The present invention relates to a method for making an ablation
transducer having a plurality of helical elements that can be operated
out of phase to orient the acoustical energy beam forward or backward in
the longitudinal direction. The transducers includes a cylindrical inner
electrode, a cylindrical piezoelectric material disposed over the inner
electrode, and a cylindrical outer electrode disposed over the
cylindrical piezoelectric material. Spiral grooves are cut through at
least the outer electrode separating the transducer into a plurality of
functionally discrete helical transducer segments. The helical transducer
segments can be operated independent from one another. An array of
intertwined helical transducers arranged linearly along a helical axis
are also contemplated.