JP3599426B2 - Biological light measurement device - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a biological light measurement device and an image creation method in the device, that is, a biological light measurement device that measures information inside a living body using light and images the measurement result, and an image creation method.
[0002]
[Prior art]
An apparatus or method for measuring the inside of a living body simply and without harming the living body is desired in clinical medicine. To meet this demand, measurement using light is very effective. The first reason is that the oxygen metabolism function inside the living body corresponds to the concentration of a specific dye (hemoglobin, cytochrome aa3, myoglobin, etc.) in the living body, that is, the concentration of the light absorber. This is because it is determined from the amount of absorption in the infrared region). The second reason is that light is easily handled by optical fibers. The third reason is that optical measurement does not harm the living body when used within the safety standards.
[0003]
Utilizing the advantages of living body measurement using such light, the living body is irradiated with light of visible to near-infrared wavelength, and the inside of the living body is measured from reflected light at a position about 10 to 50 mm away from the irradiation position. Such devices are described in, for example, JP-A-63-277038 and JP-A-5-30087. Further, an apparatus for measuring a CT image of the oxygen metabolism function from light transmitted through a living body having a thickness of about 100 to 200 mm, that is, an optical CT apparatus is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 60-72542 and 62-231625. No.
[0004]
[Problems to be solved by the invention]
As a clinical application using living body light measurement, for example, when the head is a measurement target, measurement of the activation state of oxygen metabolism in the brain and local cerebral hemorrhage can be mentioned. It is also possible to measure higher brain functions, such as movement, sensation, and thinking, in relation to oxygen metabolism in the brain. In such measurement, by measuring and displaying an image rather than a non-image, the effect is dramatically increased. For example, measurement and display as an image are indispensable for detecting a local oxygen metabolism change site or the like.
[0005]
However, the prior art has the following problems. First, in the measurement using the reflected light, a method for measurement and display for imaging is not proposed. Therefore, when oxygen metabolism is locally changed, it is difficult to detect a changed portion. An optical CT device using transmitted light can detect a local change as an image, but the intensity of transmitted light in a living body is several orders of magnitude smaller than the intensity of reflected light, and is very weak. The transmitted light signal is buried in a random noise component. Therefore, in order to measure the transmitted light signal to be sufficiently large with respect to noise, an expensive weak light detector is required, and the measurement time, that is, the measurement time, is required to remove the noise and extract the transmitted light signal. It is necessary to increase the number of times of integration. As a result, the measurement time becomes longer, which not only imposes a mental burden on the subject, but also lowers the operation efficiency of the apparatus.
[0006]
Therefore, an object of the present invention is to solve the above-mentioned problems, to use a simple detector, and to perform measurement in a shorter time, to image a state of a biological function, and to image a measurement result using the device. Is to realize a method of
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the biological measurement device of the present invention includes a plurality of light irradiating units that irradiate the subject with light having a wavelength in the visible to near-infrared region. A plurality of light receiving means for detecting the reflected light, a memory means for storing the signals detected by the light receiving means for each of the plurality of light receiving means and over time, and a signal stored in the memory means. An arithmetic unit for converting signals of a plurality of measurement points into signals to be measured and an image creating unit for displaying an output of the arithmetic unit on a two-dimensional display surface indicating the measurement position as a topographic image expressed as an intensity signal are provided. In particular, each of the plurality of light irradiation means includes a plurality of light sources having different wavelengths, a modulator for modulating the light of the plurality of light sources at mutually different frequencies, and a light guide for guiding the plurality of modulated lights to an irradiation position. A plurality of light receiving means each having a separating means for separating the intensity of light from the plurality of light sources having different wavelengths.
[0008]
When the function inside the living body is measured using the living body measuring device, the light irradiation positions of the plurality of light irradiation units are distributed and arranged on the measurement unit of the subject, and the light irradiation positions arranged and distributed. Arrange a plurality of light receiving units of the plurality of light receiving means in each peripheral portion of the, at the midpoint between the light irradiation position and the detection position of the light signal detected by the plurality of light receiving means, and with respect to the body surface An arbitrary position on a vertical line into the living body is set as a measurement point. The measurement points and the detected optical signal intensities corresponding to the measurement points are displayed on a two-dimensional image. Further, when displaying as a topography image, a signal at a position that has not been measured may be obtained by an interpolation signal of the measurement point.
