Ultrasonic Refractive Index Tomography

1. ^*Assistant Professor Dr. Chuchat Pintavirooj

email: kpchucha@kmitl.ac.th

2. ^*Adisak Romputtal

email: adisak_romputtal@yahoo.com

3. ^*Akkapob Ngamlamiad

email: s6060510@kmitl.ac.th

4. ^*Withawat Withayachumnankul

email: kwwithaw@kmitl.ac.th

5. ^**Associate Professor Dr. Kazuhiko Hamamoto

email: hama@keyaki.cc.u-tokai.ac.jp

^*Research Center for Communication and Information Technology (ReCCIT),

Department of Electronics, Department of Information Engineering and

Faculty of Engineering,

King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand.

**Department of Communications Engineering,

School of Engineering, Tokai University, Japan.

Abstract

Ultrasonic computed tomography (UCT) is one of the methods capable of tissue characterization. It is expected to provide not only a quantitative image but also diagnostic information. As in X-ray CT, UCT requires a projection data to reconstruct a cross-sectional image. In UCT such projection data are derived from the received broadband ultrasonic signal. In this paper, two methods for deriving the integrated refractive index from transmission mode signal are evaluated. The first method derives the integrated refractive index from time delay of the signal while the second method uses the phase shift of signal instead. The experimental results show the resistivity to noise of the phase shift method, especially at the center frequency of the broadband pulse.