JP2017046975A - Ophthalmic imaging apparatus and ophthalmic imaging program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ophthalmic imaging apparatus and an ophthalmic imaging program capable of easily acquiring a front image effective for diagnosis.SOLUTION: Provided is an ophthalmic imaging apparatus for imaging a subject eye, comprising: first acquisition means for acquiring, by a front observation optical system for acquiring front image data of a subject eye, first front image data on the subject eye as well as second front image data, the second front image data including a site common to a site at which the first front image data is captured; and first image processing means for comparing the first front image data with the second front image data and generating third front image data as reference image data, the third front image data including blood vessel emphasized image data in at least a portion of the site common between the first and second front image data.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates to an ophthalmologic photographing apparatus and an ophthalmologic photographing program for photographing and observing an eye to be examined.

  2. Description of the Related Art Conventionally, as a device for photographing and observing an eye to be examined, a scanning laser optometry device for photographing a front image of a subject eye by scanning laser light two-dimensionally over the subject eye and receiving the reflection thereof (SLO) is known (see Patent Document 1). In addition, a fundus camera or the like is known as an apparatus for photographing and observing an eye to be examined (for example, the fundus).

JP 2006-239196 A

  However, the front images of the subject's eye photographed with these devices may not have been finely imaged of thinner blood vessels. For this reason, it may be difficult to check the state of the eye to be inspected using these devices using the captured front image.

  In view of the above problems, an object of the present invention is to provide an ophthalmologic photographing apparatus and an ophthalmic photographing program capable of easily acquiring a front image effective for diagnosis.

  In order to solve the above problems, the present disclosure is characterized by having the following configuration.

(1) An ophthalmologic photographing apparatus according to a first aspect of the present disclosure is an ophthalmic photographing apparatus that photographs an eye to be examined, and a first front image on the eye to be examined by a front observation optical system that obtains front image data of the eye to be examined. First acquisition means for acquiring data, and acquiring second front image data including a portion common to the portion from which the first front image data has been acquired, the first front image data, and the second front image data And the third front image data including the blood vessel emphasized image data in at least a part of the portion common to the first front image data and the second front image data is generated as reference image data. And an image processing means.
(2) An ophthalmologic imaging apparatus according to a second aspect of the present disclosure is an ophthalmic imaging apparatus that images a subject's eye, and includes a scanning laser optometry optical system that obtains front image data of the subject's eye, and tomographic image data of the subject's eye The first front image data is acquired on the eye to be examined by the OCT optical system and the scanning laser optometry optical system, and the first part in the same part as the part on the eye to be examined from which the first front image data was obtained. First acquisition means for acquiring two front image data; second acquisition means for acquiring a plurality of OCT signals temporally different with respect to the same position on the eye to be examined by the OCT optical system; and the first front image data A first image processing means for generating third front image data which is blood vessel emphasized image data by comparing the second front image data and the second front image data; A second image processing unit that processes the plurality of OCT signals in the depth direction at each scanning position acquired by the stage to acquire frontal motion contrast data in the eye to be examined, and acquired by the second image processing unit Correction for correcting the front motion contrast data by dividing the front motion contrast data into a plurality of regions and aligning the front motion contrast data for each of the divided regions with the reference image data. And means.
(3) The ophthalmic imaging program according to the third aspect of the present disclosure is an ophthalmic imaging program executed in a control device that controls the operation of the ophthalmic imaging device that images the eye to be examined, and is executed by a processor of the control device. Thus, the first front image data is obtained on the eye to be examined by the front observation optical system that obtains the front image data of the eye to be examined, and the second part including the part common to the part from which the first front image data has been obtained. The first acquisition step of acquiring the front image data, the first front image data, and the second front image data are compared and common to the first front image data and the second front image data. A first image processing step of acquiring third front image data including blood vessel emphasized image data in at least a part of a region to be processed as reference image data, It is made to perform in a department radiography apparatus.

It is a block diagram explaining the structure of the optical coherence tomography apparatus which concerns on this embodiment. It is a figure which shows the outline of the OCT optical system which concerns on this embodiment. The flowchart explaining the control action at the time of processing OCT data is shown. It is a figure explaining the acquisition operation of an OCT signal. It is a figure explaining the production | generation of blood vessel emphasis image data. It is a flowchart which shows an example of the correction process operation | movement of front motion contrast data. It is a figure which shows an example of front motion contrast data. It is a figure explaining division of front motion contrast data. It is a figure explaining the detection of a motion artifact. It is a figure explaining alignment with a 3rd front image and front motion contrast data in a division field.

  Hereinafter, one exemplary embodiment will be described with reference to the drawings. In the present embodiment, an optical coherence tomography apparatus (hereinafter referred to as an OCT device) will be described as an example of an ophthalmologic imaging apparatus. Of course, a fundus camera, an ophthalmic scanning laser ophthalmoscope (SLO), or the like may be used. FIG. 1 is a block diagram illustrating a configuration of an optical coherence tomography apparatus according to the present embodiment. FIG. 2 is a schematic diagram illustrating the OCT optical system.

  An optical coherence tomography apparatus (hereinafter referred to as an OCT device) 1 processes a detection signal acquired by an OCT optical system (interference optical system) 100. In the present embodiment, the OCT device 1 has a configuration that allows an image taken by the OCT optical system 100 to be observed on a display means (for example, a monitor) 75. For example, the OCT device 1 includes an OCT optical system 100, a CPU (control unit) 70, a mouse (operation unit) 76, a memory (storage unit) 72, and a monitor 75, and each unit is connected via a bus or the like. Are electrically connected to the CPU 70. In the following description, the case where the fundus of the eye to be examined is imaged by the OCT device 1 will be described as an example. Of course, the OCT device 1 can image the anterior segment of the eye to be examined.

  The control unit 70 controls the operation of each unit based on an arithmetic program and various control programs stored in the memory 72 (details will be described later). In addition, as the control unit 70, the operation unit 76, the memory 72, and the monitor 75, various processing programs are installed on a commercially available PC by using an arithmetic processing unit, an input unit, a storage unit, and a display unit of a commercially available PC (personal computer). You may do it.

  In the present embodiment, the OCT device 1 is described as an example of an apparatus in which the OCT optical system 100 and each unit are integrated, but the present invention is not limited to this. For example, the OCT device 1 may be configured without the OCT optical system 100. In this case, the OCT device is connected to a separately provided OCT optical system or the like, receives an OCT signal or OCT image data, and performs various arithmetic processes based on the received information.

  For example, in the present embodiment, the OCT optical system 100 includes a front observation optical system 200. Of course, the OCT optical system and the front observation optical system 200 may not be integrated. The OCT optical system 100 irradiates the fundus Ef with measurement light. The OCT optical system 100 detects the interference state between the measurement light reflected from the fundus oculi Ef and the reference light by the light receiving element (detector 120). The OCT optical system 100 includes an irradiation position changing unit (for example, the optical scanner 108 and the fixation target projection unit 300) that changes the irradiation position of the measurement light on the fundus oculi Ef in order to change the imaging position on the fundus oculi Ef. The control unit 70 controls the operation of the irradiation position changing unit based on the set imaging position information, and acquires a tomographic image based on the light reception signal from the detector 120.

<OCT optical system>
The OCT optical system 100 will be described. The OCT optical system 100 has an apparatus configuration of a so-called ophthalmic optical tomography (OCT: Optical coherence tomography), and takes a tomographic image of the eye E to be examined. For example, the control unit 70 acquires the OCT signal by controlling the OCT optical system 100. The OCT optical system 100 splits the light emitted from the measurement light source 102 into measurement light (sample light) and reference light by a coupler (light splitter) 104. The OCT optical system 100 guides the measurement light to the fundus oculi Ef of the eye E by the measurement optical system 106 and guides the reference light to the reference optical system 110. Thereafter, the detector 120 receives interference light obtained by combining the measurement light reflected by the fundus oculi Ef and the reference light.

  The detector 120 detects an interference signal between the measurement light and the reference light. In the case of Fourier domain OCT, the spectral intensity (spectral interference signal) of the interference light is detected by the detector 120, and a complex OCT signal is obtained by Fourier transform on the spectral intensity data.

  For example, in the Fourier domain OCT, the depth profile (A scan signal) in a predetermined range is acquired by calculating the absolute value of the amplitude in the complex OCT signal acquired by Fourier transform on the spectral intensity data. OCT image data (tomographic image data) is acquired by arranging the depth profiles at each scanning position of the measurement light scanned by the optical scanner 108. Furthermore, three-dimensional OCT image data (three-dimensional tomographic image data) may be acquired by scanning the measurement light two-dimensionally. In addition, from the three-dimensional OCT image data, OCT front (Enface) image data (for example, integrated image data integrated in the depth direction, integrated values of spectrum data at each XY position, XY values in a certain depth direction) Luminance data at a position, retina surface layer image data, etc.) may be acquired.

