3-D Quantitative Reconstruction for the Medical Sound Velocity Measurement of Biological Tissue with Ultrasonic Diffraction Tomography

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In this study, 3D quantitative rconstruction method for obtaining the sliced biological velocity image on the multi-layred horizontal plane is proposed based on the transmission/receiving data of the sound wave around the vertical axis of the object. For the first thing, to comply with the 3D reconstruction problem compatible with the limited observation aperture and the moderate amount of the data collection and hardware resources, a method was proposed for reducing the original 3D reconstruction problem into the multi-layred 2D tomographic reconstruction by introducing the spatial filter processing in a vertical direction to discriminate the scattered wave from the 2D sliced horizontal surface. As a result, the quasi-3D sound velocity parameter images were reproduced by the 2D image reconstruction operation for the inside of the horizontal surface. For the second things, sound variation of the object was previously restricted to the range within 3 or 4% and observation distance to the immediate vicinity of the object. To resolve this problem, the backward propagation Rytov approximation was proposed aiming at the mitigation of the restriction caused by the weak scattering assumption in the conventional Rytov approximation. It was verified that sound velocity images could be reproduced to the extent of the accuracy as high as average error being within 0.1% even when the sound velocity of the object was varied in a range of approximately <plus-minus>10% and observation distance was prolonged over 50 wavelengths. Above all, its expected that quantitative sound velocity images can be reproduced to satisfy the practical requirement in the medical diagnosis such as for the human breast cancer screening tes