US5676142A — Method and apparatus for measuring scattering pro…

Claim 1

Independent Claim 249 words

A method for measuring a scattering property and an absorption property in a scattering medium, comprising: a first step of transmitting pulsed measuring light generated by a light source and having a predetermined wavelength into a scattering medium using an entrance light guide; a second step of detecting, by a photodetector, either of light intensity or number of photons at every measuring time in said measuring light having diffusively propagated in said scattering medium at light detection positions corresponding to a plurality of combinations, each comprising a light incidence position on said scattering medium where said measuring light entered said scattering medium and a light detection position on said scattering medium where said measuring light is detected, having different incidence-detection distances between the light incidence position and the light detection position, according to a time-resolved management; a third step of calculating a plurality of mean optical pathlengths of said measuring light corresponding to said plurality of incidence-detection distances, based on results of said time-resolved measurement measured in said second step; and a fourth step of calculating a scattering coefficient and an absorption coefficient in said scattering medium, based on a plurality of simultaneous relations consisting of calculation values of said plurality of mean optical pathlengths corresponding to said plurality of incidence-detection distances, calculated in said third step, and a theoretical equation of said mean optical pathlength derived in correspondence to light diffusion properties comprising a scattering property and an absorption property in diffusive propagation paths inside said scattering medium.

Claim 2

Independent Claim 249 words

A method for measuring a scattering property and an absorption property in a scattering medium, comprising: a first step of transmitting pulsed measuring light generated by a light source and having a predetermined wavelength into a scattering medium using an entrance light guide; a second step of detecting, by a photodetector, either of light intensity or number of photons at every measuring time in said measuring light having diffusively propagated in said scattering medium at light detection positions corresponding to a plurality of combinations, each comprising a light incidence position on said scattering medium where said measuring light entered said scattering medium and a light detection position on said scattering medium where said measuring light is detected, having different incidence-detection distances between the light incidence position and the light detection position, according to a time-resolved management; a third step of calculating a plurality of mean optical pathlengths of said measuring light corresponding to said plurality of incidence-detection distances, based on results of said time-resolved measurement measured in said second step; and a fourth step of calculating a scattering coefficient and an absorption coefficient in said scattering medium, based on a plurality of simultaneous relations consisting of calculation values of said plurality of mean optical pathlengths corresponding to said plurality of incidence-detection distances, calculated in said third step, and a theoretical equation of said mean optical pathlength derived in correspondence to light diffusion properties comprising a scattering property and an absorption property in diffusive propagation paths inside said scattering medium.

Claim 3

Dependent Claim 143 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 1, wherein said first step comprises generating said measuring light in a pulsed form at frequency f, and said second step comprises sequentially selecting reference times t B =t 0 +(M-1)/f after said measuring light is generated by a predetermined number M of repetitions from a predetermined time t 0 , as oscillation timings of said measuring light in said first step, sequentially setting measuring times t M =t B +M·Δt delayed in units of a predetermined time Δt from said reference times t B as sampling timings of said measuring light, and thereby sequentially measuring light intensities I (ρ, t M ) of said measuring light corresponding to the plurality of different said incidence-detection distances ρ at every said measuring time t M .

Claim 4

Dependent Claim 200 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 2, wherein said third step comprises calculating the plurality of mean optical pathlengths <L (ρ)>=c·Σ M {I (ρ, t M )·T M }/ Σ M I (ρ, t M ) of said measuring light corresponding to said plurality of different incidence-detection distances ρ, using the light intensities I (ρ, t M ) of said measuring light measured in said second step, time differences T M =M·Δt of said measuring times t M from said reference times t B , and a velocity c of said measuring light, and wherein said fourth step comprises calculating a transport scattering coefficient μ ST and an absorption coefficient μ A in said scattering medium, by solving the plurality of simultaneous theoretical equations <L (ρ)>=(1/z E )(ρ 2 +4z E 2 )/ 1+{(2μ A /z E )(ρ 2 +z E 2 )} 1/2 ! of said mean optical pathlength including a variable z E =2/{3(μ A +μ ST )} and corresponding to said plurality of different incidence-detection distances ρ, using the plurality of mean optical pathlengths <L (ρ)> of said measuring light calculated in said third step.

