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A multi-element ultrasonic hyperthermia applicator with independent element control
H R Underwood1, E C Burdette, K B Ocheltree
1Bioacoustics Research Laboratory, University of Illinois, Urbana 61801.
Summary
Researchers experimentally determined ultrasonic applicator acoustic fields, comparing results with theoretical models. Unequal element excitation created complex patterns, and a model with damping improved accuracy, showing potential for targeted tissue heating.
Area of Science:
- Ultrasound Physics
- Acoustic Field Characterization
- Biomedical Engineering
Background:
- Planar multi-element ultrasonic applicators are used in various medical applications.
- Understanding acoustic field patterns is crucial for effective therapeutic ultrasound.
- Existing theoretical models may not fully capture complex experimental acoustic fields.
Purpose of the Study:
- To experimentally determine acoustic field patterns from a planar multi-element ultrasonic applicator.
- To compare experimental findings with theoretical predictions.
- To assess the applicator's suitability for localized tissue heating.
Main Methods:
- Measurements of acoustic fields using square arrays of 4 and 16 elements (3.6 cm x 3.6 cm) driven at 1 MHz in water.
- Characterization of acoustic beams using transverse and axial scans for different aperture sizes and element excitations.
- Comparison of experimental data with simple theoretical models and models incorporating mechanical damping.
Main Results:
- Unequal power excitation of adjacent elements resulted in multiple-peaked acoustic intensity patterns.
- A theoretical model including mechanical damping showed improved agreement with experimental transverse and axial field patterns.
- Experimental measurements exhibited less axial pattern ripple than predicted by either theoretical model.
Conclusions:
- The study provides experimental validation of acoustic field patterns generated by a multi-element ultrasonic applicator.
- Theoretical models, particularly those including mechanical damping, can approximate experimental results but require refinement.
- The applicator demonstrated potential for generating acoustic fields suitable for localized tissue heating applications.