本研究之目的在於利用回波訊號偏移評估高能聚焦式超音波（HIFU)燒灼區 域之溫度分佈。實驗中藉由一個2.1 MHz的聚焦式超音波換能器對石墨仿體組織 進行燒灼，並以超音波成像系統擷取燒灼影像作為分析。本實驗使用互相關算法 重建超音波溫度影像，同時以逆散射能量變化評估高能聚焦式超音波燒灼區域之 溫度監視。兩種基於超音波的方法在評估超音波之溫度監視都具有可行性，只是 兩種方法各有利弊。其中基於回波訊號的變化之溫度監測方法可以較為準確的重 建受熱區域之面積，但是此方法必須預先知道超音波在組織中傳播係數以及組織 熱擴散係數；而基於散射子能量變化之溫度檢測方法可以在少許的轉換時間内分 析到不錯的溫度影像，但是CBE影像不能很好的顯示非均勻受熱區域之溫度分佈面積。

The purpose of this study is to demonstrate the feasibility to use the echo shift to monitor temperature during high-intensity focused ultrasound (HIFU). A 2.1 MHz focused ultrasound transducer was employed to produce a focus zone to ablate the graphite phantom while an ultrasound imager was utilized to collect the ultrasonic image.
In the study, the ultrasound temperature map was reconstructed by using the method of measuring the echo shifts based on the Change in the Backscattered Energy (CBE) of ultrasound. These two ultrasound-based methods for non-invasive temperature monitoring are proved to be feasible, but both methods have its advantages and shortcomings. The temperature map based on echo-shift can briefly visualize the temperature distribution in tissues, but this method needs to know the sound speed and thermal expansion coefficients in advance. On the other hand, the temperature map based on change in backscattered energy could be reconstructed into good image in short conversion time, but it could not provide visualization of the temperature distribution within tissues during non-uniform heating situation.