JPS62127034A - Apparatus for measuring living body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a biological measuring device, and more particularly, it non-invasively measures parameters indicating metabolic dynamics in a living body using visible or near-infrared laser light. The present invention relates to a bioinstrumentation device for measuring.

(Prior Art) In the medical field, it is well known that the degree of oxygen utilization in the brain of a human or animal body is a fundamentally important parameter for evaluating eyelid function. For example, if there is no oxygen in the brain for more than 10 seconds, it will cause functional impairment, and if there is no oxygen for more than a few minutes, it will cause irreversible damage. For this reason, research has been conducted for many years on methods to determine the above parameters, but recently, methods using swelling waveforms, which have been common until now, and Xe1
In place of the method of indirectly determining parameters by melting a radioactive gas such as No. 33 and injecting it into the carotid artery and measuring the gas concentration in cerebral blood externally, a method using laser light in the visible or near-infrared region is used. A method has been proposed in which the above parameters are measured directly and non-invasively by irradiating the head. for example,
The method disclosed in Japanese Patent Application Laid-open No. 60-72542 is
As shown in the figure, laser light sources 3, 31 with different wavelengths in the visible or near-infrared region are placed opposite to each other with the object 1 to be measured in between, and a light detection means 5 including a photomultiplier tube is placed opposite to the laser light source. 3
, 31, the laser beams having different wavelengths exhibiting different absorbances are alternately switched and incident on the measurement target in the object to be measured 1 by rotating the sector mirror 70.
By processing the output signals corresponding to each wavelength from the converter, the two-dimensional distribution of acid purple intensity within the object to be measured, such as cerebral blood, can be displayed as an image, and changes in oxygen intensity can be visualized. A method of observing on a display is proposed.

(Problems to be Solved by the Invention) However, in the above-mentioned conventional technology, since the detection ability of the light detection means is limited, when the power of the transmitted light is about the same as the minimum detectable power of the light detection means, In order to increase the amount of light received, it takes a very long time to measure, making it impossible to measure in real time, and it becomes impossible to measure if the power of the transmitted light is less than the minimum detectable power.

(Means for Solving the Problems) The present invention is intended to eliminate the above-mentioned conventional drawbacks.
Therefore, the bioinstrumentation device according to the present invention includes a light source section that emits modulated laser light from a laser diode having a wavelength in the visible or near infrared region, and a condensing section that forms the beam from the light source section into a parallel beam. a lens, a partial reflection tube that splits the beam emitted from the condensing lens into two beams, a subject installation part placed on the optical path of one of the split beams, and An acousto-optic modulator that forms a locally oscillated wave with a slightly different frequency from that of the other beam, a partial reflector that balances the locally oscillated wave with the light wave that has passed through the object in the object installation section, and A photomultiplier tube that receives light waves and performs heterodyne detection; a photon counting system that counts the number of photoelectrons from the output of the photomultiplier tube; and a photon counting system that counts the number of photoelectrons from the output of the photomultiplier tube. and a data processing device that calculates the parameters shown.

(Function) In the present invention, the beam from the light source is not directly incident on the body part to be measured, but is first formed into a parallel light beam by the Hayabusa lens, and then is incident on the body part to be measured. Ru.

Therefore, uniform incident light power can be applied to the entire fixed spot, and jI! Since the spot is always constant, a constant incident light power can be provided even if the measurement site changes. The beam from the light source section is emitted by alternately switching a plurality of laser diodes with different wavelengths selected according to parameters to be calculated by the data processing lid. The beam emitted from the light source is split into two beams by a partial reflection tube, one of the split beams is transmitted through the object, and the other split beam is converted into one beam by an acousto-optic modulator. It is formed into a local oscillation wave with a slightly different frequency. The light wave transmitted through the object is combined with a local oscillation wave by a partial reflecting mirror, and heterodyne detection is performed by a photomultiplier tube. By performing heterodyne detection in this manner, it is possible to lower the minimum detectable power of the photomultiplier tube and increase measurement sensitivity, thereby shortening measurement time. - According to the example, the measurement sensitivity can be improved by about two orders of magnitude compared to the case where the same photomultiplier tube is used and no heterodyne detection is performed, and therefore about 4 degrees. It is possible to measure with the same accuracy in a time of . The number of photoelectrons output from the light multiplier is counted by a photon counting system, and the light beams that have passed through the object can be well detected by MIF as the number of pulses proportional to the amount of residual light. The transmitted light power corresponding to each laser diode obtained in the form of the number of pulses from the photocalunting system is processed in data processing-I6# according to a known formula to obtain the parameters to be determined.

(Embodiments) Hereinafter, preferred embodiments of the invention will be explained with reference to the accompanying drawings.

Figure 1 is an embodiment of the present invention as a device for measuring the metabolic function of the pharynx. 11 is a laser diode, 13
is installed in front of the laser diode and forms the laser beam into a V parallel beam. 15 is a partial reflection lens for splitting the nuclear laser beam into two beams, 17 is a subject or head placed on the optical path of one of the split beams, and 19.21 is a reflection lens. 23 is an acousto-optic modulator for forming a local oscillation wave having a frequency slightly different from that of the one beam, and 25 is an acousto-optic modulator for forming a local oscillation wave with a frequency slightly different from that of the other branched beam. 27 is a photomultiplier arranged to receive the combined light; 29 is a cooling device for housing the photomultiplier 27 in order to reduce thermal noise; 31 is a photomultiplier tube 27
33 is a drive circuit for the laser diode 11, 35 is an output monitor circuit that detects the drive output of the laser diode, and 37 is a % conversion of the drive output detected by the output monitor circuit. 39 is the interface, 41
calculates the oxygen saturation level of cerebral blood, which is a parameter indicating the metabolic capacity of the subject 17, from the output signals from the photon counting system 31 and the converter 37 taken in through the interface, and calculates A microcomputer is programmed to output results and various data to a display device 43, a printer 45, and to be stored on a magnetic disk 47; 49 is a system control unit that controls the operation of the microcomputer 41 and the laser diode drive circuit 33; , 51 indicate operation units, respectively.

