Source: https://patents.google.com/patent/JP2014140491A/en
Timestamp: 2020-07-10 00:55:41
Document Index: 464537483

Matched Legal Cases: ['Application No. 2012', 'art 70', 'art 70', 'art 70', 'art 70', 'Application No. 2011', 'art 70', 'art 72', 'art 75', 'art 100']

JP2014140491A - Ophthalmology imaging apparatus - Google Patents
Ophthalmology imaging apparatus Download PDF
JP2014140491A
JP2014140491A JP2013010643A JP2013010643A JP2014140491A JP 2014140491 A JP2014140491 A JP 2014140491A JP 2013010643 A JP2013010643 A JP 2013010643A JP 2013010643 A JP2013010643 A JP 2013010643A JP 2014140491 A JP2014140491 A JP 2014140491A
JP2013010643A
JP6217085B2 (en
JP2014140491A5 (en
佑二 村瀬
2013-01-23 Application filed by Nidek Co Ltd, 株式会社ニデック filed Critical Nidek Co Ltd
2013-01-23 Priority to JP2013010643A priority Critical patent/JP6217085B2/en
2014-08-07 Publication of JP2014140491A publication Critical patent/JP2014140491A/en
2016-03-03 Publication of JP2014140491A5 publication Critical patent/JP2014140491A5/ja
2017-10-25 Publication of JP6217085B2 publication Critical patent/JP6217085B2/en
230000003287 optical Effects 0.000 claims abstract description 128
PROBLEM TO BE SOLVED: To surely acquire a tomographic image related to a preset cross position.SOLUTION: An ophthalmology imaging apparatus includes: an OCT optical system for obtaining a tomographic image of a subject's eye using a measuring beam and a reference beam applied to the subject's eye; an observation optical system for obtaining a front image of the subject's eye; image generation means for repeatedly generating the tomographic image on the basis of an output signal from the OCT optical system, and also repeatedly generating the front images on the basis of an output signal from the observation optical system; continuity determination means for detecting positional deviation between the front image preset as a reference front image and each of the front images by image processing, and determining the continuity of the front image whose positional deviation satisfies an allowable range; and select processing means for selecting the tomographic image on the basis of determination result of the continuity determination means.
The present invention relates to an ophthalmologic imaging apparatus that captures an optical tomographic image of an eye.
2. Description of the Related Art An ophthalmologic photographing apparatus that captures an optical tomographic image of an eye using optical coherence tomography (OCT) is known. For example, the apparatus scans measurement light on the fundus using an optical scanner, and acquires a tomographic image of the eye (for example, a tomographic image of the fundus). The obtained tomographic image is used for evaluation of the eye state (see Patent Document 1).
Such an apparatus acquires a plurality of tomographic images in order to average noise components included in the tomographic images, and acquires an addition average image based thereon. The addition average image is acquired by, for example, adding the luminance values at each pixel in a plurality of tomographic images related to substantially the same part and obtaining the average value.
JP 2010-110392 A
By the way, when acquiring a tomographic image regarding a preset crossing position, the eye to be examined may move. In some cases, a tomographic image different from a preset position may be acquired.
For example, when an averaged image is obtained, a good averaged image cannot be obtained if the reference template tomographic image is an image acquired at a shifted position.
In view of the above problems, an object of the present invention is to provide an ophthalmologic photographing apparatus that can reliably acquire a tomographic image relating to a preset crossing position.
An OCT optical system for acquiring a tomographic image of the eye to be inspected by using interference between the measurement light irradiated on the eye to be examined and the reference light;
An observation optical system for obtaining a front image of the eye to be examined;
Image generating means for repeatedly generating the tomographic image based on an output signal from the OCT optical system and repeatedly generating the front image based on an output signal from the observation optical system;
Continuity determining means for detecting positional deviation between the front image set as a reference front image and each front image by image processing, and determining continuity of the front image in which the positional deviation satisfies an allowable range;
Selection processing means for selecting the tomographic image based on the determination result by the continuity determination means;
According to the present invention, a tomographic image relating to a preset crossing position can be reliably acquired.
It is a schematic block diagram explaining the structure of the ophthalmologic imaging apparatus which concerns on a present Example. It is a figure which shows an example of the display screen displayed on a display part. It is a flowchart which shows an example of the determination method for determining the suitability of whether the acquired tomographic image was acquired in the preset position. It is a figure which shows an example of determination in the case of utilizing the continuity of the determination result with respect to a front image.
Embodiments of the present invention will be described with reference to the drawings. 1-4 is a figure which concerns on the Example of this embodiment.
This apparatus mainly includes an OCT optical system 100, an observation optical system 200, and a control unit 70 (see FIG. 1). The OCT optical system 100 is used to acquire a tomographic image of the eye to be examined using interference between the measurement light irradiated on the eye to be examined and the reference light. The OCT optical system 100 may include an optical scanner 108. The optical scanner 108 is used to scan the measurement light irradiated on the eye to be examined on the eye to be examined. The observation optical system 200 is used to obtain a front image of the eye to be examined.
