Abstract

We recently proposed an analytical design method of Langevin transducers for therapeutic ultrasound treatment by conducting parametric study to estimate the effect of compression force on resonance characteristics. In this study, experimental investigations were further performed under various electrical conditions to observe the acoustic power of the fully equipped transducer and to assess its heat-related bioeffect. Thermal index (TI) tests were carried out to examine temperature rise and thermal damage induced by the acoustic energy in fatty porcine tissue. Acoustic power emission, TI values, temperature characteristics, and depth/size of thermal ablation were measured as a function of transducer’s driving voltage. By exciting the transducer with 300 Vpp sinusoidal continuous waveform, for instance, the average power was 23.1 W and its corresponding TI was 4.1, less than the 6 specified by the Food and Drug Administration (FDA) guideline. The maximum temperature and the depth of the affected site were 74.5 °C and 19 mm, respectively. It is shown that thermal ablation is likely to be more affected by steep heat surge for a short duration rather than by slow temperature rise over time. Hence, the results demonstrate the capability of our ultrasonic transducer intended for therapeutic procedures by safely interrogating soft tissue and yet delivering enough energy to thermally stimulate the tissue in depth.

Highlights

  • Langevin-type transducers, invented by Paul Langevin in 1922, have been widely used to amplify ultrasonic energy in various fields, including the food industry [1,2], sonochemistry [3], and medical practices [4,5]

  • This work carried out experimental investigations under various excitation conditions to measure the acoustic power of a fully equipped Langevin transducer and to assess its heat-related bioeffect with porcine tissue

  • We first built a Langevin transducer according to our design model and excited the sample at actual resonance frequency determined by impedance analyzer

Read more

Summary

Introduction

Langevin-type transducers, invented by Paul Langevin in 1922, have been widely used to amplify ultrasonic energy in various fields, including the food industry [1,2], sonochemistry [3], and medical practices [4,5]. Typical Langevin transducers are composed of central bolts, rear/front masses, piezoelectric stacks, acoustic boosters, and attachable tools. AA sscchheemmaattiicc ddiiaaggrraamm ffoorr tteemmppeerraattuurree cchhaannggee iinn ppoorrcciinnee ttiissssuuee iiss ggiivveenn iinn FFiigguurree 77.. AAccoouussttiicc ppoowweerr wwaass mmeeaassuurreedd bbyy vvaarryyiinngg tthhee vvoollttaaggee aammpplliittuuddee ffoorr ttrraannssdduucceerr eexx-cciittaattiioonn ffrroomm 110000 VVpppp ttoo 330000 VVpppp..

Results
Conclusion
Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call