Claim 5

Dependent Claim 145 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 1, wherein said first step comprises generating said measuring light in a pulsed form at frequency f, and wherein said second step comprises sequentially selecting reference times t B =t 0 +(M-1)/f after said measuring light is generated by a predetermined number M of repetitions from a predetermined time t 0 , as oscillation timings of said measuring light in said first step, sequentially setting measuring times t M =t B +M·Δt delayed in units of a predetermined time Δt from said reference times t B as sampling timings of said measuring light, and thereby sequentially measuring numbers of photons n (ρ, t M ) of said measuring light corresponding to the plurality of different said incidence-detection distances ρ at every said measuring time t M .

Claim 6

Dependent Claim 201 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 4, wherein said third step comprises calculating the plurality of mean optical pathlengths <L (ρ)>=c·Σ M {n (ρ, t M )·T M }/Σ M n (ρ, t M ) of said measuring light corresponding to said plurality of different incidence-detection distances ρ, using the numbers of photons n (ρ, t M ) of said measuring light measured in said second step, time differences T M =M·Δt of said measuring times t M from said reference times t B , and a velocity c of said measuring light, and wherein said fourth step comprises calculating a transport scattering coefficient μ ST and an absorption coefficient μ A in said scattering medium, by solving the plurality of simultaneous theoretical equations <L (ρ)>=(1/z E )(ρ 2 +4z E 2 )/ 1+{(2μ A /z E ) (ρ 2 +z E 2 )} 1/2 ! of said mean optical pathlengths including a variable z E =2/{3(μ A +μ ST )} and corresponding to said plurality of different incidence-detection distances ρ, using the plurality of mean optical pathlengths <L (ρ)> of said measuring light calculated in said third step.

Claim 7

Dependent Claim 221 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 1. wherein said first step comprises setting a plurality of wavelengths having different absorption coefficients for absorptive constituents in said scattering medium and exceeding a number of types of said absorptive constituents, for said measuring light, said second step comprises performing time-resolved measurement of said measuring light for the plurality of wavelengths exceeding the number of types of said absorptive constituents, said third step comprises calculating the plurality of mean optical pathlengths of said measuring light for the plurality of wavelengths exceeding the number of types of said absorptive constituents, and said fourth step comprises calculating the plurality of absorption coefficients in said scattering medium for the plurality of wavelengths exceeding the number of types of said absorptive constituents, said method further comprising a fifth step of calculating concentrations of said absorptive constituents, based on a plurality of simultaneous relations consisting of the plurality of calculation values of the absorption coefficients in said scattering medium for the plurality of wavelengths exceeding the number of types of said absorptive constituents, calculated in said fourth step, and a theoretical equation of said absorption coefficient derived in correspondence to light attenuation properties including contribution of said absorptive constituents in diffusive propagation paths inside said scattering medium.

Claim 8

Dependent Claim 76 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 6, wherein said fifth step comprises calculating the concentrations of said absorptive constituents, by solving the plurality of simultaneous theoretical equations of said absorption coefficients for the plurality of wavelengths exceeding the number of types of said absorptive constituents based on Beer-Lambert's law, using the plurality of absorption coefficients in said scattering medium calculated in said fourth step.

Claim 9

Dependent Claim 64 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 7, wherein said first step comprises setting the plurality of wavelengths of said measuring light exceeding the number of types of said absorptive constituents so as to make coincident with each other background absorption terms in the plurality of simultaneous theoretical equations of said absorption coefficients.

Claim 10

Dependent Claim 113 words

A method for measuring a scattering property and an absorption property in a scattering medium according to claim 6, wherein the absorptive constituents in said scattering medium are deoxygenated hemoglobin Hb and oxygenated hemoglobin HbO 2 contained in the blood in a living tissue and the wavelengths of said measuring light are set in the range of about 700 nm to about 1.5 μm, said method further comprising a sixth step of calculating a hemoglobin oxygen saturation Y ={ HbO 2 !/( Hb!+ HbO 2 !)}×100 in the blood, using the concentration Hb! of deoxygenated hemoglobin Hb and the concentration HbO 2 ! of oxygenated hemoglobin HbO 2 calculated in said fifth step.