When the subject is a living body, the distance between the irradiation position and the detection position is preferably about 10 to 50 mm.
[0009]
[Action]
According to the present invention, since the information on the measurement position is almost uniquely determined by the light irradiation position of the light irradiation unit to the subject and the position of the light receiving unit, signal processing for displaying as a topography image can be performed easily and at high speed. . In addition, the reflected light is used when the position of the light receiving means is about 10 to 50 mm from the light irradiation position, and the detection intensity is sufficiently higher than the light transmitted through the living body of about 100 to 200 mm. Therefore, measurement can be performed with a simple photodetector in a short time.
[0010]
For example, when the measurement target (subject) is the head, if the distance between the irradiation position and the detection position is at least 30 mm, the detection light passes through the skin and the skull and reaches the surface of the brain, that is, the cerebral cortex. For example, a journal published by Patrick W. McCormick et al., "Intracerebral penetration of infrared light," published by February 1992, by Patrick W. McCormick et al. Ob Neurosurgery, Vol. 76, pp. 315-318 (J Neurosurg., 76, 315 (1992)). In addition, it is found that information at a position on a perpendicular line from the midpoint of the irradiation and detection positions to the inside of the living body with respect to the living body surface is most contained in the light detected at such a position. It is known from the propagation characteristics. For example, "Monte Carlo simulations of photon path distribution in multiple scattering media" by Shechao Feng et al., Pp. 93-93, by Shechao Feng et al. Proceedings of photon migration and imaging in random media and issues, 1888, 783, pp. 78-89 (Reported by EIE, Proceedings, Vol. 1888, Photon Movement and Imaging in Random Media and Biological Tissue, 1888, 78 (1993)). ing.
[0011]
In the biological optical measurement device of the present invention, a large number of positions are required to be measured, and a large number of light irradiating units and light receiving units are required. The topography image can be obtained at high speed by a simple calculation process of interpolating the measurement results obtained for a plurality of measurement points for each measurement point.
[0012]
【Example】
Hereinafter, examples of the present invention will be described.
FIG. 1 shows a configuration of an embodiment of a biological light measurement device according to the present invention. The present embodiment is an example in which the biological optical measurement device is applied to the measurement of blood dynamic changes (relative changes in oxidized and reduced hemoglobin concentrations) associated with brain functions. The specific part of the brain is related to the control of a specific function of the living body (for example, moving a part of the body such as a finger), and by operating the specific function, the blood dynamics of the specific part of the brain changes. The biological optical measurement device according to the present embodiment can measure a change in blood dynamics by applying a load that causes the specific function to operate, for example, moving a finger, and display the contour map on a secondary planar image representing a part of the brain. Can be performed.
[0013]
As shown in the figure, in the present embodiment, a plurality of light sources 2a to 2d having different wavelengths (the light sources 2a and 2c and the light sources 2b and 2d have the same wavelength in the visible to near-infrared region), and the plurality of light sources 2a and 2d, respectively. A modulator for intensity-modulating the light of 2b (2c and 2c) with oscillators 1a and 1b (1c and 1d) having different frequencies from each other, and the intensity-modulated light through optical fibers 3a and 3b (32c and 3c), respectively. A plurality of light irradiating means for irradiating the light from the coupler 4a (4b) to be coupled to different positions on the scalp of the subject 6 via the optical fiber 5a (5b); and the plurality of light irradiating means A plurality of light detecting optical fibers 7a to 7d and a light detecting optical fiber such that the tip is located at a position equidistant from the light irradiation position (here, 30 mm) from the light irradiation position. And a plurality of light receiving means comprising photodetectors 8a~8f provided respectively provided with A～7d. The light passing through the living body is condensed on the optical fibers by the six light detecting optical fibers 7a to 7f, and the light passing through the living body is photoelectrically converted by the photodetectors 8a to 8f, respectively. The light receiving means detects light reflected inside the subject and converts the light into an electric signal. As the photodetector 8, a photoelectric conversion element such as a photomultiplier tube or a photodiode is used.
