JP4589678B2 - Biological light measurement device - Google Patents

Description

  The present invention relates to a living body light measurement device that measures the inside of a living body by irradiating the living body with light and detecting light that has passed through the living body.

  As a device for measuring the inside of a living body simply and without causing harm to the living body, a biological light measuring device is known (Patent Document 1). The living body light measurement apparatus is configured to measure the inside of a living body by irradiating the living body with light having a wavelength from visible to infrared and detecting light that has passed through the living body. The irradiation light is propagated and irradiated from the light source to the measurement site by the irradiation optical fiber, and the light passing through the measurement site is incident on the detection optical fiber and propagated and detected by the detector. The exit end faces of the plurality of irradiation optical fibers and the entrance end faces of the plurality of detection optical fibers are alternately supported at a predetermined interval in a matrix shape such as 3 × 3 by a fixing member called a probe holder. Attached to the measurement site and fixed. Thereby, the part located between the output end surface of the irradiation optical fiber and the incident end surface of the detection optical fiber becomes a measurement point, and a plurality of measurement points (for example, 12 points) can be measured simultaneously. The light emitted from the plurality of optical fibers for light irradiation is preliminarily given different frequency modulations, so that the optical signal emitted from which optical fiber can be separated from the optical signal detected by the detector. ing.

After the detection by the photodetector, the relative change amount of the oxidized and reduced hemoglobin concentration at each measurement point is calculated from the optical signal separated for each measurement point, and this relative change amount is calculated as a biological passage intensity image (topography image). Is displayed. Thereby, for example, when the head is used as a measurement site, it is possible to measure the activation state of hemoglobin change in the brain at each measurement point in the measurement site, local cerebral hemorrhage, and the like. Conventionally, for example, Patent Document 2 discloses a biological light measurement device having a function of correcting position information of a biological passage intensity image with the positions of irradiation and detection optical fibers in order to accurately specify the position of a measurement point. ing.
Japanese Patent Laid-Open No. 11-139300 Japanese Patent Laid-Open No. 2001-79008

  When using a biological light measurement device for head measurement, the head often has hair to some extent, and the thickness of the skull, skin color, etc., differ depending on the subject and measurement site so that they cannot be ignored. Even if the light of the same light intensity is irradiated, the detected light intensity varies considerably depending on the measurement site. If the intensity difference is large, it is estimated that it is about several tens to several hundred times.

  In order to detect detection light having a difference in intensity as an accurate intensity, the dynamic range (detectable band) of the apparatus has been designed to be sufficiently wide. However, when measuring a plurality of measurement points at the same time with the light irradiation and detection optical fibers arranged in a matrix, one detection optical fiber includes, for example, four measurement points located around it. Since the transmitted light is incident at the same time, the light from the measurement point with low light transmission and the light from the measurement point with high light transmission are mixed and propagated and detected by one photodetector. The mixed optical signal detected by the detector is amplified and then separated for each optical signal by the modulation frequency component, but the amplification factor of the amplifier is usually set on the basis of light having a high signal intensity. For this reason, an optical signal with low intensity cannot obtain a sufficient S / N ratio, and as a result, the accuracy of the image may be lowered. On the other hand, when the amplification factor of the amplifier is set with reference to a low-intensity optical signal, the high-intensity optical signal may saturate beyond the dynamic range.

  An object of the present invention is to reduce a difference in signal intensity between measurement points and improve measurement accuracy in a biological light measurement device that measures a plurality of measurement points simultaneously.

  In order to achieve the above object, in the biological light measurement device of the present invention, a light intensity adjusting unit is arranged, and the light intensity detection result for each measurement point is used to align the light intensity level between the measurement points. The intensity of the emitted light is controlled with respect to the emission part. Thereafter, by performing the main measurement, the difference in signal intensity between the measurement points can be reduced, and the measurement accuracy can be improved.

