SPI Exam Dumps - ARDMS SPI Questions and Answers

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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The dead zone in ultrasound imaging refers to the region closest to the transducer where imaging is not possible due to the high amplitude of the initial pulse. In a tissue-mimicking phantom, this is the area where no useful imaging data can be obtained. The purpose of evaluating the dead zone is to ensure that it is as small as possible to maximize the usable imaging depth. In the provided image, Option A represents the area closest to the transducer face, which is typically used to evaluate the dead zone. The other areas are further away and are used for evaluating other parameters such as resolution or depth penetration.

Damping in a pulsed-wave transducer primarily affects the pulse duration. Damping refers to the process of reducing the vibration of the transducer crystal after the initial excitation. When damping is applied, it shortens the length of the ultrasound pulse by quickly reducing the vibration. This results in a shorter pulse duration, which is important for improving axial resolution. Damping does not directly affect the pulse repetition frequency, beam focus, or beam penetration, although it can have indirect effects on image quality and resolution.References:

ARDMS Sonography Principles and Instrumentation guidelines

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

According to Poiseuille's law, the flow rate of a fluid through a vessel is directly proportional to the fourth power of the vessel's radius. Therefore, a small change in the radius of the vessel has a much larger effect on blood flow compared to changes in pressure gradient, length of the vessel, or viscosity of the fluid.

ARDMS Sonography Principles and Instrumentation guidelines

Poiseuille's law in medical physics and hemodynamics literature.

The backing material, also known as damping material, in an ultrasound transducer serves to dampen the vibrations of the piezoelectric crystal.

This damping reduces the number of cycles in each pulse, leading to a shorter spatial pulse length (SPL).

Shorter SPL improves axial resolution by allowing the system to better distinguish between two closely spaced structures along the axis of the ultrasound beam.

Improved axial resolution is crucial for producing clearer, more detailed images.References:

ARDMS Sonography Principles and Instrumentation guidelines on transducer design and the role of backing material in image quality.

Comprehensive and Detailed Explanation From Exact Extract:

Reflection is maximized when the ultrasound beam strikes a tissue interface at 90 degrees (perpendicular). This angle provides optimal return of echoes for imaging.

According to sonography instrumentation reference:

“Maximal reflection occurs when the sound beam strikes a boundary at 90 degrees.”

Therefore, the correct answer is D: Reflection.

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Comprehensive and Detailed Explanation From Exact Extract:

Overall gain amplifies the strength of all returning echoes equally, regardless of depth. It does not affect the transmitted pulse or selectively compensate for attenuation; it simply amplifies received signals uniformly.

According to sonography instrumentation reference:

“Overall gain controls the amplification of all returning echoes across the entire image, increasing brightness uniformly at all depths.”

Therefore, the correct answer is B: Amplification of signals from all depths.

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Lateral resolution describes the ability of an ultrasound system to distinguish between two structures that are side by side (perpendicular to the path of the ultrasound beam). This type of resolution depends on the beam width; narrower beams provide better lateral resolution. As the ultrasound beam travels deeper into the tissue, it generally widens, which can reduce lateral resolution. Techniques such as focusing the beam can help improve lateral resolution at specific depths by narrowing the beam width.

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

Comprehensive and Detailed Explanation From Exact Extract:

Cross talk (spectral mirror artifact) appears as a duplication of the spectral waveform above and below the baseline. One primary cause is excessive Doppler gain, which amplifies weak signals and noise symmetrically. Reducing gain minimizes this artifact.

Principles and Instrumentation state:

"Cross talk in spectral Doppler may result from high gain settings. Lowering the gain can reduce or eliminate this artifact."

PRF adjustments affect aliasing, not cross talk.

Baseline shifts affect waveform positioning.

Wall filter affects low-frequency signals but not cross talk.

Therefore, the correct answer is A: By decreasing the Doppler gain.

QUESTION NO28

Which artifact is demonstrated by the arrow in this image?

A close-up of an ultrasound Description automatically generated

A. Mirroring

B. Noise

C. Shadowing

D. Enhancement

Answer: C

Comprehensive and Detailed Explanation From Exact Extract:

The image shows an area of signal dropout directly deep to the strongly reflecting structure (likely a vessel wall or calcification), indicated by the arrow. This is a classic example of shadowing artifact.

According to sonography Principles and Instrumentation:

"Shadowing occurs when a highly attenuating or reflective structure blocks the ultrasound beam, resulting in absence of signal distal to the object."

Mirroring (A) produces duplicated structures.

Noise (B) appears as random speckles.

Enhancement (D) produces increased echogenicity distal to an anechoic structure.

Therefore, the correct answer is C: Shadowing.

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Comprehensive and Detailed Explanation From Exact Extract:

Color Doppler detects flow based on the Doppler shift, which is dependent on the cosine of the angle between the ultrasound beam and the direction of blood flow. At 90 degrees, the cosine value is zero, resulting in no Doppler shift and therefore no detectable color flow signal.

According to sonography instrumentation reference:

“When the insonation angle is 90 degrees, the Doppler frequency shift is zero because the cosine of 90 degrees equals zero. As a result, no flow is displayed.”

Therefore, the correct answer is D: 90 degrees.

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