Investigation of MR-Compatible C-ShapedPhased-Array Ultrasound Transducer for Breast Tumor Treatment
Date Issued
2014
Date
2014
Author(s)
Yu, Yen-Ching
Abstract
In this study,a C-shaped phase-array focused ultrasound transducer for breast tumor treatment was developed. High-intensity focused ultrasound (HIFU) has the ability to concentratepower to generate a steep temperature elevation at the target to kill the cells. In addition, ultrasound has a great ability of soft tissue penetration and can be appliedfor non-invasive treatments.
Piezoelectric ceramics was cut with designed dimension and then filled withepoxy to made it become piezoelectric-composite. Thepiezoelectric-composite was then used to make a C-shaped ultrasound transducer with a diameter of 20cm,a radius of curvature of 10cm and a height of 2.5cm. The transducer consisted of 16 separated elements and operated at a frequency of 2.5MHz. We used a multi-channel power system to drive the transducer. The piezoelectric-composite elements generated the ultrasound power by piezoelectric effect. We madematching circuit for each element based onSmith Chart. The electro-acoustic transfer ratio was measured by radiation force test and the transducer has been working for 15 minutes continuously to confirm thestability of acoustic output power. We used thermo-sensitive phantom to observe the heating effect. The transducer was placed in an MRI environment to demonstrate its MR compatibility.
The results showed that the output power of each element could reach 30 Watt, and the electro-acoustic transfer ratio was about 30%. During a 15-min working time, the transducer could transfer the acoustic power stably. Due to the limitation of power supply, low electro-acoustic efficiency, and a large focal zone, the transducer could not reach the requirement for changing phantom’s color.
In this study, we developed a C-shaped phase-array focused ultrasound transducer for breast tumor thermal therapy. The manufacturing process of piezoelectric-composite material and the stability of transducer were confirmed. Theultrasound transducer had a certain degree of MR compatibility.
Subjects
半環形超音波換能器
熱治療
乳房腫瘤
壓電複合材料
陣列式探頭
Type
thesis
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