Simulation of the long wavelength sound-wave CT using prior information

概要

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A simulation study about the CT technique employing a stationary sound wave with long wavelength is presented. The CT is an inverse and nonlinear problem, so that an iterative appoach is inevitable. That is, starting an assumed density distribution, the field calculation is repeatedly made until a true density distribution is achieved. An inhomogeneous domain is divied into subregions in which the density is assumed to be constant. The Finite Element Method is used for calculating the acoustic field under the given particle velocity driving source and the Newton-Raphson method is used to update the initial density distribution by minimizing the scalar error between computed and measured field values. To cope with the ill-condition which essentially exist in the inverse problem, three kinds of methods are used comparatively to solve this problem. For getting a more exact reconstruction, a new algorithm employing prior information is proposed. The simulation results show that the proposed algorithm can reconstruct satisfactorily the density distribution image of the model by the proper selection of driving position and its frequency.
社団法人日本音響学会の論文