[0014]
Electric signals (hereinafter, referred to as living body passing light intensity signals) representing the living body passing light intensity photoelectrically converted by the photodetectors 8a to 8f are input to the lock-in amplifiers 9a to 9h, respectively. Here, the photodetectors 8c and 8d detect the intensity of light passing through the living body collected by the photodetection optical fibers 7c and 7d equidistant from both the optical fibers 5a and 5b. Are separated into two systems and input to the lock-in amplifiers 9c and 9e and 9d and 9f. The oscillators 1a and 1b are input to the lock-in amplifiers 9a to 9d, and the intensity modulation frequencies from the oscillators 1c and 1d are input to the lock-in amplifiers 9e to 9h as reference frequencies. Accordingly, the bio-passing light intensity signals for the light sources 1a and 1b are separated and output from the lock-in amplifiers 9a to 9d, and the bio-passing light intensity signals for the light sources 1c and 1d are separated and output from the lock-in amplifiers 9e to 9h. Is done.
[0015]
The analog-to-digital converter 10 performs analog-to-digital conversion of the separated transmitted light intensity signals output from the lock-in amplifiers 9e to 9h for each wavelength, and then stores the data in the storage device 12 inside the computer 11 or outside the computer 11. To be stored. During or after the measurement, the computer 11 calculates a relative change amount of the oxidized and reduced hemoglobin concentrations obtained from the detection signals at the respective detection points using the transmitted light intensity signal stored in the storage device, and performs a plurality of measurements. The information is stored in the storage device 12 as the time information of the point m. The above operation will be described later in detail. The display control unit 30 converts the signal stored in the storage unit 12 into a display signal of a display device 13 such as a CRT and displays the signal on the display device 13. The display signal is a signal for converting the measurement position into coordinates on the display plane of the subject and displaying an intensity signal (a relative change in the concentration of oxidized or reduced hemoglobin) at that coordinate position on a contour line.
[0016]
By using the biological optical measurement device according to the present embodiment, the relative change amount of the oxidized and reduced hemoglobin concentrations in the living body can be measured easily and at high speed. The configuration in which the number of light incident points (light irradiation positions) and the number of light detection points are increased can be easily expanded by increasing the intensity modulation frequency of the light source and the number of light sources, photodetectors, and lock-in amplifiers. With this biological optical measurement device, the spectral and light irradiation positions can be separated by the intensity modulation frequency, so even if the light irradiation positions are increased, the number of wavelengths of the irradiation light at each light irradiation position can be measured. It is only necessary to change the wavelength of the irradiation light for each light irradiation position. Therefore, the number of wavelengths of the irradiation light to be used is small, and errors due to the influence of scattering that differs depending on the wavelength can be reduced.
[0017]
FIG. 2 is a diagram for explaining an embodiment of an image creation method according to the present invention using a living body optical measurement device, and shows a relationship between a light incident point, a light detection point, and a measurement point in the above method. The image creating method of the present embodiment is a method of creating a topographic image of the relative change amount of the oxidized and reduced hemoglobin concentrations in the subject's head, and the left temporal region involved in the motor function of the right finger of the subject. This is a method of measuring the light passing through the living body by providing four points of incidence and detection points in the section, and imaging the measurement result when the movement of the right finger and the movement of the left finger are given as loads.
[0018]
As shown in the figure, light incident points 17a to 17d and detection points 18a to 18d are arranged on the left side head of the subject 16. Here, the correspondence between each light incident point and each detection point is as follows: 17a-18a, 17a-18b, 17b-18a, 17b-18b, 17b-18c, 17b-18d, 17c-18b, 17c-18c, 17d- There are 10 sets of 18c, 17d-18d. The distance between each corresponding light incident point and the detection point is 30 mm. Further, the time change of the relative change amount of the oxidized and reduced hemoglobin concentration obtained from the measurement signal at each detection point is described in "Monte Carlo Simulation of Photon Movement Path Distribution in Multiple Scattering Medium" by Shechao Feng et al. Monte Carlo simulations of photon path distribution in multiple scattering media ", Proceedings of SPI, 1993, Vol. 1888, Photon Movement and Images in Random Media and Biological Tissues, No. 78-89 (ceeding). of photon migration and imaging in random media and issues, 1888, 78 (1993)). It is As, since most reflect intermediate information of the incident point and the detection point each corresponding set measurement points 19a~19j the center of the corresponding relationship between the detection point and the point of incidence. The information of the measurement points 19a to 19j is obtained, and the size of the information is displayed as a contour line, light and shade, and a color identification diagram on a two-dimensional plane as shown in FIG.
