Information processing device, information processing method, and computer program

Abstract

To provide an information processing device, information processing method and computer program, which allow for reducing the influence of the motion of a biological object under observation.SOLUTION: An information processing device is provided, comprising a reception unit for receiving an OCT image represented by a complex signal, a division unit for dividing the OCT image received by the reception unit into multiple segments, and an aberration correction unit configured to identify a scanning direction of each of the multiple segments to correct the aberrations of the multiple segments according to the identified scanning directions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD Embodiments of the present invention relate to an information processing device, an information processing method, and a computer program. [Background technology]

[0002] Optical Coherence Tomography (OCT) uses low-coherence optical interference to resolve the depth of internal structures (time coherence gate) and amplify and detect weak scattered light from biological tissue. Furthermore, Fourier-domain OCT further enhances sensitivity by efficiently and simultaneously detecting light scattered by tissues at different depths, enabling high-speed three-dimensional imaging of biological tissues.

[0003] However, imaging deep inside biological tissues with high spatial resolution poses the problems of high numerical aperture and multiple scattering. To increase lateral spatial resolution, a high numerical aperture is necessary. However, when observing deep inside a living body with a high numerical aperture, the aberration of the optical wavefront caused by the biological tissue itself increases, resulting in a decrease in resolution. This is a common problem in optical biological imaging. Increasing the numerical aperture in OCT poses another problem. Conventional OCT uses the confocal effect to reduce the effects of multiple scattering. However, because the depth position of the focal point where light is collected is fixed, the focus shifts at depths far from the focal point in the tomographic image, resulting in a decrease in lateral resolution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent No. 9,269,144 [Patent Document 2] U.S. Patent Application Publication No. 2021 / 0109340 [Non-patent literature]

[0005] [Non-Patent Document 1] Y. Chen et al., “Three-dimensional eye motion correction by Lissajous scan optical coherence tomography”, Biomed. Opt. Express 8(3), 1783-1802 (2017). [Non-patent document 2] MF Kraus et al., “Motion correction in optical coherence tomography volumes on a per A-scan basis using orthogonal scan patterns”, Biomed. Opt. Express 3(6), 1182-1199 (2012). [Non-patent document 3] K. Liang et al., “Cycloid scanning for wide field optical coherence tomography endomicroscopy and angiography in vivo”, Optica 5(1), 36-43 (2018). Summary of the Invention [Problem to be solved by the invention]

[0006] To solve the problem of defocusing at depths far from the focal position in a tomographic image, resulting in a loss of lateral resolution, two approaches have been proposed: using an additional optical modulation device and correcting the problem through signal processing. The former method uses dynamic focusing, which combines data from multiple images taken by changing the focal position, and adaptive optics to correct aberrations. However, these methods require adding devices such as variable lenses, deformable mirrors, and wavefront sensors to the optical system, which increases costs. Another problem is that acquiring multiple data sets requires long imaging times.

[0007] In contrast, the latter approach, known as Digital Aberration Correction (DAC), takes advantage of OCT's ability to acquire optical phase information through optical interference and corrects the effects of defocus and aberrations through complex signal processing after data acquisition. While no additional equipment is required, involuntary movements of the living body present a significant hurdle. Even small image distortions due to involuntary movements can significantly affect the success of digital aberration correction, which means that the imaging speed requirements for OCT are much stricter (less than a few tenths of a second) than the typical 3D-OCT image acquisition (several seconds). Ultrafast OCT systems (>1,000,000 A-lines / s) have been developed, but they are expensive experimental devices for research purposes. The speed of typical commercial OCT systems (~100,000 A-lines / s) means they are limited to very small imaging areas. An object of the present invention is to provide an information processing device, an information processing method, and a computer program that can reduce the influence of the movement of a living body that is the observation target. [Means for solving the problem]

[0008] One embodiment of the present invention provides a method for detecting an OCT image, comprising: a reception unit that receives an OCT image represented by a complex signal; a division unit that divides the OCT image received by the reception unit into a plurality of segments; a phase correcting unit that corrects the phase of each of the plurality of segments based on phase information included in the OCT image represented by a complex signal; Identifying a scanning direction for each of the plurality of segments, and based on the identified scanning direction, Phase corrected and an aberration correction unit that corrects aberrations of the plurality of segments. An embodiment of the present invention is the information processing device described above, further comprising an image reconstruction unit that outputs a complex OCT signal, and the reception unit receives the complex OCT signal output by the image reconstruction unit as an OCT image. 。 Book In one embodiment of the invention, in the information processing device, each of the plurality of segments corresponds to a signal for one-dimensional scanning. An embodiment of the present invention is the above-mentioned information processing device, further comprising an acquisition unit that acquires information specifying a scanning trajectory of the OCT image accepted by the acceptance unit, and the aberration correction unit specifies a scanning direction for each of the plurality of segments based on the information specifying the scanning trajectory. In one embodiment of the present invention, in the aforementioned information processing device, the scanning trajectory is any one of a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory. An embodiment of the present invention is the aforementioned information processing device, further comprising a motion correction unit that corrects positional deviations due to involuntary movement of the object of observation for the plurality of segments whose aberrations have been corrected by the aberration correction unit. In one embodiment of the present invention, the information processing device further comprises a synthesis unit that synthesizes each of the plurality of segments corrected by the motion correction unit. In one embodiment of the present invention, in the information processing device, the synthesis unit converts each of the plurality of segments into real number data. In one embodiment of the present invention, in the information processing device, the synthesis unit takes a geometric mean between overlapping signals of each of the plurality of segments converted into real number data.

[0009] One embodiment of the present invention includes a method for detecting an OCT image represented by a complex signal, acquiring information specifying a scanning trajectory of the OCT image received in the receiving step, and dividing the OCT image into a plurality of segments. correcting the phase of each of the plurality of segments based on phase information included in the OCT image represented by a complex signal; Based on the information specifying the scanning trajectory, Phase corrected Identifying a scanning direction for each of the plurality of segments, and based on the identified scanning direction, Phase corrected and correcting aberrations of a plurality of said segments.

