Beam Predictability for high power transducers

Advantages of piezo-composite transducers

Focus control is an important element in designing a transducer for medical therapy : it is essential to accurately control the treatment zone and to thus protect the healthy tissue.

The intrinsic features of Imasonic’s piezo-composite structure enable radial modes to be reduced, thus favoring the vibration according to the thickness mode. The electro-acoustic response obtained is thus very close to the theory and the acoustic field does not present any hot points outside the focal point. See the illustration below.

Comparison between theory and piezocomposite transducer

Measured beam with PZT transducers

The figures below show clearly the limitations of PZT transducers through the possible generation of unexpected hot spots that may cause unexpected and uncontrolled lesions in tissues. This phenomeneon is mainly due to the generation of lamb waves inside the PZT plate.

Example of annular sectored arrays

Comparison of simulated and experimental beam on 1.2MHz, 104elts MRI compatible arrays with focused active area of 100mm active diameter


Courtesy Brigham Hospital & Insightec


Related papers

  • Comparison of acoustical fields radiated from piezoceramic and piezocomposite highly focused transducers,
    Cathignol et al., J. Acoust. Society of America 1999
  • Comparison of acoustical fields radiated from PZT piezoceramic and piezocomposite highly focused transducers.
    D. Cathignol, O. A. Sapozhnikov, J. Zhang, J-Y. Chapelon – IEEE Ultrasonics Symposium, 1995