Optical computer tomographic apparatus and image reconstruction method using optical computer tomography
First Claim
1. An optical computer tomographic apparatus comprising:
- a light-projecting unit for individually exclusively projecting measurement light onto a plurality of different first portions of an object to be examined;
a light-receiving unit for individually exclusively receiving the measurement light emitted from said light-projecting unit and transmitted through the object in a plurality of different second portions of the object; and
an arithmetic control mechanism for controlling operations of said light-projecting unit and said light-receiving unit, thereby reconstructing a tomographic image of the object on the basis of a scattering absorption state of the measurement light entering the object,wherein said arithmetic control mechanism comprisesa first arithmetic unit for calculating light densities of the measurement light obtained in the plurality of second portions on the basis of a numerical analysis method which approximates a predetermined light diffusion equation, when it is assumed that the object is divided into a plurality of fine segments as an aggregate model and all the plurality of segments have the same value as an absorption coefficient under conditions equivalent to the conditions by which the object is measured by using said light-projecting unit and said light-receiving unit,a second arithmetic unit for calculating light densities of the measurement light obtained in the plurality of second portions on the basis of the numerical analysis method, when it is assumed that only one segment sequentially selected from the plurality of segments has a specific value as an absorption coefficient under the conditions equivalent to the conditions by which the object is measured by using said light-projecting unit and said light-receiving unit,a third arithmetic unit for calculating, as influences of the plurality of segments, ratios of the light densities of the plurality of second portions calculated by said first arithmetic unit to the light densities of the plurality of second portions calculated by said second arithmetic unit, thereby obtaining an influence matrix corresponding to an arrangement of the plurality of segments,a fourth arithmetic unit for calculating relative ratios of the light densities of the measurement light obtained in the plurality of second portions on the basis of the actual measurements done by using said light-projecting unit and said light-receiving unit to the light densities in the plurality of second portions calculated by said first arithmetic unit, thereby obtaining a relative ratio matrix corresponding to arrangements of the pluralities of first and second portions, anda fifth arithmetic unit for performing a matrix calculation by using the influence matrix obtained by said third arithmetic unit and the relative ratio matrix obtained by said fourth arithmetic unit, thereby obtaining feature data of the plurality of segments.
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Abstract
An arithmetic control mechanism of the present optical CT apparatus calculates first light densities in output portions of an object on the basis of a numerical analysis method, when it is assumed that the object is divided into fine segments and all segments have the same value as an absorption coefficient under predetermined conditions equivalent to an actual measurements; and calculates second light densities in the output portions on the basis of the method, when it is assumed that sequentially selected one of the segments has a specific value as an absorption coefficient under the predetermined conditions. Further, the mechanism calculates, as influences of the segments, ratios of the first to the second light densities, thereby obtaining an influence matrix corresponding to an arrangement of the segments; calculates relative ratios of the third light densities in the output portions on the basis of the actual measurements to the fitst light densities, thereby obtaining a relative ratio matrix corresponding to arrangements of input and output portions of the object; and performs a matrix calculation by using the influence matrix and the relative ratio matrix, thereby obtaining feature data of the segments for reconstructing a tomographic image of the object.
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Citations
24 Claims
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1. An optical computer tomographic apparatus comprising:
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a light-projecting unit for individually exclusively projecting measurement light onto a plurality of different first portions of an object to be examined; a light-receiving unit for individually exclusively receiving the measurement light emitted from said light-projecting unit and transmitted through the object in a plurality of different second portions of the object; and an arithmetic control mechanism for controlling operations of said light-projecting unit and said light-receiving unit, thereby reconstructing a tomographic image of the object on the basis of a scattering absorption state of the measurement light entering the object, wherein said arithmetic control mechanism comprises a first arithmetic unit for calculating light densities of the measurement light obtained in the plurality of second portions on the basis of a numerical analysis method which approximates a predetermined light diffusion equation, when it is assumed that the object is divided into a plurality of fine segments as an aggregate model and all the plurality of segments have the same value as an absorption coefficient under conditions equivalent to the conditions by which the object is measured by using said light-projecting unit and said light-receiving unit, a second arithmetic unit for calculating light densities of the measurement light obtained in the plurality of second portions on the basis of the numerical analysis method, when it is assumed that only one segment sequentially selected from the plurality of segments has a specific value as an absorption coefficient under the conditions equivalent to the conditions by which the object is measured by using said light-projecting unit and said light-receiving unit, a third arithmetic unit for calculating, as influences of the plurality of segments, ratios of the light densities of the plurality of second portions calculated by said first arithmetic unit to the light densities of the plurality of second portions calculated by said second arithmetic unit, thereby obtaining an influence matrix corresponding to an arrangement of the plurality of segments, a fourth arithmetic unit for calculating relative ratios of the light densities of the measurement light obtained in the plurality of second portions on the basis of the actual measurements done by using said light-projecting unit and said light-receiving unit to the light densities in the plurality of second portions calculated by said first arithmetic unit, thereby obtaining a relative ratio matrix corresponding to arrangements of the pluralities of first and second portions, and a fifth arithmetic unit for performing a matrix calculation by using the influence matrix obtained by said third arithmetic unit and the relative ratio matrix obtained by said fourth arithmetic unit, thereby obtaining feature data of the plurality of segments. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. An image reconstruction method using optical computer tomography, comprising:
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the first step of controlling operations of a light-projecting unit and a light-receiving unit by using an arithmetic control mechanism, thereby causing said light-projecting unit to individually exclusively project measurement light onto a plurality of different first portions of an object to be examined and said light-receiving unit to individually exclusively receive the measurement light emitted from said light-projecting unit and transmitted through the object in a plurality of different second portions of the object; the second step of causing said arithmetic control mechanism to calculate light densities of the measurement light obtained in the plurality of second portions on the basis of a numerical analysis method which approximates a predetermined light diffusion equation, when it is assumed that the object is divided into a plurality of fine segments as an aggregate model and all the plurality of segments have the same value as an absorption coefficient under conditions equivalent to the conditions by which the object is measured by using said light-projecting unit and said light-receiving unit; the third step of causing said arithmetic control mechanism to calculate light densities of the measurement light obtained in the plurality of second portions on the basis of the numerical analysis method, when it is assumed that only one segment sequentially selected from the plurality of segments has a specific value as an absorption coefficient under the conditions equivalent to the conditions by which the object is measured by using said light-projecting unit and said light-receiving unit; the fourth step of causing said arithmetic control mechanism to calculate, as influences of the plurality of segments, ratios of the light densities of the plurality of second portions calculated in the second step to the light densities of the second portions calculated in the third step, thereby obtaining an influence matrix corresponding to an arrangement of the plurality of segments; the fifth step of causing said arithmetic control mechanism to calculate relative ratios of the light densities of the measurement light obtained in the plurality of second portions in the first step to the light densities in the plurality of second portions calculated in the second step, thereby obtaining a relative ratio matrix corresponding to arrangements of the pluralities of first and second portions; and the sixth step of causing said arithmetic control mechanism to perform a matrix calculation by using the influence matrix obtained in the fourth step and the relative ratio matrix obtained in the fifth step, thereby obtaining feature data of the plurality of segments in order to reconstruct a tomographic image of the object on the basis of a scattering absorption state of the measurement light entering the object. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification