研發應用於磁振影像導引腫瘤熱治療之承載超音波換能器 三維移動系統

Abstract

聚焦超音波手術是一種組織熱燒灼的方法，並可利用磁振造影系統來導引及監控，且國外已經有證實影像導引式超音波熱手術用於子宮肌瘤，因此本研究主要在研發應用於磁振影像導引腫瘤熱治療之承載超音波換能器三維移動系統，使用壓克力材料製作運動帄台的本體，利用磁相容壓電陶瓷線性馬達驅動運動帄台，使用PID控制器控制馬達，磁相容光學尺回授帄台位置，由於超音波的傳遞需有水當介質，因此換能器及帄台會放置在水槽中，並在帄台周圍放置玻璃片，藉此帄衡帄台所產生的浮力，藉此可降低馬達的負載，提升帄台移動時的準確度及穩定度。運動帄台經過測試後，可承載超音波換能器進行三維移動，移動最大誤差值均小於100㎛，可相容於磁振造影系統，且符合基本超音波熱手術的需求。

Focused ultrasound surgery (FUS) is a method of tissue ablation that can be guided and monitored with magnetic resonance imaging (MRI). Magnetic resonance-guided focused ultrasound surgery (MRgFUs) has been shown clinically effective in the treatment of uterine fibroids and it is being evaluated as a method of thermal ablation for other benign and malignant tumor. In this study, a three-dimensional motion platform system bearing an ultrasound transducer for MRI-guided tumor thermal surgery was developed. We use an acrylic material to make the motion platform. A non-magnetic piezoelectric ceramic motor was used to move the platform and the linear encoder to track the platform motion. Because ultrasound waves need a medium for propagation, the transducer and the platform were placed in a water tank. Glass slides were put uniformly on the top of the platform in order to counterbalance the buoyancy. Therefore, the motor loading can be reduced and the accuracy of the platform can be effectively improved. The performance of the system was evaluated. It can bear the ultrasound transducer and perform the three-dimensional motion control during the MRI-guided thermal surgery. The localization error is smaller than 100..