[0010] One embodiment of the present invention provides a method for performing a scan on a computer, the method comprising the steps of: receiving an OCT image represented by a complex signal; acquiring information specifying a scanning trajectory of the OCT image received in the receiving step; and dividing the OCT image into a plurality of segments. correcting the phase of each of the plurality of segments based on phase information included in the OCT image represented by a complex signal; Based on the information specifying the scanning trajectory, Phase corrected Identifying a scanning direction for each of the plurality of segments, and based on the identified scanning direction, Phase corrected and correcting aberrations of the plurality of segments. [Effects of the Invention]

[0011] According to the embodiments of the present invention, it is possible to provide an information processing device, an information processing method, and a computer program that can reduce the influence of the movement of a living organism that is an observation target. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram illustrating an example of a configuration of an information processing apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating an example of processing performed by the information processing apparatus according to the present embodiment. [Figure 3] FIG. 2 is a diagram illustrating an example of processing performed by the information processing apparatus according to the present embodiment. [Figure 4] 10 is a flowchart illustrating an example of the operation of the information processing apparatus according to the present embodiment. [Figure 5] FIG. 10 is a diagram illustrating another example of the configuration of the information processing apparatus according to the present embodiment. [Figure 6] FIG. 10 is a diagram illustrating an example of the configuration of an information processing device according to a modified example of the embodiment. [Figure 7] FIG. 10 is a diagram showing an example of a Lissajous scanning trajectory. [Figure 8] FIG. 10 is a diagram illustrating an example of a raster scanning trajectory. [Figure 9] FIG. 10 is a diagram showing an example of a cycloidal scanning orbit. [Figure 10] FIG. 10 is a diagram illustrating an example of an operation of an information processing apparatus according to a modified example of the embodiment. [Figure 11] FIG. 10 is a diagram illustrating an example of an operation of an information processing apparatus according to a modified example of the embodiment. [Figure 12] 10 is a flowchart illustrating an example of an operation of an information processing apparatus according to a modified example of the embodiment. [Figure 13A] FIG. 10 is a diagram illustrating an example 1 of a processing result of the information processing device according to the modified example of the embodiment. [Figure 13B] FIG. 10 is a diagram illustrating an example 1 of a processing result of the information processing device according to the modified example of the embodiment. [Figure 13C] FIG. 10 is a diagram illustrating an example 1 of a processing result of the information processing device according to the modified example of the embodiment. [Figure 14] FIG. 10 is a diagram illustrating a second example of a processing result of the information processing device according to the modified example of the embodiment. [Figure 15] FIG. 10 is a diagram illustrating an example 3 of a processing result of the information processing device according to the modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, an information processing apparatus, an information processing method, and a computer program according to the present embodiment will be described with reference to the drawings. The embodiment described below is merely an example, and the embodiments to which the present invention is applied are not limited to the following embodiments. In all the drawings for explaining the embodiments, the same reference numerals are used for components having the same functions, and repeated explanations will be omitted. Furthermore, in this application, "based on XX" means "based on at least XX," and includes cases where it is based on other elements in addition to XX. Furthermore, "based on XX" is not limited to cases where XX is used directly, but also includes cases where it is based on XX that has been calculated or processed. "XX" is any element (for example, any information).

[0014] (Embodiment) (Information processing device) FIG. 1 is a diagram illustrating an example of the configuration of an information processing apparatus according to an embodiment of the present invention. The information processing device 10 of this embodiment receives an OCT image represented by a complex signal (complex OCT signal). An example of an OCT image is an image obtained by an OCT device. An example of an OCT device is a scanning coherent imaging device that samples overlapping positions of in vivo biological tissue by changing the scanning direction. An example of an OCT image is a front image, where the observation plane is perpendicular to the depth direction of the sample. Here, the depth direction of the sample is the direction in which the measurement light is incident on the sample. The front is also called the en-face plane. The information processing device 10 generates an image in which the effects of optical aberrations are reduced from multiple data sets in different scanning directions, including phase information acquired by the OCT device. The information processing device 10 corrects the reduction in resolution due to optical aberrations in scanning coherent imaging by signal processing. Specifically, the information processing device 10 divides the received OCT image represented by a complex signal into multiple segments. For example, the information processing device 10 divides the OCT image represented by a complex signal into short rigid segments that are acquired in a short acquisition time and have little motion distortion. By dividing the image into segments with little motion distortion, digital aberration correction can be applied. The information processing device 10 identifies the scanning direction of each of the multiple segments. Here, the scanning direction is the direction in which the OCT probe light is scanned. The information processing device 10 performs digital aberration correction on each of the multiple segments based on the identified scanning direction. The information processing device 10 outputs the results of the digital aberration correction on each of the multiple segments.

[0015] The information processing device 10 is realized by a device such as a personal computer, a server, a smartphone, a tablet computer, or an industrial computer. The information processing device 10 includes, for example, an input unit 11, a receiving unit 12, a dividing unit 13, an aberration correction unit 16, an output unit 19, and a storage unit 20. The input unit 11 inputs information. As an example, the input unit 11 may have an operation unit such as a keyboard and a mouse. In this case, the input unit 11 inputs information according to an operation performed by a user on the operation unit. As another example, the input unit 11 may input information from an external device. The external device may be, for example, a portable storage medium. An OCT image represented by a complex signal is input to the input unit 11. An example of an OCT image represented by a complex signal is an image in which the observation plane is the front (en-face) plane perpendicular to the depth direction of the sample. Examples of objects to be observed as samples include living human or animal organisms, non-living objects, etc. Examples of living organisms include the fundus of the eye, blood vessels, teeth, subcutaneous tissue, etc. Examples of non-living objects include artificial structures such as electronic components and machine parts, natural structures such as stone and minerals, and substances without a specific shape.

