JP2018201648A - Imaging device - Google Patents

Abstract

To provide an imaging device having a near infrared light illumination for capturing an image, which allows fluid in a living body, such as blood, to be observed.SOLUTION: The imaging device includes: illumination means (a visible light emission part 2 and a near infrared light emission part 4) for emitting a light of a wavelength band including a near infrared band and irradiating a subject with the light; high-speed imaging means (a camera head block part 12) for capturing a light image from the subject of the wavelength band including a near infrared band at high speed by using the illumination means; and image processing means (a visible image processing part 13 and a near infrared image processing part 14) for capturing an image of the subject, and executing signal processing for observing fluid flowing in the subject on the basis of the image captured by the high-speed imaging means. The image processing means includes brightness detection means for detecting the brightness from the image captured by the high-speed imaging means, and movement amount detection means for detecting a movement amount per unit time of the brightness detected by the brightness detection means.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a medical imaging apparatus, and more particularly to an imaging apparatus that observes blood flow and the like together with imaging of an affected area.

  Conventionally, endoscope systems for observing tissue in a body cavity are widely known, and a normal image is obtained by imaging a portion to be observed in a body cavity by irradiation with white light, and the normal image is displayed on a monitor screen. Electronic endoscope systems have been widely put into practical use.

  Moreover, as an endoscope system as described above, a normal image and a fluorescent image displayed on a monitor screen by capturing an autofluorescent image emitted from an observed part by irradiation of excitation light to obtain an autofluorescent image. Imaging systems are widely used.

  For example, fluorescence observation of vascular blood flow and lesion tissue by administration of indocyanine green (ICG), which is a fluorescent contrast agent, has been performed for a long time, and fluorescence of 830 to 840 mm is emitted for excitation light irradiation of 750 to 790 mm. It is generally known that it can be obtained. Since the wavelength band is near infrared, the image obtained here is monochrome, and the observer visually confirms blood flow in the blood vessel using the obtained luminance change image. This is applied not only to an endoscope but also to a surgical microscope.

  Therefore, in the fluorescence observation apparatus described in Patent Document 1, it has been proposed that a normal image and a fluorescence image are appropriately switched and displayed on a monitor screen so that an observer can easily observe.

Japanese Patent No. 3560671

  However, in the current medical imaging apparatus, it is only necessary to display a captured image as a visible light image and a fluorescent image, and an observer needs to visually confirm the blood flow in the blood vessel from the obtained luminance change image.

  In addition, as an example of quantitative observation, there is an example in which partial blood flow changes can be observed by performing post-processing with software on recorded images. It is not always easy to use because it is necessary to set the detection position sequentially.

  The present invention has been made in view of the above problem, and provides an imaging apparatus capable of performing desired observation simultaneously with imaging.

  An imaging apparatus according to the present invention is a medical imaging apparatus, and includes an illumination unit that emits light in a wavelength band including near infrared and irradiates a subject, and includes the near infrared using the illumination unit. A high-speed imaging unit that captures a light image from a subject in a wavelength band at high speed, and a signal process for observing a fluid flowing in the subject along with the imaging of the subject based on the image captured by the high-speed imaging unit An image processing means, wherein the image processing means detects a luminance from an image picked up by the high-speed image pickup means, and a moving amount per unit time of the luminance detected by the luminance detection means. A movement amount detecting means for detecting.

  According to the present invention, it is possible to observe the inside of a living body non-invasively by using near infrared light for illumination.

  Further, according to the present invention, it is possible to observe a blood flow with a high flow velocity by using a high-speed imaging means.

  According to the present invention, it is possible to perform observation simultaneously with image display by detecting a change in luminance while imaging.

It is a block diagram which shows schematic structure of the imaging device which concerns on Embodiment 1 of this invention. It is a block diagram which shows the internal structure of the camera head block 12 shown by FIG. FIG. 3 is a characteristic diagram of the notch filter 28 shown in FIG. 2. It is a block diagram which shows the internal structure of the near-infrared image processing part 14 shown by FIG. It is a figure which shows the image processing example of the near-infrared image process part 14 shown by FIG. It is the image processing flowchart for observation by the near-infrared image processing part 14 shown by FIG. FIG. 2 is a block diagram illustrating an internal configuration of a camera head block 12 illustrated in FIG. 1 for describing an imaging device according to a second embodiment of the present invention. FIG. 7 is a diagram illustrating an image processing apparatus according to Embodiment 2 of the present invention, and illustrating an example of image processing performed by the near-infrared image processing unit 14 illustrated in FIG. 1.

