JP2008237432A - Fundus oculi blood flow imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fundus oculi blood flow imaging apparatus for precision measurement of blood flow dynamic state. <P>SOLUTION: This imaging apparatus for a blood flow at the fundus oculi is provided with a laser beam irradiation system 1 to irradiate laser beam to blood flow through the biomedical tissues, a beam reception system having a beam receiver composed of many pixels to detect reflected light from the biomedical tissues, an image introducing part to continuously capture a plurality of images at a regular interval based on a signal from the beam receiver, an image memory to store this plurality of images, and an operation part to calculate blood flow velocity within the biomedical tissues from the temporal response of output signals among pixels corresponding to each of different stored images. The laser beam irradiation system is composed of a plurality of laser beam sources generating laser beams with different wavelengths used for the measurement. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a blood flow imaging apparatus for measuring a blood flow state of a living tissue. More specifically, the present invention is an apparatus for measuring the blood flow state of the fundus of the eye to be examined using laser light, and by varying the wavelength of the laser light for measurement, The present invention relates to a fundus blood flow imaging apparatus capable of measuring the blood flow state of each layer with high accuracy.

Contrast-enhanced examination of the retina and choroid is very important for diagnosing ophthalmic diseases. These include fluorescein fluorescence fundus angiography (FA) and indocyanine green fluorescence fundus angiography (IA). However, since both methods inject the fluorescent dye intravenously, serious side effects such as drug-induced shock sometimes appear. In addition, nausea and vomiting occur frequently, and pigmentation and the like occur on the skin. On the other hand, the technique based on the laser principle according to the present invention does not require the use of a contrast medium when examining the fundus and the like, and scans with a low-power laser beam. It is useful and various developments and improvements are underway.

When laser light is irradiated toward a living tissue such as the fundus, the laser light is scattered by the particles that make up the living tissue, and the intensity distribution of the reflected scattered light is a dynamic laser speckle ( A random spotted pattern). It is known that this pattern is detected by an image sensor on the imaging plane, the temporal change of the pattern in each image is quantified, and displayed on the map to visualize the blood flow distribution in the capillary near the living body surface. ing.

By utilizing such a phenomenon, conventionally, an image sensor such as a solid-state image device (CCD camera) or the like is formed by irradiating a blood cell of a living tissue such as a fundus of a subject's eye with a laser beam, and an image formed by reflected light from the blood cell. A number of images are taken and stored continuously at predetermined time intervals, and a predetermined number of images are selected from the stored images, and the amount of time variation of output at each pixel of each image There is known a blood flow velocity measuring apparatus that calculates a value obtained by integrating the values of the blood flow rate and calculates a blood cell velocity (blood flow velocity) from the value. In this type of blood flow velocity measuring device, the output fluctuation amount of each pixel corresponds to the moving speed of the blood cell. Therefore, based on the calculated output fluctuation value of each image or the reciprocal value thereof, The blood flow velocity distribution is displayed as a two-dimensional image on the monitor image. This type of device has many calculation functions for clinical use, and various clinical improvements and improvements have been made.

  For example, Japanese Patent Application Laid-Open No. Sho 62-275431 (the following Patent Document 1), Japanese Patent Application Laid-Open No. 2-274220 (the following Patent Document 2), Japanese Patent Application Laid-Open No. 2003-164431 (the following Patent Document 3), etc. As a method for irradiating and measuring a blood flow state of the fundus, a laser speckle method using a scattering interference effect of laser light by a living tissue and an image processing method of measurement data are described. In these publications, a He—Ne laser (wavelength 632.8 nm), an Ar laser (wavelength 488 nm or 514.5 nm) or a semiconductor laser (wavelength 780 nm) is used as a laser light source at a single wavelength, and the blood flow state of the fundus is determined. A method of measuring is disclosed.

  Japanese Laid-Open Patent Publication No. 5-111469 (Patent Document 4 below) discloses a surface that can accurately measure blood flow at a predetermined depth of a measurement site, which is based on a laser Doppler method different from the method according to the present invention. A blood flow meter is disclosed. However, it does not describe that the wavelength of the laser beam is made variable by changing the output of the incident laser beam to obtain information in the depth direction of the measurement site.