[0019]
Next, the relative change amount of each hemoglobin concentration from the measurement signal at each light detection point according to the present invention, that is, the specific part of the brain due to the operation of a specific function of a living body (for example, moving a part of the body such as a finger) is operated. An embodiment of a method for obtaining a change in the concentration of moglobin will be described.
FIG. 3 is a graph showing a temporal change of the measurement signal 14 and the predicted no-load signal 15 obtained from the measurement signal 14 at one of the detection points 18a to 18d of the living body light measurement device in the above embodiment of FIG. The horizontal axis of the graph represents the measurement time, and the vertical axis represents the relative density change. The predicted no-load signal 15 is a pre-load time T1 and a post-load time, except for the signal at the load application time (load time) Tt and the time until the post-load signal returns (relaxation time) T2 from the measurement signal 14. This is obtained by fitting an arbitrary function to the measurement signal 14 at the time T2 using the least square method. In this embodiment, the arbitrary function is processed as a fifth-order linear polynomial, and each time is processed as T1 = 40 seconds, T2 = 30 seconds, Tt = 30 seconds, and T3 = 30 seconds.
[0020]
FIG. 4 is a graph showing a time change of a relative change amount of the oxidized and reduced hemoglobin concentrations at one measurement point (hereinafter, referred to as a ΔCoxy (t) signal 20 and a ΔCdeoxy (t) signal 21, respectively). The horizontal axis of the graph represents the measurement time, and the vertical axis represents the relative density change. The time indicated by the hatching is the load application time (the exercise period of the right finger). The relative change amount is calculated from the two-wavelength measurement signal 14 and the predicted no-load signal 15 shown in FIG. 2 by calculating the relative change amount of the oxidized and reduced hemoglobin (HbO ₂ , Hb) due to the application of the load by the following calculation processing. Ask.
[0021]
The relationship between the predicted no-load signal Str (λ, t) at the wavelength λ and the light source intensity I0 (λ) is expressed by the following equation (2) by separating light attenuation in a living body into scattering and absorption. Expressions (2) and (3) can also be derived from Expression (8) on page 61, "Biometric Measurement Using Light-Path to Optical CT", 2nd O plus E, June 1987, page 61.
−Ln {Str (λ, t) / I0 (λ)}
= Εoxy (λ) · Coxy (t) · d + εdeoxy (λ) · Cdeoxy (t) · d + A (λ) + S (λ) (2)
here,
εoxy (λ): extinction coefficient of oxyhemoglobin at wavelength λ εdeoxy (λ): extinction coefficient of reduced hemoglobin at wavelength λ A (λ): attenuation due to absorption other than hemoglobin at wavelength λ S (λ): scattering at wavelength λ Attenuation Coxy (t): oxygenated hemoglobin concentration at measurement time t Cdeoxy (t): reduced hemoglobin concentration d at measurement time t: effective optical path length in a living body (in a region of interest).
[0022]
The relationship between the measurement signal Sm (λ, t) and the light source intensity I0 (λ) is represented by the following equation (3).