  Also, motion contrast data is acquired from at least two or more OCT signals at the same position (the same part) at different times. That is, at least two or more complex OCT signals are analyzed and motion contrast data is acquired. For example, one-dimensional motion contrast data is acquired from the complex OCT signal. Two-dimensional motion contrast data is acquired by arranging the one-dimensional motion contrast data at each scanning position of the measurement light scanned by the optical scanner 108. Further, three-dimensional motion contrast data (motion contrast volume data) is acquired by two-dimensionally scanning the measurement light in the XY directions. Further, from the three-dimensional motion contrast data, front motion contrast data (for example, Doppler front image data, speckle variance front image data, etc.) is acquired. Each data may be generated image data, or may be signal data before an image is generated. Details of the motion contrast data will be described later.

  For example, examples of the Fourier domain OCT include Spectral-domain OCT (SD-OCT) and Swept-source OCT (SS-OCT). For example, Time-domain OCT (TD-OCT) may be used. In the case of SD-OCT, a low-coherent light source (broadband light source) is used as the light source 102, and the detector 120 is provided with a spectroscopic optical system (spectrometer) that separates interference light into each frequency component (each wavelength component). . The spectrometer includes, for example, a diffraction grating and a line sensor. In the case of SS-OCT, a wavelength scanning light source (wavelength variable light source) that changes the emission wavelength at a high speed in time is used as the light source 102, and a single light receiving element is provided as the detector 120, for example. The light source 102 includes, for example, a light source, a fiber ring resonator, and a wavelength selection filter. Examples of the wavelength selection filter include a combination of a diffraction grating and a polygon mirror, and a filter using a Fabry-Perot etalon.

  The light emitted from the light source 102 is split into a measurement light beam and a reference light beam by the coupler 104. Then, the measurement light flux passes through the optical fiber and is then emitted into the air. The luminous flux is condensed on the fundus oculi Ef via the optical scanner 108 and other optical members of the measurement optical system 106. Then, the light reflected by the fundus oculi Ef is returned to the optical fiber through a similar optical path.

  The optical scanner 108 scans the measurement light two-dimensionally (XY direction) on the fundus. The optical scanner 108 is arranged at a position substantially conjugate with the pupil. The optical scanner 108 is, for example, two galvanometer mirrors, and the reflection angle thereof is arbitrarily adjusted by the drive mechanism 50.

  As a result, the reflection (advance) direction of the light beam emitted from the light source 102 is changed and scanned at an arbitrary position on the fundus. Thereby, the imaging position on the fundus oculi Ef is changed. The optical scanner 108 may be configured to deflect light. For example, in addition to a reflective mirror (galvano mirror, polygon mirror, resonant scanner), an acousto-optic device (AOM) that changes the traveling (deflection) direction of light is used.

  The reference optical system 110 generates reference light that is combined with reflected light acquired by reflection of measurement light at the fundus oculi Ef. The reference optical system 110 may be a Michelson type or a Mach-Zehnder type. The reference optical system 110 is formed by, for example, a reflection optical system (for example, a reference mirror), and reflects light from the coupler 104 back to the coupler 104 by being reflected by the reflection optical system and guides it to the detector 120. As another example, the reference optical system 110 is formed by a transmission optical system (for example, an optical fiber), and guides the light from the coupler 104 to the detector 120 by transmitting the light without returning.

  The reference optical system 110 has a configuration in which the optical path length difference between the measurement light and the reference light is changed by moving an optical member in the reference optical path. For example, the reference mirror is moved in the optical axis direction. The configuration for changing the optical path length difference may be arranged in the measurement optical path of the measurement optical system 106.

<Front observation optical system>
The front observation optical system 200 acquires front image data of the eye to be examined. The front image data may be generated image data or signal data before an image is generated. For example, the front observation optical system 200 is provided to obtain a front image of the fundus oculi Ef. In the present embodiment, the front observation optical system 200 is disposed, for example, at a position substantially conjugate with the fundus and an optical scanner that two-dimensionally scans the fundus with measurement light (for example, infrared light) emitted from a light source. And a second light receiving element that receives fundus reflected light through the confocal aperture, and has a so-called ophthalmic scanning laser ophthalmoscope (SLO) device configuration.

  The configuration of the front observation optical system 200 may be a so-called fundus camera type configuration. Further, for example, an infrared imaging optical system that images a subject using infrared light may be used. Further, for example, the OCT optical system 100 may also serve as the front observation optical system 200. That is, the front image data (hereinafter referred to as a front image) may be acquired using data forming a tomographic image (OCT front image) obtained two-dimensionally.

  The front observation optical system 200 may not be integrated with the OCT device or the like. In this case, for example, front image data acquired by a front observation optical system 200 provided separately is received by an OCT device or the like.

<Fixation target projection unit>
The fixation target projecting unit 300 includes an optical system for guiding the line-of-sight direction of the eye E. The fixation target projection unit 300 has a fixation target to be presented to the eye E, and can guide the eye E in a plurality of directions.

  For example, the fixation target projection unit 300 has a visible light source that emits visible light, and changes the presentation position of the target two-dimensionally. Thereby, the line-of-sight direction is changed, and as a result, the imaging region is changed. For example, when the fixation target is presented from the same direction as the imaging optical axis, the center of the fundus is set as the imaging site. When the fixation target is presented upward with respect to the imaging optical axis, the upper part of the fundus is set as the imaging region. That is, the imaging region is changed according to the position of the target with respect to the imaging optical axis.

  As the fixation target projection unit 300, for example, a configuration in which the fixation position is adjusted by the lighting positions of LEDs arranged in a matrix, the light from the light source is scanned by an optical scanner, and the fixation position is controlled by lighting control of the light source. Various configurations such as a configuration to be adjusted are conceivable. The fixation target projection unit 300 may be an internal fixation lamp type or an external fixation lamp type.

<Control unit>
The control unit 70 includes a CPU (processor), a RAM, a ROM, and the like. The CPU of the control unit 70 controls the entire apparatus such as each member of each configuration 100 to 300. The RAM temporarily stores various information. The ROM of the control unit 70 stores various programs for controlling the operation of the entire apparatus, initial values, and the like. The control unit 70 may be configured by a plurality of control units (that is, a plurality of processors).

  A non-volatile memory (storage means) 72, an operation unit (control unit) 76, a display unit (monitor) 75, and the like are electrically connected to the control unit 70. The non-volatile memory (memory) 72 is a non-transitory storage medium that can retain stored contents even when power supply is interrupted. For example, a hard disk drive, a flash ROM, the OCT device 1, and a USB memory that is detachably attached to the OCT optical system 100 can be used as the nonvolatile memory 72. The memory 72 stores an imaging control program for controlling imaging of front image data and tomographic image data by the OCT optical system 100. The memory 72 stores a fundus analysis program that enables the OCT device 1 to be used. In addition, the memory 72 stores information on imaging positions of tomographic image data (OCT image data), three-dimensional tomographic image data (three-dimensional OCT image data), front image data (fundus frontal image data), and tomographic image data in a scanning line. Etc., various information relating to photographing is stored. Various operation instructions by the examiner are input to the operation unit 76.

  The operation unit 76 outputs a signal corresponding to the input operation instruction to the control unit 70. For the operation unit 74, for example, at least one of a mouse, a joystick, a keyboard, a touch panel, and the like may be used.

  The monitor 75 may be a display mounted on the apparatus main body or a display connected to the main body. A display of a personal computer (hereinafter referred to as “PC”) may be used. A plurality of displays may be used in combination. The monitor 75 may be a touch panel. When the monitor 75 is a touch panel, the monitor 75 functions as an operation unit. Various images including tomographic image data and front image data captured by the OCT optical system 100 are displayed on the monitor 75.

<Signal processing method>
An arithmetic processing method for acquiring motion contrast data from the OCT signal in this embodiment will be described. In this embodiment, in order to acquire motion contrast data, the control unit 70 acquires at least two frames of interference signals (OCT signals) having different times at the same position.

  In the present embodiment, the control unit 70 acquires motion contrast data (for example, two-dimensional motion contrast data) from a plurality of OCT signals by performing processing related to the Doppler phase difference method and processing related to the vector difference method. . As a method of processing the complex OCT signal, for example, a method of calculating a phase difference of the complex OCT signal, a method of calculating a vector difference of the complex OCT signal, a method of multiplying the phase difference and the vector difference of the complex OCT signal, and the like are considered. It is done. In the present embodiment, a method of multiplying a phase difference and a vector difference will be described as an example.

  First, the control unit 70 controls the OCT optical system 100 to acquire an OCT signal. The control unit 70 performs Fourier transform on the OCT signal acquired by the OCT optical system 100. The control unit 70 obtains a complex OCT signal by Fourier transform. The complex OCT signal includes a real component and an imaginary component.

  In order to obtain a blood flow signal, it is necessary to compare images at the same position at different times. For this reason, it is preferable that the control unit 70 aligns images based on image information. Image registration is a process of arranging a plurality of images in alignment. Possible causes of the image position shift include, for example, the movement of the subject's eye during imaging (for example, fixation fine movement, adjustment fine movement, and pulsation). Note that even if alignment between frames is performed, a phase shift may occur between A scan lines in the same image. Therefore, it is preferable to perform phase correction. Note that the registration and phase correction processes are intended to facilitate the process of the present embodiment, and are not essential.

  Next, the control unit 70 calculates a phase difference with respect to the complex OCT signal acquired at least two or more different times at the same position. The controller 70 removes a random phase difference that exists in a region where the S / N ratio (signal-to-noise ratio) is low.