The control unit 70 is used as an image generation unit, for example. Therefore, the control unit 70 may repeatedly generate the tomographic image based on the output signal from the OCT optical system 100 and may repeatedly generate the front image based on the output signal from the observation optical system 200. The tomographic image and the front image that are repeatedly generated are temporarily stored in the memory 74, for example.
<Determination of continuity>
The control unit 70 is used as, for example, a continuity determination unit. Therefore, the control unit 70 detects the positional deviation between the front image set as the reference front image and each front image by image processing, and determines the continuity of the front images in which the positional deviation satisfies the allowable range. Also good. As the reference front image, for example, a front image acquired when an image acquisition start signal is issued is used. Further, as the reference front image, a front image used when setting the scanning position on the still image may be used (for details, refer to Japanese Patent Application No. 2012-47176). For example, the control unit 70 determines the continuity of the front images generated by the image generation unit (control unit 70) and stored in the memory 74.
When determining continuity, the control unit 70 may determine whether or not front images satisfying an allowable range of positional deviation are continuous (for example, twice) with respect to the reference front image. The control unit 70 may determine whether or not the front image satisfying the allowable range of the positional deviation continues at least three times with respect to the reference front image.
More specifically, when determining the continuity of misalignment, for example, a plurality of front images in which the acquisition order is continuous are targeted. As a front image in which the acquisition order is continuous, for example, a front image that is repeatedly acquired as a live image and that is continuous in units of one frame can be considered. For example, when a plurality of front images (the acquisition order is continuous) continuously satisfy the allowable range (for example, all), the control unit 70 considers that the front images satisfying the allowable range are continuous.
<Selection of tomographic images using continuity determination>
The control unit 70 is used as a selection processing unit, for example. Therefore, the control unit 70 may select the tomographic image based on the continuity determination result. By providing the above configuration, for example, selection of tomographic images can be appropriately performed using the front image. The control unit 70 may select a tomographic image when it is determined that there is continuity. The process of discarding a tomographic image when it is determined that there is no continuity is one aspect of the process of selecting a tomographic image when it is determined that there is continuity. For example, the control unit 70 performs a selection process on the tomographic image stored in the memory 74 using the determination result of continuity. When the tomographic image is discarded, the once stored tomographic image may be deleted from the memory 74.
As the selection process, the control unit 70 may associate the determination result with a tomographic image obtained during acquisition of a series of front images used for acquisition of the determination result. The control unit 70 may distinguish each tomographic image using the determination result. The control unit 70 uses the determination result to obtain the tomographic image acquired when the front images satisfying the allowable range of displacement and the front images satisfying the allowable range of discontinuity are not consecutive. Images may be selected.
<Application of selection processing>
The control unit 70 is used as, for example, an image synthesis unit that synthesizes a plurality of acquired tomographic images. Therefore, the control unit 70 may select a reference tomographic image for image synthesis from tomographic images that are repeatedly generated based on the determination result of continuity. Then, the control unit 70 may synthesize the selected reference tomographic image and the tomographic image acquired at a timing different from the reference tomographic image. Thereby, for example, since a tomographic image acquired at an appropriate position is set as a reference image, a good composite image can be obtained.
As a method of image synthesis, a method of synthesizing a plurality of tomographic images obtained at the same preset scanning position can be considered. In addition, the composite image includes an addition average image, a super-resolution image, a blood flow measurement image obtained by calculating a difference between each tomographic image, a composite image of a retinal tomographic image and a choroidal tomographic image, a panoramic tomographic image, and luminance between tomographic images. A function OCT image for obtaining a change, a polarization characteristic image in which images of the first polarization component and the second polarization component in PS-OCT are combined, and the like can be considered.
The control unit 70 is used as a scanning control unit, for example. Therefore, the control unit 70 may control the driving of the optical scanner 108 so that the measurement light is scanned a plurality of times at the same preset scanning position. The control unit 70 may select a tomographic image corresponding to a preset scanning position based on the continuity determination result. Thereby, for example, a tomographic image corresponding to a preset scanning position can be reliably acquired from a tomographic image obtained by scanning at the same scanning position.
Note that the scanning position may change from the initial scanning position due to eye movement. The control unit 70 may control the driving of the optical scanner 108 based on the front image acquired by the observation optical system 200 to activate an operation (tracking) for correcting the scanning position.
The control unit 70 may control the driving of the optical scanner 108 to sequentially scan the measurement light at a plurality of scanning positions set by a scanning pattern formed from a plurality of scanning lines. The control unit 70 may select a tomographic image corresponding to the scanning position based on the continuity determination result. Thereby, for example, even when obtaining tomographic images at a plurality of different transverse positions, it is possible to reliably acquire tomographic images at preset scanning positions.
