| Summary: | 碩士 === 國立臺灣大學 === 醫學工程學研究所 === 101 === The main purpose of this study is to develop an MR-compatible three-dimensional positioning system applied in MRI-guided focused ultrasound thermal therapy for breast tumors. The positioning system is used to move a ring-shaped phased array ultrasound transducer to deliver sufficient acoustic power to the desired region for breast tumor treatment. The combination of MRI system and FUS (Focused Ultrasound) can supply tumor examination, treatment planning, treatment monitoring, non-invasive treatment etc. for tumor therapy.
In this study, the positioning system consists of three ultrasonic motors used as the actuators and linear three-axial guides stacked up together for a three-dimensional motion control with a ramp mechanism for the transmission of mechanical movement in the Z-dimension. The travel ranges of X-, Y-, and Z-dimension are all 50 mm. When the system drives a ring-shaped ultrasound transducer, the transducer/transducer holder and the ramp mechanism are placed in a rectangular water tank, and all components are manufactured from MR compatible materials. Under the severe MRI conditions and treatment requirements, it is a challenge for a mechanical engineer to develop an MR-compatible positioning system to meet the needs.
The developed prototype of positioning system under the driving of the ring-shaped ultrasound transducer has been examined using a laser distance device for its positioning characteristics. The results showed that the position error is less than 500 μm after system calibration. For the MRI-compatibility test, the results revealed that the positioning system owns great MR compatibility. The positioning system can drive the ultrasound transducer to the desired locations with great precision without causing significant interference to MRI.
In this study, we focused on the development of an MRI-compatible positioning system which is used to drive a ring-shaped ultrasound transducer for breast tumor thermal therapy. The system has great movement precision and MR compatibility, and owns the potential to effectively drive the ultrasound transducer for MRI-guided focused ultrasound thermal therapy.
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