## 4pSP10. Quasi-three-dimensional inverse scattering computerized tomography for high-precision sound velocity measurement in tissues.

### Session: Thursday Afternoon, December 5

### Time: 4:35

**Author: Akira Yamada**

**Location: Graduate School of Bio-Applications & Systems Eng., Tokyo Univ. of Agriculture and Technol., Koganei-shi, Tokyo, 184 Japan**

**Abstract:**

A quasi-3-D inverse scattering technique is proposed to reconstruct sound
velocity slices of the weak scattering tissues by transmitting and receiving
acoustic waves around a single rotational axis. The reconstructing procedure
proposed is as follows. First, a backpropagation operation is introduced using
the holographic formula for a homogeneous medium. This backpropagation
preprocessing operation contributes dramatically to the reduction of the final
quantitative reconstruction errors. Next, after the Rytov transform over the
marginal backpropagated plane, data are then filtered in the perpendicular
direction to discriminate the horizontally scattered wave. Consequently,
quasi-3-D sound velocity images on the horizontal sliced plane of an object can
be obtained, using the conventional 2-D inverse scattering reconstruction
procedure. Precision of the proposed 3-D reconstructed sound velocity image is
investigated using the calculated scattered data from the spherical object. As a
result, it is demonstrated that quantitative precision of the reconstructed 3-D
velocity image is verified to be within 1% over the range of the velocity
inhomogeneity from -10% to 10%. The results obtained are promising for actual
clinical applications such as the human breast cancer screening test.

ASA 132nd meeting - Hawaii, December 1996