Note that the control unit 70 uses the same reference front image in determination of continuity used for selection of tomographic images at the first crossing position and determination of continuity used for selection of tomographic images at the second crossing position. May be used. Thereby, the positional relationship in each crossing position is ensured.
The selection process is not limited to the above method. In addition, you may make it use when obtaining the tomographic image of the same position as the crossing position acquired in the past in follow-up observation. For example, the control unit 70 detects a positional shift between a front image (reference front image) acquired at the same time as a past tomographic image and a front image acquired in real time on different days. Then, the continuity of the positional deviation of the front image is determined, and a tomographic image acquired in parallel with the front image used for acquiring the determination result is selected using the determination result. Further, it can be used when selecting a tomographic image in one line photographing.
<Correspondence between front image and fault fault>
The control unit 70 may select a tomographic image obtained during acquisition of a series of front images determined to have continuity as a tomographic image acquired at an appropriate position. Thereby, for example, a tomographic image acquired at an appropriate position can be reliably selected.
The control unit 70 is used as a specific processing unit that specifies a tomographic image obtained during acquisition of a series of front images, for example. Therefore, for example, the control unit 70 may specify the tomographic image obtained during the acquisition of the series of front images using the generation timing of the front image generated by the image generation unit (control unit 70). Good.
The control unit 70 may specify a tomographic image obtained during acquisition of a series of front images based on control information when the observation optical system 200 is controlled. When the observation optical system 200 is an SLO optical system, for example, the drive position of the scanner can be considered as control information.
FIG. 1 is a schematic configuration diagram illustrating the configuration of the ophthalmologic photographing apparatus according to the present embodiment. In the following description, a fundus imaging apparatus that performs fundus imaging of the eye to be examined will be described as an example of an ophthalmologic imaging apparatus. Of course, the ophthalmologic imaging apparatus is not limited to the fundus imaging apparatus, and includes an anterior ocular segment imaging apparatus that performs anterior segment imaging of the eye to be examined.
A schematic configuration of an ophthalmologic photographing apparatus 10 according to the present embodiment will be described with reference to FIG. The ophthalmologic imaging apparatus 10 of the present embodiment mainly includes an OCT optical system 100, an observation optical system 200, a fixation target projection unit 300, and a control unit 70.
More specifically, the coupler (light splitter) 104 divides the light emitted from the measurement light source 102 into an optical path of the measurement optical system 106 and an optical path of the reference optical system 110. The measurement optical system 106 guides measurement light to the fundus oculi Ef of the eye E. The reference optical system 110 generates reference light. The OCT optical system 100 synthesizes the measurement light reflected by the fundus oculi Ef and the reference light. The detector 120 (light receiving element) receives the combined light.
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.
The detector 120 (light receiving element) detects an interference state between the measurement light and the reference light. In the case of Fourier domain OCT, the spectral intensity of the interference light is detected by the detector 120, and a depth profile (A scan signal) in a predetermined range is obtained by Fourier transform on the spectral intensity data. Various types of OCT can be employed for the ophthalmologic imaging apparatus 10. For example, any one of Spectral-domain OCT (SD-OCT), Swept-source OCT (SS-OCT), Time-domain OCT (TD-OCT), and the like may be employed in the ophthalmic imaging apparatus 10.
The reference optical system 110 generates reference light. As described above, the reference light is combined with the reflected light acquired by the reflection of the measurement light on 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 observation optical system (front image observation device) 200 is provided to obtain a front image of the fundus oculi Ef. The observation optical system 200 includes, for example, an optical scanner that two-dimensionally scans the fundus of measurement light (for example, infrared light) emitted from a light source, and a confocal aperture that is disposed at a position substantially conjugate with the fundus. And a second light receiving element for receiving the fundus reflection light, and has a so-called ophthalmic scanning laser ophthalmoscope (SLO) device configuration.
Note that the configuration of the observation optical system 200 may be a so-called fundus camera type configuration. The OCT optical system 100 may also serve as the observation optical system 200. That is, the front image may be acquired using data forming a tomographic image obtained two-dimensionally (for example, an integrated image in the depth direction of a three-dimensional tomographic image, at each XY position). Of the spectrum data, luminance data at each XY position in a certain depth direction, retina surface layer image, etc.).
A non-volatile memory (hereinafter abbreviated as “memory”) 72, an operation unit 74, a display unit 75, and the like are electrically connected to the control unit 70. The 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, and a USB memory that is detachably attached to the ophthalmologic photographing apparatus 10 can be used as the memory 72. The memory 72 stores an imaging control program for controlling imaging of front images and tomographic images by the ophthalmologic imaging apparatus 10. Also, the memory 72 stores various types of information relating to imaging, such as information on the imaging position of the captured two-dimensional tomographic image, three-dimensional image, front image, and tomographic image. Various operation instructions by the examiner are input to the operation unit 74.