[0016] The receiving unit 12 receives an OCT image represented by a complex signal input to the input unit 11. The OCT image represented by a complex signal is represented by a complex signal. The receiving unit 12 stores the received OCT image represented by the complex signal in the storage unit 20. The dividing unit 13 acquires an OCT image represented by a plurality of complex signals stored in the storage unit 20. The dividing unit 13 divides the acquired OCT image represented by the complex signals into a plurality of segments based on the scanning trajectory of the OCT image represented by the complex signals. An example of each of the plurality of segments corresponds to a signal for one-dimensional scanning. Here, the dividing unit 13 acquires in advance information indicating the scanning trajectory of the OCT image represented by the complex signals. The aberration correction unit 16 acquires the plurality of segments from the division unit 13. The aberration correction unit 16 identifies the scanning direction of each of the acquired plurality of segments.

[0017] FIG. 2 is a diagram showing an example of processing by the information processing device of this embodiment. In FIG. 2, the horizontal axis is horizontal and the vertical axis is vertical. FIG. 2 shows an example of a scanning pattern (trajectory) of the OCT probe light. Here, the OCT probe light is scanned along a curve. Point 1, point 2, and point 3 are points on the scanning pattern of the probe light. In one example of a scanning pattern, point 1 is scanned in the vertical direction, point 2 is scanned in the diagonal direction (the direction in which the vertical axis increases as the horizontal axis increases), and point 3 is scanned in the horizontal direction. Here, as an example, the explanation will continue assuming that the aberration correction unit 16 acquires points 1, 2, and 3 as multiple segments, and specifies the vertical direction as the scanning direction for point 1, the diagonal direction as the scanning direction for point 2, and the horizontal direction as the scanning direction for point 3. Each of points 1, 2, and 3 is a signal for one-dimensional scanning. Each of points 1, 2, and 3 may be spaced at unequal intervals. The aberration correction unit 16 corrects the aberration of each of the multiple segments based on the specified scanning direction. For example, the aberration correction unit 16 performs a convolution operation between each of the multiple segments and an aberration correction filter. The aberration correction unit 16 corrects the aberration of point 1 based on the vertical direction specified as the scanning direction of point 1, corrects the aberration of point 2 based on the oblique direction specified as the scanning direction of point 2, and corrects the aberration of point 3 based on the horizontal direction specified as the scanning direction of point 3.

[0018] Fig. 3 is a diagram showing an example of processing by the information processing device of this embodiment. Fig. 3 schematically shows the results of aberration correction for each of points 1, 2, and 3. Fig. 3 shows the distribution of point images for each of points 1, 2, and 3. The aberration correction unit 16 performs digital aberration correction in the vertical direction relative to point 1. As a result, the distribution of point images in the vertical direction becomes narrower, as shown at point 1a, thereby improving vertical resolution. The aberration correction unit 16 performs digital aberration correction in the oblique direction relative to point 2 (the direction in which the vertical axis decreases as the horizontal axis increases). As a result, the distribution of point images in the oblique direction (the direction in which the vertical axis also increases as the horizontal axis increases) becomes narrower, as shown at point 2a, thereby improving diagonal resolution (the direction in which the vertical axis also increases as the horizontal axis increases). The aberration correction unit 16 performs digital aberration correction in the horizontal direction relative to point 3. As a result, the distribution of point images in the horizontal direction becomes narrower, as shown at point 3a, thereby improving horizontal resolution. Returning to Figure 1, we will continue our explanation.

[0019] The output unit 19 outputs information. As an example, the output unit 19 may have a display with a screen. In this case, the output unit 19 displays and outputs information on the screen. As another example, the output unit 19 may output information to an external device. The external device may be, for example, a portable storage medium. The output unit 19 acquires the results of digital aberration correction performed on points 1, 2, and 3 from the aberration correction unit 16, and outputs the acquired results of digital aberration correction performed on points 1, 2, and 3. The storage unit 20 stores information. The storage unit 20 stores the OCT image represented by the complex signal output by the reception unit 12.

[0020] The reception unit 12, division unit 13, aberration correction unit 16, and output unit 19 are realized by, for example, a hardware processor such as a CPU (Central Processing Unit) executing a computer program (software) stored in a storage unit 20. Furthermore, some or all of these functional units may be realized by hardware (including circuitry) such as an LSI (Large Scale Integration), an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a GPU (Graphics Processing Unit), or may be realized by a combination of software and hardware. The computer program may be stored in advance in a storage device such as an HDD (Hard Disk Drive) or flash memory, or may be stored in a removable storage medium such as a DVD (Digital Versatile Disc) or CD-ROM, and installed by inserting the storage medium into a drive device.

[0021] (Operation of information processing device 10) 4 is a flowchart showing an example of the operation of the information processing device of this embodiment. With reference to FIG. 4, the operation after an OCT image represented by a complex signal is input to the information processing device 10 will be described. (Step S1-1) The receiving unit 12 receives an OCT image represented by a complex signal input to the input unit 11. The receiving unit 12 stores the received OCT image represented by a complex signal in the storage unit 20. (Step S2-1) The dividing unit 13 acquires an OCT image represented by a complex signal stored in the storage unit 20. The dividing unit 13 divides the acquired OCT image represented by a complex signal into a plurality of segments based on the scanning trajectory of the OCT image represented by a complex signal. (Step S3-1) The aberration correction unit 16 acquires the plurality of segments from the division unit 13. The aberration correction unit 16 identifies the scanning direction of each of the acquired plurality of segments. The aberration correction unit 16 corrects the aberration of each of the plurality of segments based on the identified scanning direction. (Step S4-1) The output unit 19 acquires the results of the digital aberration correction performed on each of the plurality of segments from the aberration correction unit 16, and outputs the acquired results of the digital aberration correction performed on each of the plurality of segments.