  In the biological light measurement device, since light from one light emitting unit passes through a plurality of measurement points and is received by different optical fibers for detection, for example, the light intensity adjustment unit includes all measurement points. A ratio of a predetermined value to the light intensity value of the measurement point having the highest light intensity among a plurality of measurement points through which the light emitted from one light emitting part passes is obtained, and the emitted light intensity of the light emitting part is determined by this ratio. It can be configured to control to increase at a ratio.

  In addition, the light intensity adjusting unit may be configured to control the emitted light intensity for at least one of the plurality of light emitting units in accordance with an instruction received from the operator via the input unit. In this case, the light intensity adjustment unit may be configured to display the light intensity at each measurement point detected by the detection unit on an external display device in order to receive an instruction to adjust the emitted light intensity from the operator. Is possible.

A biological light measurement apparatus according to an embodiment of the present invention will be described with reference to the drawings.
(Embodiment 1)

  The biological light measurement device of the present embodiment includes a light irradiation module 10, a light detection module 20, and a calculation control unit 30, as shown in the block diagram of the overall configuration in FIG. In the light irradiation module, four laser modules 101 to 104, laser drive circuits 111 to 114 connected thereto, and a control circuit 15 for controlling the laser drive circuits 111 to 114 are arranged. Here, a description will be given by taking as an example a biological light measurement device that can simultaneously measure 12 measurement points by using optical fibers whose end faces are arranged in a 3 × 3 matrix.

  The laser modules 101 to 104 include semiconductor lasers with wavelengths of 780 nm and 830 nm, respectively, and are configured to mix and emit these two wavelengths of light. Under the control of the control circuit 115, the laser drive circuits 111 to 114 modulate the laser modules 101 to 104 with different modulation frequencies and emit light with a predetermined light intensity. Supply drive current of frequency and current density. In the laser drive circuits 111 to 114, power adjustment circuits 111a to 114a are arranged, respectively, and the drive current is adjusted according to an instruction from the control circuit 115 to adjust the emission intensity of the laser modules 101 to 104.

  The laser modules 101 to 104 include irradiation optical fibers 11 to 14 that propagate mixed light having wavelengths of 780 nm and 830 nm to which predetermined frequency modulation is applied, guide them to the measurement site of the subject 17, and emit the light from the emission end face. It is connected. The light emitted from the end faces of the irradiation optical fibers 11 to 14 toward the subject 17 passes through the measurement points of the subject 17 and enters and propagates through the end faces of the five detection optical fibers 21 to 25. The The light detection module 20 includes five photodiodes 201 to 205 connected to the detection optical fibers 21 to 25, respectively, and light detection / amplification circuits 211 to 215 connected to the photodiodes 201 to 205, respectively. Yes. The photodetection / amplification circuits 211 to 215 are circuits that respectively extract and amplify signals of a plurality of modulation frequencies included in the optical signals detected by the photodiodes 201 to 205.

  The four irradiating optical fibers 11 to 14 and the five detecting optical fibers 21 to 25 have their exit end faces and incident end faces alternately arranged in a 3 × 3 matrix as shown in FIG. It is inserted into a probe holder (not shown) and fixed. By attaching the probe holder to the measurement site of the subject 17, the optical fibers 11 to 14 and 21 to 25 can be fixed to the subject. By irradiating the measurement site from the end faces of the four irradiation optical fibers 11 to 14 and receiving the light by the five detection optical fibers 21 to 25, the irradiation optical fibers 11 to 14 and the detection optical fibers Information of 12 parts (measurement points 1 to 12) located between 21 and 25 can be detected as the passing light intensity.

  The arithmetic control unit 30 includes a measurement control unit 31 and an image generation unit 32. The measurement control unit 31 instructs the control circuit 115 to start and end the emission of the laser modules 101 to 104 and the modulation frequency, and also instructs the light detection / amplification circuits 211 to 215 to specify the amplification factor. In the present embodiment, the laser power setting unit 33 is arranged in the measurement control unit 31 and the emission intensity is set in each of the laser modules 101 to 104. Thereby, even if there is a distribution of the thickness of the hair or the skull, etc. at the measurement site where the irradiation optical fibers 11 to 14 are mounted by the probe holder, the influence on the measurement by adjusting the light emission intensity Therefore, measurement accuracy can be increased.