For example, the control unit 70 acquires a tomographic image by image processing based on the light reception signal output from the detector 120 of the OCT optical system 100, and based on the light reception signal output from the light receiving element of the observation optical system 200. Get a front view. Further, the control unit 70 controls the fixation target projection unit 300 to change the fixation position.
For example, the control unit 70 controls the display screen of the display unit 75. The acquired fundus image is output to the display unit 75 as a still image or a moving image and is stored in the memory 72. The control unit 70 controls each member of the OCT optical system 100, the observation optical system 200, and the fixation target projection unit 300 based on the operation signal output from the operation unit 74.
<Control action>
The control operation of the apparatus having the above configuration will be described. The examiner instructs the subject to gaze at the fixation target of the fixation target projection unit 300. An anterior ocular segment observation image taken by an anterior ocular segment observation camera (not shown) is displayed on the display unit 75. Therefore, the examiner performs an alignment operation so that the measurement optical axis is positioned at the center of the pupil of the anterior eye part.
The control unit 70 controls the driving of the optical scanner 108 and scans the measurement light on the fundus in a predetermined direction. The controller 70 forms a tomographic image by acquiring a light reception signal corresponding to a predetermined scanning region from the output signal output from the detector 120. The control unit 70 also controls the OCT optical system 100 to acquire a tomographic image, and also controls the observation optical system 200 to acquire a fundus front image. And the control part 70 acquires a tomographic image by the OCT optical system 100, and a fundus front image by the observation optical system 200 at any time.
FIG. 2 is a diagram illustrating an example of a display screen displayed on the display unit 75. The control unit 70 displays the front image 20, the index 25, and the tomographic image 30 acquired by the observation optical system 200 on the display unit 75. The scanning pattern 25 is an index representing the measurement position (acquisition position) of the tomographic image on the front image 20. The scanning pattern 25 is electrically displayed on the front image on the display unit 75.
The control unit 70 displays the pointer 21 (for example, a cross mark, a dot mark, a pen mark, etc.) on the display unit 75. The control unit 70 moves the pointer 21 based on the operation signal from the operation unit 74.
In the present embodiment, the operation unit 74 is operated with the pointer 21 positioned on the front image 20 (for example, a drag operation or a click operation) so that shooting conditions can be set. The pointer 21 is used for designating an arbitrary position on the display unit 75.
<Scanline settings>
Hereinafter, a case where a line scan pattern is set as the scan pattern will be described as an example. The scanning pattern 25 is set in advance to an arbitrary shape based on the examiner's operation. For example, a plurality of scanning patterns are selected.
When the tomographic image and the front image are displayed on the same screen, the examiner sets the position of the tomographic image to be photographed from the front image on the display unit 75. Here, the examiner moves the scanning pattern 25 with respect to the front image by performing a moving operation (for example, a drag operation) using the operation unit 74.
When the scan pattern 25 is moved relative to the front image 20 by the examiner, the control unit 70 sets the scan position as needed. Then, the control unit 70 acquires a tomographic image at the scanning position corresponding to the set position. Then, the acquired tomographic image is displayed on the display screen of the display unit 75 as needed. Further, the control unit 70 changes the scanning position of the measurement light based on the operation signal output from the operation unit 74, and displays the scanning pattern 25 at the display position corresponding to the changed scanning position. In this manner, the control unit 70 updates the moving image of the tomographic image by continuously executing the setting of the scanning position and the acquisition of the tomographic image at a certain frame rate.
The operation of this apparatus will be described below. After the setting of the measurement position is completed, when a capture start signal (capture start signal) is input from the operation unit 74, the control unit 70 starts tomographic image and front image capture operations.
In the present embodiment, in order to obtain one tomographic image (B-scan image) in which noise components are suppressed, measurement light is scanned a plurality of times in a predetermined scanning region, and a plurality of tomographic images are obtained and acquired. The plurality of tomographic images are added by the control unit 70 and averaged. In this case, the control unit 70 divides each tomographic image into a plurality of regions that are the same with respect to the scanning direction of the measurement light, and detects a positional deviation between the respective tomographic images for each divided area to obtain positional deviation information. And the control part 70 correct | amends the positional offset between each picked-up image for every divided | segmented area | region based on the acquired positional offset information. Then, the control unit 70 adds the corrected captured images and averages them.
When obtaining the addition average image, the control unit 70 uses, for example, the absolute values (A scan signals after imaging) of the real number component and the imaginary number component of the depth information forming the tomographic image to form a plurality of tomographic images. An addition average image may be acquired. Further, the control unit 70 may acquire the addition average image by using the real / imaginary component in the Z space that is the basis of each tomographic image. The control unit 70 obtains the first addition average data using the signal of the real number component, obtains the second addition average data using the signal of the imaginary number component, and combines them into a plurality of tomographic images. An addition average image may be acquired.