[0022] In the above-described embodiment, the case where the observation target plane is a front surface perpendicular to the depth direction of the sample has been described, but this is not limiting. For example, the present invention can be applied to a case where the observation target plane is a surface that crosses a part or all of the observation target region. In the above-described embodiment, the information processing device 10 receives an OCT image represented by a complex signal (complex OCT signal), but this is not limiting. For example, a detection signal from a sensor that receives interference light in an OCT device may be input to the information processing device 10. FIG. 5 is a diagram showing another example of the configuration of the information processing device of this embodiment. This other configuration example of the information processing device is different from the information processing device 10 in that it includes an input unit 11-1 instead of the input unit 11 and an image reconstruction unit 11-2. A detection signal from a sensor is input to the input unit 11-1, which outputs the input detection signal to the image reconstruction unit 11-2. The image reconstruction unit 11-2 acquires the detection signals output by the input unit 11-1 and reconstructs an image based on the acquired detection signals. For example, the image reconstruction unit 11-2 can apply image reconstruction of normal Fourier domain OCT. The image reconstruction unit 11-2 acquires an OCT image represented by a complex signal (complex OCT signal) by reconstructing the image. The image reconstruction unit 11-2 outputs the acquired complex OCT signal to the reception unit 12. The receiving unit 12 receives the complex OCT signal input to the input unit 11 as an OCT image represented by a complex signal. The receiving unit 12 stores the received complex OCT signal in the storage unit 20.

[0023] According to the information processing device 10 of this embodiment, the information processing device 10 includes a receiving unit 12 that receives an OCT image represented by a complex signal, a dividing unit 13 that divides the OCT image represented by the complex signal received by the receiving unit 12 into a plurality of segments, and an aberration correction unit 16 that identifies a scanning direction for each of the plurality of segments and corrects aberrations for each of the plurality of segments based on the identified scanning direction. With this configuration, the information processing device 10 can divide the OCT image represented by a complex signal into multiple segments based on the scanning trajectory of the OCT image represented by a complex signal. The information processing device 10 can identify the scanning direction of each of the multiple segments and correct the aberration of each of the multiple segments based on the identified scanning direction. Therefore, the information processing device 10 can perform digital aberration correction on the OCT data even when there is an effect due to the movement of the living body being observed. The information processing device 10 can perform digital aberration correction on OCT data captured at high resolution over a certain range without using an expensive ultra-high-speed device. The information processing device 10 further includes an image reconstruction unit 11-2 that outputs a complex OCT signal, and the reception unit 12 receives the complex OCT signal output by the image reconstruction unit 11-2 as the OCT image represented by a complex signal. With this configuration, the information processing device 10 can receive a detection signal from the sensor of the OCT device.

[0024] In the information processing device 10, each of the plurality of segments corresponds to a signal for one-dimensional scanning. With this configuration, the aberration correction unit 16 in the information processing device 10 can identify the scanning direction of each of the acquired signals for the multiple one-dimensional scans and correct the signals for the multiple one-dimensional scans based on the identified scanning direction. For example, each of the signals for the multiple one-dimensional scans may be spaced at unequal intervals. Therefore, the information processing device 10 can perform digital aberration correction on the OCT data even when there is an effect due to the movement of the living body being observed.

[0025] (Modification of the embodiment) (Information processing device) 6 is a diagram showing a configuration example of an information processing device according to a modified embodiment. The information processing device 10a according to the modified embodiment receives an OCT image represented by a complex signal. In one example of an OCT image represented by a complex signal, the observation plane is a front (en-face) surface perpendicular to the depth direction of the sample. The information processing device 10a acquires information specifying the scanning trajectory of the OCT image represented by the received complex signal. Examples of the scanning trajectory include a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory. The information processing device 10a divides the received OCT image represented by the complex signal into multiple segments based on information specifying the scanning trajectory of the OCT image represented by the acquired complex signal. For example, the information processing device 10 acquires multiple segments by dividing the OCT image represented by the complex signal into cycles of the scanning trajectory of the OCT image represented by the complex signal. The information processing device 10a corrects the phase of each of the plurality of segments. For example, the information processing device 10a performs bulk-phase-correction on each of the plurality of segments.

[0026] The information processing device 10a identifies the scanning direction of each of the plurality of segments based on information identifying the scanning trajectory of the OCT image represented by the acquired complex signal, and performs digital aberration correction on each of the plurality of segments based on the identified scanning direction. The information processing device 10a corrects the positional deviation due to the involuntary movement of the object of observation for each of the plurality of segments that have been digitally corrected for aberration. The information processing device 10a synthesizes each of the plurality of segments whose positional deviations have been corrected, and outputs the result of synthesizing each of the plurality of segments whose positional deviations have been corrected.

[0027] The information processing device 10a is realized by a device such as a personal computer, a server, a smartphone, a tablet computer, an industrial computer, etc. The information processing device 10a includes, for example, an input unit 11, a receiving unit 12, a dividing unit 13a, a phase correcting unit 14, an acquiring unit 15, an aberration correcting unit 16a, a motion correcting unit 17, a combining unit 18, an output unit 19a, and a storage unit 20. The acquiring unit 15 acquires information specifying the scanning trajectory of the OCT image represented by the complex signal received by the receiving unit 12. An example of the scanning trajectory is any one of a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory. For example, the acquisition unit 15 may acquire information specifying a scanning trajectory associated with identification information of an OCT image represented by a complex signal received by the reception unit 12 from a storage unit that stores scanning trajectory related information that associates identification information of an OCT image represented by a complex signal with information specifying a scanning trajectory used to acquire the OCT image represented by the complex signal. Here, the storage unit may be provided in the information processing device 10a or in a cloud.

