DMS 104 Final Exam Review 2026 – Advanced Sonography Principles and
Imaging Study Guide
Transducers - correct answer ✔✔ Ultrasound transducers convert electrical energy into acoustic
energy during transmission and acoustic to electrical energy during reception.
Ultrasound transducers - correct answer ✔✔ TRANSDUCER is any device that converts one form
of energy into another. (e.g., acoustic (sound) to electrical; electrical to thermal).
Electric motor transducer - correct answer ✔✔ converts electrical energy into mechanical
Light bulb transducer - correct answer ✔✔ converts electrical energy into heat and light
Muscle transducer - correct answer ✔✔ converts chemical energy into mechanical energy
Loudspeaker transducer - correct answer ✔✔ converts electrical energy into acoustic energy
PIEZOELECTRIC EFFECT - correct answer ✔✔ A property of certain materials to create a voltage
when they are mechanically deformed. The conversion of mechanical (sound) energy into
electrical energy. Ultrasound transducers work this way when we receive sound back from the
body.
REVERSE PIEZOELECTRIC EFFECT: - correct answer ✔✔ Piezoelectric materials change shape and
vibrate when a voltage is applied to them. The conversion of electrical energy into mechanical
(sound) energy.
This is how ultrasound transducers work when we are sending sound. Their primary component
is a crystal with piezoelectric properties.
, Piezoelectric Materials ferroelectric. - correct answer ✔✔ Found in nature: quartz, Rochelle
salts, and tourmaline
Man-made: barium titanate, lead metaniobate, lead titanate, lead zirconate titanate (PZT)
Currie Temperature - correct answer ✔✔ If we heat piezoelectric material above this
temperature, the material is depolarized and loses its piezoelectricity forever! We cannot heat
sterilize or autoclave transducers. (300-400C) (365 C for PZT)
Damping material - correct answer ✔✔ 1. shortens the spatial pulse length and pulse duration.
2. improves picture quality.
3. increases bandwidth (the range of frequencies within the pulse).
4. decreases the "Q" factor. A low Q transducer.
5. decreases the transducer's sensitivity to reflected echoes
6. decreases output intensity
Impedance in decreasing order: - correct answer ✔✔ PZT> matching layer > gel > skin
Continuous wave (CW): - correct answer ✔✔ Doppler units use two crystals in the transducer:
one to transmit the sound waves of constant frequency continuously and one to receive the
reflected echoes continuously
While the transmitter is constantly sending out US energy (duty factor --- 1.0) the receiver is
continuously listening.
Sound cannot be used for imaging.
Disadvantage of CW - correct answer ✔✔ system is a lack of anatomic information.
Imaging Study Guide
Transducers - correct answer ✔✔ Ultrasound transducers convert electrical energy into acoustic
energy during transmission and acoustic to electrical energy during reception.
Ultrasound transducers - correct answer ✔✔ TRANSDUCER is any device that converts one form
of energy into another. (e.g., acoustic (sound) to electrical; electrical to thermal).
Electric motor transducer - correct answer ✔✔ converts electrical energy into mechanical
Light bulb transducer - correct answer ✔✔ converts electrical energy into heat and light
Muscle transducer - correct answer ✔✔ converts chemical energy into mechanical energy
Loudspeaker transducer - correct answer ✔✔ converts electrical energy into acoustic energy
PIEZOELECTRIC EFFECT - correct answer ✔✔ A property of certain materials to create a voltage
when they are mechanically deformed. The conversion of mechanical (sound) energy into
electrical energy. Ultrasound transducers work this way when we receive sound back from the
body.
REVERSE PIEZOELECTRIC EFFECT: - correct answer ✔✔ Piezoelectric materials change shape and
vibrate when a voltage is applied to them. The conversion of electrical energy into mechanical
(sound) energy.
This is how ultrasound transducers work when we are sending sound. Their primary component
is a crystal with piezoelectric properties.
, Piezoelectric Materials ferroelectric. - correct answer ✔✔ Found in nature: quartz, Rochelle
salts, and tourmaline
Man-made: barium titanate, lead metaniobate, lead titanate, lead zirconate titanate (PZT)
Currie Temperature - correct answer ✔✔ If we heat piezoelectric material above this
temperature, the material is depolarized and loses its piezoelectricity forever! We cannot heat
sterilize or autoclave transducers. (300-400C) (365 C for PZT)
Damping material - correct answer ✔✔ 1. shortens the spatial pulse length and pulse duration.
2. improves picture quality.
3. increases bandwidth (the range of frequencies within the pulse).
4. decreases the "Q" factor. A low Q transducer.
5. decreases the transducer's sensitivity to reflected echoes
6. decreases output intensity
Impedance in decreasing order: - correct answer ✔✔ PZT> matching layer > gel > skin
Continuous wave (CW): - correct answer ✔✔ Doppler units use two crystals in the transducer:
one to transmit the sound waves of constant frequency continuously and one to receive the
reflected echoes continuously
While the transmitter is constantly sending out US energy (duty factor --- 1.0) the receiver is
continuously listening.
Sound cannot be used for imaging.
Disadvantage of CW - correct answer ✔✔ system is a lack of anatomic information.