In response to the input of the acquisition start signal, the control unit 70 controls the OCT optical system 100 in order to repeat tomographic images at a set frame rate (for example, 10 to 15 Hz (super fine mode)). Note that the frame rate for obtaining the tomographic image may or may not be changed before and after the start of capturing.
The control unit 70 acquires a plurality of tomographic images at the same scanning position. For this reason, scanning at substantially the same position on the fundus is repeated. By such a plurality of scans, the control unit 70 can acquire a plurality of tomographic images at substantially the same position.
Specifically, the control unit 70 scans the measurement light a plurality of times using the optical scanner 108 with respect to the set scanning position. Then, the controller 70 generates a plurality of frames (n (n ≧ 2)) of tomographic images at the same scanning position. The control unit 70 stores the generated tomographic images in the memory 72 as needed.
On the other hand, in response to the input of the capture start signal, the control unit 70 controls the observation optical system 200 in order to repeat the front image at a set frame rate (for example, 10 to 15 Hz). Note that the frame rate for obtaining the front image may or may not be changed before and after the start of capturing. Note that the frame rate for obtaining the tomographic image and the frame rate for obtaining the front image may be the same frame rate or different frame rates. Further, in the operation of acquiring the tomographic image and the front image, they may be synchronized or asynchronous.
The control unit 70 repeats the operation of acquiring the front image while a plurality of tomographic images are acquired. With such control, the control unit 70 monitors eye movement while tomographic images are continuously acquired.
Specifically, the control unit 70 receives reflected light from the front of the fundus by the operation of the observation optical system 200. The control unit 70 generates a plurality of front images by processing the received reflected light. The control unit 70 stores the generated plurality of front images in the memory 72 as needed. As described above, the control unit 70 causes generation of the front image in parallel with generation of the tomographic image.
<Appropriateness determination of tomographic image using front image>
FIG. 3 is a flowchart illustrating an example of a determination method for determining whether or not the acquired tomographic image is acquired at a preset position. The determination is made in real time. The determination result is used to set an OCT template image (first reference image) of a tomographic image when performing the averaging process.
First, the control unit 70 sets a template image (second reference image) of the front image for detecting the positional deviation of the front image. As the second reference image, for example, a front image when an acquisition start signal is input is used.
The control unit 70 captures the live image of the front image. The control unit 70 calculates a positional shift between the second reference image and the repeatedly generated live front image by image processing. Thereby, the shift amount D1 of the OCT imaging position is detected in real time. The deviation amount D1 is updated at the timing when the deviation amount between the front image and the second reference image is newly detected.
The controller 70 determines whether or not the deviation amount D1 satisfies an allowable range (for example, a predetermined threshold). Here, every time one frame of the front image is acquired, the control unit 70 determines whether or not the shift amount D1 with respect to the second reference image satisfies the allowable range. That is, the control part 70 acquires the determination result for every front image acquired continuously in real time.
When the deviation amount D1 does not satisfy an allowable range (for example, a predetermined threshold), the control unit 70 controls the optical scanner 108 and corrects the OCT imaging position. For example, the control unit 70 appropriately controls driving of the two galvanometer mirrors of the optical scanner 108 so that the shift of the scanning position is corrected. Thereby, since the scanning position is corrected, the photographing position is corrected. (Tracking control).
The above operation is repeated until the added number reaches the set upper limit number or until the end operation is performed by the examiner.
Next, an operation when setting an OCT template image (first reference image) will be described. The control unit 70 captures the live image of the tomographic image in parallel with the acquisition of the live image of the front image. Therefore, the control unit 70 determines whether or not an OCT template image is set.
When the OCT template image is not set, the control unit 70 determines whether or not the deviation amount of the OCT imaging position is updated. If it has not been updated, it is returned to the capture of the OCT live image.
If it has been updated, it is determined whether or not the aforementioned deviation D1 satisfies an allowable range (for example, a predetermined threshold). When the shift amount D1 does not satisfy the allowable range, the control unit 70 discards the captured live image (OCT template candidate image) of the tomographic image. Then, the operation returns to the OCT live image capturing operation. On the other hand, when the deviation D1 satisfies the allowable range, the process proceeds to the next step.
In the next step, the control unit 70 determines whether or not an OCT template candidate image is held. In the case of No, the control unit 70 holds the captured live image of the tomographic image as an OCT template candidate image. In the case of Yes, the control unit 70 sets a previously stored OCT template candidate image as the OCT template image.
When the OCT template image is set as described above, the control unit 70 determines whether or not the above-described deviation amount D1 satisfies the allowable range. In the case of No, the live image of the captured tomographic image is discarded or ignored, and the process returns to capturing the tomographic image. In the case of Yes, the control unit 70 performs an addition averaging process using the captured tomographic image and the OCT template image. The above operation is repeated until the added number reaches the set upper limit number or until the end operation is performed by the examiner.