  Japanese Patent Application Laid-Open No. 11-113849 (Patent Document 5 below) uses a laser Doppler method different from the method according to the present invention, but uses different wavelengths (for example, red light and green light) for the same target region of the fundus of the eye to be examined. A fundus blood flow meter that measures blood flow velocity by irradiating light) is disclosed. However, the technique disclosed here uses a laser diode for measurement and optimizes the light reception state using another light source for tracking, and it obtains information in the depth direction of the measurement site. Not intended.

JP-A-62-275431 JP-A-2-274220 JP 2003-164431 A JP-A-5-111469 JP-A-11-113849

  The present invention is an apparatus for measuring the blood flow state of the fundus of a subject's eye using laser light, and by varying the wavelength of the laser light for measurement, An object of the present invention is to provide a fundus blood flow imaging device that can differentiate a blood flow state and measure it with high accuracy.

  Conventionally, when measuring the blood flow state of the fundus of the eye using laser light, it is necessary to reach the choroid when measuring the blood flow state of the choroid. Light is used. In such a conventional apparatus, since the laser light is measured at a single wavelength near 800 nm, the blood flow of the retina other than the blood flow of the choroid is also added and displayed, so that the accuracy is higher. There is a problem that blood flow measurement data cannot be obtained. Further, when the blood flow state of the retina is measured with the same device, the blood flow of the choroid is added to the blood flow of the retina, and similarly, there is a problem that highly accurate blood flow measurement data cannot be obtained.

  As described above, it is also possible to obtain information in the depth direction of the measurement site by changing the output of the laser beam. However, the greater the measurement depth, the greater the output of the laser beam, and there is a problem in examining the fundus.

  When measuring blood flow at the level of diseases associated with hypertension and arteriosclerosis such as diabetic retinopathy and retinal artery and vein occlusion, the wavelength of the laser beam that does not reach the choroid may be used. However, this measurement wavelength makes it impossible to measure blood flow in the diagnostic choroid for diseases caused by neovascularization such as age-related macular degeneration. Therefore, in order to measure the blood flow state of each layer such as the retina and choroid with high accuracy, it is necessary to eliminate information on tissues not targeted and differentiate blood flow between tissues.

  The present invention relates to a laser beam irradiation system for irradiating a blood flow of a biological tissue with a laser beam, a light receiving system having a light receiving unit composed of a large number of pixels for detecting reflected light from the biological tissue, An image capturing unit that continuously captures a plurality of images at predetermined time intervals, an image storage unit that stores the plurality of images, and a temporal change in an output signal of each corresponding pixel of the stored plurality of images In a blood flow imaging apparatus including a calculation unit that calculates a blood flow velocity in a living tissue, the laser light irradiation system is configured to include a plurality of laser light sources that generate laser beams having different wavelengths used for measurement. .

  According to the present invention, based on the above-described device configuration, the wavelength of the laser light is appropriately switched from 480 nm to 830 nm and used, and the blood flow state by layer in the tissue to be measured can be measured with high accuracy. It is. The penetration depth of laser light into a living tissue varies depending on the wavelength of the laser light, and the penetration depth increases as the wavelength of the laser light increases. The difference in the penetration depth is due to the fact that the degree of scattering and absorption of laser light by living tissue, blood cell particles, and the like differs depending on the wavelength of the laser light.

Specifically, blood flow from the choroid to the sclera can be measured at a wavelength of laser light near 830 nm, and blood flow to the vicinity of the retinal pigment epithelium can be measured at a wavelength of laser light near 600 nm to 800 nm. The blood flow of the retina can be measured at a wavelength of laser light around 480 to 600 nm.

