Investigation of Ring-Shaped Phased-Array Focused Ultrasound with MRI System for Breast Tumor Treatment
Date Issued
2011
Date
2011
Author(s)
Lin, Bo-Sian
Abstract
High-intensity focused ultrasound (HIFU) has the characteristics of power concentration and can generate the steep temperature elevation at the target to kill the cells by hyperthermia. Because ultrasound has great ability of penetration to soft tissue and can apply non-invasive treatments, it becomes a new method for cancer therapies.
In this study, we develop a ring-shaped phase-array focused ultrasound transducer for the breast tumor treatment. The transducer size is 20cm in diameter, with a radius of curvature of 10cm and a height of 2cm. The transducer consists of 16 separated piezoelectric ceramics, and operate at the frequency of 1MHz. Piezoelectric ceramics generate the ultrasound power by the piezoelectric effect of materials. We measure the electro-mechanical coupling constant and the electro-acoustic transverse ratio to confirm the acoustic output power stability of the transducer.
According to different clinical requirements, we set different phase of output acoustic wave to form different heating results for the different thermal treatment strategies. We assume the tumor is located at the center of the breast, and use the breast phantom and pork sample in vitro to do the ablation experiments of different heating models. Furthermore, the ablation experiment apparatus is collocated with the MRI system to observe the heating patterns and the temperature change in the focal region. Experiment results show that the ring-shaped phase-array focused ultrasound transducer using different heating models can generate sufficient heating range and make the effective temperature rise at the tumor in the center of breast, achieve the treatment purpose of tissue denature and necrosis.
Subjects
ring-shaped phase-array ultrasound transducer
breast tumor
hyperthermia
MRI thermometry
SDGs
Type
thesis
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