−Ln {Sm (λ, t) / I0 (λ)}
= Εoxy (λ) · {Coxy (t) + C′oxy (t) + Noxy (t)} · d
+ Εdeoxy (λ) · {Cdeoxy (t) + C′deoxy (t) + Ndeoxy (t)} · d + A ′ (λ) + S ′ (λ) (3)
here,
C'oxy (t): Change in oxidized hemoglobin concentration due to load application at measurement time t C'deoxy (t): Change in reduced hemoglobin concentration due to load application at measurement time t Noxy (t): Noise or oxidation at measurement time t High frequency fluctuation of hemoglobin concentration Ndeoxy (t): High frequency fluctuation of reduced hemoglobin concentration at noise or measurement time t Here, if A (λ) and S (λ) do not change in the state of applying and not applying load, That is, assuming that the change in the measurement signal caused by the load is caused only by the change in the oxidized and reduced hemoglobin concentrations, the difference between the expressions (2) and (3) is expressed by the following expression (4).
[0023]
Ln {Str (λ, t) / Sm (λ, t)} = εoxy (λ) ｛C′oxy (t) + Noxy (t)｝ d
+ Εdeoxy (λ) ｛C'deoxy (t) + Ndeoxy (t)｝ d (4)
Here, the time change of the relative change amount of the oxidized and reduced hemoglobin concentration due to the load is represented by ΔCoxy (t) and ΔCdeoxy (t), respectively, and is defined by the following equation.
ΔCoxy (t) = {C'oxy (t) + Noxy (t)} d
ΔCdeoxy (t) = {C'deoxy (t) + Ndeoxy (t)} d (5)
Here, since it is usually difficult to specify d, the dimension of these density changes is the product of the density and the distance d.
[0024]
However, in equation (5), the distance d acts in the same way as ΔCoxy and ΔCdeoxy, so equation (5) is used as the relative change of each hemoglobin concentration. If two wavelengths are used for the measurement, the obtained equation (4) is a binary simultaneous equation for ΔCoxy (t) and ΔCdeoxy (t), and the predicted no-load signal Str (λ, t) and the measurement signal Sm ( From λ, t), ΔCoxy (t) and ΔCdeoxy (t) are obtained. Further, the values represented by ΔCoxy (t) and ΔCdeoxy (t) other than the load time and the relaxation time are represented by C′oxy (t) = 0 and C′deoxy (t) = 0, so that noise or biological oxidation This indicates the high-frequency fluctuation of the hemoglobin concentration and the reduced hemoglobin. The ΔCoxy (t) signal 20 and ΔCdeoxy (t) signal 21 shown in FIG.
[0025]
FIGS. 5 and 6 show contour image (topographic image) created from the temporal change of the relative change amount of the oxyhemoglobin concentration at each of the measurement points with the movement of the left finger and the right finger of the subject as loads. A method of creating a topography image is as follows. The computer 11 calculates a time integration value (or a time average value) of the relative change ΔCoxy (t) signal 20 during the load application time (the hatched period in FIG. 4), and calculates each measurement point. The values in between are created by linearly interpolating in the X-axis direction and the Y-axis direction. As the topographic image, in addition to the contour lines as shown in FIGS. From the comparison between the images in FIGS. 5 and 6, it is apparent that the oxyhemoglobin concentration is increased at a specific position during the right hand exercise. By displaying such spatial distribution information as an image, the recognition of the measurement result is made quick and easy. The images shown in FIGS. 5 and 6 were created using the time integrated value of the relative change in concentration during the load application time, and similarly, the images were similarly calculated based on the relative change in the oxyhemoglobin concentration at each measurement point at the same measurement time. It is also possible to create a topographic image. If the plurality of created topography images are displayed or displayed as a moving image in the order of the measurement time, it is possible to grasp the time change of the relative change amount of the oxyhemoglobin concentration.
[0026]
Further, the self- and cross-correlation functions of the time change of the relative change amount of the oxyhemoglobin concentration at one arbitrary measurement point and the time change of the relative change amount of the oxyhemoglobin concentration of the own and other measurement points are calculated, and the correlation function at each measurement point is calculated. Topographic images can also be created. Since the correlation function at each measurement point is a function defined by the time lag τ, if a topography is created from the values of the correlation function at the same time lag τ and displayed in the order of τ or displayed as a moving image, changes in blood dynamics Can be visualized as it propagates.
Here, the relative change in the oxyhemoglobin concentration is described as a representative, but the relative change in the reduced hemoglobin concentration or the total change in the total hemoglobin concentration calculated by the sum of the relative changes in the oxidized and reduced hemoglobin concentrations is described. Quantities can create topography as well.
