Probe holder in brain function measuring apparatus using light

Abstract

In brain function measurement using light, it is difficult to simultaneously install a light emitting probe that emits light, a light receiving probe that detects light, a light emitting and receiving probe having a function of emitting and detecting light, and the like along the scalp of a subject. To provide an installation means of a probe following a plurality of differently curved scalps for simultaneously, stably and correctly installing many probes on the scalps.SOLUTION: An arm 1-2 having a hole having a connecting function with an adjacent holder is arranged in a holder 1-1 for fixing a probe, and a plurality of holders are connected by using a fixture 1-3 for connecting these holes. The hole diameter of the arm and the diameter, length, and the like of the fixing tool are adjusted to provide a movable range in a three dimensional direction in the connection portion, and the holder is held so as to be perpendicular to the scalp of the subject. By attaching six arms to one holder at intervals of 60 degrees from the center, expansion in a two dimensional direction is enabled, and a measurement unit following a required measurement region can be realized.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus for measuring brain function by placing multiple light-emitting probes that emit light, light-receiving probes that detect light, and light-emitting and light-receiving probes that have the function of emitting and detecting light on the head of a subject, and in particular to a holder for correctly placing the probes on the scalp of the subject, and a brain function measurement apparatus. [Background technology]

[0002] One method of measuring brain function using light is called NIRS, which uses near-infrared spectrophotometry. Brain function can be measured by measuring the changes in the concentrations of oxygenated hemoglobin, deoxygenated hemoglobin, cytochromes, and water in brain tissue using the differences in their near-infrared absorption spectra.

[0003] Brain function measurements using near-infrared light use a light-emitting probe to emit near-infrared light and a light-receiving probe to detect light reflected from brain tissue. Recently, hybrid probes, which combine light-emitting and light-receiving functions, have also been used. Measurements require the placement of the light-emitting window of the light-emitting probe, the light-receiving window of the light-receiving probe, and the light-emitting and light-receiving window of the hybrid probe on the subject's scalp. If there is a gap between the contact surface of the light-emitting and light-receiving windows of the light-receiving and hybrid probes and the subject's scalp, external light can penetrate through the gap, resulting in noise that can affect the measurement results. Light leaking from the gap in the light-emitting probe can potentially enter the adjacent light-receiving and hybrid probes, generating noise.

[0004] Holders are used to attach the above three types of probes to the subject's scalp. Regarding such holders, more specifically, the fixation of a light-emitting probe, a light-receiving probe, and a hybrid probe to a subject, for example, Patent Document 1 below discloses a brain function measurement device and holder that can be easily adapted to the subject's shape and increase the amount of information obtained from the subject. In this conventional brain function measurement device and holder, holes formed in two holder components are overlapped, and sockets inserted into the overlapped holes are attached with nuts to connect multiple holder components to form a mesh. In this conventional brain function measurement device and holder, a light-transmitting probe or a light-receiving probe is attached to the socket, and the angle in the tangent plane of the surface of the measurement object at the joint where the multiple holder components are connected can be arbitrarily adjusted by adjusting the screw tightening of the socket and the nut. Furthermore, in this conventional optical biometric device and holder, the holder components are flexible, allowing the holder to be deformed to fit the curvature of the head when attached.

[0005] Furthermore, Patent Document 2 below discloses a two-stage probe that adjusts the orientation of the probe to match the scalp of the subject. The holder on the skin side is elastic and adjusts the three-dimensional orientation of the probe relative to the scalp, and the orientation is adjusted by adjusting the position of the outer holder, and the relationship is maintained by a screw.

