JP4651186B2 - Biological light measurement device - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a biological light measurement device that measures in vivo information using light, and particularly relates to a biological light measurement device that has a function of analyzing a concentration signal of a measured in vivo substance.
[0002]
[Prior art]
Biological light measurement irradiates the living body with light having a wavelength in the visible to infrared region, and detects light reflected from the living body or transmitted through the living body, so that blood circulation, hemodynamics, hemoglobin change, etc. inside the living body are detected. In vivo information is measured. Since such optical measurement is simple, can be measured with low restraint on the subject and does not harm the living body, various biological optical measuring devices have been put into practical use and have been proposed (for example, special features (Kaisho 57-115232, JP-A 63-275323, etc.).
[0003]
In particular, optical topography that measures changes in hemoglobin concentration at a plurality of measurement positions within a predetermined region and makes it possible to display a graph (topograph) like a contour line is an example of a brain active site when a specific operation is performed. It is expected to be used for identification and local focus identification of epileptic seizures. Furthermore, in relation to hemoglobin changes in the brain, it is also possible to measure higher brain functions, such as movement, sensation, language, and thought.
[0004]
For example, “Near-infrared cerebral blood flow mapping method (CLINICAL NUEROSCIENCE Vol.17, No.11 1999-11)” reports on hemoglobin changes in the brain during exercise and language tasks. Here, the amount of hemoglobin change In addition, the time until the maximum amount of change is reached is used as an index for determining the active state of the brain when performing exercise or language task.
[0005]
[Problems to be solved by the invention]
In order to make a clinical diagnosis from hemoglobin change data measured in this way, the amount of change and factors over time are required. Specifically, the differential value of the hemoglobin change graph represents the hemoglobin change rate flowing into the activation region, and is an important value for knowing the reaction of the subject to the task (stimulation). The difference (latency time) between the position at which the change in hemoglobin starts or the position at which the change ends and the time when the stimulation is actually started or the time when the stimulation is ended is also an indicator of the response time to the task. Furthermore, the integrated value of the hemoglobin change graph corresponds to the total amount of hemoglobin change in the active region and serves as an index of how much the brain has reacted.
[0006]
However, since the conventional biological light measurement device has only the function of displaying the amount of change as described above as a topobluff and the function of displaying a change curve, it is necessary to visually measure for further clinical application. We had to identify the rate of change, amount of change, latency, etc. for each position.
Accordingly, an object of the present invention is to provide a living body light measurement device that can obtain not only hemoglobin change but also information (quantitative data) important for living body function measurement and diagnosis as an output of the living body light measurement device. The present invention also provides data such as a function for performing statistical processing using data of a plurality of persons obtained by biological light measurement, or comparing data before and after the same person in order to confirm the effect of rehabilitation treatment, for example. It is an object of the present invention to provide a biological light measurement device having an analysis function.
[0007]
[Means for Solving the Problems]
The biological light measurement apparatus of the present invention that solves the above-described problems irradiates a subject with light of a predetermined wavelength, detects light that has passed through the subject, and adjusts the concentration of the substance in the subject to absorb the light. An optical measurement unit that generates a corresponding signal; a signal processing unit that inputs a signal from the optical measurement unit, performs a quantity analysis on a concentration change curve along a time axis of the signal, and creates quantitative data; and And a display unit for displaying quantitative data created by the signal processing unit.
[0008]
According to such a biological optical measurement device, information that is important for diagnosis and function determination is obtained by performing quantitative analysis on the raw concentration data obtained by the optical measurement unit and displaying the quantitative data as a result of the analysis. Can be obtained directly.
[0009]
As the quantity analysis performed by the signal processing unit, for example, a differential value and / or an integral value is obtained for a concentration change curve, and the start time or end time of the cause on the subject side that causes a change in the substance in the subject, and the concentration There is a case where a difference between a time point at which a signal change becomes equal to or higher than a predetermined threshold value or a time point when the signal change becomes equal to or lower than a predetermined threshold value is obtained as a latency time.
[0010]
In addition, the biological light measurement device of the present invention includes storage means for storing concentration signal data measured during measurement or in a plurality of measurements with different measurement targets. In this case, the signal processing unit may include means for calculating a density change amount for a plurality of density signal data read from the storage means, and calculating a difference, an addition average, and the like.