Note that the light source section (laser diode 11 and condensing lens 13), light receiving section (photomultiplier tube 27 and cooling device 29), acousto-optic modulator 23, and reflective The mirrors 15, 19, 21, and 25 are fixed on a dedicated measuring table 53, and this measuring table 53 is for blocking light.

The whole is covered with a cover 55. The subject 17 is exposed to the light source through an opening (not shown) provided in the measuring table 53.
It is positioned between the light receiving parts.

In this configuration, the laser diode drive circuit 33 is driven via the system control unit 49 in response to a startup command from the operation unit 51, and the laser diode 11 emits a modulated laser beam. In this case, the laser diode 11 has two different wavelengths (for example, human = 760rn+,
, l, = 800+stm), the corresponding laser diodes are switched and driven to alternately generate laser light.

The laser beam is made into parallel beams by the condensing lens 13, and is divided into two beams by the partial reflecting mirror [5, one of which is incident on the head 17 of the subject. The other branched laser beam is transmitted to the acousto-optic modulator 2 by a reflecting mirror 19.
3, where a local oscillator wave is formed. head(
The detected light that encounters and propagates through the scalp, skull, brain parenchyma) is directed to a partial reflector 25 by a reflection beam 21, where it is combined with a local oscillation wave, and the combined light is compared with near-infrared light. The light passes through the #290 cooling device quartz window material 29α, which has high optical transparency, and enters the light-receiving surface of the photomultiplier tube 27. Photoelectron multiplier tube 27
outputs a number of photoelectrons proportional to the incident light band amplified by the local oscillation wave, and a photon counting system 31 counts pulses corresponding to the number of photoelectrons. On the other hand, the drive output of the laser diode mentioned above is measured by the output monitor circuit 35 and converted. The detected number of photoelectrons and the digitized output of the laser diode are input to the microcomputer 41 via the interface 39. The microcomputer 41 uses the output of the photon counting system and the output of the laser diode, which correspond to laser beams of two different wavelengths, as input data, processes the data according to a dedicated algorithm, and calculates the oxygen phase change, which is a parameter indicating the metabolic function of the brain. seek. FIG. 2 shows a processing flowchart in the case of determining the oxygen saturation level X (%) in cerebral blood using two beams of laser light with input r = 760rc*, person = 800ram. In this example, the laser diode output P0
defines the standard for the outputs of the detector ptao T, P2O3, which are eventually erased. The parameters thus determined are displayed as a two-dimensional distribution image on the display device 143 or output to the printer 45. If it is a cloak, various data including the above parameters are stored on the magnetic disk 47.

In addition, although the above example specifically describes the case where the oxygen saturation level in cerebral blood is determined using laser light of two specific wavelengths, the parameters indicating the metabolic capacity inside the living body that can be measured by the device of the present invention are as described above. The wavelength and number of laser beams can be appropriately selected depending on the parameters to be measured.

(Effects of the Invention) As described above, according to the present invention, in order to non-preferentially measure parameters indicating metabolic dynamics inside a living body using visible or near-infrared laser light, Rougue light can be divided into two. One of them is used as a signal light that passes through the living body part, and the other is used to form a local excavation wave, and both lights are combined and set up as a heterodyne wave using a photomultiplier tube, so photoelectron multiplication is possible. The measurement sensitivity of the tube can be greatly increased, and therefore accurate measurements can be made even if the measurement time is greatly shortened so that real-time measurements can be made. Furthermore, since the light transmitted through the living body part is detected by counting the number of photoelectrons output from the photomultiplier tube, accurate measurements can be made even if the amount of transmitted light is weak.

[Brief explanation of drawings]

Fig. 1 is a system configuration diagram showing an example of the device of the present invention;
The figure is a flowchart showing an example of processing by a microcomputer, and FIG. 3 is a diagram showing an example of the configuration of a conventional device. Patent applicant: Sumitomo Electric Industries, Ltd. (5 others) 3rd area/l Curtain 2

Claims (3)

[Claims] (1) A light source unit that emits modulated laser light from a laser diode having a wavelength in the visible or near-infrared region, and a condenser lens that forms the beam from the light source unit into a parallel beam;
a partial reflecting mirror that splits the beam emitted from the condensing lens into two beams; a subject installation part disposed on the optical path of one of the split beams; consists of an acousto-optic modulator that forms local oscillation waves with slightly different frequencies, a partial reflector that superimposes the light waves that have passed through the test object and the local oscillation waves in the test object installation section, and a heterodyne system that receives the superimposed light waves. A photomultiplier tube that performs detection, a photon counting system that counts the number of photoelectrons from the output of the photomultiplier tube, and data processing that calculates parameters indicating metabolic dynamics within the body part to be measured from the output of the photon counting system. A biological measurement device comprising: (2) The light source section is capable of alternately emitting light beams of two different wavelengths, and the photon counting system is capable of separately counting the number of photoelectrons corresponding to the light beams of the two different wavelengths. The biometric device according to item 1. (3) The bioinstrumentation device according to claim 2, wherein the parameter indicating the metabolic dynamics is a change in local oxygen saturation of cerebral blood.