ARDMS SPI (Sonography Principles & Instrumentation) Exam — Questions and Answers

Question 1: The time-averaged mean velocity (TAMV) is the denominator used to calculate which Doppler index?

Systolic-to-Diastolic (S/D) Ratio
Acceleration Index (AI)
Pulsatility Index (PI) (Correct answer)
Resistive Index (RI)

Correct answer: Pulsatility Index (PI)

The Pulsatility Index = (PSV - EDV) / TAMV; it is the only common index using the mean velocity as the denominator, making it calculable even when end-diastolic flow is zero or reversed.

Question 2: The speed of sound for tissue comparable phantoms should be equal to:

4.28 mm/us
1,540 m/s (Correct answer)
1,960 m/s
1.84 mm/us

Correct answer: 1,540 m/s

The average speed of sound in soft human tissue is approximately 1,540 meters per second (or 1.54 mm/µs). For phantoms to accurately simulate human tissue and allow for proper calibration and quality assurance of ultrasound equipment, their speed of sound must match this value. This ensures that the ultrasound system's distance measurements and image reconstruction are accurate.

Question 3: Posterior acoustic enhancement (increased echoes deep to a structure) occurs when sound passes through:

A calcified region
A gas-containing interface
A fluid-filled structure with low attenuation (Correct answer)
A highly attenuating structure such as bone

Correct answer: A fluid-filled structure with low attenuation

Fluid-filled cysts attenuate sound less than surrounding tissue, so the beam emerges stronger, producing brighter echoes (enhancement) posterior to the cyst.

Question 4: Posterior acoustic enhancement (increased through-transmission) is seen deep to structures that:

Reflect nearly all incident sound energy
Have high acoustic impedance relative to surrounding tissue
Attenuate sound less than surrounding tissue (Correct answer)
Contain gas bubbles

Correct answer: Attenuate sound less than surrounding tissue

Fluid-filled cysts attenuate sound minimally, so echoes returning from deep to the cyst are stronger than expected, appearing brighter.

Question 5: Color Doppler 'color bruit' (perivascular color artifact) around an AV fistula is caused by:

High-velocity turbulent flow causing tissue vibration that is detected as Doppler shifts (Correct answer)
Color bleed from high gain settings
Flash artifact from patient breathing
Mirror image of the vessel

Correct answer: High-velocity turbulent flow causing tissue vibration that is detected as Doppler shifts

Tissue vibration from high-velocity turbulent flow in an AV fistula generates low-frequency Doppler shifts in surrounding soft tissue, producing a color bruit.

Question 6: Which of the following describes the piezoelectric effect as it is utilized in an ultrasound transducer during sound wave reception?

Conversion of an electrical signal into a mechanical vibration.
Conversion of acoustic energy into light.
Conversion of electrical energy into heat.
Conversion of a pressure wave into an electrical signal. (Correct answer)

Correct answer: Conversion of a pressure wave into an electrical signal.

The piezoelectric effect is the ability of certain materials to generate an electric charge in response to applied mechanical stress. During reception, the returning sound echoes (which are pressure waves) cause the piezoelectric crystals to vibrate, and this mechanical deformation is converted back into an electrical signal for processing by the ultrasound system.

Question 7: A pulsed sound wave is best described by the following acoustic parameter:

Period
Frequency
Propagation speed
Duty factor (Correct answer)

Correct answer: Duty factor

The duty factor is the fraction of time that the pulsed ultrasound system is actively transmitting sound. It is a dimensionless number representing the ratio of pulse duration to the pulse repetition period. Since a pulsed wave involves intermittent periods of transmission and listening, the duty factor is a key acoustic parameter that specifically characterizes its intermittent nature.

Question 8: Which index is calculated as (PSV − EDV) / PSV and is used to describe the shape of an arterial Doppler waveform?

S/D ratio
Pourcelot (Resistivity) Index (Correct answer)
Pulsatility Index
Acceleration Index

Correct answer: Pourcelot (Resistivity) Index

The Resistivity Index (RI), also called the Pourcelot Index, is (PSV − EDV) / PSV and reflects downstream vascular resistance; values range from 0 (no resistance) to 1 (absent diastolic flow).

Question 9: When depth is raised, which of the following happens?

Time of flight decreases
Tframe shortens
Frame rate decreases (Correct answer)
Temporal resolution increases

Correct answer: Frame rate decreases

When imaging depth is increased, the ultrasound pulse must travel a greater distance to and from the deepest reflector. This increases the 'time of flight' for each pulse, which in turn lengthens the pulse repetition period (PRP) and decreases the pulse repetition frequency (PRF). Since frame rate is directly proportional to PRF, an increase in depth ultimately leads to a decrease in the frame rate.

Question 10: Which of the following statements is true regarding the relationship between axial and lateral resolution?

Axial resolution remains constant with depth, while lateral resolution varies. (Correct answer)
Axial resolution is typically better than lateral resolution in the far field.
Lateral resolution is primarily determined by the spatial pulse length.
Both axial and lateral resolution are independent of imaging depth.

Correct answer: Axial resolution remains constant with depth, while lateral resolution varies.

Axial resolution is determined by the spatial pulse length, which does not change as the beam travels through tissue. Therefore, axial resolution is constant at all depths. Lateral resolution, however, is determined by the beam width. The beam width changes with depth, being narrowest at the focal zone and widening in the near and far fields. This means lateral resolution varies with depth.

Question 11: Which tissue type has the highest acoustic propagation speed?

Soft tissue
Air
Fat
Bone (Correct answer)

Correct answer: Bone

Bone has the highest stiffness among listed tissues, giving it the greatest propagation speed (~3500 m/s).

Question 12: The resonant frequency of a piezoelectric crystal is primarily determined by its:

Surface area
Thickness (Correct answer)
Electrical capacitance
Diameter

Correct answer: Thickness

Resonant frequency is inversely proportional to crystal thickness: f = c / 2t, where c is the propagation speed within the crystal.

Question 13: A sonographer is performing a quality assurance test on a duplex ultrasound system to verify the accuracy of spectral Doppler velocity measurements. Which type of phantom is most appropriate for this task?

Beam profile/slice thickness phantom
Doppler flow phantom (Correct answer)
AIUM 100mm test object
Tissue-equivalent phantom with anechoic cysts

Correct answer: Doppler flow phantom

A Doppler flow phantom is specifically designed to evaluate Doppler systems. It contains a blood-mimicking fluid that moves at known velocities through tubes, allowing for the verification of velocity accuracy, color flow sensitivity, and spectral Doppler measurements. The other phantoms are designed for B-mode imaging evaluation.

Question 14: A high-resistance spectral Doppler waveform is characterized by:

Absent systolic peak with preserved diastolic flow
Continuous forward flow throughout the entire cardiac cycle
Low or absent end-diastolic velocity with a sharp systolic peak (Correct answer)
High end-diastolic velocity with low peak systolic velocity

Correct answer: Low or absent end-diastolic velocity with a sharp systolic peak

High-resistance vessels (such as resting peripheral arteries) display a sharp systolic peak with little or no diastolic flow and may demonstrate brief flow reversal in early diastole.