[0011]
According to this biological light measurement device, for example, by averaging the data obtained from a plurality of different measurement objects, it is possible to obtain an average value of the biological reaction for the cause (task or stimulus) that causes the concentration change, In addition, an average template graph can be created. Or by taking the difference of the data obtained by the measurement performed at different times for the same object, it is possible to give a quantitative index when diagnosing the degree of recovery of motor function before and after rehabilitation.
[0012]
In the biological optical measurement device of the present invention, the signal processing unit and the display unit can be configured integrally with the optical measurement unit or can be configured as an independent external device. In the case of an independent external device, for example, measurement results at a remote location can be centrally stored and managed, or processing can be performed at a place with diagnosis / judgment skills. In that case, the signal processing unit and the optical measurement unit can transmit and receive data using, for example, a LAN cable, a communication network, and a portable recording medium.
[0013]
In the living body optical measurement device of the present invention, the optical measurement unit may be an optical measurement device including a combination of a single light emitting element and a light receiving element, or an optical measurement device having a plurality of measurement channels.
[0014]
The optical measurement device having a plurality of measurement channels has a plurality of measurement positions determined by the light irradiation position on the subject and the light receiving position for receiving the light, and the number of density signals corresponding to the plurality of measurement positions. And an existing optical topography apparatus can be used. By using such an optical topography device, quantitative information about a predetermined region can be obtained.
[0015]
When an optical measurement device having a plurality of measurement channels is used as the optical measurement unit, the signal processing unit preferably processes a concentration signal having a large amount of change in concentration among concentration signals for a plurality of measurement positions. Do.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the biological light measurement device of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing an embodiment of the biological light measurement device of the present invention. This biological light measurement device irradiates a desired portion of the subject 104 (the head in the illustrated example) with light 103 and light with a predetermined wavelength including position information. A light measurement unit 101 that detects light reflected from the subject and generates a signal corresponding to the hemoglobin value (hemoglobin signal), and performs a calculation such as frequency analysis and differentiation on the hemoglobin signal generated by the light measurement unit 101. A biometric information calculation unit (signal processing unit) 105 for generating and displaying biometric information is provided.
[0017]
The probe 103 and the optical measurement unit 101 are connected via an optical cable 102. The biological information calculation unit 105 can also serve as a computer provided in the optical measurement unit 101. Here, the biological information calculation unit 105 is configured by a computer system independent of the optical measurement unit 101, such as a personal computer. The biological information calculation unit 105 may be connected to the optical measurement unit 101 via a network such as a local area network or the Internet, or may be a magneto-optical recording medium (MO), a magnetic recording medium (FD), or the like. It is also possible to receive data from the optical measurement unit 101 via a portable recording medium.
[0018]
The probe 103 is arranged such that the end portions of the plurality of optical cables 102 are arranged in a predetermined arrangement and fixed in a shape that can be worn by the subject. Usually, the optical fiber end for irradiation and the optical fiber end for receiving light are two-dimensionally arranged. Alternatingly arranged in the direction, it is a matrix. As a result, the light irradiated from the end of the irradiation optical cable, transmitted through the subject's skin and reflected in the tissue is sent to the optical measurement unit from the ends of the plurality of light receiving optical cables arranged in the vicinity (periphery) of the end. It has become.
[0019]
FIG. 2 shows an example of the arrangement of the ends of the irradiation optical cable and the light receiving optical cable. In the illustrated example, four irradiation optical cable ends R1 to R4 and five light receiving optical cable ends D1 to D5 arranged alternately are shown. The midpoint between the end of the irradiation optical cable and the end of the light receiving optical cable is the measurement position. In this example, there are 12 measurement positions. This measurement position corresponds to a measurement channel of the detection unit in the optical measurement unit 220 described later.
[0020]
The optical measurement unit 101 further includes a light emitting unit 210, a detection unit 220, and a control unit 230, as shown in FIG. As the optical measurement unit 101, a conventional optical topography apparatus can be used as it is.
