For the purpose of attaining higher accuracy of the 3D velocity quantitative CT image of the biological tissue based on the inverse scattering analytical method, introduction was made with such improved methods as of quasi-3D image reconstruction, correction of the 2nd order bias of the Rytov approximation based on the data collection on the aperture of a cylinder, together with its performance evaluation. As a result of the value test by means of the simulation for a sphere or cylindrical

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... t, it is verified that a sound velocity quantitative CT image with by far higher accuracy and higher quality than the conventional one can be brought to realization under the condition of the sound velocity ratio and observation distance satisfying requirement for practicality.