| Summary: | 碩士 === 國立臺灣大學 === 醫學工程學研究所 === 92 === The common practice in ultrasound thermal surgery for treating large tumors is to introduce a large lesion for each exposure with some proper heating strategies. The purpose of this study is to investigate the feasibility of using a sector-vortex phased array of ultrasound transducer with mechanical scanning to produce a large thermal lesion.
The proposed system is composed of a mechanical scanning system with a sector-vortex phased array. The sector-vortex phased array can produce different types of broadened focal zones by tuning the phase and the amplitude of each array element. The mechanical scanning system can control the tilt angle, rotation angle, heating depth, and scanning radius. The previous simulation results suggest that the temperature rise, heating time, and the power density are the dominating factors affecting the treatment results. The results also show that the proposed system can produce conformal thermal dose patterns for different tumors. In experiments, we use mode 0 (as a spherical transducer) and mode 1 in a sector-vortex phased array with four elements to sonicate the porcine liver. The lesion shapes in the in vitro experiments are close to those in the simulations.
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