  In addition, a display unit 50, an input unit 60, and a recording unit 40 are connected to the arithmetic control unit 30. The arithmetic control unit 30 includes a memory in which a program is stored in advance and a CPU. The CPU reads the program in the memory and executes it, whereby the operation of the measurement control unit 31 and the image generation unit 32 are controlled. Realize operation. That is, when the operator receives an instruction that the operator operates the input unit 60 to start measurement, as shown in FIG. 3, the arithmetic control unit 30 sets the laser light intensity suitable for the main measurement to each laser. The determined operation is performed on the module (step 301). This is the operation of the laser power setting unit 33. Next, the light intensity of the measurement points 1 to 12 is acquired by the operation of the main measurement (step 302), and the image generation unit 32 generates a topographic image of the measurement site using this data (step 303). 50 is displayed (step 304).

  Specifically, the operation of step 301 in FIG. 3 by the laser power setting unit 33 is performed as shown in the flow of FIG. First, the arithmetic control unit 30 instructs the control circuit 115 to emit light from the laser modules 101 to 104 at a predetermined constant intensity (step 401). The control circuit 115 controls each of the laser drive circuits 111 to 114, and all have the same light intensity and set different modulation frequencies for each of the laser modules 101 to 104 in advance. As a result, the laser modules 101 to 104 emit light having a constant intensity although the modulation frequencies are set to the respective frequencies. This light is emitted from the end faces of the irradiation optical fibers 11 to 14 to the subject 17. Are emitted. The emitted light passes through the measurement points 1 to 12, enters from the end faces of the detection optical fibers 21 to 25, and is detected by the photodiodes 201 to 205.

  The arithmetic control unit 30 instructs the light detection / amplification circuits 211 to 215 to select a signal having a predetermined modulation frequency, and thereby the intensity of the optical signal transmitted through each measurement point 1 to 12 is determined. To detect. However, a fixed specified value is set as the amplification factor (step 402). As a result, the light detection / amplification circuit 215 receives the laser modules 101, 102, 103, and 103 emitted from the irradiation optical fibers 11, 12, 13, and 14 from the light reception signal of the light incident on the center detection optical fiber 25. By selecting and detecting an optical signal having a modulation frequency of 104, the intensity of light transmitted through the measurement points 1, 2, 3, and 4 is detected. The light detection / amplification circuit 211 selects an optical signal having a modulation frequency of the laser modules 101 and 102 emitted from the irradiation optical fibers 11 and 12, respectively, from the light reception signal of the light incident on the detection optical fiber 21. By detecting, the intensity | strength of the light which each permeate | transmitted the measurement points 6 and 7 is detected. Similarly, the other light detection / amplification circuits 212 to 214 detect the light intensity at the remaining measurement points 5 and 8 to 12.

  As shown in FIG. 5, for example, when the hair is present at the end face position of the irradiation optical fiber 11 and the light transmittance of the hair is 1/5 of the case where there is no hair, the photodiode 205 of the detection optical fiber 25 The detected light intensity from the irradiation optical fiber 11 is １ ／ compared with the light intensity from the other irradiation optical fibers 12, 13, and 14 (see FIG. 6A). Even if this is amplified by the light detection / amplification circuit 215 as in the prior art, the intensity of the optical signal from the irradiation optical fiber 11 is 1/5 of the other optical signal intensity after amplification, and S / N The ratio is also five times lower than the others (see FIG. 6B).

  Therefore, in the present embodiment, even if there are obstacles in the vicinity of the end faces of some of the irradiation optical fibers 11 to 14 that adjust the light emitted from the laser modules 101 to 104 and prevent the irradiation of laser light such as hair. The level of the detected light intensity is made substantially constant. That is, in step 403 of FIG. 4, for each laser module 101-104, the measurement point detected by the light of the laser module is selected, and the highest light intensity is selected. For example, for the laser module 101 (irradiation optical fiber 11), since the emitted light passes through the measurement points 1, 5, and 6, the light intensity at the measurement points 1, 5, and 6 is detected by the light detection / amplification circuit 211, The light intensity E1 of the measurement point (for example, measurement point 1) having the highest light intensity is selected from the output signals 204 and 205.

  Next, a magnification K1 = Emax / E1 is obtained by calculation from the light intensity E1 and the maximum intensity Emax that can be measured and detected by the photodiode 201 and the like and the light detection / amplification circuit 211 and the like obtained in advance. A command is output to instruct the control circuit 115 to increase the intensity of the emitted light by K1 (step 404). Similarly, for the laser modules 102 to 104, the largest light intensities E2 to E4 are obtained from the light intensities at the measurement points through which the emitted light from them passes, and the output light intensity is calculated from the light intensity and the aforementioned maximum intensity Emax. The magnifications K2 to K4 are obtained by calculation, and the control circuit 115 is instructed. The laser power determination process 301 in FIG. 3 ends. The control circuit 115 interprets the command from the arithmetic control unit 30, identifies the laser modules 101 to 104 instructed to improve the emitted light intensity, and the power drive circuits 111a to 114a of the laser drive circuits 111 to 114. A control signal is output to a drive current for setting the output light intensity to a designated magnification, for example, K1. However, the control circuit 115 sets a drive current that provides the maximum light emission intensity when the light intensity when changed at the instructed magnification exceeds the maximum light emission intensity of the laser modules 101 to 104.

  Thereby, for example, the light intensity emitted from the laser module 101 is set to about 5 times, so that even if the hair is located on the emission end face of the irradiation optical fiber 11, it enters the detection optical fiber 25 and detects the light. The light intensity detected by the amplifier circuit 215 is substantially constant at the measurement points 1, 2, 3, 4 as shown in FIG. In this state, in step 302 of FIG. 3, the main measurement is performed, and the light detection amplification circuits 211 to 215 perform amplification at an appropriate amplification factor, thereby detecting any optical signal as shown in FIG. 7B. It becomes possible to amplify to near the maximum of the dynamic range of the amplifier circuit. Thereby, the arithmetic control unit 30 can acquire the light intensity signals at the measurement points 1 to 12 with high intensity and store them in the recording unit 40.

  The arithmetic control unit 30 uses the light intensity signals for the measurement points 1 to 12 stored in the recording unit 40, and changes in oxygenated hemoglobin concentration, deoxygenated hemoglobin concentration, and total hemoglobin concentration for each measurement point 1 to 12. Etc. are calculated and associated with the position information of the measurement points 1 to 12, thereby generating respective topographic images (step 303). This is displayed on the display unit 50 (step 304). At this time, the shape image and the topography image of the measurement site (here, the head) stored in advance in the recording unit can be superimposed and displayed as necessary. Thereby, it is possible to perform display in which information indicated by the topography image can be easily recognized. The operations in steps 303 and 304 are the operations of the image generation unit 32.

  As described above, the living body light measurement apparatus according to the present embodiment is configured so that the laser power setting unit 33 performs setting for adjusting the intensity of the laser light emitted from the laser modules 101 to 104 before the main measurement. The intensity of the optical signal from each of the measurement points 1 to 12 detected at ˜205 can be made substantially the same level. Thereby, it becomes possible to reduce the difference in the S / N ratio between the measurement points 1 to 12. Therefore, measurement accuracy is improved, and as a result, improvement in diagnostic efficiency can be expected.

  In the above-described embodiment, the laser power setting process in step 301 is performed only once before the main measurement (step 302). However, in the flowchart shown in FIG. 3, the laser power setting in step 301 is performed. It is also possible to perform the processing a plurality of times. Thereby, the precision which makes the intensity | strength of the optical signal from each measurement point 1-12 substantially the same level can be improved.

