Abstract
Although pulse-echo ultrasound images are clinically useful, they are not quantitative and have artifacts since ultrasound does not travel in straight lines through the biological medium which is subject to the acoustic properties such as the diffraction effects caused by the complex structure of the medium.
Computed tomography considering wave diffraction is called “Diffraction Tomography”. We can get the image of “refractive index” quantitatively using diffraction tomography, and it have a merit of reconstructing the higher resolution image than the order of wave length. In clinical uses, however, the range of the incident angles is restricted by various factors, It is therefore important problem how accurate image under this ill-posed condition can be reconstructed.
We applied “Max Entropy Method (MEM)” to ill-posed reconstructed problem of diffraction tomography, in order to restore confused image by MEM combining with iterative revision (IR) in space and frequency domain. Simulation results showed that it is possible to improve the quality of reconstructions more rapidly than the case of using only MEM or IR.
