What are two characteristics of high-frequency pulsed wave imaging transducers?

What are two characteristics of high-frequency pulsed wave imaging transducers?

• A. Thicker PZT crystals; PZT with lower speeds
• B. Thicker PZT crystals; PZT with higher speeds
• C. Thinner PZT crystals; PZT with lower speeds
• D. Thinner PZT crystals; PZT with higher speeds

Answer: (D)

High-frequency imaging is achieved by raising the transducer’s resonant frequency, which is set mainly by the thickness of the PZT element and the speed of sound in that material. For a thickness-mode transducer, the resonant frequency is roughly f ≈ v/(2d), with v being the PZT’s speed of sound and d the crystal thickness. To increase frequency, you can make the crystal thinner or use a material with a higher speed of sound, or both. Therefore, high-frequency pulsed-wave transducers use thinner PZT crystals and PZT materials with higher speeds of sound. Thicker crystals or slower PZT would lower the resonant frequency and reduce the imaging frequency.

High-frequency imaging is achieved by raising the transducer’s resonant frequency, which is set mainly by the thickness of the PZT element and the speed of sound in that material. For a thickness-mode transducer, the resonant frequency is roughly f ≈ v/(2d), with v being the PZT’s speed of sound and d the crystal thickness. To increase frequency, you can make the crystal thinner or use a material with a higher speed of sound, or both. Therefore, high-frequency pulsed-wave transducers use thinner PZT crystals and PZT materials with higher speeds of sound. Thicker crystals or slower PZT would lower the resonant frequency and reduce the imaging frequency.