Correction device, imaging device, correction method, and imaging system

Abstract

To accurately measure the activity of a biological tissue in a living body.SOLUTION: A correction device comprises: an OCT image acquisition unit that acquires an OCT (Optical Coherence Tomography) image obtained by performing OCT imaging of a biological tissue in a living body as a sample; a selection unit that selects, as a reference image, any one of the plurality of OCT images taken at different times; a calculation unit that calculates an amount of displacement between a position of the sample represented in the OCT image taken at a time different from the time when the reference image was taken, and a position of the sample represented in the reference image; a correction unit that corrects the position of the sample in the OCT image on the basis of the displacement amount calculated by the calculation unit; and an output unit that outputs the OCT image corrected by the correction unit.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to a correction device, a photographing device, a correction method, and a photographing system.

Background Art

[0002] In recent years, a technique called "optical coherence tomography imaging" has been studied for morphological imaging of cultured samples or excised samples using an optical coherence tomography (OCT). Also, a signal analysis method called "dynamic OCT (DOCT)" has been proposed that enables imaging of tissue activities such as metabolism based on the temporal change in OCT signal intensity in OCT images that are continuous over a long period of time (see, for example, Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, a living body (e.g., the body of a subject) always performs movements (involuntary movements) unrelated to the will, such as breathing and heartbeat. The magnitude of such movements is larger than the movements of living tissue activities such as metabolism. In conventional dynamic OCT, when observing the activities of living tissue such as metabolism, involuntary movements become motion artifacts (noise), making it extremely difficult to observe the activities of living tissue such as metabolism.

[0005] Therefore, the present invention has been made in view of the above points, and an object thereof is to provide a technique capable of accurately measuring the activities of living tissue in a living body.

Means for Solving the Problem

[0006] [1] One aspect of the present invention is an OCT image acquisition unit that acquires an OCT image obtained by performing optical coherence tomography (OCT) imaging on a living tissue in a living body as a sample, a selection unit that selects any one of the plurality of OCT images taken at different times as a reference image, a calculation unit that calculates the amount of deviation between the position of the sample represented in the OCT image taken at a time different from the time when the reference image was taken and the position of the sample represented in the reference image, and based on the amount of deviation calculated by the calculation unit, a correction unit that corrects the position of the sample in the OCT image, and an output unit that outputs the OCT image corrected by the correction unit. It is a correction device provided with.

[0007] [2] Further, in one aspect of the present invention, the calculation unit calculates the amount of deviation between the reference image and each of the other plurality of OCT images.

[0008] [3] Further, in one aspect of the present invention, the selection unit further selects, as a target image, the OCT image taken at a time separated from the time when the reference image was taken by a predetermined time, and the calculation unit calculates the deviation amount between the reference image and the target image. When the OCT image taken at a time separated from the time when the target image was taken by the predetermined time and not selected as a reference image or a target image is included in a plurality of OCT images taken at different times, the target image is newly used as a reference image, and the selection unit and the calculation unit perform repetitive processing.

[0009] [4] Further, in one aspect of the present invention, the calculation unit calculates the deviation amount between the reference image and each of a plurality of other OCT images, and the selection unit selects any one of the plurality of OCT images taken at different times as a reference image. Further, the selection unit selects, as a target image, the OCT image taken at a time separated from the time when the reference image was taken by a predetermined time, and the calculation unit calculates the deviation amount between the reference image and the target image. When the OCT image taken at a time separated from the time when the target image was taken by the predetermined time and not selected as a reference image or a target image is included in the plurality of OCT images, the target image is newly used as a reference image, and the selection unit and the calculation unit perform repetitive processing.

[0010] [5] Further, in one aspect of the present invention, the calculation unit performs calculations using the OCT image based on a value expressed in decimal, and the output unit converts and outputs the OCT image based on a value expressed in decimal into an OCT image based on a value expressed in logarithm.

[0011] [6] Also, one aspect of the present invention is an imaging system including an imaging unit that images an OCT image obtained by performing optical coherence tomography (OCT) on a biological tissue in a living body as a sample, and a fixing unit provided in the imaging direction of the imaging unit so that the position relative to the imaging unit does not change, the fixing unit having a space in which the imaging unit can image the sample, and being pressed around a portion of the sample to be imaged by the imaging unit by relatively moving the position with respect to the sample, and the above-described correction device.

[0012] [7] Also, one aspect of the present invention is a correction method including an OCT image acquisition step of acquiring an OCT image obtained by performing optical coherence tomography (OCT) on a biological tissue in a living body as a sample, a selection step of selecting any one of the plurality of OCT images taken at different times as a reference image, a calculation step of calculating a deviation amount between the position of the sample represented in the OCT image taken at a time different from the time when the reference image was taken and the position of the sample represented in the reference image, a correction step of correcting the position of the sample in the OCT image based on the deviation amount calculated in the calculation step, and an output step of outputting the OCT image corrected in the correction step.

[0013] [8] Also, one aspect of the present invention is an imaging device including an imaging unit that images an OCT image obtained by performing optical coherence tomography (OCT) on a biological tissue in a living body as a sample, and a fixing unit provided in the imaging direction of the imaging unit so that the position relative to the imaging unit does not change, the fixing unit having a space in which the imaging unit can image the sample, and being pressed around a portion of the sample to be imaged by the imaging unit by relatively moving the position with respect to the sample.

[0014] [9] Further, in one aspect of the present invention, the above-described imaging device further includes a marker that is temporarily fixed to the surface of the sample and has a space in which the imaging unit can image the sample, and the fixing unit is pressed against at least one of the marker and the region around the marker.