For example, when measuring using laser light near 830 nm, a part of the laser light is scattered when it passes through the retina, resulting in speckle light. It also includes blood flow data of the retina. Therefore, for example, subtracting the blood flow data obtained using the laser light near 500 nm from the blood flow data obtained using the laser light near 830 nm results in blood flow data from only the layer corresponding to the choroid region. , More accurate blood flow data in the choroid can be obtained. In addition, by setting appropriate wavelengths, for example, 800 nm and 650 nm, and changing the wavelength finely, measurement is performed, and blood flow data of a portion not to be measured is removed to remove fine blood flow such as retinal pigment epithelium. Can also be measured. Basically, blood flow data measured using short-wavelength laser light may be subtracted from blood flow data measured using long-wavelength laser light.

  The wavelength of the laser light can be varied by arranging a plurality of laser light sources and switching them. If as many laser light sources as possible are arranged, the wavelength of the laser light can be changed finely. However, the wavelength of the laser beam can be changed finely, except for measurement that stratifies the area near the boundary of the tissue, such as the vicinity of the boundary between the retina and the retinal pigment epithelium, or the boundary between the retinal epithelium and the choroid. However, the contribution to improvement of measurement accuracy is scarce. Therefore, it is not necessary to increase the number of laser sources. For example, the number of laser light sources may be 2 to 8. Considering the configuration of the apparatus, the number of laser light sources is preferably 3 to 6. However, the number of laser light sources need only be plural, and is not limited to this number.

  The method for switching the laser light source is not particularly limited. For example, it can be performed by linearly arranging a plurality of laser light sources and moving them. Further, a method of changing the optical path of the laser beam by appropriately operating the mirror may be used.

  As a laser light source, a device that generates laser light having a specific wavelength, such as a gas laser or a semiconductor laser, can be used, but a wavelength conversion device may be used in combination to obtain a predetermined wavelength. When a wavelength range that can be used by the wavelength conversion device is used, the wavelength can be varied electrically, and the choice of wavelengths becomes large. Further, a variable wavelength laser such as a die laser can be used.

  Further, the present invention provides a method for analyzing a plurality of blood flow data for each laser beam having different wavelengths obtained by sequentially irradiating the same part of the living tissue with laser beams having different wavelengths from the laser light source. 1 is a blood flow imaging device including a calculation unit that calculates a blood flow velocity. Blood flow data of a living tissue is acquired using a laser beam having an appropriately selected first wavelength, and then the blood flow of the living tissue at the same site using a laser beam having an appropriately selected second wavelength. Get the data. A plurality of data obtained in this way is stored, the stored data is read, and the scattering and absorption by the living tissue according to the wavelength of the laser beam is corrected, and the other blood flow data is removed from one blood flow data It is comprised including the calculating part to perform.

As a result, it is possible to differentiate and measure with high accuracy the blood flow state by layer within the tissue to be measured.

  According to the present invention, by varying the wavelength of the laser beam for measuring the blood flow state of the fundus of the eye to be examined, it is possible to measure the blood flow state of each layer in the tissue to be measured with high accuracy. It is possible to provide a fundus blood flow imaging apparatus that has been made possible.

According to the present invention, since the blood flow state of the fundus retina, retinal pigment epithelium, choroid, and sclera can be measured with high accuracy, angiogenesis from the choroid such as age-related macular degeneration is a cause. Can provide useful data for the diagnosis of diseases.

  A blood flow imaging device according to the present invention includes a laser light irradiation system that irradiates a blood flow of a biological tissue with laser light, a light receiving system that includes a light receiving unit including a plurality of pixels that detect reflected light from the biological tissue, An image capturing unit that captures a plurality of images continuously at predetermined time intervals based on a signal from the light receiving unit, an image storage unit that stores the plurality of images, and an output of each corresponding pixel of the stored plurality of images It is comprised from the calculating part which calculates the blood flow velocity in a biological tissue from the time change of a signal. The laser beam irradiation system includes a plurality of laser light sources that generate laser beams having different wavelengths.