[0028] FIG. 7 is a diagram showing an example of a Lissajous scan trajectory (see, for example, Non-Patent Document 1). A Lissajous scan trajectory is a scan trajectory represented by a plane figure obtained by combining two mutually orthogonal simple harmonic motions. In FIG. 7, the left diagram is an example of a Lissajous scan trajectory, and the right diagram is an enlarged view of the center part of the left diagram. Sampling points are indicated by black dots. The curved line is an example of a single horizontal cycle. An OCT image is obtained by OCT scanning the probe light based on the Lissajous scan trajectory.

[0029] FIG. 8 is a diagram showing an example of a raster scanning trajectory (see, for example, Patent Document 1 and Non-Patent Document 2). In FIG. 8, solid arrows indicate the acquisition of B-scans, and dotted arrows indicate flyback. In FIG. 8, as shown in the left diagram, an XFAST scan is composed of B-scans parallel to the X-axis of the OCT scanner coordinate system, and as shown in the right diagram, a YFAST scan is composed of B-scans parallel to the Y-axis. dfast and dslow are interchangeable between the two scan types. An OCT image is obtained by the OCT device scanning the probe light based on the raster scanning trajectory. FIG. 9 shows an example of a cycloidal scanning trajectory (see, for example, Patent Document 2 and Non-Patent Document 3). A cycloidal scanning trajectory is a scanning trajectory represented by a planar curve obtained as the locus of a fixed point on a circle as the circle rotates according to a certain rule. The black dots indicate the spots of each circle scanned at equal time frame intervals, and due to the mirror inversion effect, they slowly rotate locally around the center of the circle during scanning. An OCT image is obtained by OCT scanning the probe light based on the cycloidal scanning trajectory. We will return to FIG. 6 to continue the explanation.

[0030] The dividing unit 13a acquires an OCT image represented by a plurality of complex signals stored in the storage unit 20. The dividing unit 13a acquires information specifying the scanning trajectory of the OCT image represented by the complex signals from the acquisition unit 15. The dividing unit 13a divides the OCT image represented by the acquired complex signals into a plurality of segments based on the information specifying the scanning trajectory of the OCT image represented by the acquired complex signals. An example of each of the plurality of segments corresponds to a signal for one-dimensional scanning at non-equidistant intervals. For example, when the information processing device 10 acquires information specifying a Lissajous scan trajectory, the information processing device 10 acquires multiple segments by dividing an OCT image represented by a complex signal into cycles of the Lissajous scan trajectory. Each example of the multiple segments corresponds to a signal for one-dimensional scanning at non-equidistant intervals. For example, when the information processing device 10 acquires information specifying a raster scanning trajectory, the information processing device 10 acquires a plurality of segments by dividing an OCT image represented by a complex signal into B-scans. For example, when the information processing device 10 acquires information specifying a cycloidal scanning orbit, the information processing device 10 acquires a plurality of segments by dividing the OCT image represented by a complex signal into cycles of the cycloidal scanning orbit, with each example of the plurality of segments corresponding to a signal for one-dimensional scanning at non-equidistant intervals. The phase corrector 14 acquires a plurality of segments from the divider 13a, and performs bulk phase correction on each of the acquired plurality of segments.

[0031] The aberration correction unit 16a can be the aberration correction unit 16. However, the aberration correction unit 16a acquires multiple segments that have undergone bulk phase correction from the phase correction unit 14. For example, the aberration correction unit 16a performs a convolution operation between each of the multiple segments that have undergone bulk phase correction and an aberration correction filter. Specifically, the aberration correction unit 16a acquires information specifying the scanning trajectory of the OCT image represented by a complex signal from the acquisition unit 15. Based on the acquired information specifying the scanning trajectory of the OCT image represented by the complex signal, the aberration correction unit 16a identifies the scanning direction of each of the multiple segments for which bulk phase correction has been performed. The scanning direction can be identified from the sampling position on the scanning trajectory of the OCT image represented by the complex signal, which is identified based on the OCT sampling timing. The aberration correction unit 16a corrects the aberrations of the multiple segments based on the identified scanning direction. For example, when the aberration correction unit 16a acquires information specifying a Lissajous scan trajectory, it performs a Lissajous cycle-wise convolution operation using each of the multiple segments on which bulk phase correction has been performed and the aberration correction filter. For example, when the aberration correction unit 16a acquires information specifying the raster scanning trajectory, it performs a B-scan-wise convolution operation using each of the multiple segments for which bulk phase correction has been performed and the aberration correction filter. For example, when the aberration correction unit 16a acquires information specifying a cycloidal scanning orbit, it performs a cycle-wise convolution operation using each of the multiple segments for which bulk phase correction has been performed and the aberration correction filter.

[0032] The motion correction unit 17 acquires a plurality of segments with aberrations corrected from the aberration correction unit 16a. The motion correction unit 17 corrects positional deviations due to involuntary movements of the observation object for the acquired aberration-corrected segments (see, for example, Non-Patent Document 1). As a result, a plurality of data items with different scanning directions are acquired at a certain point on the observation object. Here, the multiple segments for which aberrations have been corrected are either the result of performing a Lissajous cycle-wise convolution operation using each of the multiple segments for which bulk phase correction has been performed and an aberration correction filter, the result of performing a B-scan-wise convolution operation using each of the multiple segments for which bulk phase correction has been performed and an aberration correction filter, or the result of performing a cycle-wise convolution operation using each of the multiple segments for which bulk phase correction has been performed and an aberration correction filter.

[0033] Fig. 10 is a diagram showing an example of the operation of an information processing device of a modified example of an embodiment. Fig. 10 is a schematic diagram showing that, as a result of correcting positional deviation due to involuntary movement of the object of observation, a plurality of data A, B, and C in different scanning directions are obtained at a point P on the object of observation. Returning to Fig. 6, the explanation will be continued. The synthesis unit 18 acquires a plurality of aberration-corrected segments in which positional deviations due to involuntary movements of the object of observation have been corrected from the motion correction unit 17. The synthesis unit 18 synthesizes each of the acquired aberration-corrected segments. For example, the synthesizer 18 converts each of the multiple segments into a real value. Specifically, the synthesizer 18 generates each signal to be imaged from the original complex signal. A signal representing the light intensity that forms a typical so-called OCT image is also generated at this stage. This results in an OCT intensity signal or an optical coherence tomography angiography (OCTA) signal. The synthesis unit 18 performs a geometric mean (incoherent synthesis) between overlapping signals of each of the multiple segments converted into real values. The synthesis unit 18 reconstructs an image that has been corrected for optical aberrations in two dimensions from the one-dimensional correction data in multiple scanning directions.