[0015]

[10] Further, in one aspect of the present invention, the marker has a shape that is not point-symmetrical when viewed from the imaging direction of the imaging unit.

[0016]

[11] Further, in one aspect of the present invention, the marker has a shape that is not line-symmetrical when viewed from the imaging direction of the imaging unit.

[0017]

[12] Further, in one aspect of the present invention, the above-described imaging device further includes a display unit that displays the OCT image representing at least one of a cross-section of at least one of the marker temporarily fixed to the surface of the sample and having a space in which the imaging unit can image the sample, the fixing unit, and a cross-section of the sample, and the fixing unit is pressed against at least one of the sample and the marker with a magnitude of force set according to the position of the surface of the sample with respect to the marker or the fixing unit.

[0018]

[13] Further, in one aspect of the present invention, the above-described imaging device further includes a pressure sensor that measures the pressure with which the fixing unit presses the sample or the marker by being disposed so as to be sandwiched between at least one of the space between the marker temporarily fixed to the surface of the sample and having a space in which the imaging unit can image the sample and the fixing unit, and the space between the sample and the fixing unit. [Advantages of the Invention]

[0019] According to the present invention, the activities of biological tissues in a living body can be accurately measured. [Brief Description of the Drawings]

[0020]

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[0021] [Overview] A preferred embodiment of the correction device, imaging device, and imaging system according to the present embodiment will be described in detail below with reference to the accompanying drawings. Note that the present embodiment is not limited to these embodiments, but also includes those with various modifications or improvements. That is, the components described below include those that can be easily assumed by those skilled in the art and substantially identical ones, and the components described below can be combined as appropriate. Also, in the present embodiment, various omissions, substitutions, or changes of components can be made without departing from the gist of the present invention.

[0022] FIG. 1 is a diagram for explaining a method for evaluating a biological tissue according to an embodiment. First, with reference to the figure, an overview of the method for evaluating a biological tissue according to the embodiment will be described. In the following description, as an example of a biological tissue (in vivo) in a living body that an OCT (optical coherence tomography) system observes, it is described as a sample Sm. The sample Sm is, for example, the skin of a living person.

[0023] First, the OCT system performs a plurality of OCT (optical coherence tomography) imaging on the same site of the biological tissue at the same position. Here, an OCT image obtained by one OCT imaging is described as an imaging frame (or simply a frame). The OCT system obtains a plurality of OCT images by performing a plurality of OCT imaging over time.

[0024] Next, the OCT system quantitatively evaluates the activity of the biological tissue based on the temporal change in the OCT signal intensity obtained from a plurality of OCT images of the same site of the biological tissue taken at the same position. The OCT system quantitatively evaluates the activity of the biological tissue by visualizing minute fluctuations of the biological tissue. The imaging system according to the embodiment performs some functions of the OCT system.

[0025] FIG. 2 is a block diagram for explaining an example of the functional configuration of the imaging system according to the embodiment. The functional configuration of the imaging system 1 will be described with reference to the figure. The imaging system 1 includes an imaging device 10 and a correction device 20. A person who observes the sample Sm (hereinafter simply referred to as the observer) uses the imaging system 1 to capture images and evaluates the activities of living tissues using the corrected OCT images. In the present embodiment, two types, hardware (imaging device) and software (correction device), are used to reduce the influence of the motion architecture generated by the involuntary movement of the living body.

[0026] [Configuration of Hardware] FIG. 3 is a first diagram for explaining the mode of OCT imaging using the imaging device according to the embodiment. The imaging device 10 will be specifically described with reference to FIG. 3. FIG. 3(A) is a side view showing the situation before fixing the sample Sm. FIG. 3(B) is a side view showing the situation after fixing the sample Sm. The imaging device 10 includes an imaging unit 11, a fixing unit 12, a driving unit 13, a marker 14, and a display unit 15. The imaging device 10 according to the embodiment performs OCT imaging by pressing the fixing unit 12 against the sample Sm.

[0027] The imaging unit 11 performs OCT imaging (measurement) on the sample Sm. Specifically, the imaging unit 11 performs OCT imaging a plurality of times (from several times to several hundred times = from several frames to several hundred frames), preferably 10 frames or more, more preferably 15 frames or more, within a predetermined period (for example, from 1 to 15 minutes, typically within 3 minutes). The imaging unit 11 according to the embodiment performs OCT imaging of 32 frames. The imaging unit 11 outputs the captured OCT images to the display unit 15 and the correction device 20.

[0028] FIG. 4 is a diagram for explaining an example of the shape of the fixing unit according to the embodiment. The fixing unit 12 will be specifically described with reference to the figure. The fixing part 12 is fixed in the imaging direction of the imaging part 11 so that its position relative to the imaging part 11 does not change in order to fix the part of the sample Sm to be imaged. Specifically, the fixing part 12 is fixed so that the focus of the imaging part 11 is on the vicinity of the tip on the side contacting the sample Sm (hereinafter, may be simply referred to as the tip of the fixing part 12). Also, the fixing part 12 has a space where the imaging part 11 can image the sample Sm. This imaging possible space is, for example, a cylindrical cavity connecting from the imaging part 11 to the sample Sm. Thereby, after the fixing part 12 fixes the sample Sm, it is not necessary to adjust the position of the imaging part 11 by focusing the imaging part 11 on the part of the sample Sm to be imaged. That is, the fixing part 12 according to the embodiment can reduce the time required for OCT image imaging.

[0029] Also, the fixing part 12 may be created for each part of the sample to be imaged, that is, for each subject or for each part of the subject to be imaged (forearm or palm). By creating the fixing part 12 according to the shape of the part of the subject to be imaged, the fixing part 12 can fix the sample Sm more reliably.