Question 15: Increasing the depth setting on an ultrasound system will have what effect on frame rate?

Frame rate decreases (Correct answer)
Frame rate increases
Frame rate doubles
Frame rate is unaffected

Correct answer: Frame rate decreases

Increasing depth requires longer pulse travel time, reducing the number of frames that can be acquired per second.

Question 16: In the Doppler equation, doubling the transmitted frequency while keeping all other variables constant will have what effect on the detected Doppler shift?

The Doppler shift will double (Correct answer)
The Doppler shift will remain unchanged
The Doppler shift will be halved
The Doppler shift will quadruple

Correct answer: The Doppler shift will double

Since Δf = 2f₀v cosθ / c, the Doppler shift is directly proportional to the transmitted frequency f₀; doubling f₀ doubles Δf when velocity, angle, and speed of sound remain constant.

Question 17: Which of the following properties of a medium has the most significant influence on the propagation speed of an acoustic wave?

Stiffness (Correct answer)
Temperature
Viscosity
Density

Correct answer: Stiffness

Propagation speed is primarily determined by the stiffness (or bulk modulus) and density of the medium. Of these two, stiffness has the greater influence. Sound travels faster in stiffer materials. While density does affect speed (higher density generally leads to slower speed), its effect is less pronounced than that of stiffness. For example, bone is much denser than soft tissue, but it is also significantly stiffer, resulting in a much higher propagation speed. [11, 13]

Question 18: During a renal artery duplex examination, the acceleration time (AT) from a waveform sampled in the intrarenal arteries is measured at 0.12 seconds. This finding is:

Abnormal; AT >0.07 s (some labs use >0.10 s) suggests hemodynamically significant proximal renal artery stenosis (Correct answer)
Normal; AT <0.07 s is the threshold for significant stenosis
Normal because AT should always exceed 0.10 s
Irrelevant; only PSV is used for renal artery evaluation

Correct answer: Abnormal; AT >0.07 s (some labs use >0.10 s) suggests hemodynamically significant proximal renal artery stenosis

Acceleration time >0.07–0.10 seconds in intrarenal waveforms is associated with proximal renal artery stenosis; the prolonged upstroke reflects dampening of the waveform distal to the obstruction.

Question 19: Coded excitation in ultrasound systems is used primarily to:

Improve signal-to-noise ratio and penetration without increasing peak pressure (Correct answer)
Increase lateral resolution at shallow depths
Eliminate grating-lobe artifacts from phased arrays
Reduce the pulse repetition interval

Correct answer: Improve signal-to-noise ratio and penetration without increasing peak pressure

Coded excitation (e.g., chirp or Golay codes) spreads pulse energy over time and uses matched-filter compression on receive, boosting SNR and penetration at the same mechanical index.

Question 20: On a spectral Doppler display, flow moving AWAY from the transducer will appear:

Below the baseline as a negative deflection (Correct answer)
At the baseline without deflection
Above the baseline as a positive deflection
Simultaneously above and below the baseline

Correct answer: Below the baseline as a negative deflection

By convention, flow toward the transducer produces a positive frequency shift and appears above the baseline, while flow away from the transducer produces a negative shift and appears below the baseline.

Question 21: A sonographer performing an extended neonatal brain exam should be MOST concerned about which type of Thermal Index?

TI is irrelevant for neonatal imaging
TIS — because soft tissue heating dominates in neonates
TIC — because the cranial bone is in the near field of the beam (Correct answer)
TIB — because fetal bone is the target near the fontanelle

Correct answer: TIC — because the cranial bone is in the near field of the beam

TIC (Cranial Bone Thermal Index) applies when the beam passes through the skull in the near field, as the bone absorbs energy and heats the adjacent brain tissue.

Question 22: Which of the following would be MOST likely to increase the Thermal Index (TI) during a diagnostic ultrasound examination?

Increasing the receiver gain
Decreasing the imaging depth
Using a lower frequency transducer
Switching from B-mode to Color Doppler (Correct answer)

Correct answer: Switching from B-mode to Color Doppler

Switching to modes like Color Doppler or Pulsed-Wave Doppler generally increases the acoustic output and energy deposited in the tissue, leading to a higher Thermal Index (TI). Receiver gain only amplifies the returning echoes and does not change the transmitted power. Decreasing imaging depth or using a lower frequency transducer does not inherently increase the TI as significantly as changing to a higher-energy mode like Doppler.

Question 23: The reflection coefficient at a tissue interface is primarily determined by the difference in:

Pulse repetition frequencies
Frequencies of the incident waves
Acoustic impedances of the two media (Correct answer)
Transducer depths

Correct answer: Acoustic impedances of the two media

The intensity reflection coefficient depends on (Z2 − Z1)² / (Z2 + Z1)², where Z1 and Z2 are the acoustic impedances of the two media.

Question 24: Which of the following statements accurately describes a key characteristic of Continuous-Wave (CW) Doppler?

It provides excellent range resolution by using a small sample volume.
It utilizes a single piezoelectric element that alternates between sending and receiving.
It cannot determine the exact depth from which a velocity signal originates. (Correct answer)
It is limited by the Nyquist criterion for high-velocity measurements.

Correct answer: It cannot determine the exact depth from which a velocity signal originates.

Because a CW Doppler system transmits and receives sound continuously along the entire beam, it detects all velocities in its path. It cannot isolate a specific depth, a characteristic known as range ambiguity.

Question 25: The PZT crystal in a linear phased array transducer is divided into 280 distinct active elements. This transducer has how many channels?

560
1
280 (Correct answer)
140

Correct answer: 280

In a phased array transducer, each distinct active PZT element is typically connected to its own independent electronic circuit, known as a channel. These channels allow for individual control of each element's excitation, enabling electronic steering and focusing of the ultrasound beam. Therefore, if a transducer has 280 active elements, it has 280 channels.

Question 26: The angle of refraction is related to the angle of incidence by:

The attenuation coefficient equation
Beer's law
Snell's law (Correct answer)
The impedance mismatch formula

Correct answer: Snell's law

Snell's law (sin θ₁/c₁ = sin θ₂/c₂) governs the relationship between the angle of incidence and angle of refraction.

Question 27: The duty factor of a pulsed ultrasound system is defined as:

Peak intensity divided by average intensity
Frequency divided by propagation speed
Pulse duration divided by pulse repetition period (Correct answer)
Number of pulses per second

Correct answer: Pulse duration divided by pulse repetition period

Duty factor = pulse duration (on-time) / pulse repetition period (on+off time), indicating the fraction of time the transducer is actively transmitting.