[0006] Patent Document 3 listed below shows a method of mounting a probe on a cloth covering the scalp, with dummy probes provided around the probe to be measured, ensuring an appropriate angle between the measurement probe and the scalp. Regardless of the area to be measured, the method involves wearing a cloth that covers the entire head, and placing the probe and dummy probe in the area to be measured to perform the measurement. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-313741 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-178192 [Patent Document 3] Japanese Patent Application Publication No. 2018-29778 Summary of the Invention [Problem to be solved by the invention]

[0008] Prior patent documents have described the fixation of light-emitting probes, light-receiving probes, and hybrid probes to subjects. However, the shape of the human head is complex, and there are differences in age and individuality, making it extremely difficult to accommodate all of them. Figure 2 shows an example of measuring the curvature of the head surface from the front, side, and top of a standard skull. R70 indicates the curvature of a circle with a diameter of 70 mm, directly below the center of the arrow. In Figure 2, the left and right sides of the top of the head are R70 when viewed from the front, but the front and back when viewed from the side are R100. This local variation, and the placement of probes at different points depending on the direction, as well as the accurate placement of the light-emitting probe's light-receiving window, the light-receiving probe's light-receiving window, and the hybrid probe's light-emitting and light-receiving window on the subject's scalp, are difficult.

[0009] Furthermore, in recent years, it has become common to measure multiple areas simultaneously. Research into brain function is being conducted by simultaneously measuring the frontal lobe and motor cortex, the frontal lobe and language cortex, the frontal lobe and both motor cortices, etc. In this case, it is necessary to simultaneously install and measure a large number of probes, which necessitates a holder that allows multiple probes to be installed correctly in a short time without placing a burden on the subject. An object of the present invention is to provide a holder that correctly positions a probe at each of different curvatures of the subject's head. [Means for solving the problem]

[0010] In order to achieve the above object, in the present invention, holders are connected to each other by an arm having a joint function. In brain function measurement devices using light, the distance between the basic light-emitting probe, light-receiving probe, and hybrid probe is generally 30 mm, and the probes are arranged in a two-dimensional direction while maintaining a distance of 30 mm. The holder of the present invention is designed to maintain a distance of 30 mm between the probes attached to the holder when connected by a holder with a joint function. In recent years, research has been conducted on measurements by changing the measurement probe spacing, so the spacing is not limited to 30 mm.

[0011] The joint has a circular hole at the tip of the arm, and the circular holes of the two arms are overlapped and fixed using a cylindrical fastener. By making the diameter of the cylindrical fastener smaller than the diameter of the circular holes in the arms, the joint can rotate freely. Furthermore, by making the diameter of the cylindrical fastener even smaller than the diameter of the circular holes in the arms, the probe can have a range of motion in a direction other than the rotation direction.

[0012] Furthermore, by extending arms evenly in six directions from each holder, multiple holders can be densely arranged while maintaining a distance of 30 mm. Each joint has a range of motion in three dimensions, and by applying tension to the outermost joints, the distance between each holder is kept even. When a group of holders connected in six directions is placed on the subject's scalp, each holder has a range of motion in six directions, allowing each to achieve the optimal placement direction on the scalp.

[0013] In addition, the range of motion of the joint can be controlled by changing the diameter and length of the fastener, so it is possible to change the type of fastener only for the joint where there is an extreme angle from the top of the head to the back of the head. [Effects of the Invention]

