Optical measuring apparatus, optical measuring method, and storage medium that stores optical measuring program

• US 8,369,914 B2
• Filed: 05/31/2007
• Issued: 02/05/2013
• Est. Priority Date: 05/31/2006
• Status: Active Grant

• Current Assignee: National University Corporation Shizuoka University
• Original Assignee: National University Corporation Shizuoka University
• Inventors: Niwayama, Masatsugu
• Primary Examiner(s): Towa, Rene
• Assistant Examiner(s): Leedy, Megan
• Application Number:
  US12/303,040
• Publication Number:
  US 20090209836A1
• Time in Patent Office: 2,077 Days
• Field of Search: 600322-324, 600/326, 600/328, 600/331, 600/473, 600/475, 600/476, 600/477
• US Class Current: 600/323
• CPC Class Codes: A61B 5/0059 using light, e.g. diagnosis by transillumination, diascopy, fluorescence A61B5/0093, A61B5/1455, A61B5/02416 and A61B5/0261 take precedence
• CPC Class Codes: A61B 5/14532 for measuring glucose, e.g. by tissue impedance measurement
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: G01N 2021/3144 for oxymetry
• CPC Class Codes: G01N 2021/4797 time resolved, e.g. analysis of ballistic photons
• CPC Class Codes: G01N 21/31 Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry G01N21/72 takes precedence
• CPC Class Codes: G01N 21/4795 spatially resolved investigating of object in scattering medium in vivo A61B
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

The present invention provides an optical measuring apparatus and an optical measuring method for being able to correct the influence of a superficial tissue to be able to accurately measure a degree of light absorption of a deep layer tissue such as a human body and fruits, and a storage medium that stores an optical measuring program. The optical measuring apparatus includes a probe, and the probe includes one light emitting diode and two photodiodes. In a configuration of the optical measuring apparatus, one of the photodiodes receives light which is emitted from the light emitting diode and transmitted through a superficial layer and a deep layer of a tissue, and the other photodiode receives light having a deep layer transmission distance different from that of the light received by one of the photodiodes. The light received by the other photodiode is also transmitted through the superficial layer and deep layer of the tissue. Based on intensity of the light received by each photodiode, a control unit computes a propagation constant in a medium through which the light propagates. An arithmetic expression is selected in accordance with an input fat thickness of the tissue, and an absorption coefficient of the light from a muscle tissue using the arithmetic expression based on the fat thickness and a spatial slope. A hemoglobin concentration and an oxygen saturation are obtained based on the obtained absorption coefficient of the light.

Claims

1. An optical measuring apparatus comprising:

a light emitter for irradiating with light a layered structure which is an object of measurement, the layered structure comprising a plurality of layers including at least a superficial layer and a deep layer;

a light receiver for receiving, at a position at a first predetermined distance from the light emitter, light emitted from the light emitter and transmitted through the superficial layer and the deep layer, and for receiving, at a position at a second predetermined distance from the light emitter, light which is emitted from the light emitter and transmitted through the superficial layer and the deep layer and which has a deep layer transmission distance which is different from that of the light received at the position at the first predetermined distance from the light emitter;

a spatial slope computation device for obtaining a spatial slope based on intensities of the light received at the position at the first predetermined distance from the light emitter and the light received at the position at the second predetermined distance from the light emitter;

storage means in which a computation parameter for computing a degree of light absorption in the deep layer is stored for each superficial layer;

an input device for inputting a thickness for each superficial layer; and

computing means for reading a stored computation parameter corresponding to an input superficial layer thickness, and obtaining the degree of light absorption in the deep layer based on a quadratic function of the spatial slope including the read computation parameter.

2. The optical measuring apparatus of claim 1, wherein the layered structure is a part of a living body, the superficial layer is a fat tissue, and the deep layer is a muscle tissue.

3. The optical measuring apparatus of claim 2, wherein the computing means obtains at least one of an oxygenated hemoglobin concentration, a deoxygenated hemoglobin concentration, and an oxygen saturation, based on the degree of light absorption.

4. The optical measuring apparatus of claim 1, wherein the light receiver comprises a first light receiving unit, which is located at the first predetermined distance from the light emitter, and a second light receiving unit, which is located at the second predetermined distance from the light emitter.

5. The optical measuring apparatus of claim 2, wherein the light receiver comprises a first light receiving unit, which is located at the first predetermined distance from the light emitter, and a second light receiving unit, which is located at the second predetermined distance from the light emitter.

6. The optical measuring apparatus of claim 3, wherein the light receiver comprises a first light receiving unit, which is located at the first predetermined distance from the light emitter, and a second light receiving unit, which is located at the second predetermined distance from the light emitter.

7. An optical measuring method comprising:

irradiating with light a layered structure which is an object of measurement, the layered structure comprising a plurality of layers including at least a superficial layer and a deep layer;

receiving, at a position at a first predetermined distance from a light irradiation position, light of the irradiation light which has been transmitted through the superficial layer and the deep layer, and receiving, at a position at a second predetermined distance from the light irradiation position, light of the irradiation light which has been transmitted through the superficial layer and the deep layer and which has a deep layer transmission distance which is different from that of the light received at the position at the first predetermined distance from the light irradiation position;

obtaining a spatial slope based on intensities of the light received at the position at the first predetermined distance from the light irradiation position, the light received at the position at the second predetermined distance from the light irradiation position, the first predetermined distance, and the second predetermined distance;

inputting a thickness for each superficial layer; and

reading a stored computation parameter corresponding to an input superficial layer thickness, where computation parameters for computing a degree of light absorption in the deep layer are stored for each superficial layer thickness in the storage device, and obtaining the degree of light absorption based on the read computation parameter and the spatial slope.

8. A non-transitory storage medium that stores an optical measuring program for causing a computer to execute processing, the processing including:

irradiating with light a layered structure which is an object of measurement, the layered structure comprising a plurality of layers, the plurality of layers including at least a superficial layer and a deep layer;

receiving, at a position at a first predetermined distance from a light irradiation position, light of the irradiation light which has been transmitted through the superficial layer and the deep layer, and receiving, at a position at a second predetermined distance from the light irradiation position, light of the irradiation light which has been transmitted through the superficial layer and the deep layer, and which has a deep layer transmission distance which is different from that of the light received at the position at the first predetermined distance from the light irradiation position;

obtaining a spatial slope based on intensities of the light received at the position at the first predetermined distance from the light irradiation position, the light received at the position at the second predetermined distance from the light irradiation position, the first predetermined distance, and the second predetermined distance;

inputting a thickness for each superficial layer; and

reading a stored computation parameter corresponding to an input superficial layer thickness, where computation parameters for computing a degree of light absorption in the deep layer are stored for each superficial layer thickness in the storage device, and obtaining the degree of light absorption based on the read computation parameter and the spatial slope.