Liquid flow state estimation method and liquid flow state estimation system

Abstract

The flow state estimation method of the present invention has: a step (a) of applying heat to a liquid; a step (b) of acquiring a temperature distribution of the liquid to which heat is applied; and a step (c) of estimating the flow state of the liquid based on the acquired temperature distribution. In addition, the flow state estimation system of the present invention is provided with: a heating unit (1) that applies heat to a liquid; a temperature distribution acquisition unit (2) that acquires a temperature distribution of the liquid to which heat is applied; and an estimation unit (3) that estimates the flow state of the liquid based on the acquired temperature distribution. According to such a flow state estimation method of a liquid and a flow state estimation system of a liquid, the flow of a liquid can be estimated in a non-invasive manner.

Description

Technical Field

[0001] This invention relates to a method and system for estimating the flow state of a liquid. Background Technology

[0002] Aqueous humor (APH) serves to supply nutrients to avascular tissues within the eye, remove metabolic waste, and regulate intraocular pressure. Normally, intraocular pressure remains constant through a circulation in which aqueous humor produced within the eye drains out through the fibrous stroma and Schlemm's ducts. However, if the fibrous stroma becomes blocked, the flow and drainage of aqueous humor decrease, leading to elevated intraocular pressure. Elevated intraocular pressure is well-known as one of the main mechanisms of glaucoma pathogenesis; compression of the optic nerve results in decreased visual function, manifesting as narrowed visual field and reduced visual acuity. Therefore, understanding the flow of aqueous humor within the eye is crucial for the early detection and treatment of glaucoma.

[0003] As a technique for understanding the flow of aqueous humor in the eye, for example, Patent Document 1 discloses that traceable components such as dyes or fluorescent substances are locally added to the aqueous humor to make the flow of the aqueous humor visible for monitoring.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: International Publication No. 2003 / 073968 Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] However, the technology disclosed in Patent Document 1 requires the use of syringes or the like in order to add traceable components to the aqueous humor, which is not ideal due to its invasiveness, considering that it involves adding aqueous humor into the eye.

[0009] Besides understanding the flow of aqueous humor within the eye, there is a need in various fields to non-invasively observe very subtle fluid flows (micro-flow rates) or fluid flows invisible to the naked eye. Specific examples include: understanding the flow patterns of water or oil to detect leaks or their origins; understanding blood flow in the human body; and verifying the precision of microfluidic circuit fabrication.

[0010] The present invention addresses the above-mentioned problems and aims to provide a method and system for estimating the flow state of a liquid, which can estimate the flow state of a liquid in a non-invasive manner.

[0011] (II) Technical Solution

[0012] In order to achieve the above objective, in a first aspect (invention 1), the present invention provides a method for estimating the flow state of a liquid, comprising: a step of applying heat to a liquid (a); a step of obtaining a temperature distribution of the heated liquid (b); and a step of estimating the flow state of the liquid based on the obtained temperature distribution (c).

[0013] According to the invention described above (Invention 1), by utilizing the property that heat can be applied to a liquid in a non-invasive manner, and by understanding the temperature distribution of the heated liquid, the flow state of the liquid can be estimated in a non-invasive manner.

[0014] In the above invention (Invention 1), in step (b), multiple temperature distributions of the liquid at different times are obtained, and in step (c), the flow state of the liquid is estimated based on the multiple temperature distributions obtained (Invention 2).

[0015] According to the invention described above (Invention 2), the flow state of a liquid is estimated by integrating the flow states of liquids estimated based on multiple temperature distributions, thereby improving the estimation accuracy compared to estimating the flow state of a liquid based on a single temperature distribution.

[0016] In the above inventions (Inventions 1 and 2), preferably, step (c) includes: step (c1), setting two pairs of positions in the area where the temperature distribution is obtained, and determining the temperature difference or temperature ratio of the two positions; step (c2), selecting a pair of positions with the largest temperature difference or temperature ratio from multiple pairs of positions in the area where step (c1) is performed multiple times and the temperature distribution is obtained; and step (c3), estimating the direction of liquid flow from the position on the lower temperature side to the position on the higher temperature side in the two positions constituting the selected pair as the direction of liquid flow (Invention 3).

[0017] In the above invention (Invention 3), step (c) may further include step (c4), in which the velocity of the liquid flow is estimated based on the temperature difference or temperature ratio of the two positions constituting the pair selected in step (c2) (Invention 4).

[0018] In the above inventions (Inventions 1-4), in step (c), the area where the temperature distribution is obtained is divided into multiple unit areas, and the flow state of the liquid is estimated based on the temperature of the multiple unit areas (Invention 5).

[0019] In the above invention (Invention 5), the temperature of a unit area can be calculated as the average of the temperature of the unit area determined according to the temperature distribution and the temperatures of other unit areas adjacent to the unit area (Invention 6).