In the operation up to the setting of the OCT template image in the flowchart, when the determination that the deviation D1 satisfies the allowable range is the first time, the acquired tomographic image is held as an OCT template candidate image. Thereafter, when the determination that the deviation amount D1 satisfies the allowable range is performed twice in succession, the acquired tomographic image is held as an OCT template candidate image. On the other hand, if the determination that the deviation amount D1 satisfies the allowable range is not continued, the OCT template candidate image held by the first determination is discarded.
That is, the control unit 70 determines the suitability of the tomographic image using the continuity of the determination result with respect to the front image. Then, the control unit 70 sets a reference image (first reference image) of the tomographic image when performing the averaging process based on the determination result of suitability.
Specifically, the control unit 70 determines that the tomographic image acquired when the front images satisfying the allowable range are continuous is appropriate, and determines that the tomographic image acquired when the front images satisfying the allowable range are not continuous is inappropriate. Is determined. Then, the control unit 70 combines the reference image and another tomographic image using the tomographic image determined to be appropriate as a reference image, and generates an addition average image.
4 is a diagram showing an example of determination when the continuity of the determination result for the front image is used, and FIG. 4 is a diagram when the acquisition timing of the tomographic image and the front image is asynchronous.
For example, for the first front image E1 and the second front image E2 in which the acquisition order is continuous, the front image E2 satisfies the allowable range, but the front image E1 does not satisfy the allowable range. Therefore, the tomographic image T1 obtained during the acquisition of the front image E1 and the front image E2 is determined to be inappropriate. Similarly, regarding the front image E2 and the front image E3, the tomographic image T2 is determined to be inappropriate because the front image E2 does not satisfy the allowable range. Moreover, since both the front image E3 and the front image E4 do not satisfy the allowable range, the tomographic image T3 is determined to be inappropriate. Further, regarding the front image E4 and the front image E5, since the front image E4 does not satisfy the allowable range, the tomographic image T4 is determined to be inappropriate.
The controller 70 considers that both the front image E5 and the front image E6 satisfy the allowable range, that is, the front images that satisfy the allowable range are continuous. Therefore, the tomographic image T5 obtained during the acquisition of the front image E5 and the front image E6 is determined to be appropriate. The control unit 70 stores the tomographic image T5 in the memory 74 as a template image (first reference image) of the tomographic image when performing the averaging process.
The control unit 70 distinguishes between tomographic images acquired during the acquisition of a plurality of front images (in which the acquisition order is continuous). For example, the control unit 70 may output a timing signal (outputs a time stamp) when the generation of each front image is completed. Here, the control unit 70 outputs the first timing signal when the generation of the first front image is completed. Thereafter, the control unit 70 outputs a second timing signal when the generation of the next second front image is completed. Then, the control unit 70 is acquiring the first front image and the second front image for the tomographic image that has been generated in the time interval from when the first timing signal is output until the second timing signal is output. It is regarded as a tomographic image acquired in When a plurality of tomographic images are acquired during acquisition of a plurality of front images, they are stored together in the memory 72 as tomographic images.
Hereinafter, the processing after the template image is acquired will be described in detail. When the next tomographic image is acquired after the template image of the tomographic image is acquired, the control unit 70 obtains the addition average data by combining them by image processing. The obtained addition average data is stored in the memory 74. Note that the addition average data may be the addition average image itself (or luminance information that is the basis of the addition average image (luminance information obtained by adding the luminance of each image). In this case, the control unit 70 preferably performs alignment between tomographic images by image processing (for example, refer to Japanese Patent Application Laid-Open No. 2010-110392 for the alignment method).
For example, the control unit 70 repeatedly acquires the tomographic image and the front image until the number of tomographic images to be added reaches a predetermined number. Furthermore, every time a tomographic image is added, the control unit 70 updates the added average data by synthesizing the added average data added in advance and the added tomographic image. The updated composite data is stored in the memory 74.
In the flowchart of FIG. 3, the control unit 70 determines the suitability of the tomographic image used for the addition process using the deviation amount D1. Then, the control unit 70 uses the tomographic image for which the deviation amount D1 is determined to be within the allowable range for the addition process with the template image. The control unit 70 does not use the tomographic image determined that the shift amount D1 does not satisfy the allowable range for the addition process with the reference image. In addition, regarding the suitability of the tomographic image used for the addition process with the reference image, a positional shift between the tomographic images, a correlation degree, or the like may be used.
When the number of tomographic images to be added reaches a predetermined number, the control unit 70 ends the image capturing operation. Then, the control unit 70 generates an addition average image of the tomographic image based on the addition average data stored in the memory 74. The control unit 70 displays the generated addition average image on the display unit 75. In addition, the control unit 70 stores the generated addition average image in the memory 74.
As described above, by setting the tomographic image acquired when the front images satisfying the allowable range are continuous as the reference image, there is a high possibility that the tomographic image is acquired at the same position as the preset scanning position. A tomographic image is set as a reference image. For this reason, a highly accurate addition average image can be obtained smoothly.