[0030] The driving part 13 will be described with reference to FIGS. 3 and 5. FIG. 5 is a second diagram for explaining the mode of OCT imaging using the imaging device according to the embodiment. FIG. 5 shows a top view representing the situation before the sample Sm is fixed. Based on the operation of the observer, the driving part 13 moves the imaging part 11 and the fixing part 12 to press the fixing part 12 against the sample Sm. Thereby, the driving part 13 fixes the part of the sample Sm to be imaged and its vicinity. By the driving part 13 moving the imaging part 11 and the fixing part 12 and pressing the fixing part 12 against the sample Sm, the imaging part 11 can image the human body serving as the sample Sm in a state where the body has relaxed the force. Therefore, according to the driving part 13 of the present embodiment, by imaging in a state where the force is relaxed, the movement of the sample Sm can be suppressed and motion artifacts can be reduced.

[0031] FIG. 6 is a diagram for explaining an example of a marker according to an embodiment. The marker 14 will be described with reference to this figure. The marker 14 has a space in which the imaging unit 11 can image the sample Sm. The space in which the sample Sm can be imaged by the marker 14 may have a figure whose contour shape is not point-symmetric when viewed from the imaging direction of the imaging unit 11. The contour shape of the space in which the sample Sm can be imaged may be, for example, a square figure that is point-symmetric but has concave or convex portions, or a figure that is not line-symmetric. That is, the contour shape of the space in which the sample Sm can be imaged by the marker 14 may be a shape having asymmetry. The marker 14 is temporarily fixed to the surface of the sample Sm so that the imaging target portion of the sample Sm fits into the space in which the sample Sm can be imaged. The drive unit 13 fixes the sample Sm by pressing the fixing unit 12 against the surface (skin) of the sample Sm in the marker 14 or in the region around the marker 14.

[0032] Note that, depending on one of the shape of the tip of the fixing unit 12 or the shape of the marker 14, the other shape may be determined. Specifically, when the shape of the outer edge of the marker 14 is a circle, the shape of the opening at the tip of the fixing unit 12 may be a circle of the same size as the outer edge of the marker 14. According to this, the imaging unit 11 can more accurately fit the imaging target portion of the sample Sm within the imaging region. Also, when the angle or position at which the fixing unit 12 fixes the sample Sm is different from the preset angle or position, the marker 14 does not fit into the fixing unit 12, so the observer can notice that the angle or position at which the sample Sm is fixed, that is, the imaging location and angle of the imaging unit 11, are different from the setting. Therefore, according to the fixing unit 12 according to the embodiment, the reproducibility of the imaging result when the imaging unit 11 images the sample Sm can be improved. Further, the shape of the outer edge of the marker 14 may be a figure other than a circle. The marker 14 according to the embodiment has a convex portion on the outer edge. Thus, when a straight line orthogonal to the surface of the marker 14 is used as the axis of rotation, if the fixing portion 12 rotates more than a preset angle, the marker 14 will not fit into the fixing portion 12. Therefore, the observer can notice that the angle at which the sample Sm is fixed, that is, the photographing angle of the photographing unit 11 is different from the setting. Accordingly, the reproducibility of the photographing result when the photographing unit 11 photographs the sample Sm can be improved. Furthermore, the shape of the marker 14 may have an asymmetry such that it does not become the same as the original marker shape by a combination of an inversion operation and a rotation operation of the photographed OCT image. That is, the marker 14 may satisfy at least one requirement of a shape that is not point-symmetric and a shape that is not line-symmetric. According to this, the observer can notice that the appearance of the OCT image of the photographed location is different from the setting (for example, the OCT image is rotated or inverted compared to the setting).

[0033] The display unit 15 displays the OCT image photographed by the photographing unit 11. The display unit 15 is a device possessed by the observer, and may be, for example, a device such as a personal computer, a tablet computer, or a smartphone. FIG. 7 is a diagram showing an example of an image displayed by the display unit. FIG. 7 shows a cross-sectional image IM of a portion of the sample Sm to be photographed and a cross-section of the marker 14 temporarily fixed to that portion. The stronger the fixing portion 12 is pressed against the sample Sm, the more the surface of the sample Sm at the location to be photographed bulges. The observer may adjust the pressure at which the driving unit 13 presses the fixing portion 12 against the sample Sm according to the degree of the bulge of the surface of the sample Sm represented in the OCT image displayed on the display unit 15. Specifically, the observer can determine the pressure at which the driving unit 13 presses the fixing portion 12 against the sample Sm by comparing the height of a part (for example, a notch) of the marker 14 with the height of the highest position of the surface of the sample Sm, and can adjust the pressure. In addition, for the image IM, an auxiliary line indicating the height that the surface of the sample Sm reaches when the fixing part 12 is pressed against the sample Sm with a preset pressure may be displayed. By adjusting the pressure so that the height of the surface of the sample Sm matches the auxiliary line, the observer may adjust the pressure to be the same as the preset pressure.

[0034] In the above-described embodiment, an example is shown in which the driving unit 13 moves the photographing unit 11 and the fixing unit 12 by being operated by an observer. However, this embodiment is not limited to this example. The driving unit 13 may move the photographing unit 11 and the fixing unit 12 so as to search for the location of the part of the sample Sm to be photographed and the position of the marker 14 by a sensor (not shown) such as a camera, and press the fixing part 12 against that position. Further, the driving unit 13 may adjust the pressure for pressing the fixing part 12 against the sample Sm according to the degree of swelling of the surface of the sample Sm represented in the OCT image photographed by the photographing unit 11.

[0035] In the above-described embodiment, an example is shown in which the photographing apparatus 10 includes the driving unit 13. However, this embodiment is not limited to this example, and the subject may move his or her own body and press the part to be photographed (for example, the position where the marker 14 is attached) against the fixing part 12.

