非線形パラメータ・トモグラフィ

概要

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In this paper, a novel tomographic system for imaging the nonlinear parameter B/A which is closely related to the detailed properties of tissue is described. In our system, relatively high intensity scanned low frequency ultrasonic pumping waves are used to illuminate the object under observation so that sound pressure over the object field is modulated sinusoidally. A low intensity high frequency probe beam is propagated perpendicular to the pumping waves. The phase of the probing wave is modulated in proportion to the integral of the product of nonlinear parameter B/A and the pressure of pumping waves, which varies sinusoidally along the probe beam. This phase change provides a Fourier component of the distribution of the nonlinear parameter B/A for the spatial frequency corresponding to the wave length of the pumping wave. By changing the frequency of the pumping waves, a set of spatial Fourier coefficients of the distribution of the nonlinear parameter B/A is obtained. Inverse operation gives the image along the probe beam. If the probe beam is scanned mechanically, the entire cross-section image is obtained. Several images of the nonlinear parameter of biological objects are obtained. Experimental results show the usefulness of this method.
社団法人日本音響学会の論文
1983-08-01