EDELMAN UNDERSTANDING ULTRASOUND FINAL PAPER
2025/2026 QUESTIONS WITH ANSWERS GRADED A+
✔✔True or false? The piezoelectric crystal of a transducer typically has an impedance
higher than the impedance of skin. - ✔✔True
✔✔Which of the following lists orders the impedance from highest to lowest?
a. Skin, gel, matching layer, PZT
b. PZT, gel, matching layer, skin
c. Gel, PZT, matching layer, skin
d. PZT, matching layer, gel, skin - ✔✔PZT, matching layer, gel, skin
✔✔What is the thickness of the matching layer of a 2 MHz pulsed wave transducer?
a. 1.54 mm
b. 0.77 mm
c. Half of the wavelength of the sound wave in the PZT
d. One-quarter the wavelength of sound in the matching layer - ✔✔One-quarter the
wavelength of sound in the matching layer
✔✔True or false? THe acoustic impedance of the skin is greater than the acoustic
impedances of both the matching layer and the piezoelectric element. - ✔✔False
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The damping material helps to decrease the pulse
repetition period achieved at a given imaging depth. - ✔✔False
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The backing material helps to decrease the duty cycle
at a particular PRF. - ✔✔True
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The pulse duration is increased as a result of the
presence of backing material. - ✔✔False
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The backing material decreases the quality factor. -
✔✔True
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The spatial pulse length is decreased with the
application of backing material. - ✔✔True
,✔✔Assume that the frequency of sound with the greatest power emitted by a transducer
is 5 MHz. However, the pulse contains acoustic energy with frequencies as low as 3.5
MHz and as high as 6.5 MHz. What is the bandwidth of the transducer?
a. 6.5 MHz
b. 5.0 MHz
c. 3.5 MHz
d. 3.0 MHz - ✔✔3.0 MHz
✔✔True or false? In general, ultrasound imaging transducers have a lower quality factor
and a wider bandwidth than therapeutic ultrasound transducers. - ✔✔True
✔✔Damping material is secured to piezoelectric material during the fabrication of an
ultrasonic imaging transducer. Which of the following is not a consequence of this
attachment?
a. Bandwidth increases
b. Quality factor decreases
c. Sensitivity increases
d. Transducer case is longer - ✔✔Sensitivity increases
✔✔Which of the following actions would cause a PZT crystal to lose its special
properties?
a. Breaking it in pieces
b. Exposing it to high temperatures
c. Exposing it to electrical current
d. Exposing it to low pressures - ✔✔Exposing it to high temperatures
✔✔All of the following are true about transducers except :
a. It is necessary to sterilize transducers before use
b. Most transducers simply require disinfection as they do not penetrate mucous
membranes
c. Sterilization could depolarize PZT
d. They are unlikely to transmit infection - ✔✔It is necessary to sterilize transducers
before use
✔✔Which properties of the piezoelectric crystal of a continuous wave transducer result
in the highest emitted acoustic wave frequency?
a. Thin, high propagation speed
b. Thick, slow propagation speed
c. Thin, slow propagation speed
d. None of the above - ✔✔None of the above
✔✔What helps to determine the frequency of the sound produced by the transducer of a
continuous wave ultrasound system?
a. Piezoelectric crystal diameter
,b. Piezoelectric crystal thickness
c. Damping material density
d. Ultrasound system electronics - ✔✔Ultrasound system electronics
✔✔With pulsed wave ultrasonic imaging, what helps to establish the primary frequency
of the acoustic energy discharged by the transducer?
a. Piezoelectric crystal diameter
b. Piezoelectric crystal thickness
c. Damping material density
d. Ultrasound system electronics - ✔✔Piezoelectric crystal thickness
✔✔An ultrasonic pulse is traveling in soft tissue. Which of the following is most
important in the determination of the frequency of the sound?
a. The propagation speed of the ultrasound transducer's matching layer
b. The thickness of the transducer's backing material
c. The impedance of the transducer's matching layer
d. The propagation speed of the transducer's active element - ✔✔The propagation
speed of the transducer's active element
✔✔What is the best estimate of the propagation speed of the ferroelectric element of a
transducer used in a typical diagnostic imaging laboratory?
a. 1.2 mm/microsecond
b. 4.0 m/sec
c. 4.0 mm/microsecond
d. 1.0 km/sec - ✔✔4.0 mm/microsecond
✔✔Which properties of the piezoelectric crystal of an imaging transducer result in the
highest emitted acoustic wave frequency?
a. Thin, high propagation speed
b. Thick, slow propagation speed
c. Thin, slow propagation speed
d. None of the above - ✔✔Thin, high propagation speed
✔✔You are asked to fabricate a pulsed ultrasound transducer with the highest possible
frequency. Which piezoelectric crystal would you select?