  Embodiment 1 FIG.

  Hereinafter, the imaging apparatus according to Embodiment 1 of the present invention will be described with reference to the drawings as an example applied to a rigid endoscope system. 1 is a block diagram showing a schematic configuration of an imaging apparatus according to Embodiment 1 of the present invention, FIG. 2 is a block diagram showing an internal configuration of a camera head block 12 shown in FIG. 1, and FIG. 3 is shown in FIG. FIG. 4 is a block diagram showing the internal configuration of the near-infrared image processing unit 14 shown in FIG. 1, FIG. 5 shows an example of image processing, and FIG. 6 shows a flowchart of image processing.

  As shown in FIG. 1, the imaging apparatus according to Embodiment 1 of the present invention includes a visible light emitting unit 2 using a laser light source, a near-infrared light emitting unit 4, and the like. Visible light and near-infrared light from the near-infrared light emitting unit 4 are mixed by the illumination mixing unit 5, injected into the rigid mirror 7 by the delivery fiber 6, and irradiated to the subject from the illumination emitting unit 8.

  At this time, near-infrared light is emitted at an excitation wavelength center of about 785 mm of indocyanine green (hereinafter referred to as ICG), which is a contrast agent for blood flow observation, and has good fluorescence emission efficiency. Visible light constitutes visible illumination by emitting three primary colors of blue, green and red.

  The light image from the subject is sent to the camera head block 12 through the objective lens 10 and the adapter lens 11 of the rigid mirror 7 together with the visible reflected light and the fluorescent image from the ICG. The camera head block 12 constitutes a high-speed imaging means that uses a lighting means and picks up a light image from a subject in a wavelength band including near infrared at high speed, and its schematic configuration is shown in FIG. The ICG excitation light is cut by the notch filter 28 and then subjected to wavelength spectroscopy by the beam splitter 21, and the normal visible light image L3 is transmitted to the visible sensor 26 via the imaging optical system 25, and the near infrared light image L4. Passes through the special light cut filter 22 and is sent to the near-infrared sensor 24 via the imaging optical system 23 to perform photoelectric conversion.

  Here, the notch filter 28 has its characteristics 30 and 31 shown in FIG. The excitation light needs to be cut, and the visible band and the fluorescence band are slightly suppressed in order to secure the contrast during fluorescence observation.

  An image signal that is photoelectrically converted and output by the visible sensor 26 and the near-infrared sensor 24 of the camera head block 12 is subjected to CDS / AGC (correlated double sampling / automatic gain control) processing or A / The D conversion process is performed, and the signal is sent to the visible image processing unit 13 and the near infrared image processing unit 14 as the subsequent image processing unit, and the signal processing for blood flow observation is performed together with the captured image display.

  In FIG. 1, 15 is an image display unit that displays a signal processing result for blood flow observation together with a captured image, 16 controls the visible image processing unit 13 and the near infrared image processing unit 14, and a visible light emitting unit. 2 and a control unit that gives control instructions to the visible light emission control unit 1 and the near infrared light control unit 3 that control the near infrared light emission unit 4.

  Next, regarding the signal processing for blood flow observation, the internal configuration of the near infrared image processing unit 14 shown in FIG. 4, the image processing example of the near infrared image processing unit 14 shown in FIG. 5, and the near red shown in FIG. A description will be given with reference to an image processing flowchart for observation by the outer image processing unit 14.

  Since the blood flow velocity in the body exceeds 60 cm per second in the aorta such as the carotid artery, the conventional 30-frame camera system is out of frame depending on the angle of view, so it is not suitable for real-time blood flow observation. . Therefore, in the present invention, as the near infrared sensor 24, a sensor capable of photographing at a speed higher than 30 frames is adopted, so that simultaneous observation with imaging is possible.