[0020] In the above inventions (Inventions 1-6), in step (b), at least one of the following temperature distributions can be obtained: the temperature distribution of the liquid during heating when heat is applied to the liquid, and the temperature distribution of the liquid during cooling after heating is stopped. In step (c), the flow state of the liquid is estimated based on at least one of the temperature distribution during heating and the temperature distribution during cooling (Invention 7).

[0021] In the above inventions (Inventions 1-7), in step (a), heat may be applied to the liquid by irradiating the liquid with light from a light source (Invention 8).

[0022] In the above inventions (Inventions 1-8), in step (b), the temperature distribution of the liquid can be obtained by using a thermal imaging camera to photograph the liquid (Invention 9).

[0023] In a second aspect, the present invention provides a system for estimating the flow state of a liquid, comprising: a heating unit that applies heat to a liquid; a temperature distribution acquisition unit that acquires the temperature distribution of the heated liquid; and an estimation unit that estimates the flow state of the liquid based on the acquired temperature distribution (Invention 10).

[0024] (III) Beneficial Effects

[0025] The liquid flow state estimation method and system according to the present invention utilize the property that heat can be applied to a liquid in a non-invasive manner, and estimate the liquid flow state by understanding the temperature distribution of the heated liquid, thus enabling the non-invasive estimation of the liquid flow state. Attached Figure Description

[0026] Figure 1 This is a schematic structural diagram of the liquid flow state estimation system according to an embodiment of the present invention.

[0027] Figure 2 This is a structural block diagram illustrating the estimation device of the liquid flow state estimation system of this embodiment.

[0028] Figure 3 This is a functional block diagram illustrating the main function of the estimation device in the liquid flow state estimation system of this embodiment.

[0029] Figure 4 This is an explanatory diagram schematically showing the temperature distribution of a liquid heated by the liquid flow state estimation system of this embodiment.

[0030] Figure 5 This is an illustration showing the state of setting a resolution region for a temperature distribution image of a liquid.

[0031] Figure 6 It is an illustrative diagram that schematically shows the situation of presuming the direction of liquid flow in the analytical region of a temperature distribution image.

[0032] Figure 7 This is a flowchart illustrating the process of estimating the flow state of a liquid using the liquid flow state estimation system of this embodiment.

[0033] Figure 8 These are illustrations of variations of the analytic region, (a) is an example of a analytic region consisting of square unit regions, and (b) is an example of a analytic region consisting of concentric circles divided into multiple unit regions with unit regions of equal size.

[0034] Figure 9 This is a schematic structural diagram of the evaluation device used in the embodiment.

[0035] Figure 10 This is a schematic diagram illustrating a temperature distribution image representing the time-varying temperature distribution of Example 1.

[0036] Figure 11 This is a schematic diagram illustrating the temperature distribution image of Example 2, representing the temperature distribution difference based on the flow rate difference.

[0037] Figure 12 This is a diagram showing the state of two regions defined in a temperature distribution image obtained from the embodiment.

[0038] Figure 13 It is a graph showing the change in temperature difference between two regions over time.

[0039] Figure 14 It is a graph showing the change in temperature difference for each flow rate pattern. Detailed Implementation

[0040] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings. Furthermore, the embodiments described below are merely illustrative, and the present invention is not limited to these embodiments.

[0041] In this embodiment, the example described is the use of the liquid flow state estimation system 100 to estimate the flow state of the aqueous humor in the examined eye E. Furthermore, the flow state of aqueous humor includes the concepts of whether or not aqueous humor flows, the direction of flow, and the flow velocity. In this embodiment, the liquid flow state estimation system 100 is used to confirm whether or not aqueous humor flows, and to estimate the direction and velocity of flow.

[0042] like Figure 1 As shown, the liquid flow state estimation system 100 of this embodiment includes: a light source 1 that irradiates near-infrared light onto the eye E to heat the aqueous humor of the eye E; a thermal imaging camera 2 that captures images of the eye E to obtain the temperature distribution of the aqueous humor of the eye E heated by the light source 1; and an estimation device 3 that estimates the flow state of the aqueous humor based on the acquired temperature distribution information of the aqueous humor (the captured temperature distribution image).

[0043] In this embodiment, the light source 1 used to heat the aqueous humor of the examined eye E can be, for example, a halogen lamp (halogen heater) capable of irradiating near-infrared light. By continuously irradiating the examined eye E with near-infrared light using the light source 1 for a predetermined time, such as 20 seconds, the near-infrared light can pass through the cornea of ​​the examined eye E and enter the aqueous humor, thereby heating the aqueous humor using the near-infrared light. The light source 1 is one example of the "heating unit" in this invention, but it is not limited to this as long as it can apply heat to the liquid; for example, it can also be a laser light source, an LED light source, etc. Alternatively, a heat pack, a hot towel, etc., can be used as the "heating unit" instead of the light source 1.

[0044] Although the location where near-infrared light is irradiated from light source 1 onto the eye E being examined is used as the heating location of the eye E, for ease of understanding, light source 1 can also be set to irradiate the eye E from multiple light sources at different angles, and the intersection of these multiple light sources can be used as the heating location for understanding.

