Patent US3993647A successfully refreshed from Google Patents.
EP0628804A1
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Method and apparatus for measuring concentration of absorptive constituent in scattering medium
Assignee: Hamamatsu Photonics KK
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Filing: 1994-06-09
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Granted: —
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Expires: 2014-06-09
Abstract
Abstract An optical pulse emitted from an optical pulse source is incident on a living tissue and is input to an optical sampling unit. The optical sampling unit detects intensities f of optical pulses detected at the respective timings of trigger signals input from a delay unit. A first accumulator calculates products t·f of the intensities f and the delay times t from the delay unit. A second accumulator accumulates the light intensities f. An average optical pathlength calculating unit calculates an average optical pathlength using the accumulation results as the products t·f and the intensities f. An SO₂ value calculating unit calculates a ratio of V HbO2 to V Hb from the average optical pathlength to calculate an SO₂ value.
Inventors
- 👤 Motoki Oda
- 👤 Yutaka Yamashita
- 👤 Kazuyoshi Ohta
- 👤 Mamoru Tamura
- 👤 Goro Nishimura
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 08:59
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; A; A61; A61B; A61B5/00; A61B5/145; A61B5/1455; A61B5/14551; A61B5/14553; G01N21/4795; G01N2021/4797
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
208 words
A method of measuring a concentration of an absorptive constituent in a scattering medium, characterized by comprising causing light having a predetermined wavelength to be incident from a predetermined position of a scattering medium containing n (n ≧ 2) types of absorptive constituents, detecting the light, scattering in said scattering medium, at a predetermined position spaced apart from the light incident position by a predetermined distance, calculating an average optical pathlength or a mean flight time of the light having the predetermined wavelength in said scattering medium on the basis of the detected light, obtaining respective average optical pathlengths or respective mean flight times of light components having n+1 types of wavelengths while a wavelength of light incident on said scattering medium is changed, obtaining respective average optical pathlength differences or respective mean flight time differences between respective pairs of light components having different wavelengths from the average optical path lengths or the mean flight times, and obtaining a concentration ratio of the respective absorptive constituents in said scattering medium in accordance with a relationship representing that the average optical pathlength difference or the mean flight time difference is in inverse proportion to a difference in absorbance of the absorptive component between the light components having two wavelengths.
Claim 2
Dependent Claim
236 words
A method of measuring a concentration of an absorptive constituent in a scattering medium according to claim 1, characterized in that said scattering medium contains two types of absorptive constituents A and B, and the incident light components have three different wavelengths Aλ, λ2, and λ3, and a ratio V A : V B of a concentration V A and to a concentration V B of said absorptive constituents A and B in said scattering medium is set as follows: V A : V B = {(ε Bλ3 - ε Bλ1 )Δ<t> λ2,λ1 - (ε Bλ2 - ε Bλ1 )Δ<t> λ3,λ1 }: {-(ε Aλ3 - ε Aλ1 )Δ<t> λ2,λ1 + (ε Aλ2 - ε Aλ1 )Δ<t> λ3,λ1 } where Δ<t> λ2,λ1 is a mean flight time difference between the incident light components having the wavelengths λ2 and λ1, Δ<t> λ3,λ1 is a mean flight time difference between the incident light components having the wavelengths λ3 and λ1, ε Aλ1 and ε Bλ1 are extinction coefficients of said absorptive constituents A and B with respect to the incident light component having the wavelength λ1, ε Aλ2 and ε Bλ2 are extinction coefficients of said absorptive constituents A and B with respect to the incident light component having the wavelength λ2, and ε Aλ3 and ε Bλ3 are extinction coefficents of said absorptive constituents A and B with respect to the incident light component having the wavelength λ3.
Claim 3
Dependent Claim
94 words
A method of measuring a concentration of an absorptive constituent in a scattering medium according to claim 1, characterized in that the average optical pathlength is calculated by detecting a light intensity of each pulse light obtained at the detection position a predetermined delay time after each pulse light is incident on said scattering medium, dividing a sum of products of the delay times and the light intensities respectively corresponding to the delay times by a sum of the respective intensities to obtain a quotient, and multiplying the quotient with a speed of light.
Claim 4
Dependent Claim
94 words
A method of measuring a concentration of an absorptive constituent in a scattering medium according to claim 2, characterized in that the average optical pathlength is calculated by detecting a light intensity of each pulse light obtained at the detection position a predetermined delay time after each pulse light is incident on said scattering medium, dividing a sum of products of the delay times and the light intensities respectively corresponding to the delay times by a sum of the respective intensities to obtain a quotient, and multiplying the quotient with a speed of light.
Claim 5
Dependent Claim
86 words
A method of measuring a concentration of an absorptive constituent in a scattering medium according to claim 1, characterized in that the average optical pathlength is calculated by causing pulse light to be incident on said scattering medium, detecting each of photons reaching the detection position with different delay times upon incidence of each pulse light, dividing a sum of the delay times of the photons detected by a number of photons detected to obtain a quotient, and multiplying the quotient with a speed of light.
Claim 6
Dependent Claim
86 words
A method of measuring a concentration of an absorptive constituent in a scattering medium according to claim 2, characterized in that the average optical pathlength is calculated by causing pulse light to be incident on said scattering medium, detecting each of photons reaching the detection position with different delay times upon incidence of each pulse light, dividing a sum of the delay times of the photons detected by a number of photons detected to obtain a quotient, and multiplying the quotient with a speed of light.