  First, for normal visible image display, the visible image processing unit 13 performs processing according to the image output form. At the same time, for near-infrared fluorescence image display, the near-infrared image processing unit 14 detects luminance information fn greater than a certain value by the luminance value detection unit 35 at the nth frame as shown in FIG. fn: A1 (X1, Y1)

  That is, the peak amount of fluorescence luminance that moves at high speed in the blood vessel during ICG administration is detected (step S50 in FIG. 6), and the amount (A) and position (X, Y) are temporarily stored in the storage unit 37. The peak amount at this time is defined as a value corresponding to the cross-sectional area of the blood vessel, which is a high-luminance range that exceeds a specified value.

Then, image comparison is performed in unit time (step S51 in FIG. 6). That is, the luminance information f (n + 1) in the next n + 1 frame after the n frame is extracted, and the comparison unit 36 compares the luminance information fn in the n frame and detects the difference in unit time. Is detected (step S52 in FIG. 6).
f (n + 1): A2 (X2, Y2)

  By repeating this detection every unit time ns as shown in FIG. 5 showing an image processing example of the near-infrared image processing unit 14, the detection data is collectively stored in the control unit 15. In FIG. 5, 40-44 indicates frames n and n + 1 to n + 4 for each unit time ns, and 45-49 indicates the peak amount in each frame.

By repeating the difference detection, the flow velocity, flow rate, and directionality are detected (step S53 in FIG. 6). For example, if the difference in position (YX) between frames is 1 mm and the amount is 2 mm ² under the condition of an imaging system of 200 frames per second and an angle of view of about Φ50 mm, the blood flow rate is 20 cm / second and the blood flow is , 400 mm ³ / sec. These calculations are performed by the calculation unit 38 and controlled by the control unit 16.

  As described above, the imaging apparatus according to Embodiment 1 uses a fluorescence image that is relatively easily obtained with a blood contrast agent such as ICG while requiring an excitation light suppression measure such as the notch filter 28 in the configuration shown in FIG. Then, by detecting and calculating the difference in peak amount and position of the luminance in unit time, it becomes possible to measure blood flow in a living body such as blood simultaneously with imaging.

  In the above description, a repetition period of 200 frames per second is used for calculation for measurement. However, any value may be used as long as blood flow measurement is possible, and it is not fixed in consideration of calculation efficiency. It may be variable. Moreover, although the application example to the rigid endoscope was shown, it is needless to say that the present invention is not limited to this and may be applied to a surgical microscope.

  Moreover, although energy efficiency improves by utilizing a laser light source for illumination, even if it is LED, it is a content which can be realized. When performing blood flow observation from collected images, motion vectors may be used in addition to the above, and motion detection functions may be added to the measurement. This simultaneous observation is possible. The fluorescent contrast agent is not limited to ICG, and any wavelength can be used as long as it is measurable. Rather, near-infrared light that is minimally invasive to the body is preferable.

  In addition, the number of pixels of the image sensor used for the image pickup means may be basically any as long as blood flow measurement is possible. A high-definition pixel number exceeding 1 is desirable. In this case, the high-definition sensor often has a problem of imaging sensitivity. For example, a pixel addition may be performed as necessary, and a method of ensuring the necessary sensitivity at the expense of resolution is possible. Needless to say.

  Embodiment 2. FIG.

  Next, an imaging apparatus according to Embodiment 2 of the present invention will be described with reference to the drawings as an example applied to a rigid endoscope system. In the imaging apparatus according to Embodiment 2 of the present invention, as in Embodiment 1, the schematic configuration of the imaging apparatus shown in FIG. 1, the internal configuration of the near-infrared image processing unit 14 shown in FIG. 4, and FIG. A flowchart of the image processing shown is used. However, the block diagram shown in FIG. 7 is used as the internal configuration of the camera head block 12 shown in FIG. 1, and FIG. 8 is used as an image processing example of the near-infrared image processing unit 14. In FIG. 7, unlike FIG. 2, the notch filter 28 is not used.

  As shown in FIG. 1, the imaging apparatus according to Embodiment 2 of the present invention includes a visible light emitting unit 2 using a laser light source, a near-infrared light emitting unit 4, and the like. Visible light and near-infrared light from the near-infrared light emitting unit 4 are mixed by the illumination mixing unit 5, injected into the rigid mirror 7 by the delivery fiber 6, and irradiated to the subject from the illumination output unit.