Question 28: The acoustic streaming artifact in color Doppler is seen as:

Color signal within a fluid-filled cyst caused by acoustic radiation force (Correct answer)
Color aliasing in a deep vessel
Color bleed from a hyperechoic mass
Twinkling behind a stone

Correct answer: Color signal within a fluid-filled cyst caused by acoustic radiation force

Acoustic streaming occurs when ultrasound radiation force displaces fluid within a cyst, producing color Doppler signal in an otherwise avascular structure.

Question 29: According to the Bernoulli principle, as blood flows through a stenosis, what happens to velocity and pressure?

Velocity increases, pressure decreases (Correct answer)
Velocity decreases, pressure increases
Both velocity and pressure decrease
Both velocity and pressure increase

Correct answer: Velocity increases, pressure decreases

Energy conservation (Bernoulli principle) dictates that at a stenosis, the cross-sectional area decreases so velocity must increase while pressure drops.

Question 30: In pulsed-wave Doppler, increasing the depth of the sample gate will require the system to:

Increase PRF to maintain sensitivity
Decrease wall filter settings
Increase transmit frequency
Decrease PRF to allow sufficient time for echoes to return from the greater depth (Correct answer)

Correct answer: Decrease PRF to allow sufficient time for echoes to return from the greater depth

Greater sample gate depth requires a longer round-trip travel time for the pulse echo, so PRF must be decreased to avoid range ambiguity.

Question 31: The Doppler angle cursor should be aligned parallel to which structure during angle correction?

The vessel wall perpendicular to flow
The beam axis
The direction of blood flow (Correct answer)
The transducer face

Correct answer: The direction of blood flow

The angle correction cursor must be aligned parallel to the direction of blood flow so that the cosine of the angle can accurately correct the measured velocity.

Question 32: There are three main variations of the Thermal Index (TI) displayed on ultrasound systems. Which variant is specifically designed for use when scanning through or near bone, such as in second or third-trimester obstetric exams?

TIB (Bone Thermal Index) (Correct answer)
TIG (General Thermal Index)
TIS (Soft Tissue Thermal Index)
TIC (Cranial Bone Thermal Index)

Correct answer: TIB (Bone Thermal Index)

The Bone Thermal Index (TIB) is the appropriate variant to use when bone is near the focus of the ultrasound beam, which is common in second and third-trimester fetal scans due to ossification. Bone absorbs more acoustic energy than soft tissue, leading to a greater potential for heating. TIS is for soft tissue, and TIC is specifically for imaging the cranium.

Question 33: Which statement correctly describes range ambiguity artifact in PW Doppler?

It is caused by side lobe interference
It occurs when echoes from a previous pulse return after the next pulse has been transmitted, causing signals from two depths to be displayed simultaneously (Correct answer)
It only occurs with color Doppler, not spectral Doppler
It occurs when the sample gate is placed incorrectly

Correct answer: It occurs when echoes from a previous pulse return after the next pulse has been transmitted, causing signals from two depths to be displayed simultaneously

Range ambiguity occurs when a high PRF is used and echoes from deep structures return after the next pulse is already transmitted, causing signals from multiple depths to be displayed as if from the gate location.

Question 34: A tissue-mimicking phantom contains hyperechoic spherical masses. These targets are primarily used to test which system performance parameter?

Doppler sensitivity
Dead zone depth
Contrast resolution for high-reflectivity lesions (Correct answer)
Temporal resolution

Correct answer: Contrast resolution for high-reflectivity lesions

Hyperechoic spherical targets surrounded by uniform background material test the system's ability to detect and resolve high-amplitude echoes against background speckle.

Question 35: On a color Doppler image, a vessel appears with both red and blue colors side by side in a straight segment. The most likely explanation is:

Correct color map assignment
Turbulent flow
Aliasing at peak systole
The vessel curves so one limb moves toward and one away from the transducer (Correct answer)

Correct answer: The vessel curves so one limb moves toward and one away from the transducer

When a vessel curves, different portions move toward and away from the transducer, producing opposite color assignments even in laminar flow.

Question 36: When performing angle correction for Doppler velocity calculations, ARDMS guidelines recommend keeping the Doppler angle at:

60° or less to minimize angle-related velocity errors (Correct answer)
Greater than 75° for best sensitivity
Exactly 45° at all times
90° for the most accurate measurement

Correct answer: 60° or less to minimize angle-related velocity errors

Angles ≤60° are recommended because small errors in angle estimation cause proportionally larger velocity errors as the angle increases, especially above 60°.

Question 37: Which component of an ultrasound transducer is specifically designed with an acoustic impedance intermediate between the piezoelectric crystal and the patient's skin to improve sound transmission?

The damping material
The acoustic lens
The piezoelectric element
The matching layer (Correct answer)

Correct answer: The matching layer

The matching layer has an acoustic impedance that is between that of the piezoelectric element (crystal) and the soft tissue of the patient. This intermediate impedance reduces the large impedance mismatch at the transducer-skin interface, which in turn decreases reflection and allows more sound energy to be transmitted into the body.

Question 38: The spatial pulse length (SPL) is calculated as:

Number of cycles × wavelength (Correct answer)
Frequency × pulse duration
Amplitude / frequency
Wavelength / bandwidth

Correct answer: Number of cycles × wavelength

SPL = number of cycles × wavelength; shorter SPL yields better axial resolution.

Question 39: Which of the following is an ergonomic device built into sonographic equipment for the sonographer's musculoskeletal safety?

Fixed control panel
Monitor articulation (Correct answer)
Wrist support brace
Long transducer cable

Correct answer: Monitor articulation

Monitor articulation allows sonographers to adjust the display screen's height, tilt, and swivel to their individual needs and scanning position. This ergonomic feature helps reduce neck, back, and eye strain by promoting a neutral posture during examinations. By minimizing physical discomfort and awkward positions, it directly contributes to musculoskeletal safety and helps prevent work-related injuries.

Question 40: A sonographer observes that the intensity of the ultrasound beam has decreased by 3 dB. This corresponds to what change in intensity?

A tenfold decrease
A twofold decrease (Correct answer)
A threefold decrease
A twofold increase

Correct answer: A twofold decrease

The decibel (dB) scale is logarithmic. A change of -3 dB represents a halving, or a twofold decrease, in intensity. Conversely, a +3 dB change represents a doubling of intensity. A -10 dB change corresponds to a tenfold decrease. [12, 16]

Question 41: Dynamic range in ultrasound refers to:

The bandwidth of frequencies included in the transmit pulse
The ratio of the largest to smallest echo amplitudes the system can process and display (Correct answer)
The maximum frame rate achievable at a given depth
The range of depths over which the system can focus

Correct answer: The ratio of the largest to smallest echo amplitudes the system can process and display

Dynamic range (expressed in dB) describes the span between the strongest and weakest signals that can be meaningfully represented, influencing the number of displayed gray levels.

Question 42: What is the primary acoustic effect that enables Doppler ultrasound to detect moving blood cells?