[0034] Fig. 11 is a diagram showing an example of the operation of an information processing device according to a modified example of the embodiment. Fig. 11 is a schematic diagram showing incoherent synthesis of multiple pieces of data from different scanning directions. Two-dimensional lateral resolution recovery can be performed by synthesizing a point image with a narrow vertical distribution, a point image with a narrow oblique distribution, and a point image with a narrow horizontal distribution. The output unit 19a can be the same as the output unit 19. However, the output unit 19a acquires the result of taking the geometric mean between overlapping signals of each of the multiple segments converted into real values ​​from the synthesis unit 18. The output unit 19a outputs the result of taking the geometric mean between overlapping signals of each of the multiple segments converted into real values ​​that has been acquired.

[0035] The reception unit 12, division unit 13a, phase correction unit 14, acquisition unit 15, aberration correction unit 16a, motion correction unit 17, synthesis unit 18 and output unit 19a are realized, for example, by a hardware processor such as a CPU executing a computer program stored in the memory unit 20. Furthermore, some or all of these functional units may be realized by hardware (including circuitry) such as an LSI, ASIC, FPGA, or GPU, or may be realized by a combination of software and hardware. The computer program may be stored in advance in a storage device such as a HDD or flash memory, or may be stored on a removable storage medium such as a DVD or CD-ROM and installed by inserting the storage medium into a drive device.

[0036] (Operation of the information processing device 10a) 12 is a flowchart showing an example of the operation of the information processing device of the modified embodiment. With reference to FIG. 12, the operation after an OCT image represented by a complex signal is input to the information processing device 10a will be described. (Step S1-2) The receiving unit 12 receives an OCT image represented by a complex signal input to the input unit 11. The receiving unit 12 stores the received OCT image represented by a complex signal in the storage unit 20. (Step S2-2) The acquiring unit 15 acquires information specifying the scanning trajectory of the OCT image represented by the complex signal received by the receiving unit 12. The scanning trajectory is one of a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory. (Step S3-2) The dividing unit 13a acquires an OCT image represented by a plurality of complex signals stored in the storage unit 20. The dividing unit 13a acquires information specifying the scanning trajectory of the OCT image represented by the complex signals from the acquiring unit 15. The dividing unit 13a divides the received OCT image represented by the complex signals into a plurality of segments based on the information specifying the scanning trajectory of the OCT image represented by the acquired complex signals.

[0037] (Step S4-2) The phase corrector 14 acquires a plurality of segments from the divider 13a, and performs bulk phase correction on each of the acquired plurality of segments. (Step S5-2) The aberration correction unit 16a acquires multiple segments for which bulk phase correction has been performed from the phase correction unit 14. The aberration correction unit 16a acquires information specifying the scanning trajectory of the OCT image represented by a complex signal from the acquisition unit 15. The aberration correction unit 16a identifies the scanning direction of each of the multiple segments for which bulk phase correction has been performed, based on the information specifying the scanning trajectory of the OCT image represented by the acquired complex signal. The aberration correction unit 16a corrects the aberrations of the multiple segments based on the identified scanning direction. (Step S6-2) The motion corrector 17 acquires a plurality of segments for which aberrations have been corrected from the aberration corrector 16a, and corrects the acquired plurality of segments for positional deviations due to involuntary movements of the subject.

[0038] (Step S7-2) The synthesis unit 18 acquires multiple segments in which positional deviations due to involuntary movements of the object of observation have been corrected from the motion correction unit 17. The synthesis unit 18 converts each of the multiple segments into a real value. The synthesis unit 18 performs a geometric mean between overlapping signals of each of the multiple segments converted into real values. (Step S8-2) The output unit 19a acquires the result of geometric averaging between overlapping signals of each of the multiple segments converted into real values ​​from the synthesis unit 18. The output unit 19a outputs the result of geometric averaging between overlapping signals of each of the multiple segments converted into real values ​​acquired.

[0039] In the above-described modified example of the embodiment, the case where the observation plane is a front surface perpendicular to the depth direction of the sample has been described, but the present invention is not limited to this example. For example, the observation plane may be a surface that crosses part or all of the observation region. In the modification of the embodiment described above, the acquiring unit 15 acquires any one of a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory as information specifying the scanning trajectory of the OCT image represented by the complex signal received by the receiving unit 12. However, the present invention is not limited to this example. For example, any scanning trajectory can be applied, not limited to a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory. In the modified example of the embodiment described above, the information processing device 10a receives an OCT image represented by a complex signal, but this is not limiting. For example, a detection signal from a sensor that receives interference light in an OCT device may be input to the information processing device 10a. The method described in the embodiment can be applied to the processing in this case.

[0040] According to an information processing device 10a of the modified embodiment, the information processing device 10a includes a receiving unit 12 that receives an OCT image represented by a complex signal, a dividing unit 13 that divides the OCT image represented by the complex signal received by the receiving unit 12 into multiple segments, a phase corrector 14 that corrects the phase of each of the multiple segments, and an aberration corrector 16a that identifies a scanning direction for each of the multiple segments and corrects aberrations of the multiple segments based on the identified scanning direction. The aberration corrector 16a corrects the aberrations of the multiple segments whose phases have been corrected by the phase corrector 14. With this configuration, the information processing device 10a can correct the phase of each of the multiple segments, thereby correcting the aberrations of the multiple phase-corrected segments. Therefore, the information processing device 10a can perform digital aberration correction on OCT data even when it is affected by the movement of the living body being observed. The information processing device 10a can perform digital aberration correction on OCT data captured at high resolution over a certain range, even without using an expensive ultra-high-speed device.

