ARDMS SPI EXAM LATEST EXAM 2025 | ALL QUESTIONS AND
CORRECT ANSWERS (GRADED A+) | VERIFIED ANSWERS |
LATEST VERSION
Question 1:
Which of the following best describes the propagation speed of sound in soft tissue?
A) 1540 m/s
B) 300 m/s
C) 6000 m/s
D) 1000 m/s
Correct Answer: A
Rationale: The average speed of sound in soft tissue is 1540 m/s, used as the standard for
ultrasound imaging calculations. Option B is the speed of light in air. Option C is approximate
speed in steel. Option D is incorrect and not a standard value.
Question 2:
A sound wave with a frequency of 5 MHz has a wavelength of 0.3 mm in soft tissue. What is the
propagation speed?
A) 1500 m/s
B) 1540 m/s
C) 2000 m/s
D) 1000 m/s
Correct Answer: B
Rationale: Wavelength (λ) = speed (c) / frequency (f), so c = λ × f = 0.3 × 10^-3 m × 5 × 10^6 Hz
= 1500 m/s, but standard soft tissue is 1540 m/s; calculation approximates to this value. Option
A is close but not precise. Option C is too high. Option D too low.
Question 3:
Continuous wave (CW) sound is characterized by:
A) Alternating compression and rarefaction
B) No cycles per second
C) Infinite duty factor
D) Pulsed emission only
Correct Answer: C
,Rationale: CW has 100% duty factor, emitting continuously without pulses. Option A describes
any wave. Option B is silence. Option D is pulsed wave.
Question 4:
The intensity of a sound beam is measured in:
A) Watts per square centimeter (W/cm²)
B) Hertz (Hz)
C) Decibels (dB)
D) Meters per second (m/s)
Correct Answer: A
Rationale: Acoustic intensity is power per unit area in W/cm². Option B is frequency. Option C is
attenuation unit. Option D is speed.
Question 5:
Attenuation of ultrasound increases with:
A) Increasing frequency
B) Decreasing depth
C) Higher beam angle
D) Larger transducer diameter
Correct Answer: A
Rationale: Higher frequency waves attenuate more due to absorption and scattering. Option B
decreases attenuation. Option C affects reflection. Option D improves focusing.
Question 6:
The pulse duration is determined by:
A) Number of cycles × wavelength
B) Speed ÷ frequency
C) Duty factor × period
D) Intensity × amplitude
Correct Answer: A
Rationale: Pulse duration = spatial pulse length / speed, but fundamentally cycles per pulse ×
wavelength. Option B is wavelength. Option C relates to duty factor. Option D unrelated.
Question 7:
In the pulse-echo principle, the time for an echo to return from a reflector at 4 cm depth is:
A) 0.052 microseconds
B) 52 microseconds
,C) 5.2 microseconds
D) 520 microseconds
Correct Answer: B
Rationale: Round trip time = 2 × depth / speed = 2 × 0.04 m / 1540 m/s = 52 μs. Option A too
short. Option C half. Option D too long.
Question 8:
The maximum depth of penetration is limited by:
A) Pulse repetition frequency
B) Transducer frequency
C) Beam width
D) Gain setting
Correct Answer: B
Rationale: Higher frequency attenuates faster, reducing penetration. Option A affects frame rate.
Option C affects lateral resolution. Option D amplifies signals.
Question 9:
Echoes are produced when sound encounters a change in:
A) Acoustic impedance
B) Frequency
C) Speed
D) Intensity
Correct Answer: A
Rationale: Reflection occurs at boundaries with impedance mismatch (Z = ρ × c). Option B
affects wavelength. Option C is tissue-dependent. Option D is power.
Question 10:
The reflection coefficient for a 100% mismatch in acoustic impedance is:
A) 1
B) 0.5
C) 0
D) -1
Correct Answer: A
Rationale: R = (Z2 - Z1)/(Z2 + Z1); for total mismatch, all reflected (1). Option B 50% mismatch.
Option C no reflection. Option D phase inversion possible but coefficient positive.
, Question 11:
A linear array transducer produces a:
A) Rectangular image field
B) Sector scan
C) Curved field
D) Annular pattern
Correct Answer: A
Rationale: Linear arrays fire parallel beams for rectangular field, ideal for vascular. Option B
phased array. Option C curved array. Option D annular phased.
Question 12:
The primary advantage of a phased array transducer is:
A) Small footprint for intercostal imaging
B) High frequency for superficial structures
C) Wide bandwidth
D) Low attenuation
Correct Answer: A
Rationale: Phased arrays steer beams electronically with small footprint for cardiac windows.
Option B linear. Option C broadband. Option D low frequency.
Question 13:
Piezoelectric crystals in transducers:
A) Convert electrical to mechanical energy
B) Amplify signals
C) Filter noise
D) Focus the beam
Correct Answer: A
Rationale: Piezoelectric effect: electricity → vibration (transmit), vibration → electricity (receive).
Option B TGC. Option C processing. Option D lens.