[0014] The holder according to the present invention makes it possible to easily position the light-emitting probe, light-receiving probe, and hybrid probe in accordance with differences in curvature of the subject's forehead, parietal, temporal, and occipital regions, differences in curvature due to differences in the degree of growth from child to adult, differences in curvature due to individual differences, etc. Furthermore, since the head is not entirely covered with cloth or the like, sweating does not occur even when worn for a long period of time, and the range of application for brain function measurement can be expanded. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing a minimum configuration according to an embodiment of the present invention. [Figure 2] A diagram showing an example of measuring the curvature of the head surface from the front, side, and top of a standard skull. [Figure 3] A diagram showing how the diameter of the fastener in Figure 1 can be changed to change the range of motion of the arm. [Figure 4] A diagram showing how the range of motion of the arm can be changed by changing the length of the fastener in Figure 1. [Figure 5] FIG. 4 is a diagram showing an example in which the fastener in FIG. 3 is changed and made to follow the angle of the subject's scalp. [Figure 6] FIG. 2 is a diagram showing the positional relationship between the arm and the fixture when the holder in FIG. 1 is placed on the subject's scalp. [Figure 7] 5 is a diagram showing a structure in which the length of the fastener in FIG. 4 can be changed in stages. [Figure 8] This figure shows a structure in which the angle between the arm and the perpendicular plane of the holder in Figure 1 is tilted toward the scalp. [Figure 9] 2 is a diagram showing a holder having six arms shown in FIG. 1 at an angle of 60 degrees from the center of the holder. [Figure 10] This is a diagram of seven holders shown in Figure 9 connected together using fasteners. [Figure 11] This figure shows an example in which 13 holders shown in Figure 9 are connected using fasteners, and five light-emitting probes and eight light-receiving probes are attached. [Figure 12] FIG. 10 is a diagram showing an example in which 13 holders shown in FIG. 9 are connected using fasteners and 13 hybrid probes are attached. [Figure 13] 1. FIG. 4 is a diagram showing a method of connecting a holder using an arm having a hole at the tip and a second arm having a fastener at the tip in the arm of FIG. 1. [Figure 14] 10 is a diagram showing a holder having six arms in the holder of FIG. 9, in which three arms with holes at the tip and three arms with fixing devices are arranged alternately. [Figure 15] FIG. 15 is a diagram showing an example in which 12 holders shown in FIG. 14 are connected together. [Figure 16] FIG. 10 is a diagram showing an example of a fixture that contacts the subject's head to fix the holder. [Figure 17] 12 is a diagram illustrating the direction of tension applied to the connection portions of each arm when tension is applied vertically in the arrangement of FIG. 11. FIG. [Figure 18] 12 is a diagram showing an example in which the holder shown in FIG. 1 is connected to the fixture shown in FIG. 11 to apply tension. DETAILED DESCRIPTION OF THE INVENTION

[0016] An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing the minimum configuration of a holder according to the present invention. In the figure, 1-1 denotes the holder of the present invention, 1-2 denotes an arm mounted on the holder, 1-3 denotes a fastener connecting two holders, and 1-4 denotes a light-emitting probe, a light-receiving probe, and a hybrid probe. The internal shape of the holder is formed to match the shape of the probe; however, FIG. 1 shows a cylindrical probe as an example, and the shape is not limited to circular. The bottom surface of the holder is the part that contacts the subject's scalp, and the probe is placed inside the holder and can be advanced to the subject's scalp along the direction of the holder. The holder has an arm for connecting to other holders, with a circular hole at its tip. The holes of the two holders are overlapped and joined using a cylindrical fastener. The diameter of the fastener is made smaller than the hole diameter of the arm, allowing a minimum range of motion at the joint, making it possible to place the two holders, or in other words, the probes, on the scalp at an angle that follows the curvature of the subject's scalp. There are several ways to change the range of motion of the joint, which will be explained below.

[0017] The first method allows the range of motion of the joint to be adjusted by changing the size of the fastener and the arm. Figure 3 shows an example where the diameter of the fastener is changed. In the figure, 3-a shows the case where a fastener with a standard diameter is used, and 3-b shows the case where a fastener with an even smaller diameter is used. 3-1 shows a fastener with a standard diameter, and 3-2 shows a fastener with a diameter smaller than the standard. 3-3 shows the part with a hole at the end of the arm. The greater the difference between the hole diameter and the diameter of the fastener, the greater the angle between the two arms can be, meaning that it can accommodate larger curvatures.

[0018] The second method is to adjust the range of motion of the joint by changing the length of the fastener. The structure is shown in Figure 4. In the figure, 4-1 indicates a standard-length fastener, 4-2 indicates a fastener that is longer than the standard length, and 4-3 indicates the part with a hole at the end of the arm. The longer the fastener, the larger the angle of the arm can be, i.e., the larger the curvature can be. The range of motion can also be changed by changing the hole diameter of the arm, but this requires creating multiple different holders and replacing them as needed, which is not preferable in terms of labor and cost compared to changing the fastener.

[0019] Figure 5 shows an example in which the present invention is applied to an example in which the curvature of the head surface was measured from the front, side, and top of the standard skull shown in Figure 2. This can be achieved by attaching the fastener (3-2) with a thin shaft shown in Figure 3 to the frontal area (R70) and using a fastener (3-1) with a standard diameter to the parietal area (R150). Here, this is achieved by changing the diameter of the fastener, but it can also be achieved by changing the overall length of the fastener as shown in Figure 4. Of course, depending on individual differences, it may be possible to cover all areas with a fastener of a standard diameter, so it is not necessarily necessary to change it.