  The controller 70 removes a portion having a small phase difference. This is to remove a reflection signal from a highly reflective portion such as NFL (nerve fiber layer). This makes it easy to distinguish whether the signal is from a highly reflective part or from a blood vessel. In the present embodiment, one frame for which the phase difference is calculated is acquired. When there are a plurality of frames for which the phase difference has been calculated, it is better that the control unit 70 performs an averaging process on the signals of the frames subjected to the above processing to remove noise. Of course, a configuration without noise removal processing may be used.

  Next, the control unit 70 calculates a vector difference of the complex OCT signal. For example, the vector difference of the complex OCT signal detected by the OCT optical system is calculated. For example, a complex OCT signal can be represented as a vector on the complex plane. Therefore, by detecting two signals at the same position at different times and calculating a vector difference, contrast image data in the eye to be examined is generated. In addition, when imaging a vector difference, you may image based on phase information other than the magnitude | size of a difference, for example. In the present embodiment, one frame for which the vector difference is calculated is acquired. When there are a plurality of frames for which the vector difference is calculated, it is better that the control unit 70 performs an averaging process on the signal of the frame subjected to the above-described processing to remove noise.

  The control unit 70 uses the phase difference calculation result as a filter for the vector difference calculation result. In the description of the present embodiment, “filtering” means, for example, weighting a certain numerical value. For example, the control unit 70 performs weighting by multiplying the calculation result of the vector difference by the calculation result of the phase difference. That is, the vector difference of the portion having a small phase difference is weakened, and the vector difference of the portion having a large phase difference is strengthened. Thereby, the calculation result of the vector difference is weighted by the calculation result of the phase difference. Further, for example, the weighting may be a non-linear weighting by providing a threshold, weakening a vector difference in a portion where a certain phase difference is less than the threshold, and not correcting a phase difference greater than or equal to the threshold.

  In the process of the present embodiment, the control unit 70 multiplies the vector difference calculation result and the phase difference calculation result, for example. Thus, the control unit 70 generates two-dimensional motion contrast data weighted by the phase difference calculation result.

  By multiplying the calculation result of the vector difference and the calculation result of the phase difference, the disadvantages of the respective measurement methods can be negated, and the image data of the blood vessel part can be successfully acquired.

  The control unit 70 performs the above arithmetic processing on each scanning line, and acquires two-dimensional motion contrast data in each scanning line. Then, by acquiring two-dimensional motion contrast data at these multiple positions, it is possible to acquire frontal motion contrast data used as a pseudo angiographic image.

  In the present embodiment, the control unit 70 has been described by taking as an example a configuration in which the vector difference calculation result and the phase difference calculation result are multiplied in order to obtain motion contrast data. However, the present invention is not limited to this. Not. For example, the motion contrast data may be acquired using a vector difference calculation result. Further, for example, the motion contrast data may be acquired using a phase difference calculation result. Further, for example, the motion contrast data may be acquired by an amplitude difference result, Amplitude-decorrelation, Speckle variance, Phase variance, or the like.

  In the present embodiment, the control unit 70 has been described with an example of a configuration in which motion contrast data is acquired using two OCT signals, but is not limited thereto. The motion contrast data may be acquired by two or more OCT signals.

<Shooting operation>
Hereinafter, a series of imaging operations using the OCT device 1 will be described. FIG. 3 shows a flowchart for explaining the control operation when processing the OCT data. Note that the following description will be given taking as an example the case of acquiring front motion contrast data. Of course, the technique disclosed in the present invention can be applied when obtaining motion contrast data. For example, it can be applied to the case where one-dimensional motion contrast data is acquired or the case where two-dimensional motion contrast data is acquired.

  First, the examiner instructs the subject to gaze at the fixation target of the fixation target projection unit 300, and then monitors an anterior ocular segment observation image captured by an anterior ocular segment observation camera (not shown) on the monitor 75. , An alignment operation is performed using an operation unit 76 (for example, a joystick (not shown)) so that the measurement optical axis comes to the center of the pupil of the eye to be examined.

  For example, when the alignment operation is completed, the control unit 70 controls the OCT optical system 100 and acquires three-dimensional OCT image data corresponding to the set region. Further, the control unit 70 controls the front observation optical system 200 to acquire fundus image data (fundus front image data). Then, the control unit 70 acquires three-dimensional OCT image data by the OCT optical system 100 and fundus image data by the front observation optical system 200 as needed. The three-dimensional OCT image data includes image data in which A scan signals are arranged two-dimensionally in the XY directions, a three-dimensional graphic image, and the like.

  The examiner sets the scanning position using the fundus front image of the front observation optical system 200. Then, when a photographing start signal is output from the operation unit 76, the control unit 70 controls the operation of the optical scanner 108 to cause the measurement light to scan two-dimensionally in the XY directions within a scanning range corresponding to the imaging region. Thus, the acquisition of 3D motion contrast data is started. As the scanning pattern, for example, a raster scan, a plurality of line scans, a circle shape, a refraction shape, a bent shape, and the like are conceivable.

<OCT signal acquisition (S1)>
For example, when an imaging start signal is output, the control unit 70 controls driving of the optical scanner 108 and scans the measurement light on the fundus in order to acquire frontal motion contrast data. For example, according to the output of the imaging start signal, the control unit 70 controls the OCT optical system 100 in order to acquire the OCT signal at the set frame rate. Note that the frame rate for obtaining the OCT signal may or may not be changed before and after the acquisition of the OCT signal.

  FIG. 4 is a schematic diagram for explaining photographing according to the present embodiment. The control unit 70 acquires a plurality of OCT signals at the same scanning position (the same part). The same scanning position does not have to be completely the same scanning position, and may be scanned at substantially the same scanning position. For this reason, the control unit 70 repeats scanning at the same scanning position on the fundus. By such a plurality of scans, the control unit 70 can obtain a plurality of OCT signals at the same scan position.

  As shown in FIG. 4, for example, the control unit 70 scans the measurement light in the X direction along the scanning positions (scanning lines) S1, S2,. For example, the measurement light is scanned in the X direction along the first scanning position S1. Scanning the measurement light in any one of the XY directions (for example, the X direction) in this way is called “B scan”. Hereinafter, the one-frame interference signal is described as an OCT signal obtained by one B-scan. The control unit 70 acquires the OCT signal detected by the detector 120 during scanning. In FIG. 4, the direction of the Z axis is the direction of the optical axis of the measurement light. The direction of the X axis is a direction perpendicular to the Z axis and left and right. The direction of the Y axis is assumed to be perpendicular to the Z axis and up and down.

  When the first scan is completed, the control unit 70 performs the second scan at the same position as the first scan. For example, the control unit 70 scans the measurement light again after scanning the measurement light along the first scanning line S1 shown in FIG. The controller 70 acquires the OCT signal detected by the detector 120 during the second scan. Thus, the control unit 70 can acquire two frames of OCT signals at different times at the same scanning position. For example, the control unit 70 repeatedly acquires an OCT signal and acquires a 4-frame OCT signal at the same scanning position. In the present embodiment, a configuration in which an OCT signal of 4 frames is acquired at the same scanning position is described as an example, but the present invention is not limited to this. It suffices if the OCT signal of at least two frames is acquired at the same position. For example, the scanning at the same position may be repeated 8 times to acquire continuous 8 frames of OCT signals at different times, or the scanning at the same position may be repeated 2 times to obtain 2 frames of OCT signals at different times. May be obtained.

  Note that if the OCT signal at the same position at different times can be acquired by one scan, the second scan may not be performed. For example, when two measurement lights whose optical axes are shifted by a predetermined interval are scanned at a time, it is not necessary to scan a plurality of times, and it is only necessary to obtain OCT signals having different times at the same position in the eye to be examined. That is, the same position does not need to be completely the same position, and may be scanned at substantially the same position. When two measurement lights are scanned at a time, an arbitrary blood flow velocity can be detected as a target by the interval between the two measurement lights.

<Front image acquisition>
On the other hand, the control unit 70 controls the front observation optical system 200 in order to repeatedly obtain the front image in response to the output of the imaging start signal. The control unit 70 repeats the front image acquisition operation while a plurality of OCT signals are acquired. With such control, the control unit 70 monitors the movement (movement) of the eye while the OCT signal is acquired. For example, the control unit 70 receives reflected light from the front of the fundus by the operation of the front observation optical system 200. The control unit 70 acquires a front image by processing the received reflected light. In the present embodiment, for example, the front image is acquired at an angle of view of about 15 ° to 40 °. Of course, the angle of view is not limited to this. The controller 70 stores the acquired plurality of front images in the memory 72 as needed. As described above, the control unit 70 makes the acquisition of the front image and the acquisition of the OCT signal in parallel.

<Acquisition of front motion contrast data (S2)>
When acquiring the OCT signal as described above, the control unit 70 processes a plurality of OCT signals to acquire motion contrast data (frontal motion contrast data in the present embodiment) on the fundus of the eye to be examined. The front motion contrast data is acquired based on three-dimensional motion contrast data acquired by processing a plurality of OCT signals.