Increased attenuation of sound by erythrocytes
Refraction of the sound beam by flowing blood
The Doppler effect: frequency shift in echoes from moving reflectors (Correct answer)
Impedance mismatch at the blood-vessel wall interface

Correct answer: The Doppler effect: frequency shift in echoes from moving reflectors

Moving red blood cells shift the frequency of the returning echo relative to the transmitted frequency; this Doppler frequency shift is proportional to velocity.

Question 43: A color Doppler image shows a mosaic pattern within a vessel lumen. This most likely indicates:

Laminar flow at high velocity
Color bleed from adjacent tissue
Incorrect wall filter setting
Turbulent or disturbed flow with aliasing (Correct answer)

Correct answer: Turbulent or disturbed flow with aliasing

A mosaic pattern of mixed colors represents turbulent flow combined with aliasing, commonly seen distal to a stenosis.

Question 44: The spectral window in a normal arterial Doppler waveform represents:

The area of aliased velocities
The clear area below the spectral envelope indicating organized laminar flow (Correct answer)
Turbulent flow within the vessel
Reverse flow component

Correct answer: The clear area below the spectral envelope indicating organized laminar flow

The clear spectral window below the waveform envelope reflects the narrow, uniform velocity distribution of laminar flow where few cells travel at intermediate velocities.

Question 45: Which of the following best explains why CW Doppler is NOT affected by aliasing?

CW Doppler uses a lower transmit frequency
CW Doppler continuously transmits and receives without a PRF limitation, so there is no Nyquist limit constraint (Correct answer)
CW Doppler applies a higher wall filter
CW Doppler uses phase-quadrature detection

Correct answer: CW Doppler continuously transmits and receives without a PRF limitation, so there is no Nyquist limit constraint

Because CW Doppler continuously transmits on one element and receives on another with no pulsed repetition interval, there is no PRF and therefore no Nyquist limit to cause aliasing.

Question 46: Which of the following acoustic wave types does diagnostic ultrasound primarily use for imaging?

Transverse (shear) waves
Longitudinal (compressional) waves (Correct answer)
Plate (Lamb) waves
Surface (Rayleigh) waves

Correct answer: Longitudinal (compressional) waves

Diagnostic ultrasound uses longitudinal waves in which particle displacement occurs parallel to the direction of wave propagation, as these travel efficiently through soft tissue.

Question 47: During a quality assurance check, a sonographer notes that small reflectors located in the first centimeter of the image, immediately below the transducer face, are not visible. This finding suggests a problem with which performance parameter?

Lateral resolution
Sensitivity
Axial resolution
Dead zone (Correct answer)

Correct answer: Dead zone

The dead zone is the region near the transducer face where imaging is inaccurate due to the time required for the system to switch from transmitting a pulse to receiving echoes. Reflectors within this zone may not be properly displayed. It is measured by finding the shallowest depth from which a uniform echo is displayed.

Question 48: When scanning directly over fetal bone in the third trimester, which Thermal Index should be displayed?

TIS (Soft Tissue Thermal Index)
TI (generic Thermal Index)
TIB (Bone Thermal Index) (Correct answer)
TIC (Cranial Bone Thermal Index)

Correct answer: TIB (Bone Thermal Index)

TIB (Bone Thermal Index) is used when the beam is focused at or near fetal bone, which absorbs more ultrasound energy and can heat adjacent tissue significantly.

Question 49: What is the primary purpose of recording baseline QA images when a new ultrasound system is installed?

To document the phantom's serial number
To satisfy Medicare billing requirements
To calibrate the DICOM network settings
To establish reference measurements for future performance comparisons (Correct answer)

Correct answer: To establish reference measurements for future performance comparisons

Baseline images provide documented reference values so that subsequent QA tests can detect degradation in system performance over time.

Question 50: When a sound beam travels from muscle into fat, which phenomenon occurs because fat has a lower propagation speed?

Refraction (Correct answer)
Specular reflection
Absorption
Scattering

Correct answer: Refraction

Refraction occurs when sound crosses an interface at an oblique angle between media with different propagation speeds, causing the beam to bend.

Question 51: Which QA parameter specifically evaluates the system's ability to display echoes from structures located very close to the transducer surface?

Slice thickness assessment
Axial resolution at focus
Dead zone measurement (Correct answer)
Maximum depth of penetration

Correct answer: Dead zone measurement

Dead zone measurement quantifies the region nearest the transducer where ring-down from the transmitted pulse masks true returning echoes.

Question 52: A QA test reveals that the on-screen distance measurement reads 5.2 cm for a structure the phantom certifies as 5.0 cm. What does this indicate?

Caliper or distance accuracy error exceeding acceptable tolerance (Correct answer)
Artifact from multipath reflection
Excessive focal zone depth
Normal variation within expected system noise

Correct answer: Caliper or distance accuracy error exceeding acceptable tolerance

A 4% error in distance measurement suggests a calibration issue with the system's speed-of-sound assumption or caliper circuitry.

Question 53: A post-stenotic waveform showing low PSV, slow systolic acceleration time, and absence of the early diastolic reversal component is described as:

Tardus-parvus (Correct answer)
Normal biphasic
High-resistance triphasic
Hyperemic monophasic

Correct answer: Tardus-parvus

Tardus-parvus (Latin: slow-small) describes the dampened, delayed, monophasic waveform seen distal to a hemodynamically significant stenosis or occlusion.

Question 54: Total internal reflection of an ultrasound beam occurs when the angle of incidence exceeds:

The Brewster angle
The critical angle (Correct answer)
45 degrees
90 degrees

Correct answer: The critical angle

When the incident angle exceeds the critical angle at an interface where speed increases, refraction is impossible and all energy is reflected back.

Question 55: The pulsatility index (PI) is calculated as (PSV − EDV) / mean velocity. Compared to the RI, the PI is preferred in which situation?

When end-diastolic velocity is absent or reversed, making RI calculation impossible (Correct answer)
When evaluating venous flow
When the Doppler angle is greater than 60°
When PSV exceeds 200 cm/s

Correct answer: When end-diastolic velocity is absent or reversed, making RI calculation impossible

When end-diastolic flow is absent or reversed (EDV = 0 or negative), the RI formula produces 1.0 or undefined values, but the PI can still differentiate degrees of high resistance using the time-averaged mean velocity.

Question 56: Stable cavitation differs from inertial cavitation in that stable cavitation involves:

Violent bubble collapse that produces free radicals
Immediate tissue destruction at the focal zone
Bubbles oscillating in a sustained, non-destructive manner (Correct answer)
Complete vaporization of the liquid medium

Correct answer: Bubbles oscillating in a sustained, non-destructive manner

Stable (non-inertial) cavitation describes gas bubbles that oscillate repetitively without collapsing, whereas inertial cavitation involves violent implosion.

Question 57: What is the primary function of the scan converter in a diagnostic ultrasound system?