[0020] An example of an actual attachment to the scalp of a subject is shown in Figure 6. In the figure, 6-1 indicates the holder of the present invention, 6-2 indicates the arm portion of the holder, 6-3 indicates the fastener, and 6-4 indicates the scalp of the subject. The two arms are in contact at an angle, but the angle is maintained at a moderate level by the fastener. Even if the center distance of the probe attached to the holder is maintained at 30 mm, the difference between the hole diameter of the arm and the diameter of the fastener is small, so it is possible to maintain approximately 30 mm.

[0021] Figure 7 shows an embodiment for adjusting the range of motion by changing the length of the fastener shown in Figure 4. In the figure, 7a is a female fastener, 7b is a male fastener, 7c is a state fixed in the middle of two stages, and 7d is a state fixed at the shortest point of the two stages. 7-1 indicates the female fastener, and 7-2 indicates the groove for fixing the male fastener. 7-3 indicates the male fastener, and 7-4 indicates the protruding part that fits into the groove (7-2) that secures the male fastener to the female fastener. By using a resilient material for both the female and male fasteners, it is possible to push the male fastener into the female fastener, and the length can be adjusted by fitting the protruding part (7-4) into the groove (7-2) at the required position. As shown in Figure 6, the force acting on the fastener is in the direction of the arm, so even with a detachable groove and protruding part, the male fastener and female fastener will not easily come apart.

[0022] FIG. 8 shows a second embodiment. Reference numeral 8-1 denotes the holder of the present invention, 8-2 denotes the arm mounted on the holder, 8-3 denotes a fastener connecting the two holders, 8-4 denotes the light-emitting probe, the light-receiving probe, and the hybrid probe, and 8-5 denotes the angle between the holder 8-1 and the arm 8-2. The difference from the first embodiment is that an angle θ8-5 is set between the arm 8-2 mounted on the holder and the holder 8-1. As shown in FIG. 2, the human head is essentially spherical, and by setting θ8-5 to be smaller than 90 degrees, the holder can follow the curvature of the scalp surface even when the arm 8-2 is parallel, making it possible to increase the range of motion of the angle between the holder 8-2 and the fastener 8-3.

[0023] A third embodiment of the present invention is shown in Figure 9. In the figure, 9-1 denotes a holder of the present invention, 9-2 denotes an arm mounted on the holder, and 9-3 denotes a light-emitting probe, a light-receiving probe, and a hybrid probe. One holder has six arms 9-2 in six directions, each at an angle of 60 degrees from the center. The vertical angle of the arms may be 90 degrees as shown in Figure 1 or may have an angle θ as shown in Figure 8. This structure allows easy connection to surrounding holders and expands the measurement range.

[0024] Figure 10 shows an example of connecting seven holders. In the figure, 10-1 is the holder, 10-2 is the arm, 10-3 is the light-emitting probe, light-receiving probe, and hybrid probe, and 10-4 is the fastener. The central holder is connected to the surrounding six holders with arms and fasteners, and each connection has a range of motion, making it possible to place the light-emitting probe, light-receiving probe, and hybrid probe in accordance with the scalp surface.

[0025] Figure 11 shows an example in which a total of 13 irradiating probes and light-receiving probes are connected. In the figure, 11-1 is the holder, 11-2 is the arm, 11-3 is the light-receiving probe, 11-4 is the light-irradiating probe, and 11-5 is the measurement position. The measurement position is directly below the midpoint between the irradiating probe and the light-receiving probe. In this example, there are 18 measurement points, making high-density measurement possible.

[0026] Figure 12 shows an example where 13 hybrid probes are mounted. In the figure, 12-1 indicates the holder, 12-2 indicates the arm, 12-3 indicates the hybrid probe, and 12-4 indicates the measurement position. In this example, there are 26 measurement points, making even higher density measurement possible.