[0027]
FIG. 7 shows a display example in which the topography image 22 created by the method described above is superimposed on the brain surface image 23 of the subject. Since the topography image 22 is a change in the blood dynamics of the brain that has changed in relation to the function of the living body, it is desirable to display the topography image 22 so as to overlap the brain surface image. The brain surface image 23 is measured and displayed by three-dimensional MRI or three-dimensional X-ray CT. The topography image 22 creates a topography image by performing coordinate transformation so that the coordinates of each measurement point are located on the brain surface, and interpolating values between the measurement points after the coordinate transformation. When the created topography image 22 and the brain surface image 23 are superimposed and displayed, the color of the superimposed topography image 22 is made translucent so that the underlying brain surface image can be seen through.
[0028]
FIG. 8 is a diagram for explaining a measurement point coordinate conversion method. When a morphological image of three-dimensional MRI or three-dimensional X-ray CT is taken, if a marker is placed at a measurement point set by the biological optical measurement device and taken, the skin and bone image 24 and brain image 25 are obtained from the taken morphological information. And the marker image 26 can be displayed. The photographed image has three-dimensional coordinate information. Therefore, a perpendicular 28 is calculated from the measurement point 27 indicated by the marker image 26 to the skin surface or the bottom surface of the marker image 26 at the measurement point 27, and a point that intersects with the brain image 25 is defined as a coordinate-transformed measurement point 29. As shown in the present embodiment, in the case of measuring brain function, it is known that a hemodynamic change correlated with the load occurs mainly on the brain surface (cerebral cortex). For the above reason, it is possible to know the depth at which the measurement point is coordinate-transformed by using the morphological information of the living body. However, if the measurement target is another living organ such as a muscle, it may not be possible to know the depth of the coordinate transformation from the morphological information. When the present method is used for the measurement as described above, the light propagation in the living body is calculated in advance by numerical calculation according to the Monte Carlo method, and the depth that greatly contributes to the measurement signal is obtained. Convert the measurement point to coordinates.
[0029]
【The invention's effect】
The present invention uses a low-cost light irradiating unit and photodetector, and can perform high-speed processing with an economical apparatus because of simple arithmetic processing, and can correspond to a planar image representing the shape of the measured object. Since the function can be imaged, it is an effective means particularly for measuring a predetermined function of a living body.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of an embodiment of a living body light measuring device according to the present invention. FIG. 2 is a diagram for explaining an embodiment of an image creating method using the above living body light measuring device. FIG. 4 is a diagram illustrating a temporal change of a measurement signal at one measurement point of the above embodiment and a predicted no-load signal 15 obtained from the measurement signal. FIG. 5 is a diagram showing a topographic image in one embodiment of the living body light measuring device according to the present invention; FIG. 6 is a diagram showing a topographic image in one embodiment of the living body light measuring device according to the present invention; FIG. FIG. 8 is a view showing a display example of a topography image in one embodiment of the optical measurement apparatus. FIG. 8 is a view for explaining a coordinate conversion method in another embodiment of the biological light measurement apparatus according to the present invention.
1: oscillator, 2: light source, 3: optical fiber, 4: coupler, 5: optical fiber,
6: subject, 7: photodetection optical fiber, 8: photodetector, 9: lock-in amplifier,
10: analog-digital converter, 11: computer, 12: storage device,
13: display device, 14: measurement signal, 15: predicted no-load signal, 16: subject,
17: incident point, 18: detection point, 19: measurement point, 20: ΔCoxy (t) signal,
21: ΔCdeoxy (t) signal, 22: topography image,
23: brain surface image, 24: skin and bone image, 25: brain image, 26: marker image,
27: measurement point, 28: perpendicular, 29: coordinate-converted measurement point.

Claims (21)

A plurality of light irradiating means for irradiating the subject's head with light,
A plurality of light receiving means for detecting light emitted from the light irradiation means and reflected inside the subject,
The plurality of light irradiation units and the plurality of light receiving units are arranged alternately in a grid on the subject, respectively.