[0041] The information processing device 10a further includes an acquisition unit 15 that acquires information specifying the scanning trajectory of the OCT image represented by the complex signal received by the reception unit 12. The aberration correction unit 16a specifies the scanning direction of each of the multiple segments based on the information specifying the scanning trajectory. With this configuration, the information processing device 10a can acquire information specifying the scanning trajectory of the OCT image represented by a complex signal, and can therefore specify the scanning direction of each of the multiple segments based on the acquired information specifying the scanning trajectory.

[0042] In the information processing device 10a, the scanning trajectory is any one of a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory. With this configuration, the information processing device 10a can acquire any one of a Lissajous scan trajectory, a raster scan trajectory, and a cycloid scan trajectory as information specifying the scan trajectory of an OCT image represented by a complex signal. Therefore, the information processing device 10a can specify the scan direction of each of the multiple segments based on any one of a Lissajous scan trajectory, a raster scan trajectory, and a cycloid scan trajectory.

[0043] The information processing device 10a further includes a motion correction unit 17 that corrects positional deviations due to involuntary movements of the subject for the plurality of segments whose aberrations have been corrected by the aberration correction unit 16a. With this configuration, the information processing device 10a can correct positional deviations due to involuntary movements of the observation subject, thereby further reducing the effects of movements of the living body being observed.The information processing device 10a can recover lateral resolution through digital aberration correction for living tissue with involuntary movements.

[0044] The information processing device 10a further includes a synthesis unit 18 that synthesizes each of the multiple segments corrected by the motion correction unit 17. With this configuration, the information processing device 10a can synthesize multiple segments in which the positional deviation due to the involuntary movement of the observation subject has been corrected, and thus the information processing device 10a can create an image of biological tissue with involuntary movement in which the lateral resolution has been restored by digital aberration correction.

[0045] In the information processing device 10a, the synthesis unit 18 converts each of the multiple segments into real number data. With this configuration, the information processing device 10a can convert each of the multiple segments into real data, and can create an image with restored lateral resolution based on the results of converting each of the multiple segments into real data. In applications of scanning coherent imaging, even when the observation subject moves frequently, the information processing device 10a can perform digital aberration correction. For example, the information processing device 10a can compensate for resolution loss due to focus error in ophthalmic clinical applications, OCT, and endoscopic OCT through signal processing.

[0046] In the information processing device 10a, the synthesis unit 18 calculates the geometric mean of overlapping signals of each of the multiple segments converted into real number data. With this configuration, the information processing device 10a can calculate the geometric mean of overlapping signals of the multiple segments converted into real data, thereby creating an image with restored horizontal resolution.

[0047] The information processing device 10a combines Lissajous scanning and digital aberration correction to (1) perform digital aberration correction on signals for one-dimensional scanning, (2) correct positional deviations between aberration-corrected signals due to involuntary movements, and (3) combine signals from different scanning directions to recover lateral resolution that has been reduced by defocus and aberrations. Until now, in coherent imaging, as typified by digital holography, it has been possible to correct the effects of optical aberrations such as defocus by signal processing without using adaptive optics devices. In digital holography, the structure of the sample viewed from the front is captured in one go (full-field) using a camera. However, when targeting thick, scattering tissues such as those in vivo, a scanning imaging device that suppresses the influence of multiple scattering due to the confocal effect can more easily capture images deep inside the tissue with high contrast.

[0048] However, with conventional signal processing methods for correcting optical aberrations proposed for scanning optical coherence tomography, optical aberration correction ceases to function if the sample moves during scanning. Therefore, a high imaging speed (approximately 0.2 s / volume for the fundus) is required to prevent the sample from moving during imaging. This requires either a high optical scanning speed and data recording speed, or imaging limited to a narrow field of view. Conventional digital aberration correction requires a complex OCT signal obtained by two-dimensional probe light scanning without distortion due to involuntary movements, whereas the information processing device 10 and the information processing device 10a can perform digital aberration correction using only a complex OCT signal for one-dimensional scanning. As a result, in the information processing device 10 and the information processing device 10a, spatial resolution is restored only in the scanning direction of the signal used, but the required speed is thought to be no problem even in a general OCT device (up to 100,000 A-lines / s).

[0049] The information processing device 10a can apply a motion correction method to Lissajous scanning, although positional deviations occur between corrected data due to involuntary movements (see, for example, Non-Patent Document 1). As a result, the information processing device 10a can acquire multiple pieces of data in different scanning directions at a single point on the observation target, and can perform two-dimensional lateral resolution recovery by incoherently synthesizing these multiple pieces of data. The information processing device 10a combines digital aberration correction with correction of positional deviations due to involuntary movements, enabling in vivo signal processing correction of optical aberrations. Even for biological tissues with involuntary movements, a general OCT device can achieve recovery of lateral resolution through digital aberration correction.

[0050] An example of the effect of the information processing device 10a according to the modified embodiment will be described. A principle verification was performed on the effectiveness of the information processing device 10a of the modified embodiment using a spectroscopic OCT with a wavelength band of 1 μm. Images were captured by scanning microparticles and a biological tissue sample with the OCT probe along a Lissajous scanning trajectory, and digital focus correction was performed. The effective numerical aperture of the probe was approximately 0.05.

[0051] 13A to 13C are diagrams illustrating an example 1 of a processing result of the information processing device according to the modified example of the embodiment. Figures 13A to 13C show an example of a representative cross-sectional image of a microbead phantom. The microbead phantom is a 10μ polystyrene microparticle sample. Figure 13A shows an example of an OCT probe scanning trajectory. Figures 13B and 13C show an example of a representative cross-sectional image of the microbead phantom. Figures 13B and 13C were taken of the same sample. Figure 13B shows an example of a defocused OCT cross-sectional intensity image. Figure 13C shows an example of an image obtained by refocusing Figure 13B.