Note that when it is determined whether or not a tomographic image is necessary based on a positional shift of only one front image, the tomographic image may be determined to be appropriate even if the eye moves during acquisition of the front image. For example, when determining the suitability of a tomographic image acquired after generating one front image, the eye may be moving at the time when the tomographic image is generated. As a result, a tomographic image including a positional deviation may be set as a reference image. In this case, since the acquisition position of the tomographic image is different from the preset position, it is difficult to generate a good addition average image. Therefore, by determining the continuity as described above, it is possible to determine that the next front image does not satisfy the allowable range even when the eye moves after acquisition of one front image. You can overcome the problem.
<Transformation example>
<Continuity of front image>
In the above description, the control unit 70 determines that the tomographic image acquired when the front image satisfying the allowable range is continuous twice in the front image in which the acquisition order is continuous once is appropriate, and the allowable range A tomographic image acquired when front images satisfying the condition are not continuous was determined to be inappropriate. However, the control unit 70 may use a front image in which the acquisition order is continuous twice or more. For example, the control unit 70 determines that the tomographic image acquired when the front image satisfying the allowable range is continuous twice is proper, and the tom acquired when the front image satisfying the allowable range is not continuous once or continuously. The image may be determined to be inappropriate. In this case, the control unit 70 may select the tomographic image acquired when the central front image in the series of front images satisfying the continuity of the positional deviation is acquired.
Note that the present embodiment is not limited to the configuration in which the tomographic image is acquired once while the front image is acquired twice (the rightmost column of the tomographic images in FIGS. 3 and 4). For example, even in a configuration in which a plurality of tomographic images are acquired while the front image is acquired twice (the leftmost column and the middle column in FIGS. 3 and 4), the technique of the present embodiment can be applied. Is possible.
In the above description, the SLO optical system is used as the observation optical system 200. However, the present invention is not limited to this. That is, the observation optical system 200 may be a front observation optical system that can acquire a front image of the eye to be examined. For example, the observation optical system 200 may be configured to image the fundus of the eye to be examined with an infrared camera. In the case of an infrared camera, since the frame rate is usually faster than that of an SLO optical system, continuity in a shorter span can be determined, so that a tomographic image can be determined in a short span. On the other hand, when the SLO optical system is used, there is an advantage that the suitability of the tomographic image can be appropriately determined by the continuity determination even in the case of the SLO optical system having a low frame rate.
The observation optical system 200 may be an anterior ocular segment observation optical system for observing an anterior segment image of the eye to be examined. That is, when obtaining a tomographic image of the fundus of the eye to be examined, the tomographic image may be selected by determining the continuity of the positional deviation of the anterior segment image acquired by the anterior segment observation optical system.
<Association of acquisition timing between front image and tomographic image>
In the above description, the acquisition timing of the front image and the tomographic image is associated using the timing signal acquired when the generation of each front image is completed. However, it is not limited to this.
Therefore, the control unit 70 may use control information of at least one of the OCT optical system 100 and the observation optical system 200. For example, the scanning position for obtaining the front image and the tomographic image may be used.
The control unit 70 detects the scanning position of the optical scanner 108 and the scanning position of the optical scanner of the observation optical system 200. Then, the control unit 70 outputs timing signals for starting and ending optical scanning for obtaining each front image. Here, the control unit 70 outputs the first timing signal when the scanning position in the observation optical system 200 reaches the start position for obtaining each front image. The control unit 70 outputs the second timing signal when the scanning position in the observation optical system 200 reaches the end position for obtaining each front image.
On the other hand, the control unit 70 outputs timing signals when the scanning position of the optical scanner 108 reaches the start position for obtaining each tomographic image and when it reaches the end position.
And the control part 70 is a tomographic image acquired in the time interval T2 after the 1st timing signal in a 1st front image is output until the 2nd timing signal in the next 2nd front image is output. Is specified using the scanning position of the optical scanner 108. That is, in the time interval T2, the tomographic image that has been scanned from the start position to the end position may be regarded as a tomographic image acquired during acquisition of the first front image and the second front image.
<Application to composite image other than addition average image>
In the above description, the continuity of the determination result with respect to the front image is used to obtain the addition average image in the tomographic image, but the present invention is not limited to this. In other words, any configuration may be used as long as it determines the suitability of the tomographic image used for image synthesis using the continuity of the determination result with respect to the front image. For example, the control unit 70 sets a template image (first reference image) of a tomographic image when performing image composition processing based on the determination result of suitability. The control unit 70 determines that the tomographic image acquired when the front images satisfying the allowable range are continuous and determines that the tomographic image acquired when the front images satisfying the allowable range are not continuous is inappropriate. Then, the control unit 70 uses the tomographic image determined to be appropriate as a reference image, and combines the reference image and another tomographic image to obtain a combined image. As the composite image processing, for example, super-resolution image processing (for example, see Japanese Patent Application No. 2011-173028 by the present applicant), noise removal processing, and the like can be considered.