  FIG. 1 shows an outline of the optical system of the fundus blood flow imaging apparatus of the present invention. Reference numeral 1 denotes a laser beam irradiation system, reference numeral 4 denotes a light receiving system, and reference numeral 2 denotes an eye to be examined as an example of a living tissue having blood flow. In the laser light irradiation system 1, a plurality of laser light sources 101 to 103, for example, a plurality of laser diodes are arranged. By appropriately switching this, it is possible to irradiate the eye 2 with a wavelength of a laser beam having a predetermined wavelength. Laser light from the laser light irradiation system 1 is irradiated to the eye 2 to be examined, for example, via the half mirror 3. The light receiving system 4 includes an optical system 400 including a light receiving lens, a CCD camera 401 as a light receiving unit including a large number of pixels for detecting reflected light from the eye 2 to be examined, and an amplifier circuit 403.

  To change the wavelength of laser light, a plurality of laser light sources are arranged and switched. If as many laser light sources as possible are arranged, the wavelength of the laser light can be changed finely. However, the wavelength of the laser beam can be changed finely, except for measurement that stratifies the area near the boundary of the tissue, such as the vicinity of the boundary between the retina and the retinal pigment epithelium, or the boundary between the retinal epithelium and the choroid. However, the contribution to improvement of measurement accuracy is scarce. Therefore, it is not necessary to increase the number of laser sources. For example, the number of laser light sources may be 2 to 8. Considering the configuration of the apparatus, the number of laser light sources is preferably 3 to 6. For example, in the case of four, devices that generate wavelengths of 480 nm to 600 nm, 600 nm to 700 nm, 700 nm to 800 nm, and 800 nm to 830 nm may be selected. However, the number of laser light sources need only be plural, and is not limited to this number.

  Then, one wavelength is appropriately selected from the laser light source, and the fundus is irradiated with the laser light. Laser reflected light from the fundus is imaged as a biological tissue on the CCD camera 401 by a light receiving lens in the optical system 400. The CCD camera 401 has a large number of pixels on its light receiving surface, converts a biological tissue image formed by a light receiving lens in the optical system 400 into an electric signal, reads out signal charges by a frame accumulation method, and uses it as a video signal. Output. The video signal is amplified by the signal amplification circuit 403, and the video signal amplified by the signal amplification circuit 403 is output to the analog signal processing means 5 that performs gain control and the like, and is converted into a digital signal by the A / D converter 6. The The blood flow velocity obtained based on the signal is superimposed on the fundus image and displayed on the display 9.

  Here, for example, in the case of measurement at a single wavelength where the wavelength of the laser beam is around 800 nm, the blood flow of the retina other than the blood flow of the choroid is also added and displayed. Therefore, by switching the wavelength of the laser beam, for example, measurement is performed using a laser beam having a wavelength near 500 nm, and blood flow data similar to the above is obtained. If the latter blood flow data is subtracted from the former blood flow data, it becomes data only from the choroid, so that highly accurate blood flow data of the choroid can be obtained.

In addition, measurement is performed using laser light of 780 nm and 650 nm, for example, by appropriately combining laser light wavelengths, and blood flow data obtained at the latter wavelength is subtracted from blood flow data obtained at the former wavelength. If pulled, blood flow near the retinal pigment epithelium can be measured. Furthermore, fine blood flow such as retinal pigment epithelium can be measured by finely setting the wavelength.
Basically, blood flow data measured using short-wavelength laser light may be subtracted from blood flow data measured using long-wavelength laser light. Since the degree of scattering / absorption by the living tissue differs depending on the wavelength of the laser light, the scattering / absorption of blood flow data may be corrected for each wavelength by a known method in order to improve accuracy.

  As described above, the present invention makes it possible to appropriately select a combination of laser light wavelengths for measurement by changing the wavelength of the laser light for measuring the blood flow state of the fundus of the eye to be examined. It is possible to provide a fundus blood flow imaging apparatus capable of measuring a blood flow state by layer in a measurement target tissue with high accuracy by performing a comparison operation on the blood flow data obtained by using the blood flow data. it can.

  Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the specific examples described in the embodiments, and various applications can be added according to the common general technical knowledge of those skilled in the art.

