科研之友
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摘要
In this paper, we propose a robust sensing system that protects a thin rod sensor used in the measurements of acoustic impedance in puncture needle-type ultrasonography. In this ultrasonograpy, an ultrasonic interference method using the thin rod sensor is applied. Since the thin rod made of fused quartz is not robust, a protector is required for the thin rod sensor in in vivo measurement. Therefore, the sensing system has consisted of a thin rod sensor and a hollow pipe with a top cover to protect the sensor. For the observation of a low-impedance material such as biological tissue, the measurement method requires an impedance-transforming layer as the top cover. However, since the optimum thickness of the layer decreases as the measurement frequency increases, the decrease in the thickness causes deformation of the layer. The deformation introduces an error in the measurement. To avoid such a problem, we developed a robust sensing system. The system consists of a quarter-wavelength layer that functions as an impedance transformer and a half-wavelength ( or multiple times of a half-wavelength) layer that provides the robustness of the system. We confirmed experimentally the effectiveness of the robust sensing system for acoustic impedance measurement of a tissue sample by the acoustic impedance difference method. The experimental results show that the robust sensing system is useful for puncture needle-type ultrasonography.
- 出版日期2010
