JP3939782B2 - Light scatterer measurement device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light scatterer measuring apparatus that irradiates a subject with light, receives light scattered and reflected by the subject, and optically measures the diagnosis and composition of the subject, and is applied to a biological oxygen monitor or the like Is something that can be done.
[0002]
[Prior art]
The living body is irradiated with visible to near-infrared light, the light scattered and reflected inside the living body is received, and the composition of the living body is examined or diagnosed by measuring the absorption spectrum of the scattered light. Biological monitors are known. This living body monitor includes a measurement probe made of an optical fiber or the like for irradiating a subject with light, and measures light by detecting light scattered inside the subject with a photodetector. As such a biological monitor, for example, an oxygen monitor that detects a change in the concentration of oxygenated hemoglobin or deoxygenated hemoglobin is known.
[0003]
FIG. 9 is a schematic configuration diagram of a conventional light scatterer measuring apparatus. In FIG. 9A, the light scatterer measuring device includes a measuring instrument main body 10 and a measuring probe 20, and the measuring probe 20 emits laser light from the measuring instrument main body 10 via an optical fiber 31. A light emitting unit 21 and light receiving units 22 and 23 that receive light scattered and reflected by a subject or the like are provided. The light receiving units 22 and 23 convert the detection light into an electric signal and send it to the measuring instrument main body 10 via the signal line 32. In the measuring instrument main body 10, signal processing for obtaining a change in the concentration of oxygenated hemoglobin or deoxygenated hemoglobin, for example, is performed using the detection signal.
[0004]
[Problems to be solved by the invention]
For example, in a living body monitor, a measuring device for a light scatterer is attached to a living body, which is a normal subject, in contact with a measuring probe to perform measurement. For this reason, if the measurement probe is detached during measurement, there is a problem that light such as laser light may directly enter the eyes of a person or a living body and cause damage to the eyes. In addition, the attached measurement probe may be temporarily lifted or separated from the subject due to movement of the subject, displacement of the optical fiber, or the like. In such a case, disturbance light other than the measurement light is incident on the light receiving portion of the measurement probe and becomes noise, which makes it difficult to perform accurate measurement.
[0005]
FIGS. 9B and 9C are diagrams for explaining the usage state of the measurement probe. In FIG. 9B, the light emitting unit 21 and the light receiving units 22 and 23 are attached in contact with a subject 41 which is a scatterer, and the light emitted from the light emitting unit 21 is scattered by the scatterer and scattered light. 52, and the light receiving units 22 and 23 detect the scattered light 52, respectively. When the measurement probe 20 temporarily floats or separates from the subject, the emitted light 51 is not incident on the subject 41 and is reflected by the surface or emitted in a direction other than the subject 41. Therefore, the light receiving units 22 and 23 receive the reflected light 53 from the subject 41 or disturbance light 54 entering from the surroundings, and cannot detect the scattered light 52 having information inside the subject. .
[0006]
Although it is easy to automatically stop measurement by monitoring the detection signal of a sensor or the like when the measurement probe is disconnected, a separate sensor or other light source is required, and the measurement probe Measurement cannot be resumed when returns to its original position.
[0007]
Accordingly, the present invention provides a light scatterer measurement device that solves the above-described conventional problems and reduces the obstacles caused by laser light when the measurement probe is lifted or deviated to improve safety. It is another object of the present invention to provide a light scatterer measuring device capable of automatically restarting measurement in response to temporary floating or disconnection of a measurement probe.
[0008]
[Means for Solving the Problems]
The light scatterer measurement apparatus of the present invention includes a measurement probe in which a light emitting unit that irradiates a subject with light and a light receiving unit that detects light, and a light control unit that controls irradiation of the light. , a signal processing means for signal processing the detection signals obtained by the light receiving unit, the signal processing means detects the incident state of the disturbance light, the light control means is a probe for the measurement in accordance with the incidence of disturbance light If it is determined that the float or detachment has occurred, the light emission state is changed so that the light emission interval is increased or the light emission intensity is decreased , and the float or detachment is performed. If There it is determined that the eliminated, which is returned before changing the irradiation conditions of light, thereby, improving the safety by reducing the failure by laser beam when the measuring probe out or floated Can for temporary lifting or off of the measuring probe, automatically it is possible to provide a measuring device of the light scatterer can be resumed measurements.
[0009]
In the first embodiment of the present invention, the signal processing means compares the output of the light receiving unit at the time of non-irradiation with a predetermined value, so that a separate sensor or other light source is not newly provided. It is possible to detect the floating or detachment of the measurement probe from the subject. When the light receiving unit performs light-current conversion, the signal processing unit compares the dark current with a predetermined value.
[0010]
In the second embodiment of the present invention, the light control means changes the irradiation state from the light emitting unit so that the light emission interval becomes longer when the measurement probe detects the floating or deviation from the subject. Therefore, it is possible to improve safety by reducing damage caused by light. Further, in the third embodiment of the present invention, when the light control unit detects the floating or disengagement of the measurement probe from the subject, the light control unit changes the irradiation state from the light emitting unit so that the light emission intensity is reduced. It is a change, and this can reduce the failure caused by light and improve the safety.
[0011]
In the fourth embodiment of the present invention, after detecting the floating or deviation of the measurement probe from the subject and changing the irradiation state from the light emitting unit, the signal processing means outputs the output when the light receiving unit is not irradiated ( When the light receiving unit performs light-current conversion, the dark current is compared with a predetermined value to detect the return of the measurement probe to the normal state, and the light control unit detects the irradiation state from the light emitting unit as the original. The state is changed, and the measurement can be automatically restarted.
[0012]
Therefore, in the light scatterer measurement device of the present invention, the light emitting unit intermittently irradiates the subject with light. When the measurement probe is well attached to the subject, the light receiving unit mainly receives light scattered and reflected inside the subject during irradiation, and detects dark current when not irradiated. Further, when the measurement probe is in a floating state or away from the subject, the light receiving unit mainly receives disturbance light.
[0013]
The signal processing means compares the non-irradiation output (dark current) with a predetermined value, and determines that the measurement probe floats or deviates from the subject when it is brighter than the predetermined value. When an abnormality is detected in the measurement probe, the light control unit changes the irradiation state from the light emitting unit by controlling to increase the interval of intermittent light emission or decrease the light emission intensity, and substantially irradiates the outside. Reduce the amount of light on the living body. The signal processing means continues the comparison between the output (dark current) at the time of non-irradiation and a predetermined value to detect the return of the measurement probe to the normal state, and the light control unit detects the irradiation state from the light emitting unit based on the original state. Change to state.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
An embodiment of the light scatterer measurement device of the present invention will be described with reference to the schematic block diagram shown in FIG. In FIG. 1, the light scatterer measuring apparatus includes a measuring instrument body 10 and a measuring probe 20. The measurement probe 20 includes at least one light emitting unit 21 and at least one light receiving unit 22, 23 arranged at a distance from the light emitting unit 21, and the light emitting unit 21 and the light receiving units 22, 23 have the same. It is formed integrally so that the arrangement interval and the arrangement angle do not change.
[0015]
The measuring instrument main body 10 includes storage means such as a memory 12, a hard disk 13 and a floppy disk 14 connected to the CPU 11 via a bus 15, an A / D conversion circuit 17 and a laser power source 18, and further A / D conversion. The integration circuit 16 is connected to the circuit 17, and detection signals from the light receiving units 22 and 23 of the measurement probe 20 are input via the signal line 32. The laser power source 18 supplies power to the laser light source 19 and transmits laser beams having various wavelengths (λ1 to λ4 in the drawing) to the light emitting unit 21 of the measurement probe 20 through the optical fiber 31.
[0016]
The memory 12 has various system programs for controlling the whole measuring apparatus and various calculations for calculating concentration changes of oxygenated hemoglobin and deoxygenated hemoglobin based on measurement signals measured by the light receiving units 22 and 23, for example. And a ROM for storing a control program for controlling the light emission interval and light emission intensity of the laser light source 19, a RAM for temporarily storing calculation results, and the like. Further, the hard disk 13 and the floppy disk 14 can be arbitrarily installed to store data.
The integration circuit 16 is a circuit for integrating a minute detection signal from the light receiving unit to increase the S / N ratio, and can be arbitrarily installed. The A / D conversion circuit 17 is used for measurement. This circuit is provided for digital signal processing in the main body.
[0017]
In the configuration shown in FIG. 1, the light control means is configured by the laser power supply 18, the laser light source 19, and the CPU 11 and the memory 12 related to the control function, and the CPU 11 and the memory 12 related to the signal processing function. To do.
For example, in order to obtain a change in the concentration of oxygenated hemoglobin or deoxygenated hemoglobin by using the light scatterer measurement device described above, the measurement probe 20 is attached to the subject, laser beams of various wavelengths are sent from the laser light source 19, The light scattered and reflected in the specimen is detected by the light receiving units 22 and 23, and the detected signals are obtained by signal processing. The details of the signal processing are omitted. Next, a procedure for detecting an abnormality of the measurement probe by the light scatterer measurement apparatus of the present invention will be described with reference to FIGS. Note that the abnormality of the measurement probe detected by the following procedure is mainly the floating or disengagement of the measurement probe from the subject, and other lighting states of the laser light can be detected.
Hereinafter, the check procedure using the measurement probe will be described with reference to FIGS. 2 to 4, and the control procedure performed by the control means based on the check results will be described with reference to FIGS. 5 to 8.
[0018]
The measurement probe shown in this embodiment is checked by comparing the detection signals of the two light receiving sections with a predetermined value. Then, the same determination processing is performed in both light receiving units, and the abnormal state of the measurement probe is determined by a combination of both checks.
[0019]
Therefore, in the following, the comparison between the detection signal and the predetermined value will be described only for one light receiving unit, and the comparison for the other light receiving unit is the same and will be omitted. First, constants p, q, and r used for comparison with the detection signal from the light receiving unit are set. Here, the constant p is a predetermined value for determining whether disturbance light is incident on the light receiving unit when the light emitting unit is not irradiating, and the measurement probe is attached to the subject satisfactorily. Set to a value smaller than the dark current at the time. The constant r is a predetermined value for determining whether the disturbance light incident on the light receiving unit is within the allowable range when the light emitting unit is not irradiating, and is a value larger than the constant p described above. Is set to a predetermined value such that it can be determined that it does not affect. The constant q is a predetermined value for determining whether or not the light emitting portion of the measurement probe emits a sufficient amount of light for measurement, and is set according to the subject to be measured, the characteristics of the light receiver, and the like. (Step S1).
[0020]
With the measurement probe attached to the subject, the detection signal I and the dark current D are obtained from the light receiving unit. The dark current D is a detection signal of the light receiving unit when irradiation from the light emitting unit is not performed, and the detection signal I is irradiated from the light emitting unit and is scattered and reflected in the subject. This is a detection signal. The detection signal I and the dark current D are detected by intermittently irradiating the light emitting unit, and the output of the light receiving unit at the timing of irradiation is the detection signal I, and the output of the light receiving unit at the non-irradiation timing is It can be obtained by setting the dark current D (step S2).
[0021]
Next, the dark current D is compared with the constant p to determine whether ambient light is incident on the light receiving unit (step S3). In this determination, if the dark current D is larger than the constant p, a display indicating that there is a lot of disturbance light is displayed (step S4), and further, a comparison with the constant r is performed, and the light incident on the light receiving unit is detected. It is determined whether or not it is within an allowable range (step S5). If it is determined in step S5 that the light incident on the light receiving unit exceeds the allowable range, it is determined that there is a possibility that the measurement probe is off the subject. This determination is set as c (step S6). This determination result is represented by a region indicated by c in FIG. In FIG. 3, the hatched portion with the symbol I indicates the range of the detection signal I, and the hatched portion with the symbol D indicates the range of the dark current D.
[0022]
When the dark current D is smaller than the constant p and no disturbing light is recognized in the determination of the step S3, or when the dark current D is smaller than the constant r and the disturbing light is recognized but within the allowable range. Then, it is determined that there is no possibility of the measurement probe coming off, and it is determined whether or not the laser beam is good in steps S7 to S11. In step S7, the detection signal I and the constant q are compared. If the detection signal I is larger than the constant q, it is determined that a sufficient amount of light is obtained, and it is determined that the laser light is normal. Let this determination be b. This determination result is represented by an area indicated by b in FIG. If the detection signal I is smaller than the constant q, it is determined that a sufficient amount of light has not been obtained, and the detection signal I and the dark current D are compared in magnitude (step S9).
[0023]
If the magnitude of the detection signal I and the dark current D is substantially equal in the determination in step S9, it is determined that only the dark current D is incident on the light receiving unit and the laser light source is not lit. This determination is a. This determination result is also represented by the area indicated by a in FIG. When the detection signal I is larger than the dark current D, it is determined that there is some abnormality in the laser light source because the light receiving portion is incident with light of the dark current D or more but is not sufficient. Then, a laser check is displayed (step S11). Let this determination be d. This determination result is represented by a region indicated by d in FIG.
[0024]
The above-described determination is a determination of one light receiving unit. When the measurement probe includes two light receiving units as shown in FIG. 1, the same determination is made for both light receiving units, and then FIG. According to the combination of the check results as shown in FIG. In FIG. 4, for example, when the check results of the first light receiving unit and the second light receiving unit are both normal (b in the figure), it can be determined that the measurement probe is normally lit. Further, when the check results of the first light receiving unit and the second light receiving unit are both likely to be misaligned (c in the figure), it is determined that the measurement probe is misaligned.
[0025]
Next, using FIG. 5 to FIG. 7, a procedure for changing the light emission state of the light emitting unit using the detection of the probe displacement of the measurement probe in the above procedure will be described.
The light receiving unit is checked by the above procedure, and the measurement probe is checked. In FIG. 6, four laser beams (λ1 to λ4) having different wavelengths are emitted from the laser light source sequentially at different emission timings to obtain four detection signals by each laser beam, and no laser beam is emitted. The dark current signal is obtained from the detected signal. The absolute value of the measured value can be obtained from the plurality of detection signals and the dark current signal. Note that the method for obtaining the absolute value of the measurement value is not particularly relevant to the present invention, and thus the description thereof is omitted.