  The fundus blood flow imaging device of FIG. 1 described above will be further described in detail. The laser light irradiation system 1 that irradiates the blood flow of the eye 2 to be examined, which is a living tissue, has an optical system 110 including a condenser lens and a diaphragm, and a laser light source 100 including a plurality of laser light sources 101 to 103. ing. Here, the optical system 110 has a function of appropriately converging and diffusing laser light emitted from the laser light source 100 and emitting it to the half mirror 3.

  The laser light source 100 selects a plurality of laser light sources 101 to 103 that generate laser beams having different wavelengths used for measurement, and arbitrarily selects a laser light source from the plurality of laser light sources 101 to 103 and emits the laser light to the optical system 110. And a switching unit 104 for irradiating the blood flow of the living tissue with the laser light.

Here, as described above, each of the plurality of laser light sources 101 to 103 is configured by, for example, a laser diode. The laser light source 101 is, for example, a laser diode that can generate laser light with a wavelength of 500 nm, and the laser light source 102 is a laser diode that can generate laser light with a wavelength of 650 nm, for example. The laser light source 103 is a laser diode capable of generating laser light having a wavelength of 830 nm, for example.

  In addition, the said wavelength of the laser beam which each laser light source 101-103 generate | occur | produces is an illustration, Comprising: For example, the wavelength of the laser beam which the laser light source 101 generate | occur | produces is selected from 480 nm-600 nm, and the laser which the laser light source 102 generate | occur | produces The wavelength of light may be selected from 600 nm to 800 nm, and the wavelength of laser light generated by the laser light source 103 may be selected from 800 nm to 830 nm.

  In FIG. 1, the case where three laser light sources 101 to 103 are provided is shown as an example, but the present invention is not limited to this. For example, in FIG. 1, the laser light source 103 is omitted, and only two laser light sources 101 and 102 are provided. The laser light source 101 is configured by a laser diode capable of generating laser light having a wavelength of 500 nm, for example. You may comprise with the laser diode which can generate | occur | produce the laser beam of wavelength 830nm. In this case, for example, the wavelength of the laser light generated by the laser light source 101 may be selected from 480 nm to 600 nm, and the wavelength of the laser light generated by the laser light source 102 may be selected from 800 nm to 830 nm. .

  For example, as shown in FIG. 1, the plurality of laser light sources 101 to 103 are arranged in parallel on the switching unit 104. The switching unit 104 is, for example, a stage that can fix the laser light sources 101 to 103 to the upper surface thereof, and has a movable mechanism that can slide in a horizontal direction in FIG. Accordingly, the switching unit 104 can be moved left and right to arbitrarily select one laser light source from the plurality of laser light sources 101 to 103 and emit one laser beam to the optical system 110.

  The switching unit 104 may employ a structure similar to a revolver mechanism for selecting one of a plurality of objective lenses of a microscope, for example, in addition to the above-described stage slidable in a plane. Good. In addition, the laser light sources 101 to 103 are not moved. For example, the laser light sources 101 to 103 are fixed in the laser light source 100, and a plurality of movable mirrors for receiving the laser light from the laser light sources 101 to 103 are provided. Then, these movable mirrors are used as the switching unit 104, and by appropriately operating the movable mirror, one laser light source is arbitrarily selected from the laser light sources 101 to 103, and one laser beam is emitted to the optical system 110. A configuration may be adopted.

  Although the laser light sources 101 to 103 are all configured by laser diodes, the laser light sources 101 to 103 are not limited to this, and laser light having a specific wavelength such as a gas laser or a semiconductor laser is generated in the laser light sources 101 to 103. Other devices may be employed.

  Further, instead of physically preparing a plurality of light sources like the laser light sources 101 to 103, for example, only one laser light source is prepared, and instead, a wavelength conversion device capable of electrically changing the wavelength is provided. It is also possible to prepare and input light emitted from the laser light source to the wavelength conversion device to generate a plurality of laser beams having different wavelengths. When a wavelength range that can be used by the wavelength conversion device is used, the wavelength can be varied electrically, and the choice of wavelengths becomes large.