[0045] The thermal imaging camera 2 is an apparatus that analyzes infrared radiation emitted from the aqueous humor of the examined eye E after it has been heated, and captures an image of the temperature distribution in a specified area. A known infrared thermal imaging camera can be used. The thermal imaging camera 2 is connected to the estimation device 3 and is configured to send the acquired temperature distribution information of the aqueous humor (data from the captured temperature distribution image) to the estimation device 3. Furthermore, the thermal imaging camera 2 is an example of a "temperature distribution acquisition unit" in the invention of this application.

[0046] The thermal imaging camera 2 begins to capture images of the examined eye E from the moment the light source 1 begins to illuminate it with near-infrared light, acquiring temperature distribution information of the aqueous humor of the examined eye E. For example, the thermal imaging camera 2 acquires temperature distribution information of the examined eye E at a frame-per-second interval over a period of 20 seconds from the moment the light source 1 begins to illuminate it. The acquired temperature distribution information of the examined eye E is transmitted from the thermal imaging camera 2 as a temperature distribution image of the examined eye E to the estimation device 3. The temperature distribution image transmitted from the thermal imaging camera 2 to the estimation device 3 can be displayed on the display unit 36 ​​of the estimation device 3, which will be described later.

[0047] The estimation device 3 is configured to acquire temperature distribution information transmitted from the thermal imaging camera 2, and to estimate the flow state of the aqueous humor based on the acquired temperature distribution information, and to visualize the estimated flow state of the aqueous humor. The estimation device 3 is an example of the "estimation unit" in the invention of this application, and a general-purpose personal computer can be used, for example.

[0048] like Figure 2 As shown, the estimation device 3 includes: CPU 31, ROM 32, RAM 33, storage device 34, display processing unit 35, display unit 36, input unit 37, and communication interface unit 38, and is provided with a bus 30 for transmitting control signals or data signals between the various units.

[0049] When the estimation device 3 is powered on, the CPU 31 loads various programs stored in the ROM 32 or storage device 34 into the RAM 33 and executes them. In this embodiment, the CPU 31 reads and executes the programs stored in the ROM 32 or storage device 34, thereby realizing the image generation unit 41, area setting unit 42, temperature calculation unit 43, direction estimation unit 44, and speed estimation unit 45 (as described later). Figure 3 (as shown in the image) functions.

[0050] Storage device 34 can be a non-volatile storage device such as flash memory, SSD, magnetic storage device (e.g., HDD), or optical disc, or a volatile storage device such as RAM. Storage device 34 stores the program executed by CPU 31 and the data referenced by CPU 31. In addition, the conversion table 50, which will be described later, is stored in storage device 34.

[0051] The display processing unit 35 displays the display data provided by the CPU 31 onto the display unit 36. For example, a liquid crystal display (LCD) can be used as the display unit 36.

[0052] The input unit 37 has a button group for accepting user operation input and includes an interface circuit for recognizing the pressing (operation) input of each button and outputting it to the CPU 31. However, the input unit 37 may also adopt a touch panel input method.

[0053] A thermal imaging camera 2 is connected to the communication interface section 38, and the estimation device 3 is configured to acquire a temperature distribution image transmitted from the thermal imaging camera 2. Alternatively, the communication interface section 38 may be configured to connect a light source 1, and the estimation device 3 may be used to control the illumination of near-infrared light from the light source 1 onto the examined eye E (turning the light source 1 on / off). It may also be configured to connect other terminal devices to the communication interface section 38, and the estimation device 3 may transmit the estimation result of the aqueous humor flow state to those terminal devices.

[0054] Reference Figure 3 The function of the estimation device 3 using the above structure will be explained. Figure 3 This is a functional block diagram illustrating the main functions of the estimation device 3 in this embodiment. It consists of an image generation unit 41, a region setting unit 42, a temperature calculation unit 43, a direction estimation unit 44, and a speed estimation unit 45. Not all of these units are essential structural elements of the estimation device 3. The functions of the estimation device 3 can be appropriately modified by considering factors such as the type of liquid being heated, the surrounding environment, weather conditions, the purpose of the system 100, and the computational load of the estimation device 3.

[0055] The image generation unit 41 has the following function: to generate a processing object image D for estimating the flow state of aqueous humor based on multiple temperature distribution images D acquired by the estimation device 3. P This function is implemented, for example, as follows. As a prerequisite, the thermal imaging camera 2 acquires temperature distribution information of the examined eye E at a shooting interval of 1 frame per second over a period of 20 seconds, starting from the moment the light source 1 begins to illuminate the eye. The estimation device 3 acquires a total of 20 temperature distribution images D. n (n = 1 to 20).