[0027] Figure 13 shows a second embodiment of the arm and fastener. In the figure, 13-1 indicates holder a, 13-2 indicates the arm with a hole, 13-3 indicates holder b, 13-4 indicates the arm equipped with the fastener, and 13-5 indicates the tip of the fastener. The holder can be connected by contacting arm a, which has the hole at its tip as shown in the first and second embodiments, with arm b, which is an integrated fastener and arm. The tip of arm b has a widened portion with a diameter slightly smaller than the hole diameter at the end of the arm, and a fastener with an even smaller diameter. The tip of arm b is connected by passing it through the hole in arm 1. To remove the holder, simply pull the fastener portion of arm b perpendicular to the hole diameter of arm 1. This achieves the same effect as in embodiments 1 and 2. Although fine adjustment to match the inclination of the scalp is not possible, the holder has the advantage of being easy to attach and detach.

[0028] Figure 14 shows an example of the holder shown in Figure 13. In this example, six arms are attached at 60-degree intervals around the center. In the figure, 14-1 is the holder, 14-2 is an arm with a hole, and 14-3 is an arm with a fastener. By alternately arranging arms with holes and arms with fasteners, it is possible to connect multiple arms with one type of arm.

[0029] Figure 15 shows an example of connecting 12 holders. In the figure, 15-1 is a holder, 15-2 is an arm with a hole, and 15-3 is an arm with a fastener. When multiple holders are arranged, it can be seen that the two types of arms of each adjacent holder will be a combination of an arm with a hole and an arm with a fastener, regardless of their position.

[0030] Next, a method for holding the holder on the head will be described. Figure 16 shows a head phantom and a fixture. 16-1 in the figure shows an example of a head phantom, and 16-2 shows an example of a fixture. The fixture is fixed from the lower end of the forehead, over the ears, and at the lower back of the head, covering the entire head. In the holder with arms in six directions shown in Figure 9, when the area is expanded using a fastener, there are arms that are not connected to the outermost periphery. Therefore, by connecting a fixture using the holes in those arms and applying tension in the pulling direction, tension is applied to the holder toward the scalp, allowing the light-emitting probe, light-receiving probe, and hybrid probe to be stably placed on the scalp.

[0031] The actual way tension is applied is shown in Figure 17. In the figure, 17-1 is the holder equipped with the light-emitting probe, 17-2 is the holder equipped with the light-receiving probe, 17-3 is the arm, 17-4 is fixture a, 17-5 is fixture b, 17-6 indicates the direction of force due to the cable connected to fixture b, 17-7 indicates the direction of force due to the cable connected to fixture a, 17-8 is the direction of force in the fixture generated by the force due to the cable connected to fixture b, 17-9 is the direction of force acting on the fastener due to the force due to the cable connected to fixture a, 17-10 is the direction of force generated by the tension of 17-6, but not directly, as the arms in six directions apply tension via the holder body, and 17-11 similarly indicates the direction of indirect tension generated by the force of 17-7.

[0032] In this drawing, tension is shown by the cables shown in 17-6 and 17-7, but in reality, tension is applied to the fasteners from adjacent cables and from distant, linear connections. In other words, one holder receives tension toward the scalp from six fasteners, allowing the light-emitting probe, light-receiving probe, and hybrid probe to be stably placed on the scalp. However, because tension is compounded from so many cables, strong tension is not applied locally, causing discomfort to the subject, and brain function measurements can be performed correctly.

[0033] Furthermore, it becomes possible to attach a large number of light-emitting probes, light-receiving probes, and hybrid probes in a short time, which is expected to reduce the time the subject is confined and speed up the examination.

[0034] An example of fixing to a fixture with a cable is shown in Figure 18. In the figure, 18-1 is the fixture, 18-2 is the holder, 18-3 is the arm, 18-4 is the light-emitting probe, light-receiving probe and hybrid probe, and 18-5 is the cable to apply tension. In this example, a cable is used, but any other means that can provide tension, such as a spring or rubber, can be used. [Explanation of symbols]