[0021]
The light emitting unit 210 includes a plurality of light modules 211 including a light emitting element such as a semiconductor laser and a driving circuit thereof, and a plurality of oscillators 212 having different oscillation frequencies. The semiconductor laser generates light having a wavelength that matches the target biological information. For example, when the purpose is to detect hemoglobin, light having a wavelength at which the change in the amount of received light increases with respect to the change in hemoglobin, such as the maximum absorption wavelengths of oxygenated hemoglobin and deoxygenated hemoglobin, is generated. The light from each semiconductor laser is modulated by the frequency from the oscillator. As a result, the probe 103 irradiates the subject's skin with light modulated at different frequencies from the ends of the plurality of irradiation optical cables arranged on the matrix.
[0022]
The detection unit 220 is connected to each of a plurality of light receiving optical fibers, and selectively detects the photodetection element 221 such as a photodiode and the detected optical signal component for each frequency and lock-in detection. A lock-in amplifier 222; a sample-and-hold circuit 223 that time-integrates a signal output from the lock-in amplifier 222 for each channel; and an A / D converter 224 that A / D-converts the signal after time integration. ing. The channel of the lock-in amplifier 222 corresponds to the measurement position described above.
[0023]
The control unit 230 controls the light emitting unit 210 and the detection unit 220, and performs an operation on the signal detected and digitized by the detection unit 220, for example, oxygenated hemoglobin concentration change, deoxygenated hemoglobin concentration change associated with brain activity, A computer 231 that calculates changes in total hemoglobin concentration, etc., creates a topograph, a display unit 232 that displays the calculation results of the computer 231 and the necessary conditions for control and calculation in the computer 231 and information necessary for measurement ( For example, an input unit 233 for inputting a patient ID, a patient name, etc., and a memory 234 for storing data necessary for calculation and calculation results are provided.
[0024]
The calculation performed by the computer 231, that is, a method for calculating a change in hemoglobin concentration and a method for creating an image are disclosed in, for example, Japanese Patent Laid-Open No. 9-19408 and Atsushi Maki et al. Analysis (Spatial and temporal analysis of human motor activity using noninvasive NIR topography), 1995 and Medical Physics Vol. 22, pp. 1997-2005. In the optical measurement unit of the present invention, these methods can be adopted for calculation of the measurement signal. However, in the present invention, it is not essential to create a topograph, and the signal before calculation, that is, output from the lock-in amplifier 222. A signal corresponding to the hemoglobin concentration (oxygenated hemoglobin concentration, deoxygenated hemoglobin concentration) or a signal corresponding to the total hemoglobin concentration calculated by the computer 231 is input to the biological information calculation unit 105.
[0025]
The biological information calculation unit 105 is composed of a computer system as described above, and the hardware is, for example, the CPU 108, an external storage device 107 using a fixed storage medium such as a main memory or a hard disk, or a portable storage medium. It has a configuration of a general electronic computer including an external storage device 110, a communication control device that controls communication via a network, an input device 109 such as a keyboard and a pointing device, and an output device 111 such as a display device. Then, the CPU 108 executes a program loaded in the main memory, whereby each process described below is performed. The hemoglobin signal generated by the control unit 230 of the optical measurement unit 101 described above is input to the biological information calculation unit 105 via a LAN cable, a communication network, or a portable storage medium, and is recorded on the hard disk 107 as illustrated, for example. .
[0026]
Next, an embodiment of processing performed by the biological information calculation unit 105 will be described.
FIG. 4 shows a specific processing mode. In this embodiment, as illustrated, the biological information calculation unit 105 performs filter processing, baseline processing, and frequency analysis (step 402) as basic processing.
[0027]
First, on the initial screen displayed on the display unit 111, for example, by inputting information such as patient ID or patient name, measurement date and time, desired data is retrieved, read, and displayed on the display unit 111. The displayed screen is shown in FIG. The patient information input and reading instructions described above are performed by a patient information display window 501 for displaying a patient ID and a patient name and a data reading button 507. The data read from the optical measurement unit 101 is a graph 502 showing the hemoglobin concentration (change amount) in the motor cortex region when, for example, hand gripping exercise is performed, and the vertical axis 503 in the figure indicates the hemoglobin change amount, and the horizontal axis Reference numeral 506 denotes time. Vertical lines 504 and 505 indicate the time when the exercise starts and the time when the exercise ends, respectively. In order to recognize the start and end of such movement, for example, 0-1 rectangular signal data is described in the data from the optical measurement unit in addition to the data corresponding to the above-described hemoglobin change amount.
