Biological optical measurement system

• US 20060100525A1
• Filed: 08/17/2005
• Published: 05/11/2006
• Est. Priority Date: 10/21/2004
• Status: Active Grant

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Sato, Hiroki, Obata, Akiko, Maki, Atsushi, Tanaka, Naoki, Katura, Takusige
• Granted Patent: US 7,565,192 B2
• Time in Patent Office: Days
• US Class Current: 600/476
• 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 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/14553 specially adapted for cerebral tissue
• CPC Class Codes: A61B 5/6814 Head

Abstract

A typical task assigned for measuring a brain activity signal lasts from 10 to 30 seconds. The frequency band of the Mayer wave noise signal is very close to the frequency bands of brain activity signals, a result, it is difficult to reduce the Mayer wave noise signal using a bandpass filter or a bandcut filter. Light irradiating units and light detecting units for detecting the emitted light that has been passed through or reflected within the tissue are provided. A biological signal measuring unit measures at least one of the pulsation, breathing, blood pressure, and temperature. The relationship between an optical signal obtained by the light detecting unit and a biological signal using non-linear analysis; and a computation for separating the biological noise signal from the optical signal on the basis of the obtained relationship.

Claims

1. A biological optical measurement system for measuring changes in the dynamics of blood in the brain of a test subject, said system comprising:

light-irradiating means for irradiating the head of a test subject with light;

light-receiving means for receiving the light emitted by said light-irradiating means that has propagated through the head of said test subject;

biological signal detecting means for detecting a biological signal from said test subject;

relationship computing unit for computing the relationship between an optical signal received by said light-receiving means and said biological signal detected by said biological signal detecting means; and

separation computation means for computing a biological noise signal from the relationship computed by said relationship computing unit so as to separate said biological noise signal from said optical signal.

2. The biological optical measurement system according to claim 1, comprising a display unit for displaying the relationship computed by said relationship computing unit.

3. The biological optical measurement system according to claim 1, wherein said biological signal is one or a combination of two or more factors selected from the blood pressure, heart beat or heart rate, breathing, temperature, and the movement of the throat of said test subject.

4. The biological optical measurement system according to claim 1, wherein said relationship computing unit computes the relationship between said optical signal and said biological signal by performing prediction using transfer entropy.

5. The biological optical measurement system according to claim 1, wherein said biological noise signal has a fluctuation in a band lower than that of the frequency of the heart beat or heart rate.

6. The biological optical measurement system according to claim 1, comprising a bandpass filter for removing a predetermined frequency component of said optical signal and/or said biological signal.

7. The biological optical measurement system according to claim 1, comprising a display unit for displaying said optical signal, said biological noise signal, and/or a signal obtained by removing said biological noise signal from said optical signal.

8. The biological optical measurement system according to claim 1, comprising a synchronizing unit for synchronizing said light-receiving means and said biological signal detecting means.

9. The biological optical measurement system according to claim 1, wherein said biological signal detecting means comprises a pulsation measurement unit, a heart beat or heart rate measurement unit, or a blood pressure measurement unit.