  The laser light emitted from the laser light irradiation system 1 is reflected by the half mirror 3 and proceeds to the eye 2 to be examined. The laser light that has entered the eye 2 is reflected near the fundus and returns to the half mirror 3 again. The reflected light passes through the half mirror 3 and enters the light receiving system 4.

In the light receiving system 4, the laser reflected light is imaged as a biological tissue on the CCD camera 401 by the light receiving lens in the optical system 400 as described above. The CCD camera 401 converts the imaged biological tissue image into an electrical signal and outputs it as an analog video signal. The analog video signal is amplified by the signal amplification circuit 403, and the analog video signal amplified by the signal amplification circuit 403 is output to the analog signal processing means 5 that performs gain control and the like, and is converted into a digital signal by the A / D converter 6. Converted. The analog signal processing means 5 and the A / D converter 6 cooperate to function as an image capturing unit that continuously captures a plurality of images at predetermined time intervals based on a signal from a CCD camera 401 serving as a light receiving unit. .

A digital signal from the A / D converter 6 corresponding to a plurality of image data is sent to a CPU (Central Processing).
Unit) 7. A frame memory 8 is connected to the CPU 7. The frame memory 8 functions as an image storage unit that stores digital signals from the A / D converter 6 corresponding to a plurality of image data. The CPU 7 functions as a calculation unit that calculates the blood flow velocity in the living tissue from the temporal change in the output signal of each corresponding pixel of the plurality of images stored in the frame memory 8.

More specifically, the CPU 7 applies a plurality of laser beams of different wavelengths obtained by sequentially irradiating laser beams of different wavelengths from the laser light sources 101 to 103 to the same part of the eye 2 to be examined which is a living tissue. Based on the blood flow data, the blood flow velocity in the eye 2 to be examined is calculated. That is, blood flow data in the eye 2 to be examined is acquired using a laser beam having an appropriately selected first wavelength, and then the same region of the subject is detected using a laser beam having an appropriately selected second wavelength. Blood flow data in the optometry 2 is acquired. A plurality of data thus obtained is stored in the frame memory 8, and the CPU 7 reads out the stored data and corrects scattering / absorption by the living tissue in accordance with the wavelength of the laser beam, thereby obtaining one blood flow data. The other blood flow data is removed. The calculation result in the CPU 7 can be displayed on the display 9 connected to the CPU 7.

  This will be described with reference to FIGS. 2 and 3A to 3C. FIG. 2 is a diagram showing the relationship between the penetration depth of each laser beam by wavelength and the retina, retinal pigment epithelium, choroid and sclera of the fundus, and within the eye 2 to be examined when the wavelength of the laser beam is approximately 480 nm to 600 nm. It has been shown that laser light reaches the retina, but does not reach the deeper retinal pigment epithelium, choroid, or sclera. In FIG. 2, when the wavelength of the laser beam is in the range of approximately 600 nm to 800 nm, the laser beam reaches the retinal pigment epithelium in the eye 2 to be examined, but does not reach the deeper choroid and sclera, It has also been shown that the laser light reaches the deepest choroid and sclera in the eye 2 to be examined when the wavelength of the laser light is in the range of approximately 800 nm to 830 nm.

On the other hand, FIG. 3 (a) is a figure which shows the result measured using only the laser beam of wavelength 830nm, FIG.3 (b) is a figure which shows the result measured using the laser beam alone of wavelength 500nm, FIG. 3C is a diagram showing the blood flow state of the choroid with improved measurement accuracy based on the result of measurement using laser light with a wavelength of 830 nm and a wavelength of 500 nm.

  In the case of measurement with a single wavelength of 830 nm, the blood flow near the retina other than the blood flow near the choroid is also added and displayed on the display 9 as shown in FIG. End up. Therefore, the wavelength of the laser beam is switched and measurement is performed using a laser beam having a single wavelength of 500 nm to obtain blood flow image data only in the vicinity of the retina as shown in FIG. As shown in FIG. 2, when the wavelength of the laser beam is in the range of about 480 nm to 600 nm, the laser beam reaches the retina in the eye 2 to be examined, but reaches the deeper retinal pigment epithelium, choroid and sclera. do not do. Therefore, in measurement using a laser beam having a single wavelength of 500 nm, blood flow image data only near the retina is obtained, and a blood flow image near the retinal pigment epithelium or choroid / sclera is not displayed.

