Spatial Filtering of Optical Scattered Waves in Bio-Medical Media By Inhomogeneous Waveguide Grids 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. In this paper, technical methods of spatial filtering for optical scattering superposed on transmitted and attenuated waves are discussed to improve image diagnosis. Statistical theory of optical waves is described for optical propagation, attenuation and scattering in random inhomogeneous biological media. Spatial filtering characteristics of grid structure are shown for exact image optical projection excluding scattering effects through physiological media. Spatial filtering characteristics for off-axial scattering optical waves are discussed by mode propagation properties with large attenuation for higher order modes in inhomogeneous waveguide-type grids.

I. Introduction

Medical image diagnosis and computer aided diagnosis are very important medical techniques using laser. Optical wave is important physical tool for medical diagnosis and recently automatic image diagnosis using optical wave with computers is rapidly developed[1]. However, in image processing for medical diagnosis, based on photo-electric absorption, interactions between electrons and photons of optical waves, physiological and physical phenomena of optical waves in biomedical media are not so much studied. The spatial characteristic in the received optical image is determined by the intensity of transmitted and attenuated optical waves superposed with scattered waves. The characteristics of transmitted waves depend on both the absorptionand scattering characteristics[2], [3]. Therefore, for the identification characteristics of biomedical media by optical transmission, signal to noise ratio of primitive optical diagnosis without scattering filtering is not so high. Although the use of the optical grid is efficient to remove the scattering wave from the transmitting wave, the grid has not been studied sufficiently. Also, by using spatial grid filter and the characteristic investigation of scattering, absorption, dispersion and spectroscopy properly, it may be possible to find more accurate new method of optical image diagnosis. In this paper, in order to find excellent computer aided diagnosis system based on the electromagnetic wave characteristics, primarily, the scattering filter characteristics of optical beam using the grid consisting of lossy inhomogeneous waveguide arrays are studied[4]. Based on this analysis, the optimum scattering wave filter may be found.