  More specifically, for example, when acquiring the front motion contrast data, the control unit 70 acquires the front motion contrast data by integrating the three-dimensional motion contrast data in the depth direction. Of course, the front motion contrast data may be acquired by integrating spectral data at each XY position, extracting luminance data at each XY position in a certain depth direction, and the like. For example, the front motion contrast data may be acquired in a predetermined depth region. For example, the front motion contrast data in a predetermined depth area includes all areas in the depth direction of the 3D motion contrast data (for example, all layers of each retinal layer), a part of the depth direction of the 3D motion contrast data. In the region (for example, at least one layer in each retinal layer or a plurality of layers in each retinal layer) and the like.

<Generation of blood vessel enhanced image data (S3)>
Further, for example, the control unit 70 acquires blood vessel emphasized image data (hereinafter referred to as a blood vessel) based on a front image (a front image acquired by the front observation optical system 200) acquired while a plurality of OCT signals are acquired. (Denoted as enhanced image data) is acquired (S3). Of course, the blood vessel emphasized image data may be data of a generated image or signal data before an image is generated.

  Hereinafter, acquisition of blood vessel emphasized image data will be described in more detail. For example, the control unit 70 acquires first front image data (hereinafter, referred to as a first front image) on the eye to be examined, and second front image data including a part common to the part from which the first front image is acquired. (Hereinafter referred to as a second front image). For example, the first front image and the second front image are acquired at the same site at different times. For example, the time from when the first front image is acquired to when the second front image is acquired may be set to a time during which blood flow can be extracted.

  FIG. 5 is a diagram for explaining generation of blood vessel emphasized image data. In the present embodiment, the second front image F2 including the part common to the part from which the first front image F1 is acquired is acquired at the same part as the part on the eye to be examined from which the first front image F1 was acquired. That is, the first front image F1 and the second front image F2 are imaged in the same imaging range and the same imaging region. In the present embodiment, the same need not be completely the same, and may be substantially the same. Note that the second front image F2 may be a configuration acquired so as to include a part common to the part from which the first front image F1 is acquired. For example, the first front image F1 and the second front image F2 have different shooting ranges (for example, different shooting angles of view), and the first front image F1 and the second front image F2 are shot at different positions. The structure etc. which are may be sufficient.

  The control unit 70 compares the first front image F1 and the second front image F2, and the blood vessel emphasized image data in at least a part of the portion common to the first front image F1 and the second front image F2. Third front image data (hereinafter referred to as a third front image) F3 including the following (described as a blood vessel emphasized image) is generated as reference image data (hereinafter referred to as a reference image). Of course, each image data may be image data or signal data.

For example, in the present embodiment, the control unit 70 acquires a blood vessel emphasized image in the entire portion common to the first front image F1 and the second front image F2. The configuration for acquiring the blood vessel emphasized image is not limited to this. The configuration for acquiring the blood vessel emphasized image may be a configuration acquired at least at a part of the common part between the first front image F1 and the second front image F2. For example, the configuration for acquiring the blood vessel emphasized image may be a configuration acquired in a part of a common part between the first front image F1 and the second front image F2. In this case, for example, image data of a part of the common parts of the first front image F1 and the second front image F2 are compared, and a blood vessel emphasized image of the part is acquired.
In the present embodiment, the entire third front image F3 is a blood vessel emphasized image. That is, in the present embodiment, the entire first front image F1 and the entire second front image F2 acquired at the same site are compared to obtain a third front image F3 whose entire image is a blood vessel emphasized image. To do. Of course, the third front image F3 may have a configuration in which a blood vessel emphasized image is included in a part of the image. In this case, part of the third front image F3 is a blood vessel emphasized image, and image data such as the first front image F1 is used for the other part. Of course, images acquired based on the first front image F1 and the second front image F2 may be used in the image region excluding the blood vessel emphasized image. For example, a configuration may be used in which an averaged image obtained by performing an averaging process on the first front image F1 and the second front image F2 is used.

  In the present embodiment, the third front image F3 is used as a reference image for performing various controls and various settings. For example, the third front image F3 is used as a reference image (template) serving as a reference for aligning other front images. In this case, for example, the third front image F3 is used as a reference image for correcting the front motion contrast data. Further, for example, the third front image F3 is used as an image for performing setting, confirmation, etc. of the acquisition position (scanning position) of tomographic image data by the OCT optical system 100. In the present embodiment, the third front image F3 is used as a reference image for correcting the front motion contrast data acquired as described above (details will be described later).

<Comparison processing of front images>
Hereinafter, the comparison process for acquiring the third front image F3 will be described in more detail. In the present embodiment, the third front image (in this embodiment, the blood vessel emphasized image) F3 is acquired by using statistical processing as the comparison processing. More specifically, for example, as a comparison process, the control unit 70 acquires a temporal change in the luminance value from the ratio of the luminance values of the first front image F1 and the second front image F2, and acquires the acquired luminance. Based on the change in value, the third front image F3 including the blood vessel emphasized image is generated as a reference image. Note that when generating a blood vessel emphasized image, it can be generated based on a front image of at least two frames.

  For example, the control unit 70 calculates the luminance value at each pixel position of the first front image F1 and the second front image F2. Next, the control unit 70 determines the luminance value at the predetermined pixel position on the first front image F1 and the luminance at the predetermined pixel position on the second front image F2 corresponding to the predetermined pixel position on the first front image F1. The ratio of the value is calculated at each pixel position. That is, the control unit 70 calculates the ratio between the luminance value of the pixel of the first front image F1 and the luminance value of the pixel of the second front image F2 at the same shooting position at each pixel position. In the present embodiment, since the first front image F1 and the second front image F2 are acquired at the same site, no alignment process is required. For example, when the 1st front image F1 and the 2nd front image F2 are not acquired in the same site | part, after aligning the 1st front image F1 and the 2nd front image F2, it is the structure which starts a process. There may be.

For example, a given pixel position on the first front image F1 (x, y) and luminance value I ₁ at the predetermined pixel on the second front image F2 corresponding to a predetermined pixel positions on the first front image F1 The ratio D between the luminance value I _{2 at the} position (x, y) is calculated by the following equation (1). I in the formula (1) indicates a luminance value. In the following formula (1), the calculation of the ratio D of luminance values between the jth front image acquired and the jth next (j + 1) front image is taken as an example. .

なお、血管強調画像を生成するための正面画像として、第１正面画像Ｆ１と第２正面画像Ｆ２の他に複数の正面画像が存在する場合（少なくとも４フレームの正面画像を取得している場合）、制御部７０は、以下の平均化処理及び標準偏差算出を行ってもよい。例えば、制御部７０は、各正面画像において、その前後に取得された正面画像との比率をそれぞれ算出する。制御部７０は、各正面画像にて取得された比率において、前後の比率の平均値をそれぞれ算出する。

In addition, when there are a plurality of front images in addition to the first front image F1 and the second front image F2 as front images for generating a blood vessel emphasized image (when a front image of at least 4 frames is acquired). The control unit 70 may perform the following averaging process and standard deviation calculation. For example, the control unit 70 calculates the ratio of each front image to the front images acquired before and after that. The control unit 70 calculates the average value of the ratios before and after the ratio acquired in each front image.

  More specifically, for example, when acquiring a front image of four frames and generating a blood vessel emphasized image based on the front image of four frames, the control unit 70 determines that the first acquired front image, The ratio D1 of the luminance value between the acquired front image and the front image is calculated. Further, a luminance value ratio D2 between the front image acquired second and the front image acquired third is calculated. Further, a luminance value ratio D3 between the third acquired front image and the fourth acquired front image is calculated. Next, the control unit 70 averages the front and rear ratios (in the above case, the ratio D1 and the ratio D2, the ratio D2 and the ratio D3), and calculates the average value. The controller 70 averages the ratio D1 and the ratio D2, and calculates an average value M1. In addition, the control unit 70 averages the ratio D2 and the ratio D3, and calculates an average value M2. That is, for example, when a front image of 8 frames is acquired and a blood vessel emphasized image is generated, seven ratios D1 to D7 are calculated, and six average values M1 to M6 are calculated from the seven ratios. The average value is calculated by the following equation (2). M in Formula (2) has shown the average value.

制御部７０は、平均値が算出されると、算出した平均値の標準偏差を求める。すなわち、制御部７０は、正面画像上における各画素位置の平均値の標準偏差をそれぞれ算出する。例えば、標準偏差は、以下の式（３）によって算出される。式（３）におけるＮは、正面画像のフレーム数を示しており、Ｓは標準偏差を示している。

When the average value is calculated, the control unit 70 obtains a standard deviation of the calculated average value. That is, the control unit 70 calculates the standard deviation of the average value of each pixel position on the front image. For example, the standard deviation is calculated by the following equation (3). In Expression (3), N indicates the number of frames of the front image, and S indicates the standard deviation.