[0056] First, the CPU 31 of the estimation device 3 obtains the temperature distribution image D of the examined eye E from the thermal imaging camera 2 and the communication interface unit 38. n Choose one temperature distribution image from (n = 1 to 20) as the reference image. For example, choose temperature distribution image D5 taken 5 seconds after the start of near-infrared light irradiation as the reference image D. s In addition, the reference image D s The acquisition time is not limited to 5 seconds after heating begins and can be varied depending on the type of liquid being heated, the heating method, the purpose of system 100, etc., and can be determined experimentally. Alternatively, it can be obtained from the acquired temperature distribution image D of the examined eye E. n Multiple temperature distribution images are selected from (n = 1 to 20), and the average image of these multiple temperature distribution images is used as the reference image D. s .

[0057] Next, CPU31 takes the reference image D from the image being captured. s Temperature distribution image D taken later n Select a temperature distribution image, for example, temperature distribution image D6 taken 6 seconds after the start of near-infrared light irradiation, and subtract the reference image D from temperature distribution image D6. s A differential image of the temperature distribution is generated and used as the object image D for processing. P The generated image D of the processed object. P It is not limited to one image; multiple images of the object to be processed can also be generated. P For example, select temperature distribution image D6 taken 6 seconds after the start of near-infrared light irradiation, and temperature distribution image D7 taken 7 seconds after the start of near-infrared light irradiation, and subtract the reference image D from temperature distribution image D6 and temperature distribution image D7 respectively. s This allows the generation of two images of the object being processed, D. P .

[0058] Processing object image D P It is not necessary to use the reference image D s and temperature distribution image D n The generated differential image can be used to analyze the temperature distribution image D based on factors such as the type of liquid being heated, the heating method, and the purpose of the system 100. n Image D is directly used as the object of processing. P This is used to estimate the flow state of a liquid. However, in cases where the flow state of a liquid, such as aqueous humor, is very slow-flowing and the applied heat diffuses through the liquid faster than the liquid's own flow velocity, estimations can be made using a reference image D. s and temperature distribution image D n The generated difference image is used to process the object image D. P This gives it the advantage of being able to easily visualize the flow state.

[0059] The region setting unit 42 is equipped with a processing object image D P The function of dividing into multiple unit regions is implemented, for example, in the following manner. The CPU 31 of the estimation device 3, upon obtaining... Figure 4 The image D of the examined eye E generated by the image generation unit 41, as shown. P Then, as Figure 5 As shown, for the image D being processed P Set the parsing region A.

[0060] For example, the image D of the object being processed is processed in the following manner. PDefine a resolution region A, that is, make the center of this region coincide with the position heated by light source 1 (the position on the examined eye E heated by light source 1). In this embodiment, as... Figure 5 As shown, the analytical region A is set such that the overall shape of the region is approximately hexagonal, and the unit regions of the regular hexagons are configured in a honeycomb pattern. This is achieved by processing the image D... P By defining such a resolution region A, the image D of the object being processed can be... P It is divided into multiple unit regions.

[0061] The temperature calculation unit 43 has the function of calculating the temperature of each unit area, which is implemented, for example, in the following manner. The CPU 31 of the estimation device 3 is based on the processing object image D. P To obtain the temperature of a unit area of ​​the object used for temperature calculation, and based on the processed object image D P The temperature of other unit areas adjacent to the given unit area is obtained. Then, the average of these temperatures is calculated, and this average is set as the temperature of the unit area being considered. By calculating the temperature of a unit area in this way, the temperatures of the surrounding unit areas are also taken into account, thus suppressing temperature deviations compared to directly using the temperature of a single unit area, and therefore enabling high-precision calculation of the temperature of each unit area. Furthermore, to calculate the temperature of a unit area, it is not necessary to use the temperatures of all adjacent unit areas; the temperature calculation method can be appropriately modified by considering factors such as the type of liquid being heated, the surrounding environment, meteorological conditions, the purpose of system 100, and the computational load of the estimated device 3.

[0062] For example, if such as Figure 5 If the unit region H1 shown is set as the object region for temperature calculation, then CPU31 processes the object image D. P The temperature T1 of the unit region H1 is obtained from the data, and the temperature of the object image D is obtained from the data. P The temperatures T2, T3, T4, and T5 of the four unit regions H2, H3, H4, and H5 adjacent to unit region H1 are obtained from the data. The average temperature T is calculated from all five obtained temperatures (T1, T2, T3, T4, and T5). A1 The temperature is set as the unit region H1. The CPU31 can use the same method to calculate the temperature constituting the image D being processed. P The temperature of all unit regions in the analytical region A set in the code.

[0063] The direction estimation unit 44 is equipped with a direction estimation unit based on the image D of the processing object. P The function of estimating the flow direction of aqueous humor is implemented, for example, in the following manner. First, the CPU 31 of the estimation device 3 processes the object image D.P Within the analytical region A, two pairs of locations are defined, and the temperature difference between these two locations is calculated. For example, as shown below... Figure 6 As shown in (a), two unit regions H are set in opposite positions from the unit region located on the outer periphery of the analytical region A. A1 and H A2 And calculate the unit region H A1 Temperature and unit area H A2 The temperature difference. Furthermore, for ease of understanding, in Figure 6 Image D of the processing object P Temperature distribution is not depicted.