[0036] Also, in this embodiment, an example is shown in which the photographing unit 11 photographs in the direction of gravity. However, this embodiment is not limited to this example, and the photographing unit 11 may photograph in a direction opposite to the direction of gravity. In this case, the fixing part 12 may be provided in the space above the photographing unit 11. Since the observer can place the part to be photographed on the fixing part 12 and perform photographing during photographing, the observer can relax the force. Therefore, by performing photographing in a state where the force is relaxed, the movement of the sample Sm can be suppressed, and motion artifacts can be reduced.

[0037] [Summary of Hardware] According to the above-described embodiment, the imaging unit 11 captures an OCT image obtained by performing optical coherence tomography (OCT) imaging on a biological tissue in a living body as a sample. The fixing unit 12 is provided in the imaging direction of the imaging unit 11 so that the position with respect to the imaging unit 11 does not change, has a space in which the imaging unit 11 can image the sample Sm, and is pressed against the periphery of the portion of the sample that is the imaging target of the imaging unit by relatively moving the position with respect to the sample. By fixing the sample Sm and suppressing involuntary movement, the imaging device 10 can capture an OCT image with reduced influence of motion artifacts caused by involuntary movement. That is, according to the imaging device 10, an observer can observe the activities of biological tissues such as the metabolism of a living person.

[0038] Also, according to the above-described embodiment, the marker 14 is temporarily fixed to the surface of the sample Sm, and the imaging unit 11 has a space in which the sample Sm can be imaged. The fixing unit 12 is pressed against at least one of the marker 14 and the region around the marker 14. When the imaging target location of the sample Sm is determined, the observer needs to move the imaging unit 11 and the fixing unit 12 while confirming whether the imaging target location is being imaged by the imaging unit 11. According to the marker 14 fixed in advance around the imaging target location of the sample Sm, when the fixing unit 12 is pressed against the marker 14 or the periphery of the marker 14, the imaging target location of the sample Sm falls within the imaging area of the imaging unit 11. Therefore, the imaging device 10 according to the embodiment can easily image the imaging target location even when the imaging target location of the sample Sm is determined.

[0039] Also, according to the above-described embodiment, the marker 14 has a shape that is not point-symmetrical (for example, a concave portion of the contour shape of the space in which the sample Sm can be imaged) when viewed from the imaging direction of the imaging unit 11. By determining the orientation of the OCT image based on the position of the concave portion represented in the OCT image, the observer can notice when the OCT image is rotated.

[0040] Further, according to the above-described embodiment, the marker 14 has a shape that is not line-symmetric when viewed from the imaging direction of the imaging unit 11. By determining whether the OCT image is inverted based on the shape of any part of the marker 14 represented in the OCT image, the observer can notice that the OCT image is inverted when it is inverted.

[0041] Further, according to the above-described embodiment, the display unit 15 displays an OCT image in which at least one of a cross-section of the marker 14 and a cross-section of the fixing unit 12 and a cross-section of the sample Sm are represented. Fixing unit 12 is pressed against at least one of the sample Sm or the marker 14 with a magnitude of force set according to the position of the surface of the sample Sm with respect to the marker 14 or the fixing unit 12. When the pressure for pressing the fixing unit 12 against the sample Sm is low, the fixing unit 12 cannot properly fix the sample Sm, and the observer may not be able to observe the activities of biological tissues such as metabolism due to motion artifacts. Also, when the pressure for pressing the fixing unit 12 against the sample Sm is high, the fixing unit 12 may excessively compress the blood vessels of the sample Sm, resulting in poor blood flow in the sample Sm and the photographed blood vessels becoming thinner than normal. In this case, the observer cannot appropriately observe the sample Sm. Furthermore, when photographing and comparing different samples Sm or when photographing and comparing one sample Sm multiple times, it is necessary to improve the reproducibility of the pressure for pressing the fixing unit 12 against the sample Sm. Therefore, in order to observe (measure) the sample Sm, it is necessary to press the fixing unit 12 against the sample Sm with an appropriate pressure. According to the imaging device 10 according to the embodiment, by comparing the height of a part of the position of the marker 14 with the height of the highest position of the surface of the sample Sm, the pressure at which the fixing unit 12 is pressed against the sample Sm can be determined and adjusted. Therefore, the imaging device 10 can press the fixing unit 12 against the sample Sm with an appropriate pressure, improve the reproducibility of the imaging result, and capture the target OCT image.

[0042] [Configuration of a Modification of the Hardware] The imaging device 10 according to the embodiment may include a pressure sensor 16 instead of the display unit 15. The observer may adjust the pressure with which the fixing unit 12 is pressed against the sample Sm according to the value of the pressure acquired by the pressure sensor 16. The description of the matters described in the above-described hardware configuration may be omitted.

[0043] FIG. 8 is a diagram for explaining an imaging device including a pressure sensor. FIG. 8(A) is a side view showing the situation before the sample Sm is fixed. FIG. 8(B) is a top view showing the situation before the sample Sm is fixed. The pressure sensor 16 will be described with reference to this figure. The pressure sensor 16 measures the pressure with which the driving unit 13 presses the fixing unit 12 against the sample Sm by being sandwiched between the marker 14 and the fixing unit 12 or between the sample Sm and the fixing unit 12. The pressure sensor 16 may be, for example, a sensor that obtains pressure from the strain of silicon, or a resistive film type pressure sensor. Further, the pressure sensor 16 may have a space in which the imaging unit 11 can image the sample Sm. In FIG. 8, an example in which the fixing unit 12 and the pressure sensor 16 are provided independently is shown, but the pressure sensor 16 may be provided at the tip of the fixing unit 12, that is, at the position where the fixing unit 12 contacts the sample Sm.