各画素位置における標準偏差がそれぞれ算出されると、制御部７０は、各画素位置の標準偏差をそれぞれ輝度値に変換処理する。例えば、制御部７０は、標準偏差を輝度値（例えば、０〜２５５の輝度値）に変換する。すなわち、制御部７０は、第１の画素位置の標準偏差が１０であり、第２の画素位置の標準偏差が１００であった場合、第１の画素位置における輝度値を２５に変換し、第２の画素位置における輝度値を２５５に変換する。制御部７０は、各画素位置において変換された輝度値に基づいて、画像を生成し、血管部分の強調された血管強調画像（本実施形態においては、第３正面画像Ｆ３）を生成する。このように、少なくとも２フレームの正面画像の比較処理に基づいて、より細い血管等が良好に画像化された血管強調画像を含む第３正面画像Ｆ３を取得することによって、被検眼のより詳細な状況を確認することが容易となる。

When the standard deviation at each pixel position is calculated, the control unit 70 converts the standard deviation at each pixel position into a luminance value. For example, the control unit 70 converts the standard deviation into a luminance value (for example, a luminance value from 0 to 255). That is, when the standard deviation of the first pixel position is 10 and the standard deviation of the second pixel position is 100, the control unit 70 converts the luminance value at the first pixel position to 25, The luminance value at the pixel position of 2 is converted to 255. The control unit 70 generates an image based on the luminance value converted at each pixel position, and generates a blood vessel emphasized image (the third front image F3 in the present embodiment) of the blood vessel portion. As described above, by acquiring the third front image F3 including the blood vessel emphasized image in which the finer blood vessels and the like are well imaged based on the comparison process of the front images of at least two frames, more detailed of the eye to be examined is obtained. It becomes easy to check the situation.

  In the above description, the configuration in which the blood vessel emphasized image is generated by converting the standard deviation into the luminance value is described as an example, but the present invention is not limited to this. For example, the blood vessel emphasized image may be generated by converting the ratio into a luminance value. More specifically, for example, when generating a blood vessel emphasized image based on a front image of two frames, one ratio is calculated (one ratio is calculated from the luminance value of the front image of two frames). A blood vessel emphasized image may be generated by converting a ratio at a pixel position into a luminance value. In this case, for example, the ratio may be calculated by unifying the two frames of the front image having a high luminance value as the denominator (the ratio can be unified to a numerical value of 1 or more). Further, for example, the blood vessel enhancement image may be generated by converting the average value into the luminance value. More specifically, for example, when generating a blood vessel emphasized image based on a front image of three frames, one average value is calculated (two ratios are calculated, and one average value is calculated based on the two ratios). Therefore, the blood vessel enhancement image may be generated by converting an average value at each pixel position into a luminance value. Of course, the generation of a blood vessel emphasized image by conversion processing from an average value or a ratio can be applied even when a front image of four frames or more is acquired. For example, one average value may be obtained from the entire plurality of ratios acquired based on each front image, and a blood vessel emphasized image may be generated. In addition, a blood vessel emphasized image may be generated by selecting an appropriate ratio or average value from a plurality of ratios or a plurality of average values acquired based on each front image.

  In the present embodiment, the configuration using the statistical processing is described as an example of the comparison processing, but the present invention is not limited to this. Any processing method may be used as long as the first front image F1 and the second front image F2 are compared to extract the amount of change in luminance value due to blood flow (blood vessel portion). For example, a configuration using difference processing as the comparison processing may be used. In this case, for example, the luminance value of the first front image F1 and the luminance value of the second front image F2 are detected, and a blood vessel emphasized image is generated from the difference between the luminance values. That is, in the front image, since the blood flows in the portion corresponding to the blood vessel, the luminance value changes with the passage of time. On the other hand, the change in luminance value is small in other parts. For this reason, the third front image F3 including the blood vessel emphasized image can be generated as the reference image by performing the difference process of the luminance value and acquiring the temporal change of the luminance value.

<Correction of front motion contrast data (S4)>
Here, for example, when motion contrast data (frontal motion contrast data in the present embodiment) is acquired, the imaging time becomes long, so that it is easily influenced by blinking of the eye to be examined, fixation micromotion, etc., distortion, data Discontinuity (defects) of the problem becomes a problem. In the present embodiment, for example, when acquiring the front motion contrast data, the control unit 70 uses the reference image as a template and motion contrast data (for example, two-dimensional) at each scanning position for constructing the front motion contrast data. Motion contrast data) is aligned with respect to the reference image, and the displacement of the motion contrast data at each scanning position is corrected.

  Hereinafter, correction processing for front motion contrast data will be described. FIG. 6 is a flowchart showing an example of the front motion contrast data correction processing operation. FIG. 7 is a diagram illustrating an example of the front motion contrast data A1. As shown in FIG. 7, in the front motion contrast data A1, the image acquisition position is deviated between the scanning positions due to the effect of blinking of the eye to be examined, fixation micromotion, etc., and the image regions G1 to G1 are included in the image. A positional shift occurs in the XY direction between G4. In the present embodiment, a case where positional deviation occurs only in the X direction will be described as an example. In addition, in the OCT function front image A1, motion contrast data is acquired from the plurality of OCT signals because a plurality of OCT signals cannot be acquired at the same position due to the effect of blinking of the eye to be inspected, fixation fixation or the like. In this case, motion artifacts B1 to B3 occur.

  For example, when the third front image (in this embodiment, a blood vessel emphasized image) F3 is acquired, the control unit 70 sets the third front image F3 as a reference image and corrects the front motion contrast data A1. . As a result, the front motion contrast data A1 is corrected to front motion contrast data in which displacement is suppressed.

  In the present embodiment, the control unit 70 acquires the front motion contrast data A1 (see FIG. 10) by acquiring the front motion contrast data A1 and correcting the acquired front motion contrast data A1. In the present embodiment, the control unit 70 acquires the front motion contrast data A1 once. The control unit 70 will be described by taking as an example a configuration in which the final front motion contrast data A2 is generated by aligning and correcting the acquired front motion contrast data A1 based on the reference image. Of course, the configuration for generating the final front motion contrast data A2 is not limited to this. The control unit 70 acquires motion contrast data at each scanning position (for example, two-dimensional motion contrast data at each scanning position constructing front motion contrast data). The control unit 70 may be configured to correct the front motion contrast data by aligning the motion contrast data at each scanning position based on the third front image F3 and obtain the final front motion contrast data. . In this way, for example, by aligning motion contrast data (for example, front motion contrast data) with respect to a blood vessel emphasized image such as the third front image F3, image data in which blood vessel portions are emphasized (images). Since it is possible to perform alignment between image data that are similar as data), the accuracy of alignment can be further improved. Further, for example, by aligning the motion contrast data with respect to the third front image, it is possible to acquire good front motion contrast data with little deviation between the scanning positions.

  Hereinafter, the correction process of the front motion contrast data A1 will be described in more detail. FIG. 8 is a diagram for explaining division of front motion contrast data. For example, the control unit 70 divides the front motion contrast data A1 (see S2 in FIG. 3) acquired as described above into a plurality of regions. The control unit 70 corrects the front motion contrast data A1 by aligning the front motion contrast data for each divided area with respect to the reference image.

<Detection of motion artifact (S41)>
For example, as illustrated in FIG. 8, the control unit 70 sets the division position of the front motion contrast data A1 based on the positions where the motion artifacts B1 to B3 are detected. More specifically, for example, in the front motion contrast data A1, the control unit 70 detects motion artifacts B1 to B3 by image processing from the front motion contrast data A1 (S41). FIG. 9 is a diagram for explaining detection of motion artifacts.
For example, the luminance level of the front motion contrast data A1 is detected, and the position of a portion having a predetermined luminance corresponding to the motion artifacts B1 to B3 is detected. In addition, when specifying motion artifact B1-B3, the control part 70 adds the luminance value of each horizontal direction (X direction) in front motion contrast data, for example.

  The motion artifacts B1 to B3 are displayed with substantially constant luminance values at substantially constant scanning positions in the Y direction. As shown in FIG. 9, the motion artifacts B1 to B3 usually form lines extending in the X direction (scanning direction when acquiring two-dimensional motion contrast data). For this reason, the position of the motion artifact can be specified by adding the luminance value in the X direction and detecting the added luminance value in the Y direction. For example, the control unit 70 can acquire the luminance distribution L by detecting the luminance value subjected to the addition treatment in the Y direction. The control unit 70 detects portions L1, L2, and L3 where the luminance value changes greatly (for example, the rising portion of the luminance value and the falling portion of the luminance value), and the portions L1 and L2 where the change in the detected luminance value is large. , L3 is specified as a position where motion artifacts B1 to B3 exist. As described above, the position of the motion artifact is detected.

  When the motion artifact is inspected over a predetermined area (a plurality of scanning positions in the Y direction), the detection position of the motion artifact can be set to an arbitrary position. For example, when motion artifacts are inspected over a predetermined area, the detection position of motion artifacts is the part where motion artifacts have started to be detected (for example, the rising part of the luminance value in the Y direction). It is good also as a position. In addition, for example, when motion artifacts are inspected over a predetermined area, the motion artifact detection position is an intermediate position of the area where the motion artifact is detected (for example, the rise of the luminance value and the luminance value in the Y direction). The intermediate position of the fall may be used as a motion artifact detection position. In addition, the detection method of motion artifact B1-B3 is not limited to the said method. When detecting the motion artifacts B1 to B3, detection of connection of blood vessel portions corresponding to the motion artifacts B1 to B3 (detection of a portion where the blood vessel portion is interrupted) may be used.

