A prototype hyperthermia applicator based on a sector-vortex array has been designed and constructed. The transducer consists of a disk-shaped phased array with a geometric focus divided into 16 sectors and two tracks. It uses special lead-titanate ceramic elements and an aluminum shell for impedance matching and efficient cooling. Each array element is driven by a complimentary pair of power MOS FETs at 600-800 kHz. An annular focal field approximated by the m-th-order Bessel function is theoretically predicted when the array elements are driven with a phase distribution which rotates M( less than equivalent to 8) times around the disk. Annular fields of several different diameters have been synthesized and measured three-dimensionally using a multichannel PVDF (polyvinylidene difluoride) membrane probe. The measured results compare well with the fields theoretically predicted by computer simulation.
|Number of pages||4|
|Journal||Ultrasonics Symposium Proceedings|
|Publication status||Published - 1987 Dec 1|
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