[0044] [Summary of the Modification of the Hardware] According to the above-described embodiment, the pressure sensor 16 measures the pressure with which the fixing unit 12 presses the sample Sm or the marker 14 by being arranged so as to be sandwiched between at least one of between the marker 14 and the fixing unit 12 and between the sample Sm and the fixing unit 12. The skin of the human body used as the sample Sm varies in elasticity depending on age and season. Therefore, when determining the pressure based on the swelling of the surface of the sample Sm when the fixing part 12 is pressed against it, even if the swelling of the surface of the sample Sm when the fixing part 12 is pressed against it is about the same, there is a possibility that the fixing part 12 is actually pressed against the sample Sm with different pressures. According to the pressure sensor 16 capable of quantifying and outputting the pressing pressure, the observer can determine the pressure with which the fixing part 12 is pressed against the sample Sm and adjust the pressure without being affected by individual differences in the sample Sm.

[0045] [Software Configuration] With reference to FIG. 9, the software configuration will be described. FIG. 9 is a block diagram for explaining an example of the functional configuration of the correction device according to the embodiment. The correction device 20 includes an OCT image acquisition unit 21, a selection unit 22, a calculation unit 23, a correction unit 24, and an output unit 25. Each of these functional units is realized, for example, using a computer and software. Further, each functional unit may be realized using an electronic circuit as necessary. Furthermore, each functional unit may not be included in a single device, and may be configured such that the correction device 20 is composed of a plurality of devices.

[0046] The OCT image acquisition unit 21 acquires OCT images obtained by performing optical coherence tomography (OCT) imaging at different times from the imaging unit 11 provided in the imaging device 10.

[0047] The selection unit 22 selects any one of the plurality of OCT images acquired by the OCT image acquisition unit 21 as a reference image. Further, the selection unit 22 selects any one of the OCT images that have not been selected as the reference image among the plurality of OCT images acquired by the OCT image acquisition unit 21 as a target image.

[0048] The calculation unit 23 calculates a deviation amount indicating the difference between the position of the sample Sm represented in the reference image and the position of the sample Sm represented in the target image for the reference image and the target image selected by the selection unit 22. The deviation amount may be, for example, the moving distance and direction of feature points extracted from the sample Sm represented in the reference image and the sample Sm represented in the target image respectively. Hereinafter, an example of the method for calculating the deviation amount will be specifically described.

[0049] In the first example of the method for calculating the deviation amount, the calculation unit 23 calculates the deviation amount between one reference image and each of the other OCT images. The selection unit 22 selects any one of the plurality of OCT images as the reference image. For example, the selection unit 22 may select, as the OCT image, an image captured at an intermediate time in chronological order (the 16th image when 32 images are captured in chronological order) among the OCT images. The calculation unit 23 calculates the deviation amount between the reference image and each of the other OCT images.

[0050] FIG. 10 is a flowchart for explaining a second example of the method for calculating the deviation amount. In the second example of the method for calculating the deviation amount, the calculation unit 23 calculates the deviation amount between each of the plurality of OCT images. The selection unit 22 selects any one of the plurality of OCT images acquired by the OCT image acquisition unit 21 as the reference image (step S101). Further, the selection unit 22 selects an OCT image captured at a time (for example, 204.8 [ms]) away from the time when the reference image was captured as the target image (step S102). The reference image and the target image may be two adjacent OCT images in chronological order, or two OCT images separated from each other by several frames. The calculation unit 23 calculates the deviation amount between the reference image and the target image selected by the selection unit 22 (step S103).

[0051] The selection unit 22 determines whether, at a time that is a predetermined time away from the time when the target image was captured, OCT images that have not been selected as reference images or target images, that is, OCT images that can be selected as the next target image, are included in the plurality of OCT images (step S104).

[0052] If an OCT image that can be selected as the next target image is included (step S104; Yes), the selection unit 22 selects the selected target image as the reference image (step S105). Thereafter, the selection unit 22 and the calculation unit 23 repeatedly execute the processing from step S102. If an OCT image that can be selected as the next target image is not included (step S104; No), the selection unit 22 and the calculation unit 23 end the processing.

[0053] In a third example of the method for calculating the deviation amount, the calculation unit 23 calculates the deviation amount using the first example and the second example. The calculation unit 23 may calculate the deviation amount based on the first example and the deviation amount based on the second example separately and independently. Also, the calculation unit 23 may calculate the deviation amount by combining the first example and the second example.

[0054] An example of calculating the deviation amount by combining the first example and the second example will be specifically described below. The selection unit 22 may divide the plurality of OCT images into several sets (hereinafter, may be described as blocks in some cases). The calculation unit 23 calculates the deviation amount between the OCT images for each block (second example). Also, the selection unit 22 may select one OCT image for each block, and among the selected plurality of OCT images, select one as the reference image. The calculation unit 23 calculates the deviation amount between each of the plurality of OCT images selected by the selection unit 22 and the reference image (first example).

[0055] The correction unit 24 corrects a plurality of OCT images so as to unify the positions of the sample Sm represented in the OCT images based on the deviation amount calculated by the calculation unit 23. That is, the correction unit 24 performs image alignment of the OCT images based on the deviation amount. The correction unit 24 may correct all of the plurality of OCT images, or may correct other OCT images in accordance with a reference OCT image (for example, a reference image). The correction of the OCT images by the correction unit 24 may be performed, for example, in units of sub-pixels.