<Division of Front Motion Contrast Data (S42)>
Returning to the description of FIG. For example, the control unit 70 sets the division position in the sub-scanning direction (Y direction) of the front motion contrast data. In the present embodiment, for example, the control unit 70 sets and divides the front motion contrast data A1 based on the detected positions of the detected motion artifacts B1 to B3 (S42). For example, in the example shown in FIG. 8, the control unit 70 converts the front motion contrast data A1 to the front motion contrast data in the first divided area (hereinafter referred to as first front motion contrast data) based on the set division position. A1a, front motion contrast data in the second divided area (hereinafter referred to as second front motion contrast data) A1b, front motion contrast data in the third divided area (hereinafter referred to as third front motion contrast data) A1c, fourth It is divided into front motion contrast data (hereinafter referred to as fourth front motion contrast data) A1d in the divided area. Thus, as an example, in the present embodiment, by dividing the front motion contrast data A1 with the portion where the motion artifacts B1 to B3 are generated as a boundary, at the position where the position shift of the eye to be examined has occurred, The functional OCT front image can be divided, and the alignment process can be performed satisfactorily in consideration of the shift between the scanning positions.

  In the present embodiment, the control unit 70 sets the regions of the motion artifacts B1 to B3 when setting the division position of the front motion contrast data A1 based on the detected positions of the motion artifacts B1 to B3. (For example, the region from the rising portion of the luminance value to the falling portion of the luminance value is removed), and the front motion contrast data A1 is converted into the first front motion contrast data A1a, the second front motion contrast data A1b, The data is divided into third front motion contrast data A1c and fourth front motion contrast data A1d. In the present embodiment, the configuration in which the motion artifacts B1 to B3 are removed when dividing the front motion contrast data A1 has been described as an example, but the present invention is not limited to this. For example, the control unit 70 may divide the front motion contrast data A1 in a state including at least a part of the motion artifacts B1 to B3.

  In the present embodiment, the configuration in which the division position of the front motion contrast data A1 is set based on the boundary where the motion artifact is detected has been described as an example, but the present invention is not limited to this. For example, the front motion contrast data A1 may be divided at regular intervals. Further, for example, the division position of the front motion contrast data A1 may be divided at a position selected by the examiner. In the front motion contrast data A1, when the division position is set based on the position where the motion artifact is detected, the control unit 70 sets all the positions where the motion artifact is detected as the division position. Also good. Further, for example, in the case where the division position is set based on the position where the motion artifact is detected in the front motion contrast data A1, the control unit 70 selects at least one position among the positions where the motion artifact is detected. May be set as the division position.

<Appropriateness determination of front motion contrast data in divided area (S43)>
For example, when the front motion contrast data A1 is divided, the control unit 70 determines the front motion contrast data for each divided area (in this embodiment, the first front motion contrast data A1a to the fourth front motion contrast data A1d). ) Is determined for each divided region (S43). For example, the control unit 70 performs determination based on whether or not the front motion contrast data for each divided region exceeds a predetermined reference (predetermined threshold). More specifically, for example, in the present embodiment, the control unit 70 determines the suitability of the front motion contrast data for each divided region for each divided region based on the image quality of the front motion contrast data for each divided region.

  Thus, for example, by confirming the suitability of the front motion contrast data for each divided region, it is possible to acquire appropriate front motion contrast data for each divided region. Accordingly, it is possible to apply appropriate front motion contrast data in each divided region, and the front motion contrast data constructed by them becomes better image data. That is, front motion contrast data useful for diagnosis can be acquired.

  Note that a configuration in which image data is divided and the suitability of the image data for each divided area is determined for each divided area can also be used in three-dimensional motion contrast data. This makes it possible to apply appropriate three-dimensional motion contrast data in each divided region, and the three-dimensional motion contrast data constructed by them becomes better image data. Of course, after applying appropriate 3D motion contrast data in each divided region, the front motion contrast data may be acquired based on the 3D motion contrast data. Also by this, front motion contrast data useful for diagnosis can be acquired.

  For example, when the front motion contrast data A1 is divided, the control unit 70 determines the front motion contrast data for each divided area (in this embodiment, the first front motion contrast data A1a to the fourth front motion contrast data A1d). ) Is determined for each divided region (S43). For example, the control unit 70 performs determination based on whether or not the front motion contrast data for each divided region exceeds a predetermined reference (predetermined threshold). More specifically, for example, in the present embodiment, the control unit 70 determines the suitability of the front motion contrast data for each divided region for each divided region based on the image quality of the front motion contrast data for each divided region.

  In the present embodiment, the configuration in which the determination process is performed based on the image quality of the front motion contrast data for each divided region is exemplified, but the present invention is not limited to this. The determination process may be performed based on the relationship with the front motion contrast data of other divided areas. For example, the amount of shift of the front motion contrast data between the divided areas may be calculated, and the suitability of the front motion contrast data for each divided area may be determined based on whether the shift amount exceeds a predetermined threshold.

  Hereinafter, a configuration for performing the determination process based on the image quality of the front motion contrast data for each divided area will be described. In the present embodiment, the control unit 70 calculates the evaluation value of the image quality as the determination process based on the image quality, and determines the front motion contrast data for each divided region based on whether the evaluation value exceeds a predetermined threshold. Judge the suitability. For example, the predetermined threshold is set in advance by simulation or experiment.

  For example, as the evaluation value of the image quality, a sum value of luminance values of each pixel of the front motion contrast data, a result of high or low frequency due to a spatial frequency distribution, or the like can be used. For example, in this embodiment, an evaluation value V indicating the signal strength (for example, Signal Strength Index (SSI)) of the image quality of the front motion contrast data is used. For example, the evaluation value V is obtained from the equation: V = ((average maximum luminance value of the image) − (average luminance value of the background area of the image)) / (standard deviation of the luminance value of the background area). That is, when noise is large in the front motion contrast data, the evaluation value V is small (for details, refer to Japanese Patent Laid-Open No. 2013-34658).

  For example, the control unit 70 calculates the evaluation value V for each divided region. For example, the control unit 70 calculates the evaluation value V1 of the first front motion contrast data A1a. The control unit 70 determines whether or not the calculated evaluation value V1 exceeds a predetermined threshold value. For example, when the calculated evaluation value 1 exceeds a predetermined threshold value, the control unit 70 determines that the first front motion contrast data A1a is appropriate. For example, the control unit 70 determines that the first front motion contrast data A1a is not appropriate when the calculated evaluation value V1 does not exceed a predetermined threshold. Thus, it is possible to determine suitability from only the information on the front motion contrast data in the divided area, and it is possible to easily obtain the front motion contrast data for each divided area.

<Re-acquisition of front area motion contrast data of divided area (S44)>
For example, when it is determined that the front motion contrast data is not appropriate in the predetermined divided area, the control unit 70 uses the front motion contrast data of the divided area determined to be inappropriate and each scanning position in the same divided area. A plurality of OCT signals are reacquired (S44). Note that the same does not have to be completely the same, and may be substantially the same. For example, the configuration may be such that the OCT signal is re-acquired in a region that includes the divided region determined to be inappropriate and is larger than the divided region determined to be inappropriate. Next, the control unit 70 sets the re-acquired plurality of OCT signals at the respective scanning positions as a plurality of OCT signals in the divided areas determined to be inappropriate (replaces the plurality of OCT signals).

  More specifically, for example, when it is determined that the first front motion contrast data A1a is not appropriate, the control unit 70 again outputs a plurality of OCT signals at each scanning position where the first front motion contrast data A1a is acquired. get. For example, the control unit 70 controls the optical scanner 108 based on the amount of deviation between the third front image and the front image acquired at the time of reacquisition (the front image acquired by the front observation optical system 200). Correct the scanning position. Of course, for example, at least one of the first front image and the second front image may be used instead of the third front image. Further, for example, at the time of re-acquisition, a plurality of front images are acquired, a blood vessel emphasized image (new third front image) is generated from the plurality of front images, and the blood vessel emphasized image has a deviation amount from the third front image. You may use for calculation. By calculating the shift amount with the front image in which the blood vessels are emphasized, the shift amount can be calculated with higher accuracy. For example, the control unit 70 controls the optical scanner 108, corrects the scanning position, and then starts acquiring a plurality of OCT signals again.

  For example, the control unit 70 uses the re-acquired OCT signals at the respective scanning positions as the plurality of OCT signals in the first divided area (the area where the first front motion contrast data A1a is acquired) determined to be inappropriate. Set. That is, the control unit 70 acquires front motion contrast data in the first divided region based on the plurality of OCT signals acquired again. Then, the control unit 70 discards the front motion contrast data in the first divided area determined to be inappropriate, and sets the re-acquired front motion contrast data as the front motion contrast data of the first divided area.

  For example, the control unit 70 again determines whether or not the front motion contrast data is appropriate for the re-acquired front motion contrast data in the first divided region. The control unit 70 repeatedly performs the re-acquisition process until it is determined that the front motion contrast data is appropriate. As described above, even when the front motion contrast data acquired in each divided region is not appropriate, the front motion contrast data can be acquired again. Thereby, appropriate front motion contrast data can be acquired in each divided region.