Claim 11

Independent Claim 261 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium, comprising: a light source for generating pulsed measuring light having a predetermined wavelength; an entrance light guide for outputting said measuring light coming from said light source into a scattering medium; a photodetector for detecting either of light intensity or number of photons at every measuring time in said measuring light having diffusively propagated in said scattering medium at light detection positions corresponding to a plurality of combinations, each comprised of a light incidence position on said scattering medium where said measuring light was made incident thereinto by said light guide and a light detection position on said scattering medium where said measuring light is detected, having different incidence-detection distances between the light incidence position and the light detection position, according to time-resolved measurement of said measuring light; an optical pathlength arithmetic unit for calculating a plurality of mean optical pathlengths of said measuring light corresponding to said plurality of incidence-detection distances, based on results of said time-resolved measurement measured by said photodetector; and a light diffusion arithmetic unit for calculating a scattering coefficient and an absorption coefficient in said scattering medium, based on a plurality of simultaneous relations consisting of calculation values of said plurality of mean optical pathlengths corresponding to said plurality of incidence-detection distances, calculated in said optical pathlength arithmetic unit, and a theoretical equation of said mean optical pathlength derived in correspondence to light diffusion properties comprising a scattering property and an absorption property in diffusive propagation paths inside said scattering medium.

Claim 12

Independent Claim 261 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium, comprising: a light source for generating pulsed measuring light having a predetermined wavelength; an entrance light guide for outputting said measuring light coming from said light source into a scattering medium; a photodetector for detecting either of light intensity or number of photons at every measuring time in said measuring light having diffusively propagated in said scattering medium at light detection positions corresponding to a plurality of combinations, each comprised of a light incidence position on said scattering medium where said measuring light was made incident thereinto by said light guide and a light detection position on said scattering medium where said measuring light is detected, having different incidence-detection distances between the light incidence position and the light detection position, according to time-resolved measurement of said measuring light; an optical pathlength arithmetic unit for calculating a plurality of mean optical pathlengths of said measuring light corresponding to said plurality of incidence-detection distances, based on results of said time-resolved measurement measured by said photodetector; and a light diffusion arithmetic unit for calculating a scattering coefficient and an absorption coefficient in said scattering medium, based on a plurality of simultaneous relations consisting of calculation values of said plurality of mean optical pathlengths corresponding to said plurality of incidence-detection distances, calculated in said optical pathlength arithmetic unit, and a theoretical equation of said mean optical pathlength derived in correspondence to light diffusion properties comprising a scattering property and an absorption property in diffusive propagation paths inside said scattering medium.

Claim 13

Dependent Claim 148 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 10, wherein said light source is arranged to generate said measuring light in a pulsed form at frequency f, and wherein said photodetector is arranged to sequentially select reference times t B =t 0 +(M-1)/f after said measuring light is generated by a predetermined number M of repetitions from a predetermined time t 0 , as oscillation timings of said measuring light by said light source, to sequentially set measuring times t M =t B +M·Δt delayed in units of a predetermined time Δt from said reference times t B as sampling timings of said measuring light, and thereby sequentially measure light intensities I (ρ, t M ) of said measuring light corresponding to the plurality of different said incidence-detection distances ρ at every said measuring time t M .

Claim 14

Dependent Claim 203 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 11, wherein said optical pathlength arithmetic unit calculates the plurality of mean optical pathlengths <L (ρ)>=c·Σ M {I (ρ, t M )·T M }/Σ M I (ρ, t M ) of said measuring light corresponding to said plurality of different incidence-detection distances ρ, using the light intensities I (ρ, t M ) of said measuring light measured in said photodetector, time differences T M =M·Δt of said measuring times t M from said reference times t B , and a velocity c of said measuring light, and wherein said light diffusion arithmetic unit calculates a transport scattering coefficient μ ST and an absorption coefficient μ A in said scattering medium, by solving the plurality of simultaneous theoretical equations <L (ρ)>=(1/z E )(ρ 2 +4z E 2 )/ 1+{(2μ A /z E ) (ρ 2 +z E 2 )} 1/2 ! of said mean optical pathlengths including a variable z E =2/{3(μ A +μ ST )} and corresponding to said plurality of different incidence-detection distances ρ, using the plurality of mean optical pathlengths <L (ρ)> of said measuring light calculated in said optical pathlength arithmetic unit.

Claim 15

Dependent Claim 150 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 10, wherein said light source is arranged to generate said measuring light in a pulsed form at frequency f, and wherein said photodetector is arranged to sequentially select reference times t B =t 0 +(M-1)/f after said measuring light is generated by a predetermined number M of repetitions from a predetermined time t 0 , as oscillation timings of said measuring light by said light source, to sequentially set measuring times t M =t B +M·Δt delayed in units of a predetermined time Δt from said reference time t B as sampling timings of said measuring light, and thereby to sequentially measure numbers of photons n (ρ, t M ) of said measuring light corresponding to the plurality of different said incidence-detection distances ρ at every said measuring time t M .