[0064] Similarly, as Figure 6 As shown in (b), five pairs of two unit regions located in opposite positions are defined, and the two unit regions constituting each pair are calculated (in...). Figure 6 In (b), the unit region H is... B1 and H B2 H C1 and H C2 H D1 and H D2 H E1 and H E2 H F1 and H F2 The temperature difference between two unit regions is calculated. From the six resulting pairs, the pair with the largest temperature difference between any two unit regions is selected. Here, the unit region H... B1 and H B2 The temperature difference is the largest, so select a pair consisting of these two unit regions.

[0065] Next, CPU31 will select two unit regions H that constitute a selected pair. B1 and H B2 The direction of aqueous humor flow is inferred from the unit region on the lower temperature side to the unit region on the higher temperature side. For example, in unit region H... B1 Temperature ratio per unit area H B2 In low temperatures, such as Figure 6 As shown in (c), it is presumed that the aqueous humor flows along the unit area H. B1 Oriented towards unit area H B2 The direction of aqueous humor flow is estimated. The estimated direction of aqueous humor flow is transmitted from CPU 31 to display processing unit 35 as display data, and a direction indicator image (e.g., an arrow) can be superimposed on the captured image (including temperature distribution image, processing object image, differential image, etc.) of the examined eye E displayed on display unit 36 ​​for display.

[0066] In this embodiment, the two positions in each pair are located on the outer periphery of the analytical region A and are positioned opposite each other (on a diagonal line). However, this is not the only option; for example, other positions could be arranged as follows: Figure 6 As shown in (d), one of the two positions in the pair is set at the center of the analytical region A, and the other is set in the outer periphery of the analytical region A. The flow direction of the aqueous humor is inferred based on the temperature difference between the center position of the analytical region A and the positions of the multiple outer periphery. In this example, a unit region H0 located at the center of the analytical region A and a unit region H0 located in the outer periphery are set. 01 H 02 H 03 H 04 H 05 H 06 The six pairs are respectively formed, such as the temperature of unit region H0 and the temperature of unit region H. 01 The temperature difference, the temperature per unit area H0 and the temperature per unit area H 02 The temperature difference between the two unit regions of each pair of groups is calculated in the same way as the temperature difference.

[0067] Alternatively, instead of defining each of the two locations in the group as a separate unit region, it can be defined as an aggregate of unit regions. In this case, the temperature of the aggregate of unit regions can be set as the average temperature of the unit regions forming the aggregate.

[0068] In addition, the image generation unit 41 generates multiple processing object images D. P In this case, multiple processing object images D can be obtained. P The processed object image D of the temperature of each unit region is obtained. P The average value between the points is taken as the temperature of each unit area, and the direction of flow is inferred based on this average temperature as described above. Alternatively, the multiple images of the object being processed, D, can also be used. P The direction of the flow is estimated as described above, and the results are taken into account to estimate the direction of the aqueous humor flow.

[0069] The velocity estimation unit 45 has the following function: to estimate the velocity of the aqueous humor flow based on the temperature difference between two positions used by the direction estimation unit 44 to estimate the direction of aqueous humor flow. This function is implemented, for example, in the following manner.

[0070] The CPU 31 of the estimation device 3 uses the direction estimation unit 44 to estimate the two positions of the direction of the aqueous humor flow, i.e., the unit area H. B1 and H B2The temperature difference is compared with the conversion table 50 stored in the storage device 34, and the flow rate derived from the temperature difference is estimated as the flow rate of the aqueous humor. Specifically, the conversion table 50 is a table pre-made by quantifying the relationship between the change in temperature difference between two locations and the flow rate using a model that measures the temperature difference between two locations at various flow rates, and specifies the relationship between the time change (inclination) of the temperature difference and the flow rate. By comparing the actual change in temperature difference between the two locations acquired by the device 3 with the conversion table 50, the flow rate of the aqueous humor can be estimated. The estimated flow rate of the aqueous humor is transmitted from the CPU 31 to the display processing unit 35 as display data, and can be displayed near the captured image and orientation indicator image of the examined eye E displayed on the display unit 36.

[0071] Table 1 shows an example of a conversion table 50. In conversion table 50 of Table 1, a model measuring the temperature difference between two locations at flow rates of 0 μL / min (no flow), 5 μL / min, 10 μL / min, 15 μL / min, and 20 μL / min is used to quantify the relationship between the change in temperature difference between the two locations and the flow rate. This conversion table 50 is prepared in advance and stored in storage device 34. Alternatively, a regression analysis can be performed in advance based on the relationship between the change in temperature difference and the flow rate, and the resulting regression equation can be used as conversion table 50.

