US 6,662,128 B2 · Normalized-constraint algorithm for minimizing inter-parameter crosstalk in imaging of scattering media

Abstract

A method and system for minimizing inter-coefficient crosstalk in imaging the internal properties of a scattering medium. The method and system minimizing inter-coefficient. crosstalk in image reconstruction by solving a system of linear perturbation equations with the use of relative detector values, weight matrix scaling, and constraints based on either the know or unknown direction of the perturbations in the medium's properties. The constraint being either (1) positive or negative corresponding to the direction of a known perturbations, or (2) solving the system of equations with both positive and negative constraints and summing the results where the direction of the perturbations are unknown. The advantages of the inventive method and system result in effective isolation of absorption and scattering coefficient variations, even for complex combinations of perturbations in these coefficients.

Claims42

Dependent claims

A method for minimizing crosstalk in reconstructing the internal properties of a scattering medium, comprising:

generating a system of linear perturbation equations based on measured energy emerging from the scattering medium, the measured energy originating from a source and being measured by a detector, the linear perturbation equations having a weight matrix defining the influence that localized perturbations in a property of the scattering medium will have on the detector measurements;
scaling the weight matrix;
solving the system of linear perturbation equations for the localized perturbations in the property across the scattering medium, wherein positivity constraints are imposed on iteratively computed estimates of the localized property to obtain a positively constrained solution;
solving the system of linear perturbation equations for the localized perturbations in the property across the scattering medium, wherein negativity constraints are imposed on iteratively computed estimates of the localized property to obtain a negatively constrained solution;
and
summing the positively and negatively constrained solutions to obtain the localized perturbations in the property across the scattering medium.

3 more elements

A method for minimizing crosstalk in reconstructing the internal properties of a scattering medium, comprising:

generating predicted detector readings for a reference medium;
generating at least one of an absorption and diffusion coefficient weight matrix defining the influence that localized perturbations in the coefficient of a reference medium have on surface detectors;
scaling the coefficient weight matrix;
generating a vector of detector normalized difference readings from a first vector and second vector of detector readings indicative of energy emerging from a target scattering medium, the emerging energy substantially originating from at least one source directing the energy into the target scattering medium;
generating at least one of an absorption coefficient system of linear perturbation equations and a diffusion coefficient system of linear perturbation equations wherein for the absorption coefficient equations the product of the absorption weight matrix and a perturbation in the absorption coefficient is equal to a corresponding perturbation in the normalized difference readings, and wherein for the diffusion coefficient equations the product of the diffusion weight matrix and a perturbation in the diffusion coefficient is equal to a corresponding perturbation in the normalized difference readings;
solving at least one of the generated systems of linear perturbation equations for a coefficient of the scattering medium, wherein positivity constraints are imposed on iteratively computed estimates of the coefficient to obtain a positively constrained solution;
solving at least one of the generated systems of linear perturbation equations for a coefficients of the scattering medium, wherein negativity constraints are imposed on iteratively computed estimates of the coefficient to obtain a negatively constrained solution;
and
summing the positively and negatively constrained solutions to obtain at least one of the coefficient of the scattering medium.

6 more elements

A system for minimizing crosstalk in reconstructing the internal properties of a scattering medium, comprising:

means for generating a system of linear perturbation equations based on measured energy emerging from the scattering medium, the measured energy originating from a source and being measured by a detector, the linear perturbation equations having a weight matrix defining the influence that localized perturbations in a property of the scattering medium will have on the detector measurements;
means for scaling the weight matrix;
means for solving the system of linear perturbation equations for the localized perturbations in the property across the scattering medium, wherein positivity constraints are imposed on iteratively computed estimates of the localized property to obtain a positively constrained solution;
means for solving the system of linear perturbation equations for the localized perturbations in the property across the scattering medium, wherein negativity constraints are imposed on iteratively computed estimates of the localized property to obtain a negatively constrained solution;
and
means for summing the positively and negatively constrained solutions to obtain the localized perturbations in the property across the scattering medium.