  Therefore, the CPU 7 performs arithmetic processing using each image data stored in the frame memory 8, and the blood flow image data shown in FIG. 3B is obtained from the blood flow image data shown in FIG. Subtract. In this way, since the blood flow image is displayed only in the vicinity of the choroid / sclera as shown in FIG. 3C, highly accurate blood flow data in the vicinity of the choroid / sclera is obtained. . If the blood flow velocity obtained based on the signal is superimposed on the fundus image and displayed on the display 9, blood flow in each layer can be diagnosed with high accuracy.

  The blood flow imaging apparatus according to the present invention makes it possible to separately measure and differentiate the blood flow of each tissue of the fundus by changing the wavelength of the laser light. Since blood flow in the retina, pigment epithelial cells, choroid, etc. can be measured with high accuracy, it can be used for diagnosis of age-related macular degeneration, diabetic retinopathy, glaucoma, and the like.

  Since the blood flow imaging device of the present invention applies a technology based on the laser speckle principle, it does not require the use of a contrast agent like a fluorescence contrast examination, and scans with a low-power laser in real time. Since the blood flow in the target region can be measured, the invasion given to the subject is extremely small and can be suitably used for fundus examination and the like.

FIG. 1 is a schematic diagram of a blood flow imaging device of the present invention. FIG. 2 is a diagram showing the relationship between the penetration depth of each laser beam by wavelength and the fundus retina, retinal pigment epithelium, choroid, and sclera. FIG. 3 is a conceptual diagram showing a blood flow state to be measured. FIG. 3A is a diagram showing the results of measurement using laser light alone having a wavelength of 830 nm. FIG. 3B is a diagram showing the results of measurement using a laser beam having a wavelength of 500 nm alone. FIG. 3C is a diagram showing the blood flow state of the choroid with improved measurement accuracy based on the result of measurement using laser light with a wavelength of 830 nm and a wavelength of 500 nm.

Claims (5)

A laser beam irradiation system for irradiating a blood flow of a living tissue with a laser beam;
A light receiving system having a light receiving portion composed of a plurality of pixels for detecting reflected light from the living tissue;
An image capturing unit that continuously captures a plurality of images at predetermined time intervals based on a signal from the light receiving unit;
An image storage unit for storing the plurality of images;
A blood flow imaging apparatus including a calculation unit for calculating a blood flow velocity in a living tissue from a temporal change of an output signal of each corresponding pixel of the stored plural images,
A blood flow imaging apparatus in which the laser beam irradiation system is composed of a plurality of laser light sources that generate laser beams having different wavelengths used for measurement. One laser light source can be arbitrarily selected from the plurality of laser light sources to irradiate the blood flow of the living tissue with laser light.
The blood flow imaging device according to claim 1. At least one of the plurality of laser light sources generates laser light having a wavelength of 480 nm to 600 nm, and at least one of the other laser light sources other than the at least one laser light source emits laser light having a wavelength of 800 nm to 830 nm. appear,
The blood flow imaging device according to claim 2. At least one of the plurality of laser light sources generates laser light having a wavelength of 480 nm to 600 nm;
At least one of the laser light sources other than the at least one laser light source generates a laser beam having a wavelength of 600 nm or more and 800 nm or less;
At least one of the other laser light sources other than the at least one laser light source generates laser light having a wavelength of 800 nm or more and 830 nm or less.
The blood flow imaging device according to claim 2. The calculation unit is configured to perform blood flow in a living tissue based on a plurality of blood flow data for each laser beam having different wavelengths obtained by sequentially irradiating the same part of the living tissue with laser beams having different wavelengths from the laser light source. The blood flow imaging apparatus according to claim 2, which calculates a velocity.

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