a. 6 mm thick, 4 cm diameter, 4.0 mm/microsec propagation speed
b. 8 mm thick, 2 cm diameter, 6.0 mm/microsec propagation speed
c. 4 mm thick, 9 cm diameter, 5.0 mm/microsec propagation speed
d. 2 mm thick, 6 cm diameter, 6.0 mm/microsec propagation speed - ✔✔2 mm thick, 6
cm diameter, 6.0 mm/microsec propagation speed
✔✔You are asked to fabricate a pulsed ultrasound transducer with the lowest possible
frequency. Which piezoelectric crystal would you select?
a. 6 mm thick, 4 cm diameter, 4.0 mm/microsec propagation speed
b. 8 mm thick, 2 cm diameter, 6.0 mm/microsec propagation speed
, c. 4 mm thick, 9 cm diameter, 5.0 mm/microsec propagation speed
d. 2 mm thick, 6 cm diameter, 6.0 mm/microsec propagation speed - ✔✔8 mm thick, 2
cm diameter, 6.0 mm/microsec propagation speed
✔✔What is the region from the transducer to the smallest cross-sectional area of a
sound beam called?
a. Focus
b. Half-value thickness
c. Near zone
d. Fraunhofer zone - ✔✔Near zone
✔✔The area that starts at the beam's smallest diameter and extends deeper is:
a. The distant zone
b. The Fresnel zone
c. The Fraunhofer zone
d. The depth of penetration - ✔✔The Fraunhofer zone
✔✔Which of these terms have the same meaning?
1. Far zone 2. Near zone
3. Fresnel zone 4. Focal zone
5. Fraunhofer zone 6. Lateral zone
a. 1 and 2, 3 and 4
b. 1 and 4, 2 and 3
c. 4 and 6, 5 and 1
d. 2 and 3, 5 and 1 - ✔✔2 and 3, 5 and 1
✔✔What is the point or location where a beam reaches its smallest dimension?
a. Near zone
b. Focus
c. Penetration depth
d. Focal zone - ✔✔Focus
✔✔All of the following are true of the focus except :
a. It is at the end of the near zone
b. It is at the beginning of the Fraunhofer zone
c. It has the highest spatial peak intensity
d. It is at the start of the Fresnel zone - ✔✔It is at the start of the Fresnel zone
✔✔A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The
beam is unfocused. Is the following statement true or false? The near zone is the only
region where the diameter of the sound beam is smaller than the transducer's. -
✔✔False
2025/2026 QUESTIONS WITH ANSWERS GRADED A+
✔✔True or false? The piezoelectric crystal of a transducer typically has an impedance
higher than the impedance of skin. - ✔✔True
✔✔Which of the following lists orders the impedance from highest to lowest?
a. Skin, gel, matching layer, PZT
b. PZT, gel, matching layer, skin
c. Gel, PZT, matching layer, skin
d. PZT, matching layer, gel, skin - ✔✔PZT, matching layer, gel, skin
✔✔What is the thickness of the matching layer of a 2 MHz pulsed wave transducer?
a. 1.54 mm
b. 0.77 mm
c. Half of the wavelength of the sound wave in the PZT
d. One-quarter the wavelength of sound in the matching layer - ✔✔One-quarter the
wavelength of sound in the matching layer
✔✔True or false? THe acoustic impedance of the skin is greater than the acoustic
impedances of both the matching layer and the piezoelectric element. - ✔✔False
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The damping material helps to decrease the pulse
repetition period achieved at a given imaging depth. - ✔✔False
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The backing material helps to decrease the duty cycle
at a particular PRF. - ✔✔True
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The pulse duration is increased as a result of the
presence of backing material. - ✔✔False
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The backing material decreases the quality factor. -
✔✔True
✔✔With regard to the backing material of a pulsed ultrasound transducer, is the
following statement true or false? The spatial pulse length is decreased with the
application of backing material. - ✔✔True
,✔✔Assume that the frequency of sound with the greatest power emitted by a transducer
is 5 MHz. However, the pulse contains acoustic energy with frequencies as low as 3.5
MHz and as high as 6.5 MHz. What is the bandwidth of the transducer?
a. 6.5 MHz
b. 5.0 MHz
c. 3.5 MHz
d. 3.0 MHz - ✔✔3.0 MHz
✔✔True or false? In general, ultrasound imaging transducers have a lower quality factor
and a wider bandwidth than therapeutic ultrasound transducers. - ✔✔True
✔✔Damping material is secured to piezoelectric material during the fabrication of an
ultrasonic imaging transducer. Which of the following is not a consequence of this
attachment?
a. Bandwidth increases
b. Quality factor decreases
c. Sensitivity increases
d. Transducer case is longer - ✔✔Sensitivity increases
✔✔Which of the following actions would cause a PZT crystal to lose its special
properties?
