ARDMS SPI (Sonography Principles and
Instrumentation) Practice Exam 2025 – Questions and
Correct Answers and Detailed Rationales
1. What is the primary determinant of axial resolution in ultrasound imaging?
A. Pulse repetition frequency
B. Spatial pulse length
C. Transducer diameter
D. Frame rate
Rationale: Axial resolution is determined by the spatial pulse length (SPL). The
shorter the SPL, the better the axial resolution.
2. Which artifact results from sound reflecting off a strong reflector and being
redirected back into the body?
A. Reverberation
B. Mirror image
C. Shadowing
D. Ring down
Rationale: A mirror image artifact occurs when a strong reflector (like the
diaphragm) redirects sound, creating a duplicated structure.
,3. What is the purpose of the backing material in a transducer?
A. Increase bandwidth
B. Enhance lateral resolution
C. Dampen the ringing of the crystal
D. Decrease beam divergence
Rationale: The backing material reduces the pulse duration by damping the
crystal's vibrations, improving axial resolution.
4. Which of the following improves lateral resolution?
A. Focusing
B. Decreasing frequency
C. Increasing gain
D. Increasing pulse duration
Rationale: Focusing narrows the beam width, which improves lateral resolution.
5. Which control affects the brightness of all echoes on the screen uniformly?
A. Time gain compensation
B. Dynamic range
C. Overall gain
D. Compression
Rationale: Overall gain amplifies all signals equally, affecting the brightness of the
entire image.
, 6. What type of resolution is affected by beam width?
A. Axial
B. Temporal
C. Lateral
D. Contrast
Rationale: Lateral resolution depends on the width of the sound beam, which
determines how close two objects can be side-by-side and still be distinguished.
7. What happens to propagation speed in bone compared to soft tissue?
A. It increases
B. It decreases
C. It remains the same
D. It varies randomly
Rationale: Sound travels faster in bone (~4080 m/s) than in soft tissue (~1540
m/s).
8. What artifact appears as multiple equally spaced echoes caused by the sound
bouncing between two strong reflectors?
A. Shadowing
B. Reverberation
C. Comet tail
D. Mirror image
Instrumentation) Practice Exam 2025 – Questions and
Correct Answers and Detailed Rationales
1. What is the primary determinant of axial resolution in ultrasound imaging?
A. Pulse repetition frequency
B. Spatial pulse length
C. Transducer diameter
D. Frame rate
Rationale: Axial resolution is determined by the spatial pulse length (SPL). The
shorter the SPL, the better the axial resolution.
2. Which artifact results from sound reflecting off a strong reflector and being
redirected back into the body?
A. Reverberation
B. Mirror image
C. Shadowing
D. Ring down
Rationale: A mirror image artifact occurs when a strong reflector (like the
diaphragm) redirects sound, creating a duplicated structure.
,3. What is the purpose of the backing material in a transducer?
A. Increase bandwidth
B. Enhance lateral resolution
C. Dampen the ringing of the crystal
D. Decrease beam divergence
Rationale: The backing material reduces the pulse duration by damping the
crystal's vibrations, improving axial resolution.
4. Which of the following improves lateral resolution?
A. Focusing
B. Decreasing frequency
C. Increasing gain
D. Increasing pulse duration
Rationale: Focusing narrows the beam width, which improves lateral resolution.
5. Which control affects the brightness of all echoes on the screen uniformly?
A. Time gain compensation
B. Dynamic range
C. Overall gain
D. Compression
Rationale: Overall gain amplifies all signals equally, affecting the brightness of the
entire image.
, 6. What type of resolution is affected by beam width?
A. Axial
B. Temporal
C. Lateral
D. Contrast
Rationale: Lateral resolution depends on the width of the sound beam, which
determines how close two objects can be side-by-side and still be distinguished.
7. What happens to propagation speed in bone compared to soft tissue?
A. It increases
B. It decreases
C. It remains the same
D. It varies randomly
Rationale: Sound travels faster in bone (~4080 m/s) than in soft tissue (~1540
m/s).
8. What artifact appears as multiple equally spaced echoes caused by the sound
bouncing between two strong reflectors?
A. Shadowing
B. Reverberation
C. Comet tail
D. Mirror image