  In the above-described embodiment, in step 404 of FIG. 4, the magnification K of the emitted light intensity is obtained for all the laser modules 101 to 104 so that the detected light intensity becomes the maximum intensity Emax that can be measured and detected. However, the present embodiment is not limited to this setting method, and other setting methods that can make the intensity of the optical signal from each measurement point 1 to 12 almost the same level can be used. For example, it is possible to use a setting method such as comparing the optical signal intensities from the measurement points 1 to 12 and increasing the emission intensity of the laser module that irradiates light to the measurement points where the optical signal intensity is weak.

  In the above-described embodiment, the magnification K of the emitted light intensity is obtained by K = Emax / E in step 404 of FIG. 4, but the magnification is lowered (for example, about 80%: K = (Emax / E) × 0.8) and adjusting the amplification factors of the light detection / amplification circuits 211 to 215 to make a fine adjustment.

The power adjustment circuits 111a to 114a are configured to control the light intensity by adjusting the drive current to the laser modules 101 to 104 in the above-described embodiment, but other methods, for example, the pulse duty ratio of the modulation signal Can be realized by controlling the light output time and adjusting the light intensity.
(Embodiment 2)

  In the first embodiment described above, the laser power setting unit 33 is configured to automatically set the intensity of the laser beam in steps 401 to 404 in FIG. 4. A case where the laser beam intensity is set to an arbitrary level according to the input of the input unit 60 will be described as a second embodiment.

  In this case as well, most of the configurations are the same as in the first embodiment, but after step 402, the light intensity from each of the measurement points 1 to 12 detected in steps 401 and 402 is determined for each photodiode 201 to 205. As shown in the graph of FIG. 6A, it is displayed on the display unit 50. At the same time, an input screen for accepting adjustment of the light intensity of the laser modules 101 to 104 is displayed on the display unit 50. Then, if the operator inputs a desired laser intensity or magnification for the arbitrary laser modules 101 to 104 to the input unit 60 according to his / her own judgment, the input is accepted and the control circuit 115 sets the laser intensity or magnification to the laser intensity or magnification. Thus, the instruction is output. When displaying the graph of FIG. 6A and the input screen on the display unit 50, the magnification of the light intensity when automatically adjusting by the processing of Steps 403 and 404 is simultaneously displayed as reference data, so that the operator It is also possible to help the judgment.

  By adopting the configuration of the second embodiment, the degree of freedom for the operator is increased, so that it is possible to increase the detected light intensity level of the measurement point desired by the operator.

  As described above, in the biological light measurement devices according to the first and second embodiments, the laser drive circuits 111 to 114 are provided with the power drive circuits 111a to 114a for adjusting the laser light intensity, and the arithmetic control is performed. By arranging the laser power setting unit 33 in the unit 30 and automatically or manually setting the light intensity from the measurement points 1 to 12 to the same level before the main measurement, there is a local difference in light transmittance. Even in a certain living body, the optimum incident light intensity can be set according to the contact site. Thereby, the level of the detected light can be made uniform, and the S / N ratio can be improved. Therefore, the measurement accuracy can be improved, and the diagnosis efficiency can be improved.