[0056] The output unit 25 outputs a plurality of OCT images corrected by the correction unit 24. Note that logarithmic intensity variance (LIV), which is one of the analysis methods that can visualize the dynamics image of a sample by being affected only by the time-varying component of the signal without being affected by the signal intensity, is calculated using logarithmic values. Since the OCT image acquisition unit 21, the selection unit 22, and the calculation unit 23 according to the embodiment perform processing using OCT images with pixel values represented by decimal values, the output unit 25 may convert the pixel values of the plurality of OCT images into logarithms and output them.

[0057] FIG. 11 is a flowchart for explaining an example of the processing flow of the correction device according to the embodiment. The OCT image acquisition unit 21 acquires a plurality of OCT images taken at different times by the imaging unit 11 (step S201). The selection unit 22 selects any one of the plurality of OCT images acquired by the OCT image acquisition unit 21 as a reference image (step S202). The calculation unit 23 calculates the deviation amount between the reference image selected by the selection unit 22 and other OCT images (step S203). The correction unit 24 corrects the positions of the sample Sm represented in the reference image and other OCT images based on the deviation amount calculated by the calculation unit 23 (step S204). The output unit 25 logarithmically converts the pixel values of the plurality of OCT images corrected by the correction unit 24 (step S205).

[0058] [Summary of Software] According to the above-described embodiment, the OCT image acquisition unit 21 acquires an OCT image obtained by performing optical coherence tomography (OCT) imaging on a biological tissue in a living body as a sample. The selection unit 22 selects any one of a plurality of OCT images taken at different times as a reference image. The calculation unit 23 calculates the amount of deviation between the position of the sample Sm represented in the OCT image taken at a time different from the time when the reference image was taken and the position of the sample Sm represented in the reference image. The correction unit 24 corrects the position of the sample Sm in the OCT image based on the amount of deviation calculated by the calculation unit 23. The output unit 25 outputs the OCT image corrected by the correction unit 24. The position of the sample Sm represented in the OCT image changes due to the influence of involuntary movement of the living body. For example, when the time when a certain OCT image is taken is defined as the first time, and the time when an OCT image is taken later is defined as the second time, and the position of the sample Sm moves from the first time to the second time, the position of the sample Sm represented in the OCT image also moves accordingly. If the signal intensity of the pixels in the OCT image changes due to the movement of the sample Sm, dynamic OCT will image it as if there is movement at that position, and it will be difficult to observe small movements such as the activities of biological tissues such as metabolism. The correction device 20 according to the embodiment reduces motion artifacts caused by involuntary movement by correcting the positional deviation of the sample Sm represented in the OCT image through image registration. Therefore, according to the correction device 20, an observer can observe the activities of biological tissues such as the metabolism of a living person.

[0059] Also, according to the above-described embodiment, the calculation unit 23 calculates the amount of deviation between the reference image and each of a plurality of other OCT images, using one OCT image selected by the selection unit 22 as the reference image. By calculating the displacement amounts between one OCT image and other OCT images among a plurality of OCT images respectively, even if an error occurs because the displacement amount cannot be accurately calculated between any of the OCT images, the error does not affect the displacement amounts between other OCT images. Therefore, the calculation unit 23 can accurately calculate the displacement amount. Accordingly, by accurately correcting the OCT image by the correction device 20 according to the embodiment, an observer can observe the activities of biological tissues such as the metabolism of a living person.

[0060] Also, according to the above-described embodiment, the selection unit 22 further selects, as a target image, an OCT image taken at a time that is a predetermined time away from the time when the reference image was taken. The calculation unit 23 calculates the displacement amount between the reference image and the target image. When an OCT image taken at a time that is a predetermined time away from the time when the target image was taken and that has not been selected as the reference image or the target image is included in the plurality of OCT images taken at different times, the selection unit 22 and the calculation unit 23 perform a repetitive process with the target image as a new reference image. The calculation unit 23 can calculate the displacement amount of the OCT images according to the regularity of the movement of the sample Sm by calculating the displacement amounts between the OCT images in order. Therefore, the calculation unit 23 can accurately calculate the displacement amount.

[0061] Also, according to the above-described embodiment, the calculation unit 23 calculates the displacement amounts between one OCT image selected by the selection unit 22 as a reference image and a plurality of other OCT images respectively. The selection unit 22 further selects, as a target image, an OCT image taken at a time that is a predetermined time away from the time when the reference image was taken. The calculation unit 23 calculates the displacement amount between the reference image and the target image. When an OCT image taken at a time that is a predetermined time away from the time when the target image was taken and that has not been selected as the reference image or the target image is included in the plurality of OCT images taken at different times, the selection unit 22 and the calculation unit 23 perform a repetitive process with the target image as a new reference image. That is, the deviation amount is calculated using the first example and the second example of the deviation amount calculation method. The correction unit 24 can correct the OCT image more accurately by using the deviation amount calculated by the first example and the deviation amount calculated by the second example, as compared with the case of using only the first example or the second example.

[0062] Also, according to the above-described embodiment, the calculation unit 23 performs calculations using an OCT image based on a value represented by a decimal number. The output unit 25 converts and outputs an OCT image based on a value represented by a decimal number into an OCT image based on a value represented by a logarithm. The analysis method using LIV requires an OCT image in which pixel values are represented logarithmically. However, when using an OCT image in which pixel values are represented logarithmically for calculating the deviation amount, the values of the lower digits of the pixel values may not be accurately represented, and there is a possibility that the calculation unit 23 cannot accurately calculate the deviation amount. On the other hand, for an OCT image in which pixel values are represented by decimal numbers, the values of the lower digits of the pixel values can be accurately represented. Therefore, the calculation unit 23 can accurately calculate the deviation amount by calculating the deviation amount using an OCT image based on decimal values.

