentation guidelines

Zagzebski, J. A. (1996). Essentials of Ultrasound Physics.

Incorrect color Doppler gain settings can cause the artifact known as bleed or blossoming. When the color Doppler gain is set too high, it can cause the color signal to "bleed" outside the actual boundaries of the blood vessel, leading to an overestimation of the area of flow. This artifact makes it appear as though the blood flow extends beyond the true vessel walls, which can obscure the accurate interpretation of the Doppler image.

References

ARDMS Sonography Principles and Instrumentation (SPI) Exam Study Guide

"Diagnostic Ultrasound: Principles and Instruments" by Frederick W. Kremkau

Write magnification, or pre-processing zoom, involves rescanning the region of interest (ROI) with more scan lines, thus acquiring new data for that specific area. This process increases the spatial resolution of the image in the magnified area because it gathers more detailed data by adjusting the scan parameters, resulting in improved image quality. This is different from read magnification (post-processing zoom), which simply enlarges the existing image data without increasing resolution.

A wall filter in Doppler ultrasound is designed to remove low-frequency signals that are often caused by tissue motion, vessel wall movement, or other forms of motion artifact. These low-frequency signals can clutter the Doppler spectrum, making it difficult to accurately interpret blood flow velocities. By filtering out these unwanted low-frequency signals, the wall filter helps to enhance the clarity of the Doppler signal, allowing for more accurate measurements of blood flow velocities.

American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.

Transducer beam divergence is influenced by the aperture size and frequency. A smaller aperture and lower frequency result in greater beam divergence. Among the given options, the transducer with a 4 mm aperture and 4 MHz frequency will have the greatest divergence. This is because the smaller aperture size contributes to a wider beam spread, and the lower frequency also increases the divergence compared to higher frequencies.

ARDMS Sonography Principles and Instrumentation guidelines

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

Aliasing in pulsed-wave Doppler occurs when the sampled Doppler frequency exceeds the Nyquist limit, which is half of the pulse repetition frequency (PRF). This results in an incorrect representation of the blood flow velocities, causing the waveform to wrap around and appear on the opposite side of the baseline. To correct aliasing, the PRF should be increased, which raises the Nyquist limit and allows for accurate measurement of higher velocities without aliasing. Increasing the PRF effectively reduces the likelihood of aliasing artifacts in the Doppler signal.

American Registry for Diagnostic Medical Sonography (ARDMS). Sonography Principles and Instrumentation (SPI) Examination Review Guide.

Reject: This control eliminates low-level noise and weak signals, affecting image quality but not primarily used for contrast resolution.

Output Power: This adjusts the intensity of the transmitted ultrasound waves but does not directly change contrast resolution.

Gain: This control amplifies all signals equally, affecting brightness but not specifically the contrast resolution.

Dynamic Range: Adjusting the dynamic range changes the range of grayscale that the ultrasound system displays, which directly affects the contrast resolution by altering how many shades of gray are visible between the black and white extremes.