a. Breaking it in pieces
b. Exposing it to high temperatures
c. Exposing it to electrical current
d. Exposing it to low pressures - ✔✔Exposing it to high temperatures
✔✔All of the following are true about transducers except :
a. It is necessary to sterilize transducers before use
b. Most transducers simply require disinfection as they do not penetrate mucous
membranes
c. Sterilization could depolarize PZT
d. They are unlikely to transmit infection - ✔✔It is necessary to sterilize transducers
before use
✔✔Which properties of the piezoelectric crystal of a continuous wave transducer result
in the highest emitted acoustic wave frequency?
a. Thin, high propagation speed
b. Thick, slow propagation speed
c. Thin, slow propagation speed
d. None of the above - ✔✔None of the above
✔✔What helps to determine the frequency of the sound produced by the transducer of a
continuous wave ultrasound system?
a. Piezoelectric crystal diameter
,b. Piezoelectric crystal thickness
c. Damping material density
d. Ultrasound system electronics - ✔✔Ultrasound system electronics
✔✔With pulsed wave ultrasonic imaging, what helps to establish the primary frequency
of the acoustic energy discharged by the transducer?
a. Piezoelectric crystal diameter
b. Piezoelectric crystal thickness
c. Damping material density
d. Ultrasound system electronics - ✔✔Piezoelectric crystal thickness
✔✔An ultrasonic pulse is traveling in soft tissue. Which of the following is most
important in the determination of the frequency of the sound?
a. The propagation speed of the ultrasound transducer's matching layer
b. The thickness of the transducer's backing material
c. The impedance of the transducer's matching layer
d. The propagation speed of the transducer's active element - ✔✔The propagation
speed of the transducer's active element
✔✔What is the best estimate of the propagation speed of the ferroelectric element of a
transducer used in a typical diagnostic imaging laboratory?
a. 1.2 mm/microsecond
b. 4.0 m/sec
c. 4.0 mm/microsecond
d. 1.0 km/sec - ✔✔4.0 mm/microsecond
✔✔Which properties of the piezoelectric crystal of an imaging transducer result in the
highest emitted acoustic wave frequency?
a. Thin, high propagation speed
b. Thick, slow propagation speed
c. Thin, slow propagation speed
d. None of the above - ✔✔Thin, high propagation speed
✔✔You are asked to fabricate a pulsed ultrasound transducer with the highest possible
frequency. Which piezoelectric crystal would you select?
a. 6 mm thick, 4 cm diameter, 4.0 mm/microsec propagation speed
b. 8 mm thick, 2 cm diameter, 6.0 mm/microsec propagation speed
c. 4 mm thick, 9 cm diameter, 5.0 mm/microsec propagation speed
d. 2 mm thick, 6 cm diameter, 6.0 mm/microsec propagation speed - ✔✔2 mm thick, 6
cm diameter, 6.0 mm/microsec propagation speed
✔✔You are asked to fabricate a pulsed ultrasound transducer with the lowest possible
frequency. Which piezoelectric crystal would you select?
a. 6 mm thick, 4 cm diameter, 4.0 mm/microsec propagation speed
b. 8 mm thick, 2 cm diameter, 6.0 mm/microsec propagation speed
, c. 4 mm thick, 9 cm diameter, 5.0 mm/microsec propagation speed
d. 2 mm thick, 6 cm diameter, 6.0 mm/microsec propagation speed - ✔✔8 mm thick, 2
cm diameter, 6.0 mm/microsec propagation speed
✔✔What is the region from the transducer to the smallest cross-sectional area of a
sound beam called?
a. Focus
b. Half-value thickness
c. Near zone
d. Fraunhofer zone - ✔✔Near zone
✔✔The area that starts at the beam's smallest diameter and extends deeper is:
a. The distant zone
b. The Fresnel zone
c. The Fraunhofer zone
d. The depth of penetration - ✔✔The Fraunhofer zone
✔✔Which of these terms have the same meaning?
1. Far zone 2. Near zone
3. Fresnel zone 4. Focal zone
5. Fraunhofer zone 6. Lateral zone
a. 1 and 2, 3 and 4
b. 1 and 4, 2 and 3
c. 4 and 6, 5 and 1
d. 2 and 3, 5 and 1 - ✔✔2 and 3, 5 and 1
✔✔What is the point or location where a beam reaches its smallest dimension?
a. Near zone
b. Focus
c. Penetration depth
d. Focal zone - ✔✔Focus
✔✔All of the following are true of the focus except :
a. It is at the end of the near zone
b. It is at the beginning of the Fraunhofer zone
c. It has the highest spatial peak intensity
d. It is at the start of the Fresnel zone - ✔✔It is at the start of the Fresnel zone
✔✔A PZT crystal in the shape of a disc produces a continuous ultrasound wave. The
beam is unfocused. Is the following statement true or false? The near zone is the only
region where the diameter of the sound beam is smaller than the transducer's. -
✔✔False
