Insonation of fixed porcine kidney by a prototype sector-vortex-phased array applicator.

The sector-vortex applicator, an ultrasound phased array with a geometric focus having multiple sectors and tracks, can directly synthesize, without scanning, diffuse focal patterns useful for hyperthermia. A perfused tissue phantom, consisting of an alcohol-fixed porcine kidney with thermocouples placed in the cortex, is insonated by a prototype sector-vortex applicator with 16 sectors and two tracks at an ultrasound frequency of 750 kHz. Steady-state temperature distributions are measured for a wide range of perfusion rates. Results demonstrate that the radius of the heated region can be controlled effectively by choosing the focal mode of the applicator as it is predicted by theoretical analysis.