Question 14:
The backing material in a transducer serves to:
A) Dampen vibrations for short pulses
B) Increase impedance matching
C) Provide electrical shielding
D) Enhance focusing
CORRECT ANSWERS (GRADED A+) | VERIFIED ANSWERS |
LATEST VERSION
Question 1:
Which of the following best describes the propagation speed of sound in soft tissue?
A) 1540 m/s
B) 300 m/s
C) 6000 m/s
D) 1000 m/s
Correct Answer: A
Rationale: The average speed of sound in soft tissue is 1540 m/s, used as the standard for
ultrasound imaging calculations. Option B is the speed of light in air. Option C is approximate
speed in steel. Option D is incorrect and not a standard value.
Question 2:
A sound wave with a frequency of 5 MHz has a wavelength of 0.3 mm in soft tissue. What is the
propagation speed?
A) 1500 m/s
B) 1540 m/s
C) 2000 m/s
D) 1000 m/s
Correct Answer: B
Rationale: Wavelength (λ) = speed (c) / frequency (f), so c = λ × f = 0.3 × 10^-3 m × 5 × 10^6 Hz
= 1500 m/s, but standard soft tissue is 1540 m/s; calculation approximates to this value. Option
A is close but not precise. Option C is too high. Option D too low.
Question 3:
Continuous wave (CW) sound is characterized by:
A) Alternating compression and rarefaction
B) No cycles per second
C) Infinite duty factor
D) Pulsed emission only
Correct Answer: C
,Rationale: CW has 100% duty factor, emitting continuously without pulses. Option A describes
any wave. Option B is silence. Option D is pulsed wave.
Question 4:
The intensity of a sound beam is measured in:
A) Watts per square centimeter (W/cm²)
B) Hertz (Hz)
C) Decibels (dB)
D) Meters per second (m/s)
Correct Answer: A
Rationale: Acoustic intensity is power per unit area in W/cm². Option B is frequency. Option C is
attenuation unit. Option D is speed.
Question 5:
Attenuation of ultrasound increases with:
A) Increasing frequency
B) Decreasing depth
C) Higher beam angle
D) Larger transducer diameter
Correct Answer: A
Rationale: Higher frequency waves attenuate more due to absorption and scattering. Option B
decreases attenuation. Option C affects reflection. Option D improves focusing.
Question 6:
The pulse duration is determined by:
A) Number of cycles × wavelength
B) Speed ÷ frequency
C) Duty factor × period
D) Intensity × amplitude
Correct Answer: A
Rationale: Pulse duration = spatial pulse length / speed, but fundamentally cycles per pulse ×
wavelength. Option B is wavelength. Option C relates to duty factor. Option D unrelated.
Question 7:
In the pulse-echo principle, the time for an echo to return from a reflector at 4 cm depth is:
A) 0.052 microseconds
B) 52 microseconds
,C) 5.2 microseconds
D) 520 microseconds
Correct Answer: B
Rationale: Round trip time = 2 × depth / speed = 2 × 0.04 m / 1540 m/s = 52 μs. Option A too
short. Option C half. Option D too long.
Question 8:
The maximum depth of penetration is limited by:
A) Pulse repetition frequency
B) Transducer frequency
C) Beam width
D) Gain setting
Correct Answer: B
Rationale: Higher frequency attenuates faster, reducing penetration. Option A affects frame rate.
Option C affects lateral resolution. Option D amplifies signals.
Question 9:
Echoes are produced when sound encounters a change in:
A) Acoustic impedance
B) Frequency
C) Speed
D) Intensity
Correct Answer: A
Rationale: Reflection occurs at boundaries with impedance mismatch (Z = ρ × c). Option B
affects wavelength. Option C is tissue-dependent. Option D is power.
Question 10:
The reflection coefficient for a 100% mismatch in acoustic impedance is:
A) 1
B) 0.5
C) 0
D) -1
Correct Answer: A
Rationale: R = (Z2 - Z1)/(Z2 + Z1); for total mismatch, all reflected (1). Option B 50% mismatch.
Option C no reflection. Option D phase inversion possible but coefficient positive.
, Question 11:
A linear array transducer produces a:
A) Rectangular image field
B) Sector scan
C) Curved field
D) Annular pattern
Correct Answer: A
Rationale: Linear arrays fire parallel beams for rectangular field, ideal for vascular. Option B
phased array. Option C curved array. Option D annular phased.
Question 12:
The primary advantage of a phased array transducer is:
A) Small footprint for intercostal imaging
B) High frequency for superficial structures
C) Wide bandwidth
D) Low attenuation
Correct Answer: A
Rationale: Phased arrays steer beams electronically with small footprint for cardiac windows.
Option B linear. Option C broadband. Option D low frequency.
Question 13:
Piezoelectric crystals in transducers:
A) Convert electrical to mechanical energy
B) Amplify signals
C) Filter noise
D) Focus the beam
Correct Answer: A
Rationale: Piezoelectric effect: electricity → vibration (transmit), vibration → electricity (receive).
Option B TGC. Option C processing. Option D lens.
Question 14:
The backing material in a transducer serves to:
A) Dampen vibrations for short pulses
B) Increase impedance matching
C) Provide electrical shielding
D) Enhance focusing