[0052] 14 is a diagram showing Example 2 of the processing result of the information processing device of the modified embodiment. Fig. 14 shows an example of the processing result of the information processing device 10a, which is an example of the result of imaging a 10 μm polystyrene microparticle sample. The scan area is 550 μm (horizontal) and 500 μm (vertical). In FIG. 14, (a) to (c) show front images of microbeads obtained by scanning the OCT probe according to a Lissajous scanning trajectory. (a) Image obtained in focus. (b) Image obtained out of focus. (c) Lissajous cycle-wise (LCW) refocusing applied to (b). (d) to (g) show frontal images of the microbeads obtained by scanning the OCT probe according to a raster scanning trajectory. (f) is the product of the x- and y-correction volumes of (e). (g) is the 2D refocus applied to (e).

[0053] FIG. 15 is a diagram illustrating a third example of a processing result of the information processing device according to the modified example of the embodiment. Figure 15 shows a front image of biological tissue (chicken breast) obtained by scanning the OCT probe along a Lissajous scanning trajectory. Figure 15 was taken at a depth of approximately 300 μm from the tissue surface. (a) is an image obtained in focus. (b) and (c) are images obtained out of focus (approximately 1 mm out of focus). (c) is an image obtained after digital focus correction was applied by the information processing device 10a.

[0054] 13A to 15, the effective numerical aperture of the probe is lower than that of a microscope, but the imaging depth range of OCT (approximately 1 mm) corresponds to several times the Rayleigh range. Therefore, a focus position shift of the depth range significantly reduces the resolution. It can be seen that the technique of the modified embodiment can restore the reduced resolution. Here, an example of the effect of the information processing device 10a of the modified example of the embodiment has been described, but the same applies to the information processing device 10 of the present embodiment.

[0055] Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be embodied in various other forms, and various omissions, substitutions, modifications, and combinations can be made without departing from the spirit of the invention. These embodiments and their modifications are intended to be included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims.

[0056] The information processing device 10 and the information processing device 10a each have a built-in computer. The processes of each device are stored in the form of a program on a computer-readable recording medium, and the computer reads and executes the program to perform the above processes. For example, for a scanning OCT product, the scan pattern can be changed and the processes of the information processing device 10 and the information processing device 10a can be implemented by adding them to software without developing new hardware. Here, computer-readable recording media refers to magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memories, etc. Also, this computer program may be distributed to a computer via a communication line, and the computer that receives this distribution may execute the program. The program may also be for realizing part of the above-mentioned functions. Furthermore, the above-mentioned functions may be realized in combination with a program already recorded in the computer system, that is, a so-called differential file (differential program). [Explanation of symbols]

[0057] REFERENCE SIGNS LIST 10, 10a... information processing device, 11... input unit, 12... reception unit, 13, 13a... division unit, 14... phase correction unit, 15... acquisition unit, 16, 16a... aberration correction unit, 17... motion correction unit, 18... synthesis unit, 19, 19a... output unit, 20... storage unit

Claims

1. a reception unit that receives an OCT image represented by a complex signal; a division unit that divides the OCT image received by the reception unit into a plurality of segments; a phase correction unit that corrects the phase of each of the plurality of segments based on phase information included in the OCT image represented by a complex signal; an aberration correction unit that specifies a scanning direction of each of the plurality of segments whose phases have been corrected by the phase correction unit, and corrects aberrations of the plurality of segments whose phases have been corrected based on the specified scanning direction; An information processing device comprising:

2. Image reconstruction unit that outputs complex OCT signals Furthermore, The information processing device according to claim 1 , wherein the accepting unit accepts the complex OCT signal output by the image reconstruction unit as an OCT image.

3. 3. The information processing apparatus according to claim 1, wherein each of the plurality of segments corresponds to a signal for one-dimensional scanning.

4. an acquisition unit that acquires information that identifies a scanning trajectory of the OCT image received by the reception unit; Furthermore, The information processing apparatus according to claim 1 , wherein the aberration correction unit specifies the scanning direction of each of the plurality of segments based on information specifying the scanning trajectory.

5. The information processing apparatus according to claim 4 , wherein the scanning trajectory is one of a Lissajous scanning trajectory, a raster scanning trajectory, and a cycloid scanning trajectory.

6. a motion correction unit that corrects positional deviations due to involuntary movements of an object of observation for the plurality of segments whose aberrations have been corrected by the aberration correction unit; The information processing device according to claim 1 , further comprising:

7. a synthesis unit that synthesizes each of the plurality of segments corrected by the motion correction unit; The information processing device according to claim 6 , further comprising:

8. The information processing device according to claim 7 , wherein the synthesizing unit converts each of the plurality of segments into real number data.

9. The information processing apparatus according to claim 8 , wherein the combining unit takes a geometric mean between overlapping signals of the plurality of segments converted into real number data.

10. receiving an OCT image represented by a complex signal; acquiring information specifying a scanning trajectory of the OCT image received in the receiving step; Segmenting the OCT image into a plurality of segments; correcting the phase of each of the plurality of segments based on phase information included in the OCT image represented by a complex signal; specifying a scanning direction for each of the plurality of phase-corrected segments based on the information specifying the scanning trajectory, and correcting aberrations of the plurality of phase-corrected segments based on the specified scanning direction; A computer-implemented information processing method comprising:

11. On the computer, receiving an OCT image represented by a complex signal; acquiring information specifying a scanning trajectory of the OCT image received in the receiving step; Segmenting the OCT image into a plurality of segments; correcting the phase of each of the plurality of segments based on phase information included in the OCT image represented by a complex signal; specifying a scanning direction for each of the plurality of phase-corrected segments based on the information specifying the scanning trajectory, and correcting aberrations of the plurality of phase-corrected segments based on the specified scanning direction; A computer program that executes

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