The block diagram of the biological light measuring device of a 1st embodiment. In the biological optical measurement apparatus of the first embodiment, the arrangement of the emission end face and the incident end face in a state where the irradiation optical fibers 11 to 14 and the detection optical fibers 21 to 25 are fixed by the probe holder, and the measurement points 1 to Explanatory drawing which shows the positional relationship of 12. FIG. The flowchart which shows operation | movement of the biological light measuring device of 1st Embodiment. The flowchart which shows the detailed content of the laser power setting operation | movement (step 301) in the flowchart of FIG. Explanatory drawing which shows the state in which the hair is located in the end surface of the optical fiber 11 for irradiation in the biological light measuring device of 1st Embodiment. In the biological light measurement device of the first embodiment, when the output adjustment of the laser module is not performed, (a) from the irradiation optical fibers 11 to 14 that enter the detection optical fiber 25 in the state of FIG. The graph which shows light intensity, (b) The graph which shows the signal strength at the time of amplifying as it is. In the biological light measurement apparatus of the first embodiment, after adjusting the output of the laser module, (a) a graph showing the light intensity from the irradiation optical fibers 11 to 14 incident on the detection optical fiber 25; b) A graph showing the signal intensity when amplified.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light irradiation unit, 11, 12, 13, 14 ... Irradiation optical fiber, 17 ... Subject, 20 ... Light detection unit, 21, 22, 23, 24, 25 ... Optical fiber for detection, 30 ... Calculation control unit, 31 ... Measurement control unit, 32 ... Image generation unit, 33 ... Laser power setting unit, 40 ... Recording unit, 50 ... Display , 60... Input unit, 101, 102, 103, 104... Semiconductor laser module, 111, 112, 113, 114... Laser driving circuit, 115... Control circuit, 111a, 112a, 113a, 114a ... Power adjustment circuit, 201, 202, 203, 204, 205 ... Photodiode, 211, 212, 213, 214, 215 ... Photodetection / amplification circuit.

Claims (2)

A plurality of light emitting units, a plurality of irradiation optical fibers for propagating light from the light emitting units to the subject, and irradiating the different parts of the subject, and the plurality of irradiation optical fibers Receiving a plurality of the light beams that are respectively emitted and passed through the respective measurement points in the subject, detection optical fiber that propagates the mixed light thereof, and detection that detects the light propagated through the detection optical fiber And a light intensity adjusting unit for adjusting the emitted light intensity of the light emitting unit,
The detection unit detects the intensity of the plurality of lights from the mixed light propagated through the detection optical fiber, thereby detecting the passing light intensity for each measurement point,
The light intensity adjusting unit receives the detection result of the light intensity for each measurement point from the detection unit, and controls the emitted light intensity for at least one of the plurality of light emitting units. Align the light intensity level between ,
The detection optical fiber is a plurality, and the detection unit detects, for each of the plurality of detection optical fibers, the passing light intensity for each measurement point from the mixed light that has propagated,
The light intensity adjustment unit is a predetermined value with respect to the light intensity value of the measurement point having the largest light intensity among the plurality of measurement points through which the light emitted from one of the light emission units passes among all the measurement points. The biological light measuring device is characterized in that the ratio is calculated and the intensity of the emitted light from the light emitting part is controlled to be increased at the ratio . A plurality of light emitting units, a plurality of irradiation optical fibers for propagating light from the light emitting units to the subject, and irradiating the different parts of the subject, and the plurality of irradiation optical fibers Receiving a plurality of the light beams that are respectively emitted and passed through the respective measurement points in the subject, detection optical fiber that propagates the mixed light thereof, and detection that detects the light propagated through the detection optical fiber And a control unit,
The detection unit detects the intensity of the plurality of lights from the mixed light propagated through the detection optical fiber, thereby detecting the passing light intensity for each measurement point,
The control unit includes a light intensity adjustment unit and a main measurement unit, and the light intensity adjustment unit receives a light intensity detection result for each measurement point from the detection unit, and outputs a plurality of light emission units. By controlling the emitted light intensity for at least one of the above, the light intensity level between the measurement points is aligned,
The main measurement unit performs measurement using the light intensity of the measurement point at which the light intensity adjustment unit aligns the light intensity level ,
The detection optical fiber is a plurality, and the detection unit detects, for each of the plurality of detection optical fibers, the passing light intensity for each measurement point from the mixed light that has propagated,
The light intensity adjustment unit is a predetermined value with respect to the light intensity value of the measurement point having the largest light intensity among the plurality of measurement points through which the light emitted from one of the light emission units passes among all the measurement points. The biological light measuring device is characterized in that the ratio is calculated and the intensity of the emitted light from the light emitting part is controlled to be increased at the ratio .

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