[0072] [Table 1]

[0073]

[0074] The CPU 31 calculates the change in temperature difference based on the temperature difference between two locations used by the direction estimation unit 44 to estimate the direction of aqueous humor flow, and estimates the flow velocity corresponding to this change in temperature difference in the conversion table 50 as the velocity of aqueous humor flow. For example, when the temperature difference calculated based on the temperature difference between the two locations used by the direction estimation unit 44 to estimate the direction of aqueous humor flow is 0.0158, since the closest value in the conversion table 50 is 0.016, the CPU 31 estimates the velocity of aqueous humor flow as 15 μL / min.

[0075] In this embodiment, the estimation device 3 estimates the direction and speed of aqueous humor flow based on the temperature difference between two locations within the analysis region A in the direction estimation unit 44 and the speed estimation unit 45. Alternatively, the temperature ratio can be used instead of the temperature difference for estimation.

[0076] Reference Figure 7 The flowchart shown illustrates the main processing flow of the liquid flow state estimation method for estimating the flow state of aqueous humor in the examined eye E using the liquid flow state estimation system 100 with the above-described structure.

[0077] First, the light source 1 is turned on, and near-infrared light is irradiated onto the eye being examined, E (step S101). As a result, the near-infrared light passes through the cornea of ​​the eye being examined, enters the aqueous humor, and begins to heat the aqueous humor using the near-infrared light.

[0078] While continuously irradiating the examined eye E with near-infrared light from light source 1, the thermal imaging camera 2 captures images of the examined eye E to obtain temperature distribution information of the aqueous humor in the examined eye E (step S102). In this embodiment, the thermal imaging camera 2 acquires the temperature distribution information of the examined eye E at an interval of 1 frame per second for 20 seconds from the moment the light source 1 begins to irradiate the eye. The temperature distribution information acquired by the thermal imaging camera 2 is used as the temperature distribution image D of the examined eye E. n (n = 1 to 20) are sent from the thermal imaging camera 2 to the estimation device 3. The estimation device 3 acquires a total of 20 temperature distribution images of the examined eye E, and stores all or part of the temperature distribution images in the storage device 34 as needed.

[0079] When the estimation device 3 acquires the temperature distribution image D of the examined eye E from the thermal imaging camera 2... n When (n=1~20), then from the temperature distribution image D n (n = 1 to 20) Select the temperature distribution image D5 (step S103) taken 5 seconds after the start of near-infrared light irradiation as the reference image D. s The estimation device 3 uses the reference image D as a reference. s A temperature distribution image D outside of the image n Select a temperature distribution image D from (n = 1 to 20) n From the selected temperature distribution image D n Subtract the baseline image D s A differential image of the temperature distribution is generated and used as the object image D for processing. P (Step S104).

[0080] On the other hand, the estimation device 3 processes the image D of the object. P A resolution region A, divided into multiple unit regions, is defined (step S105). Next, the estimation device 3 estimates the processing object image D. P To obtain the temperature of all unit regions constituting the analysis region A (step S106). A processing object image D... P The temperature of a unit region is taken from a processed object image D P The temperature of the unit area and the average temperature of its neighboring unit areas are calculated.

[0081] Next, the estimation device 3 processes the object image D. PWithin the analysis region A, two positions of multiple pairs are set, and the temperature difference between the two positions constituting each pair is calculated (step S107). Next, the estimation device 3 selects the pair constituting the pair with the largest temperature difference between the two positions constituting each pair from the multiple pairs (step S108), and estimates the direction from the position with lower temperature to the position with higher temperature in the two positions constituting the selected pair as the direction of aqueous humor flow (step S109).

[0082] In addition, the estimation device 3 compares the temperature difference between the two locations used to estimate the direction of aqueous humor flow with the conversion table 50 stored in the storage device 34, and estimates the speed of aqueous humor flow derived from the temperature difference (step S110).

[0083] Thus, the liquid flow state estimation system 100 of this embodiment and the liquid flow state estimation method implemented using the system 100 utilize the characteristic of being able to apply heat to the liquid in a non-invasive manner, and by understanding the temperature distribution of the heated liquid, the flow state of aqueous humor, i.e. the flow direction and velocity of aqueous humor, can be estimated in a non-invasive manner.

[0084] Furthermore, in the above-described embodiments, the temperature distribution of the aqueous humor is obtained during the heating period when near-infrared light is applied to the aqueous humor by the light source 1, and the flow state of the aqueous humor is estimated based on the temperature distribution during the heating period. However, it is also possible to obtain the temperature distribution of the aqueous humor during the cooling period after the near-infrared light irradiation of the light source 1 is stopped after the aqueous humor is heated, and the flow state of the aqueous humor is estimated based on the temperature distribution during the cooling period. Alternatively, both the temperature distribution during the heating period and the temperature distribution during the cooling period can be obtained, and the flow state of the aqueous humor can be estimated based on both.