[0063] Also, according to the above-described embodiment, the imaging system 1 includes an imaging device 10 including an imaging unit 11, a fixing unit 12, and a driving unit 13, and a correction device 20. The imaging unit 11 captures an OCT image obtained by performing optical coherence tomography (OCT) imaging on a biological tissue in a living body as a sample. The fixing unit 12 is provided in the imaging direction of the imaging unit 11 so that the position with respect to the imaging unit 11 does not change, has a space in which the imaging unit 11 can image the sample Sm, and the positions of the imaging unit 11 and the fixing unit 12 with respect to the sample Sm move relatively, whereby the sample is pressed against the periphery of the portion of the sample to be imaged by the imaging unit. The imaging system 1 can reduce motion artifacts more effectively by reducing the movement of the sample Sm during imaging (measurement) using the imaging device 10, and further correcting the position of the sample Sm represented in the OCT image captured using the correction device 20. Therefore, according to the imaging system 1 including the imaging device 10 and the correction device 20, an observer can more easily observe the activities of living tissues such as the metabolism of a living person.

[0064] [Comparison of Results] FIG. 12 is a diagram showing dynamic OCT tomographic images of human arm skin with and without using the imaging device and the correction device according to the embodiment. FIG. 12(A) is an OCT tomographic image captured without using the imaging device 10 and the correction device 20. FIG. 12(B) is an OCT tomographic image captured using the imaging device 10 and the correction device 20. In FIG. 12(A), the entire tissue of the sample Sm shows high metabolism (white). This is a motion artifact generated due to minute movement of the arm during imaging, and is an example of a failure in dynamic OCT measurement. In FIG. 12(A), it is difficult to observe (measure) the activities of living tissues due to the motion artifact. Note that although FIG. 12 is represented in grayscale, it may actually be colored according to the magnitude of the movement. FIG. 12(B) is an OCT tomographic image captured using the imaging device 10 and the correction device 20. By using the imaging device 10 and the correction device 20, a clear dynamic OCT signal can be visualized in living skin. The white line (horizontal line) visible slightly below the surface of the skin is the "epidermal basement membrane (EBM)" that could not be measured by conventional dynamic OCT. The epidermal basement membrane EBM is a central tissue in skin metabolism and is strongly related to skin health and aging. By visualizing the epidermal basement membrane EBM of a living person with dynamic OCT, it becomes possible to simply evaluate the skin health level.

[0065] Referring to FIG. 13, it will be described how much the imaging device 10 and the correction device 20 can reduce motion artifacts. When determining the degree of reduction, three ROIs (Regions of Interests) are selected from within the OCT image. Next, the LIVs at the three locations are calculated. The three ROIs (ROI1, ROI2, ROI3) do not include blood vessels and are selected from different depths of the OCT tomographic image by B-scan. Specifically, the center point of ROI1 is at a position 80 [μm] from the surface of the sample Sm. Also, the center point of ROI2 is at a position 250 [μm] from the surface of the sample Sm. Further, the center point of ROI3 is at a position 400 [μm] from the surface of the sample Sm. The calculation of the LIV is performed for five subjects, and then the average value and the standard deviation of the LIV are calculated. The smaller the values of the average and standard deviation of the LIV, the smaller the temporal change in the OCT signal intensity, that is, the smaller the influence of the motion artifacts generated by the involuntary movement of the sample Sm.

[0066] FIG. 13 is a diagram showing the average value and standard deviation of the LIV of the three ROIs for each usage situation of the imaging device and the correction device. In FIG. 13, the bar graph shows the average value of the LIV, and the error bar shows the standard deviation of the LIV. FIG. 13(A) shows the results for each ROI when neither the imaging device 10 nor the correction device 20 was used. FIG. 13(B) shows the results for each ROI when only the correction device 20 was used. FIG. 13(C) shows the results for each ROI when only the imaging device 10 was used. FIG. 13(D) shows the results for each ROI when both the imaging device 10 and the correction device 20 were used.

[0067] From FIGS. 13(A) to 13(D), the average value of LIV decreases, and the standard deviation also decreases. From this, it can be seen that by using the imaging device 10 and the correction device 20, the influence of motion artifacts due to involuntary movement of the sample Sm can be suppressed. Also, from FIG. 13(D), it can be seen that by using the imaging device 10 and the correction device 20 together, the influence of motion artifacts due to involuntary movement of the sample Sm can be further suppressed. In addition, a paired t-test was performed between FIGS. 13(A) and 13(C), and between FIGS. 13(A) and 13(D), and it was determined that there was a statistically significant difference.

[0068] [Basic Theory] FIG. 14 shows simulation results of the movement of scatterers in a sample and the LIV calculated from the movement. FIG. 14(A) shows the value of LIV when each scatterer (cell) moves independently and isotropically and randomly. FIG. 14(B) shows the value of LIV when each scatterer moves in a certain direction.

[0069] From FIG. 14(A), when the scatterers in the sample Sm move about several tens of [nm], it affects the LIV. Therefore, conventionally, in order to measure the activity of a biological tissue, it was considered necessary to suppress the involuntary movement of the sample Sm during the measurement time (for example, about 6.5 [s]) to about several tens of [nm]. However, since the involuntary movement of the sample Sm is the movement of the entire sample Sm, it can be assumed that the scatterers move in a certain direction. From FIG. 14(B), in this case, even if the sample Sm moves about 1 [μm] to 5 [μm] during the measurement time, it hardly affects the value of LIV. That is, by suppressing the involuntary movement of the sample Sm (the scatterers move in a certain direction) to a movement of about 1 [μm] to 5 [μm], the motion artifacts due to involuntary movement can be reduced, and the activity of the biological tissue (the scatterers move randomly) of the sample Sm can be measured.

