Reflection and Transmission Characteristics of Lattice Grid with Lossy Clad for Optical CT
Medical image diagnosis and computer aided diagnosis are modern important medical techniques developed with computer technology.Particularly,medical image diagnosis using optical waves of lasers is very important technical tools for physiological examination of human body.Image responses of optical transmitted projection include optical scattering characteristics that disturb transmission properties through biological structures depending on optical absorption effects due to biological characteristics consisting of atomic and molecular structure.We have studied spatial filtering for optical scattering superposed on transmitted and attenuated waves to improve image diagnosis.Spatial filtering characteristics of grid structure are shown for exact image optical projection excluding scattering effects through physiological media by FDTD method.In waveguide-type grid filters with lossy clads,scattered fields from biological structures with large scattering angles have large attenuations.Transmitted and scattered fields of small scattering angles have small attenuations and can pass through the waveguide grids.We studied statistical scattering characteristics of biological objects surrounded by inhomogeneous biological media using FDTD method and showed that spatial filtering by waveguide-type grid filter with lossy clads is very effective to suppress scattered waves with large scattering angles and to obtain accurate target object image.In this paper,reflection and transmission characteristics of waveguide-type spatial filter consisting of clad and core with relatively long length and complex refractive index of lossy clad for incident angles of the incident beam are studied by FDTD method,comparing with approximate analytical method,such as physical and geometrical optics,for optimum design of structure of spatial filter to accomplish accurate image diagnosis by optical CT.For large incident angles of the incident beam,attenuation of the amplitudes of transmitted waves become large due to the absorption by lossy clads and realization of effective spatial filter is expected.In this study,electric field distributions in waveguide-type grids are shown precisely using FDTD method.Also,field distributions are studied by approximate analytical method which gives physical interpretation for numerical results obtained by FDTD.The numerical and analytical methods can provide optimum design of lattice grid spatial filter with desired performance for accurate image diagnosis by optical CT.
Yasumitsu Miyazaki Koichi Takahashi Nobuo Goto
Department of Media Informatics,Aichi University of Technology50-2 Manori,Nishihasama-cho,Gamagori 4 Institute of Technology and Science,The University of Tokushima2-1 Minamijosanjima-cho,Tokushima 770
国际会议
Progress in Electromagnetics Research Symposium 2013(2013年电磁学研究新进展学术研讨会)
台北
英文
737-742
2013-03-01（万方平台首次上网日期，不代表论文的发表时间）