Convert polar ultrasound data into a rectangular display format (Correct answer)
Filter out high-frequency noise from the received signal
Amplify returning echoes before display
Control the transmit pulse repetition frequency

Correct answer: Convert polar ultrasound data into a rectangular display format

The scan converter maps echo data from the polar coordinate geometry of the transducer sweep into the Cartesian (rectangular) format used by the video display.

Question 58: When the Doppler angle approaches 90°, what happens to the measured Doppler shift?

It approaches zero, making velocity measurement unreliable (Correct answer)
It reaches its maximum value
It equals the transmitted frequency
It doubles

Correct answer: It approaches zero, making velocity measurement unreliable

At 90°, cos 90° = 0, so the calculated Doppler shift approaches zero regardless of actual flow velocity, making angle correction and velocity measurement unreliable.

Question 59: Which of the following best describes the transmission coefficient when sound passes from one medium to another?

It equals 1 minus the reflection coefficient (Correct answer)
It is always less than the reflection coefficient
It depends on frequency but not impedance
It equals the product of the two impedances

Correct answer: It equals 1 minus the reflection coefficient

Conservation of energy requires that the transmission coefficient T = 1 − R, where R is the reflection coefficient.

Question 60: Specular reflection occurs when sound strikes a boundary that is:

Angled at 90° to the beam
Smaller than the wavelength
Rough relative to the wavelength
Large and smooth relative to the wavelength (Correct answer)

Correct answer: Large and smooth relative to the wavelength

Specular reflectors are large, flat, smooth surfaces that reflect sound at an angle equal to the incident angle, like a mirror.

Question 61: Which processing technique maps the received echo amplitude non-linearly to compress the wide dynamic range of tissue echoes into a displayable gray scale?

Demodulation
Time-gain compensation
Log compression (Correct answer)
Envelope detection

Correct answer: Log compression

Log compression applies a logarithmic transfer function to the echo amplitudes, compressing the large dynamic range of returning signals into the narrower range the display can show.

Question 62: Which imaging mode provides the highest temporal resolution for evaluating rapidly moving structures like heart valves?

B-mode with high frame rate
M-mode (Correct answer)
3D volumetric imaging
Color Doppler

Correct answer: M-mode

M-mode records a single scan line repeatedly at very high sampling rates (up to 1000 times/sec), giving superior temporal resolution.

Question 63: A sonographer freezes an image and then activates the zoom function to enlarge a specific area of interest. This action results in larger pixels and does not improve spatial resolution. Which type of magnification was used?

Write magnification
Focal magnification
Read magnification (Correct answer)
Acoustic magnification

Correct answer: Read magnification

Read magnification is a postprocessing function that is applied to a frozen image. It takes the existing pixel data stored in the scan converter and simply enlarges it, making each pixel bigger. Because no new data is acquired, the spatial resolution is not improved and may even appear degraded. Write magnification, a preprocessing function, would rescan the area live to create a new image with more pixels, thereby improving spatial resolution.

Question 64: Increasing the wall filter setting on a spectral Doppler display will:

Remove low-frequency signals from the spectral display (Correct answer)
Remove high-frequency signals from the spectral display
Increase the Nyquist limit
Decrease the pulse repetition frequency

Correct answer: Remove low-frequency signals from the spectral display

The wall filter (high-pass filter) eliminates low-frequency Doppler signals produced by slow-moving vessel walls and surrounding tissue, reducing clutter near the baseline.

Question 65: Lateral resolution in a single-element focused transducer is BEST at the:

Transducer face
Focal zone (Correct answer)
Near field only
Far field only

Correct answer: Focal zone

Lateral (azimuthal) resolution is best at the focal zone where the beam is narrowest.

Question 66: The spectral window in a Doppler display represents:

The clear area beneath the systolic peak where few slow-moving cells are present (Correct answer)
The maximum detectable velocity before aliasing occurs
The frequency bandwidth of the transducer
The area of the vessel cross-section being sampled

Correct answer: The clear area beneath the systolic peak where few slow-moving cells are present

The spectral window is the clear area beneath the waveform envelope, indicating relatively uniform laminar flow where most cells travel at similar velocities with few slow-moving cells near the vessel wall.

Question 67: A QA test finds that the dead zone has increased significantly from the baseline value. Which clinical implication is most important?

Harmonic imaging will be impaired
Superficial structures may not be visualized accurately (Correct answer)
Color flow artifacts will increase
Doppler measurements will overestimate velocity

Correct answer: Superficial structures may not be visualized accurately

An enlarged dead zone means structures immediately beneath the transducer face may be missed or misrepresented, which is critical for superficial examinations.

Question 68: Which acoustic parameter is determined solely by the medium through which sound travels?

Propagation speed (Correct answer)
Amplitude
Period
Frequency

Correct answer: Propagation speed

Propagation speed depends entirely on the medium's density and stiffness, not on the sound source.

Question 69: Which transducer type provides the SMALLEST footprint and is therefore best suited for cardiac imaging between rib spaces?

Curvilinear array
Mechanical sector
Phased array (Correct answer)
Linear array

Correct answer: Phased array

The phased array has a small footprint that fits between ribs and uses electronic steering to produce a wide sector image from that small window.

Question 70: Frame rate in real-time ultrasound is most directly limited by:

Dynamic range setting
Focal zone placement
Transducer frequency
The speed of sound and imaging depth (Correct answer)

Correct answer: The speed of sound and imaging depth

Because the system must wait for echoes to return from maximum depth before firing the next pulse, imaging depth and the speed of sound directly limit frame rate.

Question 71: Many PZT crystals are placed in an arched line with ______ transducers.

Mechanical
Linear array
Convex array (Correct answer)
Annular array

Correct answer: Convex array

Convex array transducers, also known as curvilinear arrays, are characterized by their PZT crystals being arranged in an arched or curved line. This curved configuration allows for a wider field of view in the far field, producing a sector-shaped image. This design is commonly used for abdominal and obstetric imaging.

Question 72: Laminar flow in a vessel is characterized by:

Concentric layers of blood moving at different velocities with fastest flow centrally (Correct answer)
Random, chaotic movement of blood cells in all directions
Retrograde flow near the vessel walls
Uniform velocity across the entire vessel lumen

Correct answer: Concentric layers of blood moving at different velocities with fastest flow centrally

In laminar flow, blood moves in concentric layers (parabolic profile) with the fastest velocity at the center and slowest near the walls due to friction.

Question 73: At normal incidence, what determines the fraction of sound intensity reflected at an interface?

The beam diameter at the interface
The depth of the interface
The difference in acoustic impedance between the two media (Correct answer)
The frequency of the transducer

Correct answer: The difference in acoustic impedance between the two media

The reflection coefficient at normal incidence depends solely on the acoustic impedances of the two media.