Claim 7
Dependent Claim
85 words
A method of measuring a concentration of an absorptive constituent in a scattering medium according to claim 1, characterized in that said scattering medium is a living tissue, said absorptive constituents are deoxygenated hemoglobin Hb and oxyhemoglobin HbO₂ in blood in the living tissue, the incident light has a wavelength range of 600 nm to 1.5 µm, and a degree of saturation of oxygen in the blood in the living tissue is obtained on the basis of a calculated ratio of the absorptive constituent concentrations.
Claim 8
Independent Claim
273 words
An apparatus for measuring a concentration of an absorptive constituent in a scattering medium, characterized by comprising a light source for generating pulse light having a predetermined wavelength every predetermined time interval, light guide means for causing each pulse light from said light source to be incident on a scattering medium containing n (n ≧ 2) types of absorptive constituents from a predetermined position and extracting each pulse light scattering within said scattering medium from a predetermined position spaced apart from the light incident position by a predetermined distance, photodetecting means for time-resolved measuring each pulse light extracted by said light guide means, wavelength control means for controlling a wavelength of the pulse light emitted from said light source, optical pathlength or flight time calculating means for calculating an average optical pathlength or a mean flight time of light components having n+1 wavelengths in said scattering medium in accordance with time-resolved measurement results of pulse light components having n+1 wavelengths obtained by causing said wavelength control means to control the wavelength of the pulse light emitted from said light source, and concentration calculating means for obtaining an average optical pathlength difference or a mean flight time difference between light components having two wavelengths from the average pathlengths or the mean flight times calculated by said optical pathlength or flight time calculating means and obtaining a ratio of the absorptive constituent concentrations in said scattering medium in accordance with a relationship representing that the average optical pathlength difference or the mean flight time difference is in inverse proportion to a difference in absorbance of the absorptive component between the light components having two wavelengths.
Claim 9
Dependent Claim
106 words
An apparatus for measuring a concentration of an absorptive constituent in a scattering medium according to claim 8, characterized in that said photodetecting means detects a light intensity of each pulse light obtained at the detection position each predetermined delay time after the pulse light is incident on said scattering medium, and said optical pathlength or flight time calculating means divides a sum of products of the respective delay times and the light intensities respectively corresponding to the delay times by a sum of the light intensities to obtain a quotient, and multiplying the quotient with a speed of light to obtain the average optical pathlength.
Claim 10
Dependent Claim
87 words
An apparatus for measuring a concentration of an absorptive constituent in a scattering medium according to claim 8, characterized in that said photodetecting means calculates the average optical pathlength by detecting each of photons reaching the detection position with different delay times upon incidence of each pulse light, and said optical pathlength or flight time calculating means divides a sum of the delay times of the photons detected by a number of photons detected to obtain a quotient, and multiplying the quotient with a speed of light.
Claim 11
Dependent Claim
244 words
An apparatus for measuring a concentration of an absorptive constituent in a scattering medium according to claim 8, characterized in that said light source emits pulse light components having three different wavelengths Aλ, λ2, and λ3, and said scattering medium contains two types of absorptive constituents A and B, and said concentration calculating means sets a ratio V A : V B of a concentration V A to a concentration V B of said absorptive constituents A and B in said scattering medium as follows: V A : V B = {(ε Bλ3 - ε Bλ1 )Δ<t> λ2,λ1 - (ε Bλ2 - ε Bλ1 )Δ<t> λ3,λ1 } : {-(ε Aλ3 - ε Aλ1 )Δ<t> λ2,λ1 + (ε Aλ2 - ε Aλ1 )Δ<t> λ3,λ1 } where Δ<t> λ2,λ1 is a mean flight time difference between the incident light components having the wavelengths λ2 and λ1, Δ<t> λ3,λ1 is a mean flight time difference between the incident light components having the wavelengths λ3 and λ1, and ε Aλ1 a,d ε Bλ1 are extinction coefficients of said absorptive constituents A and B with respect to the incident light component having the wavelength λ1, and ε Aλ2 and ε Bλ2 are extinction coefficients of said absorptive constituents A and B with respect to the incident light component having the wavelength λ2, and ε Aλ3 and ε Bλ3 are extinction coefficients of said absorptive constituents A and B with respect to the incident light component having the wavelength λ3.
Claim 12
Dependent Claim
101 words
An apparatus for measuring a concentration of an absorptive constituent in a scattering medium according to claim 11, characterized in that said light source emits pulse light having a wavelength range of 600 nm to 1.5 µm, said scattering medium is a living tissue, said absorptive constituents are deoxygenated hemoglobin Hb and oxyhemoglobin HbO₂ in blood in the living tissue, and said apparatus further comprises SO₂ value calculating means for obtaining a degree of saturation of oxygen in the blood of the living tissue on the basis of a ratio of said absorptive constituent concentrations output from said concentration calculating means.
Claim 13
Independent Claim
76 words
A method of determining the concentration of an absorptive constituent in a scattering medium, the method comprising irradiating the medium at a predetermined position of incidence with radiation having a plurality of wavelength values, detecting the radiation after passage through the medium at a predetermined detection position in respect of each wavelength value and determining therefrom a relationship between the average optical pathlengths corresponding to the respective wavelengths, thereby to determine the concentration of said constituent.
References Cited (Backward Citations)
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