The light receiving unit detects light emitted from the plurality of light irradiation units adjacent to the light receiving unit,
Light emitted from the light irradiation means is detected by a plurality of light receiving means adjacent to the light irradiation means,
A biological light measurement device for measuring a change in blood dynamics of the brain, comprising a calculation means for calculating a spatial distribution of a signal to be measured from the signal detected by the light receiving means. A plurality of light irradiating means for irradiating the subject's head with light,
A plurality of light receiving means for detecting light emitted from the light irradiation means and reflected inside the subject,
The plurality of light irradiation units and the plurality of light receiving units are arranged alternately in a grid on the subject, respectively.
The light receiving unit detects light emitted from the plurality of light irradiation units adjacent to the light receiving unit at substantially the same distance from the light receiving unit,
A biological light measurement device for measuring a change in blood dynamics of the brain, comprising a calculation means for calculating a spatial distribution of a signal to be measured from the signal detected by the light receiving means. The biological light measurement device according to claim 1, further comprising an image display unit that displays a spatial distribution of the measurement target signal. The biological light measurement device according to claim 3, wherein the image display means displays the signal of the measurement target in the order of measurement time or as a moving image. A modulator that intensity-modulates the light irradiated by the light irradiation unit at a predetermined modulation frequency,
The biological light measurement device according to claim 1, further comprising a separation unit configured to separate light modulated by the modulator for each modulation frequency. 6. The living body light measurement device for measuring a change in cerebral blood dynamics according to claim 5, wherein the modulator intensity-modulates light at a different modulation frequency for each position of the light irradiation unit. The biological light measuring device according to claim 1, wherein the light irradiating unit irradiates a plurality of lights having different wavelengths. The biological light measurement device according to claim 7, wherein the number of wavelengths of the light irradiated by the light irradiation unit is the same as the number of absorbers to be measured. A modulator that irradiates the light irradiated by the light irradiating unit with intensity at a different modulation frequency for each wavelength,
The biological light measurement device according to claim 7, further comprising: a separation unit configured to separate light modulated by the modulator for each modulation frequency. 10. The living body light measurement device according to claim 5, wherein the separation unit is configured by a lock-in amplifier driven by a modulation signal of the modulator. The biological light measurement device according to claim 1, wherein the signal to be measured is a relative change amount of the oxyhemoglobin or reduced hemoglobin concentration. The biological light measurement device according to claim 3, wherein the image display means displays the signal to be measured as a time integrated value or a time average value of a relative change amount of the oxyhemoglobin or reduced hemoglobin concentration. The bio-optical measurement apparatus according to claim 3, wherein the image display unit displays the signal of the measurement target as a distribution representing a change in blood dynamics associated with a brain function. The biological light measurement device according to claim 3, wherein the image display means displays the signal of the measurement target by a contour line or an identification display based on a shade or color of a color representing an intensity signal. The biological light measurement device according to claim 1, wherein the light irradiated by the light irradiation unit is light having a wavelength in a visible to near-infrared region. The measurement point is a substantially middle point between the light irradiation unit and the light receiving unit,
The calculation means calculates the signal of the measurement target between the plurality of measurement points as an interpolation signal by a calculation process from the signal of the measurement target at the measurement point,
4. The living body light measurement device according to claim 3, wherein the image display unit displays the interpolation signal. 4. The living body light measurement device according to claim 3, wherein the image display unit displays the signal of the measurement target superimposed on a brain image of the subject. 18. The living body optical measurement device according to claim 17, wherein the brain image is an image measured by three-dimensional MRI or three-dimensional X-ray CT. The biological light measurement device according to claim 1, wherein the light irradiating unit includes a light source having a different wavelength and a waveguide unit that guides light emitted from the light source to an irradiation position. The measurement point is a substantially middle point between the light irradiation unit and the light receiving unit,
The calculation means has calculation means for calculating a cross-correlation function between a time change of the signal strength of the measurement object at the first measurement point and a time change of the signal strength of the measurement object at the second measurement point. The biological light measurement device according to claim 3, wherein: 21. The biological light measurement device according to claim 20, wherein the image display unit displays a value of the cross-correlation function.

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