Question 74: The primary function of the scan converter in an ultrasound system is to:

Calculate the Doppler shift from moving red blood cells.
Format the echo data from the spoke format into a video format for display. (Correct answer)
Convert electrical signals into acoustic pulses.
Amplify the weak returning echo signals.

Correct answer: Format the echo data from the spoke format into a video format for display.

The scan converter, or image processor, is a digital memory component that receives echo data from the receiver. Its main job is to reformat this data, which is acquired in a spoke or line-by-line format (like polar coordinates for a sector transducer), into a standard raster scan or video format (Cartesian coordinates) that can be displayed on a monitor.

Question 75: During a renal ultrasound, a sonographer places the color Doppler box over a suspected kidney stone. A rapidly changing, mosaic pattern of color appears immediately posterior to the hyperechoic structure, despite the absence of true blood flow. This specific finding is known as:

Power Doppler bloom
Twinkle artifact (Correct answer)
Crosstalk artifact
Reverberation artifact

Correct answer: Twinkle artifact

The twinkle artifact is a color Doppler phenomenon seen as a rapidly changing mixture of red and blue pixels posterior to a strongly reflecting, rough-surfaced object like a kidney stone. [17, 21] It is thought to be caused by intrinsic machine noise or random phase shifts from the rough surface creating a 'noisy' Doppler signal. [20] It is a useful sign that increases confidence in identifying calcifications. [21]

Question 76: While performing a routine QA scan on a phantom with pins spaced exactly 30 mm apart vertically, a sonographer measures the distance between two pins as 32.5 mm. This indicates a potential issue with which system parameter?

Contrast resolution
Vertical distance accuracy (Correct answer)
System sensitivity
Lateral resolution

Correct answer: Vertical distance accuracy

Vertical distance accuracy assesses the system's ability to correctly measure distances parallel to the ultrasound beam's axis. A discrepancy between the known distance in the phantom and the measured distance on the system indicates a calibration error in depth measurement.

Question 77: Which Doppler mode provides the best sensitivity for detecting slow-flow states such as organ perfusion?

Power Doppler (Correct answer)
Continuous wave Doppler
Pulsed wave Doppler
Color flow Doppler

Correct answer: Power Doppler

Power Doppler displays the amplitude (power) of the Doppler signal and is more sensitive to slow flow than color or pulsed wave Doppler.

Question 78: Elevational (slice thickness) resolution is most directly controlled by:

The fixed focusing of the transducer in the elevation plane (Correct answer)
The number of focal zones selected
The transmit frequency
The dynamic range setting

Correct answer: The fixed focusing of the transducer in the elevation plane

Elevational resolution depends on the fixed mechanical lens focus in the elevation dimension, which cannot be dynamically adjusted in most transducers.

Question 79: Which of the following phantom measurements is most useful for evaluating the effectiveness of harmonic imaging compared to fundamental imaging?

Caliper distance measurement
Contrast-detail analysis comparing anechoic cyst visibility (Correct answer)
Doppler velocity accuracy
Depth of penetration test

Correct answer: Contrast-detail analysis comparing anechoic cyst visibility

Comparing anechoic cyst detectability between fundamental and harmonic modes reveals harmonic imaging's improvement in contrast resolution by reducing reverberation and clutter.

Question 80: Non-thermal mechanical bioeffects of ultrasound include all of the following EXCEPT:

Protein denaturation from elevated tissue temperature (Correct answer)
Acoustic streaming
Microstreaming near oscillating bubbles
Acoustic cavitation

Correct answer: Protein denaturation from elevated tissue temperature

Protein denaturation is a thermal effect caused by temperature rise, not a non-thermal mechanical effect; cavitation, streaming, and microstreaming are all mechanical in nature.

Question 81: A sonographer is performing an obstetric ultrasound on a patient in her second trimester. The on-screen display shows a Thermal Index for Bone (TIB) of 1.2. According to the ALARA principle, which of the following actions is most appropriate?

Switch to the Soft-Tissue Thermal Index (TIS) to obtain a lower reading.
Continue scanning as planned, as this value is within acceptable limits.
Immediately cease the examination and consult with the radiologist.
Decrease the acoustic output power and minimize the dwell time over any single area. (Correct answer)

Correct answer: Decrease the acoustic output power and minimize the dwell time over any single area.

The ALARA (As Low As Reasonably Achievable) principle dictates that sonographers should use the lowest possible ultrasound exposure to obtain diagnostic images. A TIB of 1.2 indicates a potential for temperature increase in fetal bone. While not an absolute contraindication, the most appropriate action is to take steps to reduce the exposure. Decreasing the output power and minimizing the time the beam is focused on one spot (dwell time) are key strategies to lower the thermal exposure and adhere to the ALARA principle.

Question 82: In a 1.5D array transducer compared to a standard 1D array, the key improvement is:

Full 3D volumetric imaging capability
Higher center frequency output
Limited electronic control in the elevation dimension to improve slice-thickness resolution (Correct answer)
Faster frame rates due to reduced element count

Correct answer: Limited electronic control in the elevation dimension to improve slice-thickness resolution

A 1.5D array adds a few rows of elements in the elevation direction, allowing limited electronic focusing to reduce slice-thickness artifacts compared to a fixed lens.

Question 83: What happens to the visual display when a mechanical transducer's PZT crystal is damaged?

Inconsistent beam steering and focusing
Horizontal band of dropout
Loss of entire image (Correct answer)
Vertical band of dropout

Correct answer: Loss of entire image

A mechanical transducer typically utilizes a single, rotating or oscillating PZT crystal to generate and receive the ultrasound beam. If this sole PZT crystal is damaged, the transducer loses its ability to produce and detect ultrasound waves entirely. Consequently, this results in a complete loss of the entire image on the display.

Question 84: When a tissue-mimicking phantom is scanned with a transducer at a frequency significantly higher than the phantom's design frequency, how does this typically affect the penetration depth result?

Penetration depth is unchanged because the phantom speed of sound is fixed
Penetration depth increases because resolution improves
Penetration depth doubles due to improved axial resolution
Penetration depth decreases because higher-frequency sound attenuates faster (Correct answer)

Correct answer: Penetration depth decreases because higher-frequency sound attenuates faster

Acoustic attenuation increases with frequency, so scanning at a higher frequency than the phantom's design frequency results in greater signal loss per centimeter and shallower penetration.

Question 85: The Pulsatility Index (PI) is calculated as:

(PSV + EDV) / 2
(PSV - EDV) / PSV
(PSV - EDV) / TAMV (Correct answer)
PSV / EDV

Correct answer: (PSV - EDV) / TAMV

PI = (PSV - EDV) / TAMV (time-averaged mean velocity); unlike RI, PI can exceed 1.0 and can be calculated even when end-diastolic flow is zero or reversed.

Question 86: Which organization publishes widely used guidelines for ultrasound equipment performance testing in the United States?