[0085] In this embodiment, for the liquid flow state estimation system 100 and the liquid flow state estimation method implemented using the system 100, the flow state of the liquid, such as whether there is liquid flow or the direction of flow, can be estimated even based on a single acquired temperature distribution information of the liquid (a temperature distribution image). On the other hand, when the liquid flow state is estimated by combining the liquid flow states estimated based on multiple temperature distribution information (multiple temperature distribution images acquired at different times), the estimation accuracy can be improved compared to estimating the liquid flow state based on a single temperature distribution information.

[0086] The method and system for estimating the flow state of a liquid according to the present invention have been described above. However, the present invention is not limited to the above embodiments and various modifications are possible. For example, in the above embodiments, a resolving region consisting of multiple hexagonal unit regions arranged in a honeycomb pattern is set for the temperature distribution image. However, the invention is not limited to this as long as the direction of liquid flow can be reliably estimated within the resolving region. For example, it could also be as follows: Figure 8 As shown in (a), the analytic region A1 can be set as a unit region composed of multiple squares, or it can be like... Figure 8 As shown in (b), the resolution region A2, which divides the concentric circles into multiple unit regions, is set with each unit region having an equal size. Alternatively, the resolution region can be set with each pixel as a unit region.

[0087] Furthermore, in the above embodiment, the thermal imaging camera 2 acquires the temperature distribution image of the examined eye E at a shooting interval of 1 frame per second. However, it is not limited to this; for example, it can acquire the image at a shooting interval of 10 frames per second. Alternatively, the average image of several consecutive frames (e.g., 3 frames) can be used as the temperature distribution image processed by the estimation device 3 to estimate the flow state of the aqueous humor. By using the average image of the temperature distribution images of several consecutive frames in this way, the deviation of each captured image and the deviation of temperature changes over time can be reduced.

[0088] Furthermore, while the liquid flow state estimation method and system of the present invention are used in the above embodiments to estimate the flow state of aqueous humor, their application is not limited to this. For example, they can also be applied to: understanding the flow state of water or oil to detect whether there is a leak or oil leak or its origin; understanding the blood flow state in the human body; verifying the processing accuracy of microfluidic paths, etc.

[0089] Example

[0090] The following embodiments further illustrate the liquid flow state estimation method and system of the present invention, but the scope of the present invention is not limited to these embodiments.

[0091] [Evaluation Device]

[0092] Use such as Figure 9 The evaluation device 5 shown was used to conduct an experiment to estimate the flow state of a liquid (water). The evaluation device 5 is a device consisting of a resin gasket 52 on a glass substrate 51, forming a circular liquid flow space 521 in plan view, and a cover glass 53 disposed on the gasket 52. On one side of the liquid flow space 521 of the gasket 52 (… Figure 9An inflow section 522 is provided on the left side of the liquid flow space 521, and on the opposite side of the liquid flow space 521... Figure 9 The right side of the gasket 52 has an outlet 523, wherein the inlet 522 is inserted with an inlet pipe 54 for supplying liquid to the gasket 52, and the outlet 523 is inserted with an outlet pipe 55 for discharging liquid from the gasket 52. Furthermore, the evaluation device 5 is configured to use a pump (not shown; a Fisher Scientific MINI-PUMP VARIABLE FLOW) to supply liquid from the inlet 522 of the gasket 52 and discharge liquid from the outlet 523, thereby enabling liquid to flow within the liquid flow space 521 of the gasket 52, and by controlling the pump, the flow rate of the liquid within the liquid flow space 521 can be controlled to a desired speed.

[0093] The evaluation device 5 illuminates the center of the liquid flow space 521 of the gasket 52 with near-infrared light from a near-infrared light source (not shown; an infrared halogen lamp illumination device made by Sumida Optical Glass), and can capture an image of the temperature distribution of the liquid in the liquid flow space 521 using a thermal imaging camera (not shown; a Boson320 made by FLIR Systems, 92° (HFOV) 2.3mm).

[0094] [Example 1]

[0095] Using such an evaluation device 5, and with water as the liquid used as the object of the deduced flow state, an experiment was conducted to determine its flow state. First, water was allowed to flow at a rate of 20 μL / min within a liquid flow space 521, and near-infrared light with an intensity of 24.6 mW was applied to heat the water. Temperature distribution images of the water within the liquid flow space 521 were captured using a thermal imaging camera at the start of irradiation (0 seconds), 5 seconds after the start of irradiation, 15 seconds after the start of irradiation, and 30 seconds after the start of irradiation. The four captured temperature distribution images were then... Figure 10 The pattern is shown in the diagram. Figure 10 The figure shows the temperature distribution of water that has been continuously heated at a constant flow rate over time.

[0096] [Example 2]

[0097] Next, using such an evaluation device 5, and adjusting the flow rate of water flowing in the liquid flow space 521 to four modes—0 μL / min (no flow), 5 μL / min, 10 μL / min, and 20 μL / min—near-infrared light was applied to heat the water. A thermal imaging camera was used to capture images of the water temperature distribution within the liquid flow space 521 15 seconds after the start of irradiation. The four captured temperature distribution images were then displayed... Figure 11 The pattern is shown in the middle. Figure 11This illustrates the different temperature distributions that occur at points after a predetermined time has elapsed since the start of heating, due to variations in water flow rates.