[0028]
From this graph, it can be seen that hemoglobin increases from the start of exercise and decreases after the end of exercise. However, since noise components such as body movement, pulse wave, and biological rhythm are superimposed on the signal before processing, the signal has a poor S / N. In order to remove such noise components, filter processing and baseline processing 402 are performed.
[0029]
FIG. 6 shows a screen for performing filter processing, baseline processing, and frequency analysis processing.
In the illustrated example, a high-pass filter HPF that removes low-frequency noise, an LPF that removes high-frequency noise, and the like are used as filter processing, and the cut-off frequency and window function of these filters are set in the “filter” 607 of the display screen. can do. For the cut-off frequency, an appropriate numerical value may be set as a default, and the user may arbitrarily change it. As the window function, known ones such as a rectangular window, a Hanning window, and a Hamming window are stored in advance, and they can be displayed and selected by pull-down.
[0030]
When the conditions necessary for the filter processing are set, data 602 before the filter processing and data 604 after the processing are displayed in the upper graph of the screen shown in FIG. In the example shown in the figure, a case where data before processing is subjected to LPF processing of 0.1 Hz is shown.
[0031]
The result of the filtering process can be confirmed by frequency analysis. In the “FFT” 608 on the display screen, by setting the conditions for the fast Fourier transform process, the frequency analysis process is performed on both the pre-filter data 602 and the post-process data 603, and the result is shown in the lower side of FIG. It is displayed as shown in the graph. 604 is pre-processing data and 605 is post-processing data, and it can be seen that the signal from the 0.1 Hz band is cut by the low-pass filter processing and the S / N is improved.
Note that frequency analysis can be used not only for such noise removal confirmation but also for analysis of signal components.
[0032]
In the baseline processing, the order is set in “BASE LINE” 609 on the display screen. Based on the set order, an approximate curve for the hemoglobin data 602 is calculated, and baseline processing is performed using the approximate curve as a baseline. In other words, the baseline processing result (AfterPolyfitData) is obtained from the hemoglobin change graph (after filtering) (HbData) and the approximate curve (Polyfit) by the following equation.
(AfterPolyfitData) = (HbData) / (Polyfit)
[0033]
The order of the baseline processing may be set as an appropriate default value, for example, 5th order, or may be set and changed by the user, for example, any order between 0th order and 10th order.
[0034]
By performing the preprocessing on the raw data input from the optical measurement unit 101 in this way, it is possible to increase the effectiveness of the next quantity analysis.
[0035]
Next, using the preprocessed data, the differential value, integral value, and latency time of the specified section (the difference between the ONset position of the signal and the OFFset position and the actual motion (stimulation) start or end time) are calculated. . A screen for performing such processing is shown in FIG.
[0036]
First, the pre-processed hemoglobin data 705 is read by the “LOAD” button 710 as described above. Again, the exercise start and end times are indicated by vertical lines 706 and 708, respectively.
[0037]
Next, a threshold line 702 serving as a basis for latency time calculation, integral value calculation, and differential value calculation is set. The threshold line 702 is set by inputting a value in the “threshold” 711 on the screen. The change point at which the threshold line 702 or more is the Onset position 707 at which the hemoglobin value starts to change, and the change point at which the threshold line 702 or less is the OFFset position 709 at which the hemoglobin value returns before the change.
[0038]
Next, the difference (latency time) between the actual movement start time 706 and the Onset position 707 and the difference (latency time) between the movement end time 708 and the OFFset position 709 are calculated. For each of Onset and OFFset, the time and latency are displayed in an “Onset” window 712 and an “OFFset” window 713, respectively.
[0039]
When the threshold line 702 is set, the area of the region 704 surrounded by the threshold line 702 and the hemoglobin data 705 curve is calculated, and the value is displayed in the “area” 714 on the screen. In this case, as shown in the drawing, the area 704 whose area is calculated may be displayed on the graph by color display or gradation display.
[0040]
Further, for example, when a predetermined section is designated from the Onset position 707, a differential value in that section, that is, a hemoglobin change rate is calculated. The designation of the section and the display of the calculation result are performed in the “slope Δt” 715 window. Also in this case, the actual inclination may be displayed on the graph as a straight line as indicated by reference numeral 703 in the figure.