FDA Center for Devices and Radiological Health only
Joint Commission on Accreditation only
AIUM (American Institute of Ultrasound in Medicine) (Correct answer)
NEMA (National Electrical Manufacturers Association)

Correct answer: AIUM (American Institute of Ultrasound in Medicine)

The AIUM publishes equipment performance testing standards widely adopted by clinical facilities and accreditation bodies in the United States.

Question 87: What does 'test object fog' refer to in the context of ultrasound phantom QA?

Ghosting artifact from side lobe energy in the phantom
Low-level echoes that fill anechoic targets due to electronic noise or reverberation (Correct answer)
Condensation on the phantom surface reducing acoustic coupling
Acoustic shadow caused by high-attenuation phantom materials

Correct answer: Low-level echoes that fill anechoic targets due to electronic noise or reverberation

Test object fog describes low-level echoes that fill supposedly anechoic cysts, caused by system noise, reverberation, or electronic noise degrading contrast resolution.

Question 88: The systolic-to-diastolic (S/D) ratio used in obstetric Doppler is calculated as:

(PSV - EDV) / PSV
PSV / EDV (Correct answer)
EDV / PSV
(PSV - EDV) / TAMV

Correct answer: PSV / EDV

The S/D ratio = PSV / EDV and is commonly used in umbilical artery Doppler to assess placental resistance; it cannot be calculated when EDV is absent.

Question 89: Which property of a medium directly determines whether refraction will occur at an oblique interface?

Frequency absorption rate
Attenuation coefficient
Acoustic impedance
Propagation speed (Correct answer)

Correct answer: Propagation speed

Refraction depends on differing propagation speeds in adjacent media, not on their impedances.

Question 90: Which of the following is a primary advantage of Power Doppler when compared to conventional Color Doppler?

It is less susceptible to flash artifact from patient motion.
It provides quantitative velocity and direction information.
It has a significantly higher temporal resolution.
It is more sensitive to slow flow and is not subject to aliasing. (Correct answer)

Correct answer: It is more sensitive to slow flow and is not subject to aliasing.

Power Doppler displays the amplitude or strength of the Doppler signal, not the frequency shift (velocity). [10] This makes it more sensitive to the presence of flow, especially slow flow. [2] Because it does not measure velocity, it is not limited by the Nyquist criterion and therefore does not alias. [9] Its main disadvantages are the lack of directional/velocity information and increased susceptibility to motion artifact. [2]

Question 91: The process of reducing high-amplitude speckle noise while preserving edge detail in ultrasound images is best described as:

Adaptive image processing (speckle reduction imaging) (Correct answer)
Harmonic imaging
Coded excitation
Time-gain compensation

Correct answer: Adaptive image processing (speckle reduction imaging)

Adaptive speckle reduction algorithms analyze local image statistics to smooth homogeneous regions while retaining boundaries.

Question 92: Which clinical finding is associated with markedly increased peak systolic velocity (PSV) at a focal arterial segment?

Focal arterial stenosis with hemodynamic significance (Correct answer)
Normal vessel anatomy
Arteriovenous fistula distal to the site
Complete vessel occlusion

Correct answer: Focal arterial stenosis with hemodynamic significance

Flow accelerates as it passes through a stenotic segment due to reduced cross-sectional area, causing a focal jet with markedly elevated PSV.

Question 93: Which of the following functions is considered a preprocessing function because it can only be performed on a live image before the data is stored in the scan converter?

Write Magnification (Correct answer)
Adding caliper measurements
Adjusting the grayscale map
Read Magnification

Correct answer: Write Magnification

Preprocessing functions manipulate the image data before it is stored in the scan converter memory. Write Magnification (or Write Zoom) is a classic example of preprocessing; it rescans the selected region of interest with a higher line density to generate a new, higher-resolution image. This can only be done on a live image. Read magnification, caliper placement, and grayscale map adjustments are postprocessing functions that can be applied to a frozen image.

Question 94: A transducer's Q factor is defined as the ratio of the operating frequency to the:

Frame rate
Pulse repetition frequency
Nyquist frequency
Bandwidth (Correct answer)

Correct answer: Bandwidth

Q factor = operating (center) frequency divided by bandwidth; a low Q indicates wide bandwidth and good axial resolution.

Question 95: Which material property most determines the acoustic impedance of a tissue?

Attenuation coefficient alone
Temperature and viscosity
Density and speed of sound (Correct answer)
Absorption and scattering ratio

Correct answer: Density and speed of sound

Acoustic impedance (Z) is the product of tissue density (ρ) and the speed of sound (c): Z = ρc.

Question 96: When PRF is increased to correct aliasing, which undesirable consequence may occur?

Improved sensitivity to low-velocity flow near the baseline
Decreased temporal resolution of the waveform
Range ambiguity — inability to unambiguously sample deep vessels (Correct answer)
Increased wall thump artifact at the baseline

Correct answer: Range ambiguity — inability to unambiguously sample deep vessels

High PRF sends pulses before previous echoes return from deep structures, so the system cannot determine which echo came from which pulse depth, creating range ambiguity artifact.

Question 97: When the color Doppler gate is positioned at 90° to flow direction, the resulting color display will show:

Aliasing
No color signal (Correct answer)
Reversed color assignment
Maximum color saturation

Correct answer: No color signal

At 90° insonation angle the Doppler frequency shift is zero, so no color signal is generated.

Question 98: Which Doppler finding is most indicative of a hemodynamically significant proximal arterial stenosis?

Normal triphasic waveform distal to the lesion
Increased peak systolic velocity at the stenosis site
High-resistance waveform distal to the lesion
Monophasic, low-resistance tardus-parvus waveform distal to the stenosis (Correct answer)

Correct answer: Monophasic, low-resistance tardus-parvus waveform distal to the stenosis

A tardus-parvus (slow rise, small amplitude) waveform distal to a significant stenosis reflects the damped, delayed transmission of the pulse through the obstruction.

Question 99: The Output Display Standard (ODS) requires that real-time MI and TI values be displayed on the monitor when they exceed:

MI > 0.4 or TI > 0.4
MI > 1.0 or TI > 1.0
MI > 0.5 or TI > 0.5 (Correct answer)
MI > 2.0 or TI > 2.0

Correct answer: MI > 0.5 or TI > 0.5

The ODS mandates display of MI and TI when either exceeds 0.5, alerting operators that exposure is approaching levels warranting attention.

Question 100: A quality assurance program requires testing the system's ability to place echoes in their correct positions on the display, ensuring that a pin target appears in the same location whether imaged from the top or side of the phantom. Which parameter does this test evaluate?

Axial resolution
Uniformity
Dynamic range
Registration accuracy (Correct answer)

Correct answer: Registration accuracy

Registration accuracy is the ability of the system to display echoes in their proper anatomical positions on the screen. This test ensures that the system's internal coordinate system is correctly calibrated, so structures are mapped accurately in A-mode, B-mode, and M-mode.