[0098] As can be seen from the temperature distribution images taken in Examples 1 and 2, by applying heat to the liquid and obtaining the temperature distribution of the heated liquid, the flow state of the liquid can be inferred based on the obtained temperature distribution.

[0099] [Quantification of water flow]

[0100] The fluidity of water was quantified based on the temperature distribution images obtained under each flow rate mode in Example 2. First, temperature distribution images taken at 5-second intervals in the mode with a flow rate of 0 μL / min (no flow) and temperature distribution images taken at 5-second intervals in the mode with a flow rate of 20 μL / min were set as follows: Figure 12 The two regions shown are region a and region b. The temperature of each region is obtained using the method described above, and the temperature difference between region a and region b is calculated. If the temperature difference between region a and region b at the start of water heating (0 seconds), and after 5, 10, 15, 20, 25, and 30 seconds, is plotted on a graph with the vertical axis set to temperature difference and the horizontal axis set to elapsed time, it would look like this: Figure 13 As shown. Observe. Figure 13 It can be seen that in the mode with a flow rate of 0 μL / min (no flow), there is no temperature difference between region a and region b. In the mode with a flow rate of 20 μL / min, the plotted points are basically arranged on a straight line rising to the right.

[0101] In addition to the four flow rate modes in Example 2, the same experiment was also conducted with a mode in which the flow rate of water flowing in the liquid flow space 521 was set to 15 μL / min. This resulted in a total of five flow rate modes. Figure 13 Using the same chart, calculate the slope (Δy / Δx) of the temperature difference for each flow rate pattern. Use the calculated slope (Δy / Δx) of the temperature difference for each flow rate pattern as the change in temperature difference for that pattern. If this change is plotted on a chart with the vertical axis set to the change in temperature difference and the horizontal axis set to flow rate, it would look like this: Figure 14 As shown. Observe. Figure 14 It can be seen that the change in temperature difference remains constant and is proportional to the flow rate. By conducting such an experiment, the conversion table 50 in the above implementation method can be prepared in advance.

[0102] Explanation of reference numerals in the attached figures

[0103] 100 - Liquid flow state estimation system; 1 - Light source (heating unit); 2 - Thermal imaging camera (temperature distribution acquisition unit); 3 - Estimation device (estimation unit); 41 - Image generation unit; 42 - Area setting unit; 43 - Temperature calculation unit; 44 - Direction estimation unit; 45 - Velocity estimation unit; E - Eye under inspection; 5 - Evaluation device.

Claims

1. A system for estimating the flow state of a liquid, for estimating the weak flow state of a small flow rate of a liquid, wherein the liquid is aqueous humor, and comprises: A heating unit that applies heat to a liquid by irradiating it with light from a light source; A temperature distribution acquisition unit acquires the temperature distribution of the heated liquid; and The estimation unit estimates the flow state of the liquid based on the acquired temperature distribution. The estimation unit sets two pairs of positions within the area where the temperature distribution is obtained, calculates the temperature difference or temperature ratio between the two positions, performs the above process multiple times, selects the pair with the largest temperature difference or temperature ratio from multiple pairs of positions within the area where the temperature distribution is obtained, and estimates the direction of liquid flow from the position on the lower temperature side to the position on the higher temperature side of the selected pair of positions.

2. The liquid flow state estimation system according to claim 1, characterized in that, The temperature distribution acquisition unit acquires multiple temperature distributions of the liquid at different times. The estimation unit estimates the flow state of the liquid based on the acquired multiple temperature distributions.

3. The liquid flow state estimation system according to claim 1, characterized in that, The estimation unit further estimates the velocity of the liquid flow based on the temperature difference or temperature ratio between the two locations constituting the selected pair.

4. The liquid flow state estimation system according to claim 1, characterized in that, The estimation unit divides the area where the temperature distribution is obtained into multiple unit regions, and estimates the flow state of the liquid based on the temperature of these multiple unit regions.

5. The liquid flow state estimation system according to claim 4, characterized in that, The temperature of a unit area is calculated as the average of the temperature of that unit area determined according to the temperature distribution and the temperatures of other unit areas adjacent to that unit area.

6. The liquid flow state estimation system according to claim 1, characterized in that, The temperature distribution acquisition unit acquires at least one of the following temperature distributions: the temperature distribution of the liquid during heating when heat is applied to the liquid, and the temperature distribution of the liquid during cooling after heating is stopped. The estimation unit estimates the flow state of the liquid based on at least one of the temperature distribution during heating and the temperature distribution during cooling.

7. The liquid flow state estimation system according to claim 1, characterized in that, The temperature distribution acquisition unit uses a thermal imaging camera to photograph the liquid, thereby acquiring the temperature distribution of the liquid.

Images