[0041]
Latency time and hemoglobin change rate are indicators that indicate the response of the subject to the stimulus as described above, and area is an indicator that shows how much the brain responded to the stimulus, both of which are important for function determination Information. The operator can easily grasp this information as numerical values displayed in each display window, or by line segments or coloring displayed on the graph.
[0042]
In addition, when the optical measurement unit creates data of a plurality of measurement channels and inputs these data, the above-described processing may be performed on the data of each measurement channel, or significant among the data of each measurement channel. The quantity analysis may be performed only on the data of the channel having a slight hemoglobin change. In that case, in the biometric information calculation unit 105, after the data reading 401, before the preprocessing 402 or before the quantity analysis 403 to 405, a process of selecting data for which the maximum value and the minimum value of the signal are equal to or greater than a predetermined threshold is added. be able to.
[0043]
Next, a second embodiment of processing performed by the biological information calculation unit 105 will be described.
FIG. 8 shows a specific processing mode of this embodiment, and FIG. 9 shows an example of a display screen for processing. In this embodiment, as shown in FIG. 8, the biological information calculation unit 105 reads a plurality of hemoglobin data (step 801), and performs an addition averaging process (step 802) or a difference process (step 803). . The process after the addition averaging process or the difference process is the same as that of the first embodiment. The filtering process, the baseline process and the frequency analysis (step 804), and the hemoglobin change amount (differential value) calculation (step 805) are performed as preprocessing. ), Change area (integral value) calculation (step 806), Onset / OFFset (latency time) calculation (step 807), and calculation result display (step 808).
[0044]
The addition averaging process 802 is performed, for example, for obtaining an average value of a differential value, an integral value, and a latency time of a hemoglobin amount change graph for a large number of people. In order to perform such statistical processing, it is preferable to construct a database storing measurement data of a large number of people in the external storage device of the biological information calculation unit 105. The database preferably classifies a large number of data into predetermined categories (for example, sex, age, measurement time, region, etc.) and tree structure, and can be read out for each category. For example, data of a certain category is selected and read from such a database, and processing is performed for each category. Of course, all data may be processed.
[0045]
For this reason, the selection of a desired category in the patient information 901 on the screen and the “LOAD” button 906 are operated to read a plurality of hemoglobin data. It is also possible to select a plurality of desired patient data by repeatedly inputting the patient name and patient ID 901 as the patient information and the operation of the “LOAD” button 906. When the data reading is completed in this way, the “ADD” button 907 is operated. Thereby, the addition averaging process of hemoglobin data is performed. Since the result of this averaging process is displayed in the same manner as the screen of FIG. 5 shown for the first embodiment, after that, preprocessing and subsequent quantity analysis are performed as in the first embodiment.
[0046]
Thereby, the average data of the differential value, the integrated value, and the latency time is displayed for the selected category or patient group on the same screen as the screen of FIG. 7 shown for the first embodiment. Such data can be used to determine the deviation from the average value of individual patients and can be used as an average template graph as it is.
[0047]
The difference process 803 is used, for example, for observing the progress of the patient for the same person. For this reason, the patient information 901 on the screen of FIG. 9 is input, the measurement time is input with “COMMENT”, and the “LOAD” button 906 is operated to read hemoglobin data at the predetermined measurement time of the patient. With the patient name and patient ID as they are, a new measurement time point is input, and hemoglobin data at another measurement time point is read. FIG. 9 shows a state where two graphs 902 and 903 read in this way are displayed. Then, by operating the “DIFF” button 908, data indicating the difference between these graphs is displayed (not shown).
[0048]
Next, preprocessing 804 and quantity analysis 805 to 807 are performed, and the results are displayed. From the displayed result, for example, the effect of treatment can be quantitatively confirmed.
In the above description, the case where difference processing is performed on measurement data from the same person has been described. For example, as one read data, an average template graph created by the averaging process is read, and as the other read data, individual measurement data The read data may be differentially processed. In this case, it is possible to quantitatively grasp the deviation from the average value for the individual.