[0035] 1-1 Holder of the present invention 1-2 Arm mounted on the holder 1-3 Fastener connecting two holders 1-4 Light-emitting probes, light-receiving probes, and hybrid probes 3-1 Fasteners with standard diameters, 3-2 Fasteners with smaller diameter than standard. 3-3 The hole at the end of the arm 4-1 Standard length fasteners 4-2 Fasteners longer than standard length 4-3 The hole at the end of the arm 6-1 Holder of the present invention 6-2 Arm part of the holder 6-3 Fasteners 6-4 Subject's scalp area 7-1 Female fastener 7-2 Groove for fixing male fastener 7-3 Male fastener 7-4 The protruding part that fits into the groove (7-2) that secures the male mold to the female mold. 8-1 Holder of the present invention 8-2 Arm mounted on the holder 8-3 Fastener connecting two holders 8-4 Light-emitting probes, light-receiving probes, and hybrid probes 8-5 Angle between holder 8-1 and arm 8-2 9-1 Holder of the present invention 9-2 Arm mounted on the holder 9-3 Light-emitting probes, light-receiving probes, and hybrid probes 10-1 holder 10-2 Arm 10-3 Light-emitting probe, light-receiving probe and hybrid probe 10-4 Fasteners 11-1 holder 11-2 Arm 11-3 Light receiving probe 11-4 Light-emitting probe 11-5 Measurement position 12-1 holder 12-2 Arm 12-3 Hybrid Probe 12-4 Measurement position 13-1 Holder A 13-2 Arm with holes 13-3 Holder B 13-4 Fastener Mounted Arm 13-5 Fastener tip 14-1 holder Arm with 14-2 holes 14-3 Arm with fastener 15-1 holder Arm with 15-2 holes 15-3 Arm with fastener 16-1 Head Phantom 16-2 Example of a fixing device 17-1 Light-emitting probe holder 17-2 Light receiving probe mounting holder 17-3 Arm 17-4 Fixture a 17-5 Fixture b 17-6 Direction of force exerted by cable connected to fixture b 17-7 Direction of force exerted by cable connected to fixture a 17-8 Direction of force at each fixture caused by force from the cable connected to fixture b 17-9 Direction of force acting on fastener due to force from cable connected to fastener a 17-10 17-6 tension is generated, but the direction of the tension is not direct, but the arms in six directions are tensioned via the holder body. 17-11 Direction of indirect tension caused by the force of 17-7 18-1 Fixtures 18-2 Holder 18-3 Arm 18-4 Light-emitting probes, light-receiving probes, and hybrid probes 18-5 Tensioning Cable

Claims

1. In light-based brain function measurement, a probe holder is used to measure brain function by placing multiple light-emitting probes that emit light, light-receiving probes that detect light, and light-emitting and light-receiving probes that have the function of emitting and detecting light on the head of a subject.The probe holder has an arm with a hole at the tip for connecting to an adjacent holder, and a fastener for connecting using the hole at the tip of an adjacent similar arm, and by making the diameter of the fastener smaller than the diameter of the hole, a range of motion is provided for the two connected arms, making it possible to hold the probe while following the shape of the subject's scalp.

2. 2. The probe holder according to claim 1, wherein the diameter of the fastener is changed relative to the diameter of the hole provided at the tip of the arm, thereby making it possible to adjust the range of motion of the joint portion.

3. 2. The probe holder according to claim 1, wherein the range of motion of the joint can be adjusted by changing the length of the fastener relative to the diameter of the hole provided at the tip of the arm.

4. 2. The probe holder according to claim 1, wherein the arm having the hole at the tip is disposed inclined toward the head with respect to the side surface of the probe holder.

5. 2. The probe holder according to claim 1, wherein six arms each having a hole at its tip are provided at 60 degree intervals from the center for one probe holder.

6. A measurement unit having a plurality of probe holders as set forth in claim 5, connected by fastening portions to ensure a wide measurement area on a plane.

7. 6. The probe holder according to claim 1, wherein the probe holder has three arms, each having a hole at its tip and a fastener at its tip that connects to the arm having the hole of the holder adjacent thereto, arranged alternately.

8. A measurement unit having an arm having unconnected holes on the outermost periphery of the two-dimensionally expanded measurement unit as described in claim 6 and a fixture to be installed on the subject's head to connect with a cable or the like and apply tension.

Images