US 7,459,696 B2 · Methods and apparatus for calibrating spectral data

Abstract

The invention provides methods for calibrating spectral data acquisition systems. These calibration methods produce spectral data sufficiently accurate for use in tissue classification algorithms. The invention improves the accuracy of spectral-based tissue classification schemes, in part, by properly accounting for spatial variations, instrument-to-instrument variations, and patient-to-patient variations in the acquisition of spectral data from tissue samples. Effects that are accounted for include, for example, stray light effects, electronic background effects, variation in light energy delivered to a tissue sample, spatial heterogeneities of the illumination source, chromatic aberrations of the scanning optics, variation in wavelength response of the collection optics, and efficiency of the collection optics.

Claims44

Dependent claims

A method of calibrating spectral data obtained from a tissue sample, the method comprising the steps of:

(a) illuminating a first calibration target and obtaining a first set of calibration data from a plurality of spaced-apart locations on said first calibration target;
(b) illuminating a second calibration target and obtaining a second set of calibration data from a plurality of spaced-apart locations on said second calibration target;
(c) illuminating a tissue sample and obtaining a set of spectral data from spaced-apart locations of said tissue sample, wherein at least some of said spaced-apart locations of said tissue sample correspond to said spaced-apart locations on said first calibration target and said spaced-apart locations on said second calibration target, and wherein said tissue sample comprises in vivo cervical, vaginal, or colorectal tissue;
and
(d) calibrating said spectral data obtained from said tissue sample using said first set of calibration data and said second set of calibration data, thereby to produce calibrated data,
wherein said first calibration target has a reflectance of about 60% and said second calibration target has a reflectance of about 10%.

3 more elements

A method of calibrating spectral data obtained from a tissue sample, the method comprising the steps of:

(a) illuminating a first calibration target and obtaining a first set of calibration data from a plurality of spaced-apart locations on said first calibration target;
(b) illuminating a second calibration target and obtaining a second set of calibration data from a plurality of spaced-apart locations on said second calibration target;
(c) illuminating a tissue sample and obtaining a set of spectral data from spaced-apart locations of said tissue sample, wherein at least some of said spaced-apart locations of said tissue sample correspond to said spaced-apart locations on said first calibration target and said spaced-apart locations on said second calibration target, and wherein said tissue sample comprises in vivo cervical, vaginal, or colorectal tissue;
and
(d) calibrating said spectral data obtained from said tissue sample using said first set of calibration data and said second set of calibration data, thereby to produce calibrated data,
wherein said calibrating step comprises processing said spectral data according to the equation:
R(i,λ,t′)=[Im(i,λ,t′)/(Icp(i,λ,t′))i]·[<Ifc(i,λ,to)>i/Ifc(i,λ,to)]·Rcp,
wherein R(i,λ,t′) is an array comprising calibrated reflectance spectral data from said tissue sample at regions i, wavelengths λ, and at time t′, Im(i,λ,t′) is an array comprising reflectance spectral data from said tissue sample, Ifc(i,λ,to) is an array comprising said first set of calibration data obtained at time to different from t′, <Ifc(i,λ,to)>i is an array comprising said first set of calibration data averaged over said i regions, (Icp(i,λ,t′))i is an array comprising said second set of calibration data averaged over said i regions, and Rcp is the reflectance of said second calibration target.

5 more elements

A method of calibrating spectral data obtained from a tissue sample, the method comprising the steps of:

(a) illuminating a first calibration target and obtaining a first set of calibration data from a plurality of spaced-apart locations on said first calibration target;
(b) illuminating a second calibration target and obtaining a second set of calibration data from a plurality of spaced-apart locations on said second calibration target;
(c) illuminating a tissue sample and obtaining a set of spectral data from spaced-apart locations of said tissue sample, wherein at least some of said spaced-apart locations of said tissue sample correspond to said spaced-apart locations on said first calibration target and said spaced-apart locations on said second calibration target, and wherein said tissue sample comprises in vivo cervical, vaginal, or colorectal tissue;
and
(d) obtaining a third set of calibration data using said second calibration target,
(e) calibrating said spectral data obtained from said tissue sample using said first set of calibration data, said second set of calibration data, and said third set of calibration data, and
wherein said calibrating step comprises processing said spectral data according to the equation:
R(i,λ,t′)=[Im(i,λ,t′)/(Icp(i,λ,t′))i]·[<Ifc(i,λ,to)>i/Ifc(i,λ,to)]·Rcp,fitted,
wherein R(i,λ,t′) is an array comprising calibrated reflectance spectral data from said tissue sample at regions i, wavelengths λ, and at time t′, Im(i,λ,t′) is an array comprising reflectance spectral data from said tissue sample, Ifc(i,λ,to) is an array comprising said first set of calibration data obtained at time to different from t′, <Ifc(i,λ,to)>i is an array comprising said first set of calibration data averaged over said i regions, (Icp(i,λ,t′))i is an array comprising said second set of calibration data averaged over said i regions, Rcp,fitted is an array of values of a curve fit of Rcp(λ), where Rcp(λ)=[<Icp(i,λ,to)>i/<Ifc(i,λ,to)>i]·Rfc, and where <Icp(i,λ,to)>i is an array comprising said third set of calibration data obtained at time to and averaged over said i regions, and Rfc is the reflectance of said first calibration target.

6 more elements

Dependencies are inferred from the claim text.

Methods and apparatus for calibrating spectral data

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Methods and apparatus for calibrating spectral data

Life of this patent

Abstract

Claims44