Tracking Platform Design and Implementation for Ultrasound-Guided Focused Ultrasound Treatment

本研究的目標為建立一個超音波影像導引高能聚焦超音波加熱追蹤平台，應用於肝臟腫瘤加熱治療。有別於常見的輻射線治療，我們採用高聚能超音波加熱方式，目的是以非侵入性、非輻射性的影像導引和治療方法，不會對人體造成傷害。平台的操作範圍及自由度皆根據肝臟隨著呼吸運動型態，及超音波與高能聚焦超音波換能器的特性建立。肝臟運動與呼吸頻率有關，此現象也增加了影像導引治療系統的難度。在研究中我們採用機械方式，利用馬達帶動高能聚焦超音波換能器作即時追蹤肝臟運動。在影像方面，我們使用了超音波，因為超音波影像能提供即時肝臟資訊做為追蹤系統的回授資訊。在系統定位方面， 我們則採用磁性感測器來整合整個系統的座標系統。在追蹤系統方面，我們使用PID控制器控制馬達轉速，從超音波探頭獲得的資訊當作輸入，利用光學尺回授位置訊號，而模擬與實驗的結果顯示此追蹤系統可以符合需求。Our goal of research is to build an ultrasound guided HIFU (High Intensity Focused ultrasound) treatment system which is applied to treat the liver cancer. Liver motion is related to the frequency of respiration, it’s approximately 4 Hz in the normal situation. Therefore, it makes the treatment more different to compensate the dynamic state. Ultrasound is selected as the imaging modality, because ultrasound can provide real-time imaging and frame rate is up to 30Hz. In terms of treatment, we adopt HIFU transducer because it provides thermal dose to heat the focus instead of radiation treatment and it’s a kind of non-invasive system. Based on the image obtained from the ultrasound, HIFU transducer is carried to heat the object. The mechanical tracking system combined the motor, screw, magnetic sensor, and linear scale to track the liver motion. The mechanism design and implementation is completed, and the design is based on the liver movement, the characteristic of ultrasound, HIFU, and magnetic sensor. The experiment results show that the tracking system is able to apply the treatment and the tracking error was close to 0.25mm