[0026]
Therefore, in FIG. 6, the measurement probe constitutes one cycle with a total of five measurements including measurement with four laser beams and measurement of dark current, and the determination of the measurement probe as described above and in step S21 is performed within this one cycle. Do.
In each cycle, an abnormality of the measurement probe is determined (A in FIG. 6), and it is determined whether or not the abnormality determination has continued for, for example, T seconds. This determination of T second continuation (B in FIG. 6) makes it possible to eliminate temporary probe floating or disengagement. Note that instead of this determination of T second continuation, it is also possible to determine the corresponding number of cycles (step S22).
[0027]
If it is determined in step S22 that the measurement probe is disconnected, the light control unit changes the detection mode to change the emission state of the laser light (step S23). This change in the light emission state of the laser light can be performed, for example, by increasing the light emission interval of the laser light or lowering the light emission intensity of the laser light. FIG. 7 shows an example in which the light emission interval of the laser light is lengthened, and shows a state after the probe deviation is detected by the signal B in FIG. In FIG. 7, after the signal of the probe displacement, the interval for emitting the laser light is lengthened (C in FIG. 7). Thereby, the emitted light quantity of the laser beam is substantially reduced, and the influence on the living body can be reduced.
[0028]
FIG. 8 shows an example in which each light emission intensity of the laser light is lowered, and similarly shows a state after the probe deviation is detected by the signal B in FIG. In FIG. 8, after the probe deviation signal, the emission intensity of the laser light is lowered (E in FIG. 7). Thereby, the emitted light quantity of the laser beam is substantially reduced, and the influence on the living body can be reduced.
Even during the detection mode in which the amount of emitted laser light in step S23 is substantially reduced, the measurement probe is checked to determine whether or not the probe deviation state has been resolved (step S24). When it is determined that the measurement probe is normal, the original detection mode is restored in step S25 (F in FIGS. 7 and 8). As a result, the measurement can be automatically restarted.
[0029]
【The invention's effect】
As described above, according to the light scatterer measuring apparatus, it is possible to improve the safety by reducing the trouble caused by the laser beam when the measuring probe is lifted or detached. Further, the measurement can be automatically restarted with respect to temporary floating or disconnection of the measurement probe.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram for explaining an embodiment of a light scatterer measuring apparatus according to the present invention.
FIG. 2 is a flowchart of a procedure for detecting an abnormality of a measurement probe by the light scatterer measurement apparatus of the present invention.
FIG. 3 is a diagram showing a relationship between a detected value and a constant for detecting an abnormality of a measuring probe by the light scatterer measuring apparatus of the present invention.
FIG. 4 is a diagram showing a combination of check results for detecting an abnormality of a measurement probe by the light scatterer measurement apparatus of the present invention.
FIG. 5 is a flowchart illustrating a procedure for changing a light emission state of a light emitting unit using detection of a probe deviation according to the present invention.
FIG. 6 is a time chart illustrating a procedure for changing the light emission state of the light emitting unit of the present invention.
FIG. 7 is a time chart illustrating a procedure for changing the light emission state of the light emitting unit of the present invention.
FIG. 8 is a time chart illustrating a procedure for changing the light emission state of the light emitting unit of the present invention.
FIG. 9 is a schematic configuration diagram of a conventional light scatterer measuring apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Light scattering body measuring apparatus, 10 ... Measuring device main body, 11 ... CPU, 12 ... Memory, 13 ... HD, 14 ... FD, 15 ... Bus, 16 ... Integration circuit, 17 ... A / D circuit, 18 ... Laser Power source, 18 ... Laser power source, 19 ... Laser light source, 20 ... Measurement probe 20, 21 ... Light emitting portion, 22,23 ... Light receiving portion, 31 ... Optical fiber, 32 ... Signal line, 41 ... Subject, 51 ... Radiated light , 52 ... scattered light, 53 ... reflected light, 54 ... disturbance light.

Claims (1)

A measurement probe that integrates a light emitting unit that irradiates a subject with light and a light receiving unit that detects light, a light control unit that controls irradiation of the light, and a detection signal obtained by the light receiving unit Signal processing means for processing, wherein the signal processing means detects an incident state of disturbance light, and the light control means determines whether the measurement probe is floated or detached according to the incidence of the disturbance light , If it is determined that the float or off occurs, longer emission interval of the light, or the light emission intensity of the light changes the irradiation state of the light so as to reduce, when determining that the float or off is eliminated, the light irradiation An apparatus for measuring a light scatterer, wherein the state is returned before being changed .

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