  For example, even if the re-acquisition process is repeated a predetermined number of times, if the front motion contrast data is not determined to be appropriate, the re-acquisition may be stopped. Further, for example, even when the re-acquisition process is repeated a predetermined number of times, if the front motion contrast data is not determined to be appropriate, that fact may be notified. For example, the notification configuration includes a configuration in which the examiner is notified by an error display, a warning sound, or the like. For example, even when the reacquisition process is repeated a predetermined number of times, if the front motion contrast data is not determined to be appropriate, the process may proceed to the next process (for example, S45 in FIG. 6). .

<Front motion contrast data alignment of divided areas (S45)>
For example, when it is determined that the front motion contrast data is appropriate in a predetermined divided region, the control unit 70 sets the third front image F3 as the reference image. The control unit 70 corrects the front motion contrast data by using the reference image as a template and aligning the front motion contrast data of the divided areas determined to be appropriate with the reference image.

  This will be described in more detail. FIG. 10 is a diagram for explaining the alignment between the third front image F3 and the front motion contrast data in the divided areas. For example, when it is determined that the first front motion contrast data A1a is appropriate, the control unit 70 sets the third front image F3 as a reference image. The control unit 70 uses the third front image F3 as a template and aligns the first front motion contrast data A1a with the third front image F3. For example, the control unit 70 aligns the divided front motion contrast data A1 with respect to the scanning region F3a corresponding to the region from which the front motion contrast data A1 is acquired in the third front image F3.

  Hereinafter, the alignment procedure will be described. For example, the control unit 70 performs matching processing between the third front image F3 and the first front motion contrast data A1a, and associates the third front image F3 with the first front motion contrast data A1a.

  For example, the control unit 70 detects the positional deviation amount between the third front image F3 and the first front motion contrast data A1a as the matching process, and based on the positional deviation amount, The positional relationship with the front motion contrast data A1a is made to correspond.

  For example, there are various image processing methods (methods using various correlation functions, methods using Fourier transforms, methods based on feature point matching), non-rigid registration, etc. , Etc. can be used.

  For example, predetermined reference image data (for example, the third front image F3) or target image data (first front motion contrast data A1a) is displaced pixel by pixel, the reference image and the target image are compared, and both data are the most A method of detecting the amount of misalignment between the two data when they match (when the correlation is highest) can be considered. Further, a method of extracting a common feature point from a predetermined reference image and target image and detecting a positional shift of the extracted feature point is conceivable.

  Further, a phase-only correlation function may be used as a function for obtaining a positional deviation between two image data. In this case, first, each image data is Fourier transformed to obtain the phase and amplitude of each frequency component. The obtained amplitude component is normalized to a magnitude of 1 for each frequency component. Next, after calculating a phase difference for each frequency between the two image data, inverse Fourier transform is applied to them.

  If there is no positional deviation between the two image data, only the cosine wave is added, and a peak appears at the origin position (0, 0). Further, when there is a positional deviation, a peak appears at a position corresponding to the positional deviation. Therefore, the amount of positional deviation between the two image data can be obtained by obtaining the peak detection position. According to this method, it is possible to detect the positional deviation amount between the third front image F3 and the first front motion contrast data A1a with high accuracy and in a short time.

  In the present embodiment, the control unit 70 uses a method of extracting common feature points from the third front image F3 and the first front motion contrast data A1a and detecting the amount of positional deviation of the extracted feature points. . When detecting the positional deviation amount, the control unit 70 associates the positional relationship between the third front image F3 and the first front motion contrast data A1a based on the positional deviation amount. In this way, alignment of the front motion contrast data divided with respect to the front image is performed.

  For example, after the positioning of the first front motion contrast data A1a is completed, the control unit 70 proceeds to a determination process for the second front motion contrast data A1b. For example, the control unit 70 performs the same process as the process in the first divided area (for example, S43 to S45) in the front motion contrast data of each divided area. In this way, alignment of the front motion contrast data of each divided area is performed. In the present embodiment, the configuration in which the above processing (S43 to S45) is sequentially performed for each divided region has been described as an example, but the present invention is not limited to this. For example, after completing the determination process of the front motion contrast data in all the divided areas, the next process (S44 or S45) may be performed.

  As described above, for example, by dividing the front motion contrast data into predetermined regions and aligning the motion contrast data of each scanning position that constructs the front motion contrast data in units of predetermined regions, Misalignment correction can be performed more quickly. In particular, when alignment processing is performed for each of such divided regions, it is possible to perform alignment between image data similar as image data, so that the accuracy of alignment can be improved. it can.

  Next, for example, when the alignment process of the front motion contrast data in the predetermined divided area is completed, the control unit 70 determines whether or not the alignment process is completed in all the divided areas (S46). More specifically, for example, after the alignment of the first front motion contrast data A1a is completed, the control unit 70 detects the front motion contrast data (for example, the second front motion contrast data A1b, the third front surface) of other divided areas. It is determined whether or not the alignment of the motion contrast data A1c and the fourth front motion contrast data A1d) has been completed.

  For example, if the control unit 70 determines that the alignment of all the divided regions is not completed, the control unit 70 proceeds to the processing of the next divided region (S47). More specifically, for example, after the positioning of the first front motion contrast data A1a is completed, the control unit 70 proceeds to a determination process for the second front motion contrast data A1b. Of course, in a predetermined divided region, it is possible to proceed to the next process (for example, S48) without performing alignment.

<Re-acquisition of front motion contrast data of motion artifact detection position (S48)>
For example, when the control unit 70 determines that the alignment of all the divided regions is completed, the control unit 70 re-acquires a plurality of OCT signals at each scanning position in the same region where the motion artifact is detected (S48). ). As described above, in the present embodiment, the same need not be completely the same, and may be substantially the same. For example, the control unit 70 sets a plurality of OCT signals at the re-acquired scanning positions as a plurality of OCT signals in the region where the motion artifact is performed.

  More specifically, for example, the control unit 70 acquires a plurality of OCT signals again at each scanning position corresponding to the position (region) where the motion artifacts B1 to B3 are detected. For example, the control unit 70 corrects the scanning position by controlling the optical scanner 108 based on the amount of deviation between the third front image and the front image acquired at the time of re-acquisition. Of course, for example, at least one of the first front image and the second front image may be used instead of the third front image. Further, for example, at the time of re-acquisition, a plurality of front images may be acquired, a blood vessel emphasized image may be generated from the plurality of front images, and the blood vessel emphasized image may be used for calculating a deviation amount from the third front image. By calculating the shift amount with the front image in which the blood vessels are emphasized, the shift amount can be calculated with higher accuracy. For example, after controlling the optical scanner 108 and correcting the scanning position, the control unit 70 starts again acquiring a plurality of OCT signals at each scanning position corresponding to the region where the motion artifacts B1 to B3 are detected.

  For example, the control unit 70 sets a plurality of OCT signals at the re-acquired scanning positions as a plurality of OCT signals in the region where the motion artifacts B1 to B3 are detected. That is, the control unit 70 acquires the front motion contrast data in the region where the motion artifacts B1 to B3 are detected based on the re-acquired plurality of OCT signals. Then, the control unit 70 discards the motion artifact image data and sets the re-acquired front motion contrast data as the front motion contrast data of the area where the motion artifacts B1 to B3 are detected. Of course, the front motion contrast data in the area where the motion artifacts B1 to B3 are detected may be re-acquired without performing the division process and the determination process of the front motion contrast data of each divided area. In this case, for example, the control unit 70 may detect the motion artifact from the front motion contrast data, and re-acquire the front motion contrast data in the area where the motion artifact is detected.

  For example, the control unit 70 performs the same processing as the above-described determination processing (for example, S43 to S47) for the re-acquired front motion contrast data in the region where the motion artifacts B1 to B3 are detected. For example, the control unit 70 determines whether the front motion contrast data is appropriate. Of course, a configuration in which the suitability of the front motion contrast data is not determined may be used. In this case, the control unit 70 aligns the front motion contrast data in each region in which the motion artifacts B1 to B3 are detected without performing the determination process with respect to the third front image F3.

  For example, the control unit 70 repeatedly performs the re-acquisition process until it is determined that the front motion contrast data is appropriate. When it is determined that the front motion contrast data is appropriate, the control unit 70 aligns the front motion contrast data in each region where the motion artifacts B1 to B3 are detected with respect to the third front image F3. As described above, the motion contrast data of the motion artifact portion can be complemented by re-acquiring a plurality of OCT signals in the region where the motion artifact has occurred. Thereby, since the OCT signal can be re-acquired for the region where the motion artifact is generated, it is possible to acquire good front motion contrast data in which the motion artifact is suppressed.

  Note that the timing for re-acquiring a plurality of OCT signals at the detection position of the motion artifact is not limited after the alignment of the front motion contrast data for each divided region is completed. It can be performed at any timing. For example, it may be performed after S42.

  As described above, the control unit 70 aligns the appropriate front motion contrast data for each divided region with respect to the third front image F3. In addition, the control unit 70 reacquires the front motion contrast data for the motion artifact portion and complements the front motion contrast data for the motion artifact portion, thereby obtaining the final front motion contrast data A2. Thereby, front motion contrast data useful for diagnosis can be acquired.