[0049]
Further, in the embodiment shown in FIG. 8, the case where the filtering process, the baseline process, and the quantity analysis are performed after performing the addition averaging process 802 and the difference process 803 is shown, but the order of these processes is shown in the illustrated embodiment. It is not limited to. That is, for example, when the number of read data is small, such as difference processing between two data, filter processing and baseline processing may be performed on each of the read data, and then processing such as addition and difference may be performed.
[0050]
Further, not all the processing shown in FIG. 8 may be performed, but only desired processing may be performed.
For example, it is possible to perform only the difference and omit the subsequent processing.
As mentioned above, although embodiment of the biological light measuring device of this invention was described, this invention is not limited to these embodiment, A various change is possible. For example, although the case where an optical topography apparatus is used as the optical measurement unit has been described, an optical measurement apparatus including a single light emitting element and a light receiving element can also be applied.
[0051]
Further, as a signal corresponding to the concentration of the substance in the subject, the hemoglobin concentration signal has been described as an example, but the hemoglobin concentration signal may be oxygenated hemoglobin, deoxygenated hemoglobin, total hemoglobin, or other in vivo substances such as, for example, Cytochrome a, a3, myoglobin, and the like can be similarly applied by appropriately selecting the wavelength of light.
[0052]
【The invention's effect】
According to the present invention, since it is possible to create and directly display important numerical data by diagnosis or the like using the concentration information of the substance in the subject obtained by biological optical measurement, effective clinical application of optical measurement can be achieved. Can be possible.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a biological light measurement device of the present invention. FIG. 2 is a diagram showing a probe of the biological light measurement device. FIG. 3 is a diagram showing an optical measurement unit of the biological light measurement device. The figure which shows one Embodiment of the process which the signal processing part of the biological light measuring device of FIG. 5 is an example of the screen for performing reading of data, The figure which shows the data before a process.
6 is an example of a screen for performing preprocessing, and shows a state in which the data in FIG. 5 is processed. FIG. 7 is an example of a screen for performing quantity analysis, and shows a state in which the data in FIG. 6 is processed. FIG. 8 is a diagram illustrating another embodiment of processing performed by the signal processing unit of the biological light measurement device of the present invention. FIG. 9 is a diagram illustrating an example of a screen for reading data in the embodiment of FIG. Figure.
[Explanation of symbols]
101 ・ ・ ・ Optical measurement unit
103 ... Probe
105 ・ ・ ・ Biometric information calculation unit (signal processing unit)
111 ・ ・ ・ Display device

Claims (6)

An optical measurement unit that irradiates a subject with light of a predetermined wavelength, detects light that has passed through the subject, and generates a signal corresponding to the concentration of the substance in the subject that absorbs the light; and the optical measurement A signal processing unit that inputs a signal from the unit, performs a quantity analysis on a concentration change curve along the time axis of the signal, creates a quantitative data, and a display unit displays the quantitative data created by the signal processing unit, A living body light measuring device comprising:
The signal processing unit includes a start time or an end time of a cause on the subject side that causes a change in the substance in the subject, and a time point when the concentration change becomes a predetermined threshold value or a predetermined threshold value or less. Means for obtaining a difference as a latency time, and generating quantitative data including the latency time, a differential value of a specified section defined by the latency time, and an integral value as the quantitative data A biological light measurement device. The biological light measurement apparatus according to claim 1, comprising storage means for storing concentration signal data measured during measurement or in a plurality of measurements with different measurement targets,
The biological light measurement apparatus, wherein the signal processing unit includes means for calculating a density change amount for a plurality of density signal data read from the storage means and calculating a difference, an addition average, and the like. The biological light measurement device according to claim 1,
The biological light measurement device, wherein the signal processing unit and the display unit are configured as an external device independent of the light measurement unit. The biological light measurement device according to claim 3,
The biological light measurement device according to claim 1, wherein the signal processing unit and the optical measurement unit transmit and receive data through any one of a LAN cable, a communication network, and a portable medium. The biological light measurement device according to claim 1,
The optical measurement unit has a plurality of measurement positions determined by a light irradiation position on the subject and a light receiving position for receiving the light, and outputs a number of density signals corresponding to the plurality of measurement positions. A biological light measuring device as a feature. The biological light measurement device according to claim 5,
The biological light measurement device, wherein the signal processing unit performs processing on a density signal having the largest density change amount among density signals for the plurality of measurement positions.

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