[0070] Note that the entire functions or some of the functions of each part included in the imaging device 10 and the correction device 20 in the above-described embodiment may be realized by recording a program for realizing these functions on a computer-readable recording medium, reading the program recorded on this recording medium into a computer system, and executing it. Here, the "computer system" is assumed to include hardware such as an OS and peripheral devices.

[0071] As described above, an embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the gist of the present invention. Also, the configurations described in the above-described embodiments and each example may be combined.

Explanation of Reference Numerals

[0072] 1... Imaging system, 10... Imaging device, 11... Imaging unit, 12... Fixing unit, 13... Driving unit, 14... Marker, 15... Display unit, 16... Pressure sensor, 20... Correction device, 21... OCT image acquisition unit, 22... Selection unit, 23... Calculation unit, 24... Correction unit, 25... Output unit, Sm... Sample, EBM... Epidermal basement membrane

Claims

1. An OCT image acquisition unit that acquires an OCT image obtained by performing optical coherence tomography (OCT) imaging on a biological tissue in a living body as a sample; A selection unit that selects, as a reference image, any one of the plurality of OCT images taken at different times; A calculation unit that calculates the amount of deviation between the position of the sample represented in the OCT image taken at a time different from the time when the reference image was taken and the position of the sample represented in the reference image; A correction unit that corrects the position of the sample in the OCT image based on the amount of deviation calculated by the calculation unit; An output unit that outputs the OCT image corrected by the correction unit; A correction device comprising:

2. The calculation unit calculates the amount of deviation between the reference image and each of the other plurality of OCT images The correction device according to claim 1.

3. The selection unit further selects, as a target image, an OCT image taken at a time a predetermined time away from the time when the reference image was taken, The calculation unit calculates the amount of deviation between the reference image and the target image, When the OCT image taken at a time a predetermined time away from the time when the target image was taken and not selected as a reference image or a target image is included in the plurality of OCT images taken at different times, the target image is newly used as a reference image, and the selection unit and the calculation unit perform repetitive processing The correction device according to claim 1.

4. The calculation unit calculates the amount of deviation between the reference image and each of the other plurality of OCT images, Also, The selection unit selects, as a reference image, any one of the plurality of OCT images taken at different times, and further selects, as a target image, an OCT image taken at a time a predetermined time away from the time when the reference image was taken, The calculation unit calculates the amount of deviation between the reference image and the target image, When the OCT image taken at a time a predetermined time away from the time when the target image was taken and not selected as a reference image or a target image is included in the plurality of OCT images, the target image is newly used as a reference image, and the selection unit and the calculation unit perform repetitive processing The correction device according to claim 1.

5. The calculation unit performs calculations using the OCT image based on a value expressed in decimal, and the output unit converts and outputs the OCT image based on a value expressed in decimal to an OCT image based on a value expressed in logarithm. The correction device according to any one of claims 2 to 4.

6. An imaging unit that images an OCT image obtained by performing optical coherence tomography on a biological tissue in a living body as a sample, An imaging device comprising: a fixing unit provided in the imaging direction of the imaging unit so that the position with respect to the imaging unit does not change, having a space in which the imaging unit can image the sample, and being pressed around a portion of the sample to be imaged by the imaging unit when the position with respect to the sample moves relatively. The correction device according to any one of claims 1 to 4, An imaging system comprising.

7. An OCT image acquisition step of acquiring an OCT image obtained by performing optical coherence tomography (OCT: Optical Coherence Tomography) on a biological tissue in a living body as a sample, A selection step of selecting, as a reference image, any one of the plurality of OCT images taken at different times, A calculation step of calculating a deviation amount between the position of the sample represented in the OCT image taken at a time different from the time when the reference image was taken and the position of the sample represented in the reference image, A correction step of correcting the position of the sample in the OCT image based on the deviation amount calculated in the calculation step, An output step of outputting the OCT image corrected in the correction step, A correction method having.

8. An imaging unit that images an OCT image obtained by performing optical coherence tomography (OCT: Optical Coherence Tomography) on a biological tissue in a living body as a sample, A fixing unit provided in the imaging direction of the imaging unit so that the position with respect to the imaging unit does not change, having a space in which the imaging unit can image the sample, and being pressed around a portion of the sample to be imaged by the imaging unit when the position with respect to the sample moves relatively. An imaging device comprising.

9. Further comprising a marker temporarily fixed to the surface of the sample and having a space in which the imaging unit can image the sample. The fixing part is pressed against at least one of the marker and the area around the marker. The imaging device according to claim 8.

10. When viewed from the imaging direction of the imaging unit, the marker has a shape that is not point-symmetric. The imaging device according to claim 9.

11. When viewed from the imaging direction of the imaging unit, the marker has a shape that is not line-symmetric. The imaging device according to claim 9.

12. The imaging device further includes a display unit that displays the OCT image representing at least one of a cross-section of the marker temporarily fixed to the surface of the sample and having a space in which the imaging unit can image the sample, a cross-section of the fixing part, and a cross-section of the sample. The fixing part is pressed against at least one of the sample and the marker with a magnitude of force set according to the position of the surface of the sample with respect to the marker or the fixing part. The imaging device according to any one of claims 8 to 11.

13. A pressure sensor that measures the pressure with which the fixing part presses the sample or the marker is disposed so as to be sandwiched between at least one of the space between the marker temporarily fixed to the surface of the sample and having a space in which the imaging unit can image the sample and the fixing part, and the space between the sample and the fixing part. The imaging device according to any one of claims 8 to 11, further comprising the pressure sensor.

Images