| Summary: | 碩士 === 國立陽明大學 === 醫學工程研究所 === 91 === Temperature affects survivability of human tissue, representing the conditions of the metabolism, tissue inflammation and local blood circulation. Ultrasonic temperature monitoring becomes more potentially for its non-invasive and real-time scanning.
In recent years, ultrasound temperature estimation methods were studied based on the backscattered ultrasound power and the time shift of the received RF signals. A linear relationship between these shifts and the rise of the tissue temperature derived from cross-correlation function was experimentally validated.
An ultrasound temperature measurement algorithm was developed to validate the temperature distribution of pork and bovine liver tissue during RF ablation therapy. First, the K parameter, which is the rate of the linear relationship between echo-shift and temperature, was determined by the cross-correlation analysis of the RF signals of an in-vitro pork and bovine liver tissue which was heated by a temperature controlled apparatus. The echo signals of a 2-D ultrasound imaging system was analyzed and, by using the K parameter, the tissue temperature distribution during RF ablation therapy was calculated. Finally, the B-mode image and the temperature distribution image were combined to show the temperature distribution of the pork and bovine liver.
The temperature distribution image could be clearly identified during 30℃ to 70℃ in RF ablation therapy. These images showed the temperature increase and the heat extent nearby the heating region. The ripple artifact appeared behind both the heating zone of the abovementioned tissue. Furthermore, a simulation algorithm was used to explore the formation of artifact as well as its influence to the temperature field.
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