Claim 16

Dependent Claim 205 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 13, wherein said optical pathlength arithmetic unit calculates the plurality of mean optical pathlengths <L (ρ)>=c·Σ M {n (ρ, t M )·T M }/Σ M n (ρ, t M ) of said measuring light corresponding to said plurality of different incidence-detection distances ρ, using the numbers of photons n (ρ, t M ) of said measuring light measured in said photodetector, time differences T M =M·Δt of said measuring times t M from said reference times t B , and a velocity c of said measuring light, and wherein said light diffusion arithmetic unit calculates a transport scattering coefficient μ ST and an absorption coefficient μ A in said scattering medium, by solving the plurality of simultaneous equations of theoretical equations <L (ρ)>=(1/z E )(ρ 2 +4z E 2 )/ 1+{(2μ A /z E )(ρ 2 +z E 2 )} 1/2 ! of said mean optical pathlengths including a variable z E =2/{3(μ A +μ ST )} and corresponding to said plurality of different incidence-detection distances ρ, using the plurality of mean optical pathlengths <L (ρ)> of said measuring light calculated in said optical pathlength arithmetic unit.

Claim 17

Dependent Claim 229 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 10, wherein said light source has a wavelength controlling means for setting a plurality of wavelengths having different absorption coefficients for absorptive constituents in said scattering medium and exceeding a number of types of said absorptive constituents, for said measuring light, said photodetector performs time-resolved measurement of said measuring light for the plurality of wavelengths exceeding said number of types of absorptive constituents, said optical pathlength arithmetic unit calculates the plurality of mean optical pathlengths of said measuring light for the plurality of wavelengths exceeding the number of types of said absorptive constituents, and said light diffusion arithmetic unit calculates the plurality of absorption coefficients in said scattering medium for the plurality of wavelengths exceeding the number of types of said absorptive constituents, said apparatus further comprising a light absorption arithmetic unit for calculating concentrations of said absorptive constituents, based on a plurality of simultaneous relations consisting of the plurality of calculation values of the absorption coefficients in said scattering medium for the plurality of wavelengths exceeding the number of types of said absorptive constituents, calculated in said light diffusion arithmetic unit, and a theoretical equation of said absorption coefficient derived in correspondence to light attenuation properties including contribution of said absorptive constituents in diffusive propagation paths inside said scattering medium.

Claim 18

Dependent Claim 79 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 15, wherein said light absorption arithmetic unit calculates the concentrations of said absorptive constituents, by solving the plurality of simultaneous theoretical equations of said absorption coefficients for the plurality of wavelengths exceeding the number of types of said absorptive constituents based on Beer-Lambert's law, using the plurality of absorption coefficients in said scattering medium calculated in said light diffusion arithmetic unit.

Claim 19

Dependent Claim 63 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 16, wherein said light source sets the plurality of wavelengths of said measuring light exceeding the number of types of said absorptive constituents so as to make coincident with each other background absorption terms in the plurality of simultaneous theoretical equations of said absorption coefficients.

Claim 20

Dependent Claim 111 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 15, wherein the absorptive constituents in said scattering medium are deoxygenated hemoglobin Hb and oxygenated hemoglobin HbO 2 contained in the blood in a living tissue, the wavelengths of said measuring light are set in the range of about 700 nm to about 1.5 μm, and said light absorption arithmetic unit calculates a hemoglobin oxygen saturation Y={ HbO 2 !/( Hb!+ HbO 2 !)}×100 in the blood, using the concentration Hb! of deoxygenated hemoglobin Hb and the concentration HbO 2 ! of oxygenated hemoglobin HbO 2 calculated in said light absorption arithmetic unit.

Claim 21

Dependent Claim 37 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 10, further comprising an exit light guide for taking said measuring light having diffusively propagated in said scattering medium.

Claim 22

Dependent Claim 57 words

An apparatus for measuring a scattering property and an absorption property in a scattering medium according to claim 19, further comprising an interface member disposed between said entrance light guide or said exit light guide and a surface of said scattering medium, having a refractive index and a scattering coefficient close to those of said scattering medium.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-10-13	2001-04-14	2001-10-14	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-10-13	2005-04-14	2005-10-14	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-10-13	2009-04-14	2009-10-14	$7700.00	Window Closed / Lapsed

Method and apparatus for measuring scattering property and absorption property in scattering medium

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