<Transformation example>
In this embodiment, when re-acquiring a plurality of OCT signals in at least one of a predetermined divided area and a motion artifact occurrence area, an ophthalmic imaging apparatus (in this embodiment, before re-acquisition) The optical member in the optical coherence tomography apparatus 1) may be adjusted. For example, the adjustment of the optical member includes a configuration in which an optical path length changing member that changes the optical path length difference between the measurement light and the reference light, a focusing lens (not shown) that adjusts the focus of the OCT optical system 100, and the like. As described above, since the imaging conditions are adjusted before the re-acquisition of the plurality of OCT signals, the imaging state is good even when the imaging state is not good due to the positional deviation of the eye to be examined. Can be readjusted. Accordingly, it is possible to appropriately acquire appropriate front motion contrast data in the divided area.

  In the present embodiment, a configuration in which a plurality of OCT signals are re-acquired in at least one of a predetermined divided region and a motion artifact generation region has been described as an example, but the present invention is not limited to this. For example, a plurality of front motion contrast data is acquired in advance, and the optimum front motion contrast data for a predetermined divided area is selected from the plurality of front motion contrast data, and the front motion contrast data of the predetermined divided area is selected. It may be configured to set as.

  In the present embodiment, the configuration in which the determination process of the front motion contrast data is performed for each divided area has been described as an example. However, the determination process is not performed, and the third front image is processed for each divided area. The configuration may be such that the front motion contrast data is aligned.

  In the present embodiment, various front images can be used for the configuration for performing the front motion contrast data determination process for each divided region. For example, the front motion contrast data may be aligned for each divided region using a front image acquired by a conventional front observation optical system as a reference image. Further, for example, an OCT front image, an OCT function front image acquired at a high speed so as not to be affected by blinking of the eye to be examined, fixation micromotion, and the like may be used as the reference image. That is, the present invention can also be applied to an ophthalmologic photographing apparatus when the third front image is not used as a reference image for alignment. In this way, for example, by correcting the frontal motion contrast data appropriate for each divided region by aligning the frontal image, it has been affected by the fixation eye movement of the subject's eye during imaging. Even in this case, front motion contrast data useful for diagnosis can be acquired.

  In the present embodiment, the configuration in which the front motion contrast data is aligned with the third front image (blood vessel emphasized image) has been described, but the present invention is not limited to this. The configuration may be such that various front images are aligned with the blood vessel emphasized image. For example, the OCT optical system 100 may be configured to align the OCT front image data acquired based on the OCT signal acquired at each scanning position with respect to the third front image. In this case, for example, the control unit 70 acquires an OCT signal at each scanning position by the OCT optical system 100 that obtains tomographic image data of the eye to be examined. The control unit 70 processes the acquired OCT signal in the depth direction at each scanning position, and acquires OCT front image data in the eye to be examined. When the controller 70 acquires the OCT front image data using the reference image (third front image) as a template, the OCT image data at each scanning position for constructing the OCT front image data is obtained with respect to the reference image. Alignment is performed, and positional deviation of the OCT image data at each scanning position is corrected.

  In addition, when aligning the OCT front image data, the alignment may be performed after acquiring the entire OCT front image data, or after at least a part of the OCT front image data is acquired. May be. As described above, the image data alignment based on the feature portion is performed using the image data in which the blood vessel that is the feature portion is more emphasized, so that the alignment accuracy of the blood vessel portion can be further improved. In particular, in the case of OCT front image data acquired from only a predetermined layer region in the depth direction as OCT front image data, there may be many blood vessel portions in the image data. Since alignment can be performed between data (image data similar as image data), the alignment accuracy can be further improved.

  In the present embodiment, the ophthalmologic imaging apparatus is not limited to the optical coherence tomography apparatus that acquires the OCT signal as an example. The technique of the present disclosure can be applied to any apparatus that acquires motion contrast data from a plurality of signals.

  In the present embodiment, the imaging apparatus has been described by taking the configuration for imaging the eye to be examined as an example, but is not limited thereto. The technology of the present disclosure can be applied to an imaging device that images various living bodies. For example, ears, nose, various organs and the like can be mentioned. Further, for example, the technique of the present disclosure can also be applied to an imaging apparatus that images a sample other than a living body.

  In the present embodiment, the first front image data and the second front image data are compared, and the third front image data including the blood vessel emphasized image data is generated as an example. It is not limited to this. The technique of the present disclosure can be applied to any device that generates a conduit-weighted image data in which a conduit is emphasized by comparing the first front image data and the second front image data. For example, the duct-emphasized image data includes a configuration that emphasizes lymphatic vessels.

  Note that the present invention is not limited to the apparatus described in this embodiment. For example, ophthalmic imaging software (program) that performs the functions of the above embodiments is supplied to a system or apparatus via a network or various storage media. A control device (for example, a CPU) of the system or device can read and execute the program.

DESCRIPTION OF SYMBOLS 1 Optical coherence tomography device 70 Control part 72 Memory 75 Monitor 76 Operation part 100 Interference optical system (OCT optical system)
108 optical scanner 120 detector 200 front observation optical system 300 fixation target projection unit

Claims (8)

An ophthalmologic photographing apparatus for photographing an eye to be examined,
The first front image data is obtained on the eye to be examined by the front observation optical system for obtaining the front image data of the eye to be examined, and the second front image data including a part common to the part from which the first front image data is obtained is obtained. First acquiring means for acquiring;
By comparing the first front image data and the second front image data, blood vessel emphasized image data in at least a part of a portion common to the first front image data and the second front image data is obtained. First image processing means for generating third front image data including reference image data;
An ophthalmologic photographing apparatus comprising: The ophthalmologic photographing apparatus according to claim 1.
Second acquisition means for acquiring a plurality of OCT signals that are temporally different with respect to the same position on the eye to be examined by an OCT optical system that obtains tomographic image data of the eye to be examined;
Second image processing means for processing the plurality of OCT signals in the depth direction at each scanning position acquired by the second acquisition means to acquire frontal motion contrast data in the eye to be examined;
When acquiring the front motion contrast data, the reference image data is used as a template, and the motion contrast data at each scanning position for constructing the front motion contrast data is aligned with the reference image data, Correction means for correcting a displacement of motion contrast data at each scanning position;
An ophthalmologic photographing apparatus comprising: The ophthalmologic photographing apparatus according to claim 2,
The second image processing means processes the plurality of OCT signals in the depth direction at each scanning position to obtain the front motion contrast data,
The correction means divides the acquired front motion contrast data into a plurality of regions, and aligns the front motion contrast data for each of the divided regions with the reference image data to thereby adjust the front motion contrast. An ophthalmologic photographing apparatus characterized by correcting contrast data. The ophthalmologic photographing apparatus according to claim 3,
The second image processing means detects a motion artifact by image processing from the front motion contrast data in the front motion contrast data, and based on the position where the motion artifact is detected, the plurality of front motion contrast data An ophthalmologic photographing apparatus for setting a division position for division into regions. The ophthalmologic photographing apparatus according to claim 1.
Third acquisition means for acquiring an OCT signal at each scanning position by an OCT optical system that obtains tomographic image data of the eye to be examined;
Third image processing means for processing the OCT signal in the depth direction at each scanning position acquired by the third acquisition means to acquire OCT front image data in the eye to be examined;
With
When obtaining the OCT front image data using the reference image data as a template, the OCT image data at each scanning position for constructing the OCT front image data is aligned with the reference image data, Correction means for correcting a positional shift of the OCT image data at each scanning position;
An ophthalmologic photographing apparatus comprising: In the ophthalmologic photographing apparatus according to any one of claims 1 to 5,
The one image processing means acquires a temporal change in luminance value from the ratio of luminance values of the first front image data and the second front image data as the comparison processing, and the acquired luminance value An ophthalmologic photographing apparatus characterized in that the third front image data including the blood vessel emphasized image data is generated as the reference image data based on a change. An ophthalmologic photographing apparatus for photographing an eye to be examined,
A scanning laser optometry optical system for obtaining front image data of the eye to be examined;
An OCT optical system for obtaining tomographic image data of the eye to be examined;
The scanning laser optometry optical system obtains first front image data on the eye to be examined, and obtains second front image data in the same part as the part on the eye to be examined from which the first front image data was obtained. First acquisition means;
Second acquisition means for acquiring, by the OCT optical system, a plurality of OCT signals that are temporally different with respect to the same position on the eye to be examined;
First image processing means for generating third front image data which is blood vessel emphasized image data by comparing the first front image data and the second front image data;
Second image processing means for processing the plurality of OCT signals in the depth direction at each scanning position acquired by the OCT acquisition means to acquire frontal motion contrast data in the eye to be examined;
The front motion contrast data acquired by the second image processing means is divided into a plurality of regions, and the front motion contrast data for each divided region is aligned with the reference image data, thereby Correction means for correcting the front motion contrast data;
An ophthalmologic photographing apparatus comprising: An ophthalmic imaging program that is executed in a control device that controls the operation of an ophthalmologic imaging apparatus that images an eye to be examined
By being executed by the processor of the control device,
The first front image data is obtained on the eye to be examined by the front observation optical system for obtaining the front image data of the eye to be examined, and the second front image data including a part common to the part from which the first front image data is obtained is obtained. A first acquisition step of acquiring;
By comparing the first front image data and the second front image data, blood vessel emphasized image data in at least a part of a portion common to the first front image data and the second front image data is obtained. A first image processing step of acquiring third front image data including reference image data;
Is executed by the ophthalmologic photographing apparatus.

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