<Applications other than acquiring multiple tomographic images at the same position>
In the above description, the case where the eye to be examined is scanned a plurality of times at the same scanning position is described as an example, but the present invention is not limited to this. For example, the present embodiment can be applied even when the tomographic image is obtained with a plurality of different scanning lines by changing the scanning position on the eye to be examined.
As a scan pattern for obtaining a tomographic image with a plurality of different scan lines, for example, a scan in which scan lines in the same direction are formed at different positions, a cross scan, a raster scan, a radial scan, and the like can be considered. The cross scan is, for example, a scan pattern in which a plurality of scan lines intersect each other. The raster scan is, for example, a scan pattern that rasters measurement light within a rectangle. The radial scan is, for example, a scan pattern in which a plurality of scan lines are arranged radially.
For example, a first scan line and a second scan line are set as a plurality of different scan lines. The control unit 80 sets the front image acquired when the acquisition start signal is issued as the second reference image. The control unit 80 may set the front image when the tomographic image on the first scanning line is acquired as the second reference image.
The control unit 70 calculates the positional deviation between the template image of the front image (hereinafter referred to as the second reference image) and the front image acquired when acquiring the tomographic image on the second scanning line by image processing. The control unit 70 determines whether the positional deviation amount with respect to the second reference image satisfies the allowable range every time one frame of the front image is acquired. That is, the control part 70 acquires the determination result for every front image acquired continuously in real time.
Here, the control unit 70 determines the suitability of the tomographic image acquired by the second scanning line using the continuity of the determination result with respect to the front image. When acquiring the tomographic image in the second scanning line, the control unit 70 determines that the tomographic image acquired when the front image satisfying the allowable range is continuous is appropriate, and the front image satisfying the allowable range is not continuous. It is determined that the tomographic image acquired in 1 is improper. Then, the control unit 70 stores the tomographic image determined to be appropriate in the memory 72 as the tomographic image acquired by the second scanning line.
Thereafter, when the third scan line is set, the control unit 70 may move the second scan line to the third scan line. Since the subsequent processing is the same as the processing in the second scanning line, description thereof is omitted.
The tomographic image acquired at each scanning line is associated with the set scanning pattern. The associated tomographic image data is used for output to the monitor 74, analysis of the eye to be examined, and the like.
In this way, even when tomographic images at different scanning positions are obtained, a tomographic image having a high possibility of being acquired at the same position as the preset scanning position is acquired. That is, a tomographic image at each scanning line can be reliably acquired.
In the above description, the moving image of the tomographic image and the moving image of the front image are obtained at the same time. However, the present invention is not limited to this. For example, the technique of this embodiment can be applied even in a configuration in which a moving image of a tomographic image and a moving image of a front image are alternately acquired in units of one frame.
DESCRIPTION OF SYMBOLS 20 Front image 25 Scan pattern 30 Tomographic image 70 Control part 72 Memory 74 Operation part 75 Display part 100 OCT optical system 108 Optical scanner 200 Observation optical system
An image synthesis means for synthesizing a plurality of acquired tomographic images;
The selection processing means selects a reference tomographic image to be combined by the image combining means from the tomographic image based on the determination result,
The ophthalmic imaging apparatus according to claim 1, wherein the image synthesizing unit synthesizes the reference tomographic image selected by the selection processing unit and a tomographic image acquired at a timing different from the tomographic image.
Scanning means for scanning the measurement light applied to the eye to be examined on the eye to be examined;
Scanning control means for controlling the driving of the scanning means and scanning the measurement light a plurality of times at the same preset scanning position;
The ophthalmic imaging apparatus according to claim 1, wherein the selection processing unit selects a tomographic image corresponding to the scanning position based on the determination result.
Scanning control means for controlling driving of the scanning means and sequentially scanning the measurement light at a plurality of scanning positions set by a scanning pattern formed from a plurality of scanning lines;
The ophthalmologic imaging apparatus according to claim 1, wherein the selection processing unit selects a tomographic image corresponding to the scanning position based on the determination result.
The ophthalmologic photographing apparatus according to any one of claims 1 to 4, wherein the continuity determination unit determines whether or not the front image in which the positional deviation satisfies an allowable range continues at least three times.
The ophthalmic imaging apparatus according to claim 1, wherein the selection processing unit selects the tomographic image obtained during acquisition of a series of the front images determined to be continuous.
The ophthalmologic imaging apparatus according to claim 6, further comprising: a specific processing unit that specifies the tomographic image obtained during the acquisition of the series of the front images by using the generation timing of the front image by the image generation unit.
The ophthalmologic according to claim 6, further comprising: a specific processing unit that specifies the tomographic image obtained during the acquisition of the series of the front images based on control information when the OCT optical system or the observation optical system is controlled. Shooting device.
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