Microwave-induced thermoacoustic tomography: reconstruction by synthetic aperture.

We have applied the synthetic-aperture method to linear-scanning microwave-induced thermoacoustic tomography in biological tissues. A nonfocused ultrasonic transducer was used to receive thermoacoustic signals, to which the delay-and-sum algorithm was applied for image reconstruction. We greatly improved the lateral resolution of images and acquired a clear view of the circular boundaries of buried cylindrical objects, which could not be obtained in conventional linear-scanning microwave-induced thermoacoustic tomography based on focused transducers. Two microwave sources, which had frequencies of 9 and 3 GHz, respectively, were used in the experiments for comparison. The 3 GHz system had a much larger imaging depth but a lower signal-noise ratio than the 9 GHz system in near-surface imaging.

[1]  K. Paulsen,et al.  Near-field microwave imaging of biologically-based materials using a monopole transceiver system , 1998 .

[2]  Alexander A. Oraevsky,et al.  Backward mode detection of laser-induced wide-band ultrasonic transients with optoacoustic transducer , 2000 .

[3]  D. Schaefer,et al.  Microwave power absorption differences between normal and malignant tissue. , 1980, International journal of radiation oncology, biology, physics.

[4]  Frits F. M. de Mul,et al.  Photoacoustic blood cell detection and imaging of blood vessels in phantom tissue , 1998, European Conference on Biomedical Optics.

[5]  M. Pastorino,et al.  Numerical algorithm for dielectric-permittivity microwave imaging of inhomogeneous biological bodies , 1991, Medical and Biological Engineering and Computing.

[6]  S. S. Chaudhary,et al.  Dielectric properties of normal & malignant human breast tissues at radiowave & microwave frequencies. , 1984, Indian journal of biochemistry & biophysics.

[7]  R. Kruger,et al.  Photoacoustic ultrasound (PAUS)--reconstruction tomography. , 1995, Medical physics.

[8]  Lihong V. Wang,et al.  Microwave-induced acoustic imaging of biological tissues , 1999 .

[9]  L V Wang,et al.  Scanning thermoacoustic tomography in biological tissue. , 2000, Medical physics.

[10]  W. Joines,et al.  The measured electrical properties of normal and malignant human tissues from 50 to 900 MHz. , 1994, Medical physics.

[11]  J. Bolomey,et al.  Microwave imaging of tissue blood content changes. , 1991, Journal of biomedical engineering.

[12]  L V Wang,et al.  Scanning microwave-induced thermoacoustic tomography: signal, resolution, and contrast. , 2001, Medical physics.

[13]  F. D. de Mul,et al.  Three-dimensional photoacoustic imaging of blood vessels in tissue. , 1998, Optics letters.