SPI Exam Dumps - Sonography Principles and Instrumentation

Comprehensive and Detailed Explanation From Exact Extract:

Persistence is a frame averaging function that combines multiple sequential frames to smooth random noise and reduce speckle, particularly effective in stationary or slow-moving structures.

According to official Principles and Instrumentation guidelines:

"Persistence reduces random noise by averaging multiple frames over time, improving image clarity but potentially reducing temporal resolution."

Increasing frequency improves resolution but may increase attenuation.

Sector width affects frame rate.

Depth affects penetration but not noise reduction.

Therefore, the correct answer is D: Persistence.

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QUESTION NO22

Which adjustment produced the change from waveform A to waveform B?

A close-up of a graph Description automatically generated

A. Increased Doppler gain

B. Decreased Doppler gain

C. Increased wall filter

D. Decreased wall filter

Answer: A

Comprehensive and Detailed Explanation From Exact Extract:

Comparing waveform A to waveform B:

In image B, the Doppler spectral waveform is brighter, with stronger signal amplitude and more clearly visible Doppler shifts.

This indicates that the Doppler gain was increased, amplifying the strength of the returning Doppler signals displayed on the spectral waveform.

According to official sonography Principles and Instrumentation:

"Doppler gain controls the amplification of returning Doppler signals. Increasing the gain enhances signal amplitude, making weaker Doppler signals more visible."

Decreasing gain (B) would have produced a dimmer waveform.

Changes in wall filter (C and D) would primarily affect low-velocity signal display, not overall brightness.

Therefore, the correct answer is A: Increased Doppler gain.

QUESTION NO23

Which aspect(s) would best explain why the amplitude of the signal from reflector B in this diagram is less than that from reflector A?

A diagram of a transducer Description automatically generated

A. Attenuation

B. Elasticity of the medium

C. Propagation speed differences

D. Acoustic impedance differences

Answer: A

Comprehensive and Detailed Explanation From Exact Extract:

As ultrasound travels through tissue, it experiences attenuation — a reduction in signal amplitude due to absorption, scattering, and reflection. The deeper the reflector, the greater the attenuation. Therefore, the signal from reflector B (deeper structure) is weaker than from reflector A (shallower structure) primarily due to attenuation.

According to Principles and Instrumentation:

"Attenuation is the reduction in ultrasound beam strength as it propagates through tissue, resulting in decreased signal amplitude from deeper structures."

Elasticity affects stiffness but not amplitude directly.

Propagation speed differences cause refraction or displacement, not amplitude changes.

Acoustic impedance differences cause reflection strength variations at interfaces but do not account for depth-dependent amplitude reduction.

Therefore, the correct answer is A: Attenuation.

QUESTION NO24

Which adjustment would eliminate aliasing in the Doppler waveform in this image?

A close-up of an ultrasound Description automatically generated

A. Decrease Doppler gain.

B. Decrease wall filter.

C. Increase velocity scale.

D. Increase sample size.

Answer: C

Comprehensive and Detailed Explanation From Exact Extract:

Aliasing occurs when Doppler frequency shifts exceed the Nyquist limit (which equals half the pulse repetition frequency). Increasing the velocity scale (which increases PRF) raises the Nyquist limit, reducing or eliminating aliasing.

Principles and Instrumentation state:

"Aliasing in pulsed-wave Doppler can be corrected by increasing the pulse repetition frequency (velocity scale), allowing higher velocities to be displayed without wraparound."

Decreasing gain affects amplitude, not aliasing.

Wall filter adjustments remove low-velocity signals, not aliasing.

Increasing sample size affects spatial resolution and may reduce frame rate but does not address aliasing.

Therefore, the correct answer is C: Increase velocity scale.

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When the depth of imaging is increased, the time it takes for the ultrasound pulses to travel to and from the deeper structures also increases, which can reduce the frame rate. To maintain the same frame rate, one effective adjustment is to decrease the image width. Narrowing the image width reduces the number of scan lines required to create each frame, allowing the system to maintain a higher frame rate despite the increased depth.

ARDMS Sonography Principles and Instrumentation guidelines

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

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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Comprehensive and Detailed Explanation From Exact Extract:

Transmit focus narrows the ultrasound beam width at specific depths, improving lateral resolution — the ability to distinguish two objects side-by-side.

According to Principles and Instrumentation:

"Lateral resolution depends on beam width and is improved by focusing, which narrows the beam in the lateral dimension."

Axial resolution depends on pulse length.

Elevational resolution depends on slice thickness.

Temporal resolution relates to frame rate.

Therefore, the correct answer is C: Lateral.

QUESTION NO17

Which statement characterizes the primary difference between image A and image B?

A close-up of a medical scan Description automatically generated

A. Image A demonstrates a better axial resolution.

B. Image A demonstrates a lower overall gain setting.

C. Image A demonstrates a shallower field of view.

D. Image A demonstrates a wider scale of contrast.

Answer: B

Comprehensive and Detailed Explanation From Exact Extract:

In image A, the structures appear darker with less overall brightness compared to image B. This indicates that the overall gain (receiver amplification) is set lower in image A, resulting in a dimmer image. Gain controls how much the returning echoes are amplified after detection.

According to Principles and Instrumentation:

"Overall gain amplifies all returning echoes equally. A lower gain setting results in a darker image, while higher gain brightens the display."

Axial resolution (A) is primarily dependent on frequency and pulse length, not visible here.

Field of view (C) appears similar between both images.

Contrast scale (D) refers to dynamic range, not directly indicated here.

Therefore, the correct answer is B: Image A demonstrates a lower overall gain setting.

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The color bar on a Doppler ultrasound display indicates the range of velocities that the system can detect and display. In color bar A, the scale is set to a higher maximum velocity (64 cm/s), while in color bar B, the scale is set to a lower maximum velocity (16 cm/s). Adjusting the scale (or velocity range) changes the upper and lower limits of the velocities displayed, which affects the sensitivity of the Doppler system to detect flow velocities. Lowering the scale allows for better visualization of lower velocities, but it may also increase the likelihood of aliasing for higher velocities.

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

Temporal resolution refers to the ability of the ultrasound system to distinguish events occurring closely in time. In color flow imaging, temporal resolution is affected by the frame rate, which can be increased by decreasing the width of the color field of view. This is because a narrower color field requires fewer scan lines to be processed, allowing for more frames to be captured per second.

ARDMS Sonography Principles and Instrumentation guidelines

Edelman, S. K. (2017). Understanding Ultrasound Physics.

Acoustic Shadowing: This artifact occurs when a structure absorbs or reflects most of the ultrasound waves, causing a shadow behind the structure. It does not cause improper positioning of a reflector on the display.

Speckle: This is a form of noise in ultrasound imaging that appears as granular texture. It can affect image quality but does not lead to improper positioning of reflectors.

Enhancement: This artifact occurs when the area behind a weakly attenuating structure appears brighter. It affects the brightness of the image but does not affect the position of reflectors.

Range Ambiguity: This occurs when an echo is received after the next pulse has been sent out, causing the reflector to be placed at an incorrect depth on the display. This is because the system assumes the echo came from the most recent pulse.

Comprehensive and Detailed Explanation From Exact Extract:

Attenuation increases with both frequency and depth. The highest attenuation occurs at the highest frequency and greatest depth. 7.5 MHz attenuates faster than 5 MHz, and 5 cm represents deeper tissue penetration.

Principles and Instrumentation state:

"Attenuation is directly proportional to frequency and path length: Attenuation = Frequency × Depth × Attenuation Coefficient."

Therefore, the correct answer is D: 7.5 MHz at 5 cm.

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