Question 101: When comparing continuous-wave (CW) to pulsed-wave (PW) Doppler transducer designs, CW transducers differ in that they:

Use two separate elements—one dedicated to transmitting and one to receiving—operating simultaneously (Correct answer)
Cannot detect high-velocity flows
Use a single element that alternates between transmit and receive
Require a broader bandwidth than PW transducers

Correct answer: Use two separate elements—one dedicated to transmitting and one to receiving—operating simultaneously

CW Doppler transducers have two separate crystal elements operating simultaneously—one continuously transmitting and one continuously receiving—with no range gate.

Question 102: The sonographer increased output power by changing system settings. Which of the subsequent takes place?

Overall gain increases (Correct answer)
Voltage decreases
The displayed image darkens
Penetration decreases

Correct answer: Overall gain increases

When a sonographer increases output power, they are increasing the strength of the electrical voltage applied to the transducer, resulting in stronger ultrasound pulses transmitted into the patient. This directly increases the intensity of the sound waves and the strength of the returning echoes. Consequently, the overall signal amplitude received by the system increases, which can be interpreted as an increase in the effective 'overall gain' of the signal before display, leading to a brighter image.

Question 103: A sonographer is scanning a patient with a known lung consolidation. They should be particularly mindful of the Mechanical Index (MI) because:

The MI is always highest in the far field of the image.
Thermal effects are amplified in air-filled structures.
Consolidated lung tissue is more susceptible to overheating.
Gas bubbles present in the lung are nuclei for cavitation. (Correct answer)

Correct answer: Gas bubbles present in the lung are nuclei for cavitation.

The Mechanical Index (MI) indicates the risk of cavitation, which is the interaction of sound waves with gas bubbles. Tissues that contain gas, such as the lungs and intestines, are more susceptible to cavitation bioeffects because the pre-existing gas bubbles can act as nuclei for this phenomenon. Therefore, sonographers should be extra cautious and monitor the MI when imaging near or within such structures.

Question 104: The pulsatility index (PI) is calculated as:

PSV / EDV
(PSV + EDV) / PSV
EDV / PSV
(PSV − EDV) / mean velocity (Correct answer)

Correct answer: (PSV − EDV) / mean velocity

The Pulsatility Index = (Peak Systolic Velocity − End Diastolic Velocity) / Mean Velocity, providing a measure of downstream resistance.

Question 105: Baseline shifting in spectral Doppler is primarily used to:

Increase the maximum detectable velocity by doubling the Nyquist limit
Correct for insonation angle errors
Reposition the zero-velocity line to allocate more display range to unidirectional flow (Correct answer)
Reduce spectral broadening in turbulent flow

Correct answer: Reposition the zero-velocity line to allocate more display range to unidirectional flow

Shifting the baseline moves the zero-velocity reference line, allowing more of the display to be used for flow in one direction before aliasing wraps the signal to the other side.

Question 106: Which of the following best explains why QA phantoms must be stored at a controlled temperature?

Temperature changes alter the phantom's electrical impedance
Phantom radioactivity increases at higher temperatures
Color dyes in the phantom degrade above 25°C
Speed of sound in the phantom changes with temperature, affecting distance accuracy (Correct answer)

Correct answer: Speed of sound in the phantom changes with temperature, affecting distance accuracy

The speed of sound in phantom material is temperature-dependent; significant deviation from calibration temperature changes the apparent distances of internal targets.

Question 107: Turbulent flow on a spectral Doppler waveform appears as:

A narrow, well-defined spectral envelope
Absence of diastolic flow
Increased pulsatility with sharp systolic peaks
Spectral broadening with filling in of the spectral window (Correct answer)

Correct answer: Spectral broadening with filling in of the spectral window

Turbulence causes blood cells to move at many different velocities simultaneously, resulting in spectral broadening and filling in of the normally clear spectral window.

Question 108: The operating frequency of a single-crystal ultrasound transducer is most directly determined by which of the following physical characteristics?

The thickness of the matching layer
The diameter of the crystal
The thickness of the piezoelectric crystal (Correct answer)
The strength of the electrical voltage

Correct answer: The thickness of the piezoelectric crystal

The operating or resonant frequency of a transducer is determined by the thickness of the piezoelectric element. Specifically, the crystal is cut to a thickness that is equal to one-half of the desired wavelength of the ultrasound. Thinner crystals produce higher frequency sound waves, while thicker crystals produce lower frequency waves.

Question 109: The decibel (dB) scale is used in ultrasound because:

It eliminates the need for gain adjustment
It directly measures wavelength
It makes calculations linear
It simplifies multiplication of intensities into addition (Correct answer)

Correct answer: It simplifies multiplication of intensities into addition

The logarithmic dB scale converts large multiplicative intensity ratios into manageable additive numbers, matching human perception of loudness.

Question 110: A CW Doppler device is ideally suited for measuring flow in which clinical scenario?

Evaluating slow venous flow near the skin surface
Measuring high-velocity stenotic jets such as aortic stenosis where aliasing is a problem with PW (Correct answer)
Determining flow at a specific depth in the portal vein
Mapping color flow in the superficial femoral artery

Correct answer: Measuring high-velocity stenotic jets such as aortic stenosis where aliasing is a problem with PW

CW Doppler has no PRF limitation and therefore no aliasing, making it ideal for measuring very high velocities such as those in severe aortic stenosis (often >4 m/s).

Question 111: A phased array transducer achieves electronic steering and focusing of the ultrasound beam by:

Mechanically moving the crystal elements.
Applying a curved acoustic lens to the transducer face.
Changing the thickness of the piezoelectric elements.
Introducing precise time delays to the excitation of individual elements. (Correct answer)

Correct answer: Introducing precise time delays to the excitation of individual elements.

Phased array transducers consist of multiple small piezoelectric elements that are activated in complex patterns. By introducing minute time delays (phasing) in the electrical pulses sent to each element, the resulting ultrasound wavefront can be steered in different directions and focused electronically without physically moving the transducer.

ARDMS SPI (Sonography Principles & Instrumentation) Exam

The ARDMS SPI (Sonography Principles & Instrumentation) Exam exam validates essential knowledge and skills required for certification or licensure in this field.

110

Questions

120 min

Time Limit

70%

To Pass

Checking for saved progress...

Exam Rules

You can skip questions and return to them later
Flag questions for review before submitting
No feedback shown until you submit the entire exam
Unanswered questions count as wrong — answer everything
10 pretest questions are mixed in and don't affect your score
Timer auto-submits when time runs out
Your progress is auto-saved every 30 seconds

These practice questions were written with AI tools. They are not real exam questions. Exam facts are checked against the official sources listed below. Not reviewed by a subject-matter expert. Editorial policy

Sources & references

Exam facts on this page (fees, format, dates, passing scores) are checked against these official sources; the date is our last check. Editorial policy

inteleos.org — Exam format, passing score, registration, score release, time limit, score validity, test delivery, test dates, retake policy, fees · verified Oct 2026