  At this time, near-infrared light uses a wavelength band of 800 to 900 mm that is less invasive to the living body. Visible light constitutes visible illumination by emitting three primary colors of blue, green and red.

  As a light image from the subject, a reflected light image of visible and near infrared is sent to the camera head block 12 through the objective lens 10 and the adapter lens 11 of the rigid mirror 7. The camera head block 12 constitutes a high-speed imaging means that uses a lighting means and picks up a light image from a subject in a wavelength band including near infrared at high speed, and its schematic configuration is shown in FIG. The ICG excitation light is cut by the notch filter 28 and then subjected to wavelength spectroscopy by the beam splitter 21, and the normal visible light image L3 is transmitted to the visible sensor 26 via the imaging optical system 25, and the near infrared light image L4. Passes through the special light cut filter 22 and is sent to the near-infrared sensor 24 via the imaging optical system 23 to perform photoelectric conversion.

  After photoelectric conversion by the camera head block 12, as in the first embodiment, the photoelectrically converted image signal is further sent to a visible image processing unit 13 and a near-infrared processing unit 14 as an image processing unit in the subsequent stage, and imaging is performed. Signal processing for blood flow observation is performed along with image display.

  Next, regarding the signal processing for blood flow observation, the internal configuration of the near infrared image processing unit 14 shown in FIG. 4, the image processing example of the near infrared image processing unit 14 shown in FIG. 8, and the near red shown in FIG. A description will be given with reference to an image processing flowchart for observation by the outer image processing unit 14.

  Since the blood flow velocity in the body exceeds 60 cm per second in the aorta such as the carotid artery, the conventional 30-frame camera system is out of frame depending on the angle of view, so it is not suitable for real-time blood flow observation. . Therefore, in the present invention, as the near infrared sensor 24, a sensor capable of photographing at a speed higher than 30 frames is adopted, so that simultaneous observation with imaging is possible.

  First, for normal visible image display, the visible image processing unit 13 performs processing according to the image output form. At the same time, for near-infrared fluorescence image display, the near-infrared image processing unit 14 detects luminance information fn greater than a certain value by the luminance value detection unit 35 at the nth frame as shown in FIG.

  At that time, by using a high-definition and high-speed imaging sensor as the near-infrared sensor 24, the flow of hemoglobin or red blood cells in the blood vessel is directly observed. However, instead of observing hemoglobin or red blood cells one by one, a plurality of hemoglobins are handled as one texture (pattern) as in the textures 60 to 62 of the frames 63 to 65 per unit time nS in FIG.

That is, a texture of fluorescence intensity that moves at high speed in the blood vessel at the time of ICG administration is detected, and the amount (A) and position (X, Y) are temporarily stored in the storage unit 37. The texture value at this time is defined as a value corresponding to the cross-sectional area of the blood vessel, which is a high-luminance range that exceeds a specified value.
fn: A1 (X1, Y1)

For example, the luminance information f (n + 1) in the n + 1th frame after the nth frame is extracted and compared by the comparison unit 36 to detect the movement amount per unit time.
f (n + 1): A2 (X2, Y2)

  As shown in FIG. 8, the detection is repeated for the frames 63 to 65 for each unit time nS, so that the measurement data is collectively stored in the control unit 15.

For example, if the difference in position (YX) between frames is 1 mm and the amount is 2 mm ² under the condition of an imaging system of 200 frames per second and an angle of view of about Φ50 mm, the blood flow rate is 20 cm / second and the blood flow is , 400 mm ³ / sec. These calculations are performed by the calculation unit 38 and controlled by the control unit 15.

  Thus, according to the imaging apparatus according to the second embodiment, a value corresponding to an amount can be obtained by directly detecting the flow of hemoglobin or red blood cells with a high-definition camera without using a blood contrast agent such as ICG. The position information is detected and calculated in unit time, so that blood flow in a living body such as blood can be measured simultaneously with imaging.

  In addition, the number of pixels of the image sensor used for the image pickup means may be basically any as long as blood flow measurement is possible. However, in order to image a minute subject such as hemoglobin, 1920 × 1080 high-definition or this is also used. A high-definition pixel number exceeding 1 is desirable. In this case, the high-definition sensor often has a problem of imaging sensitivity. For example, a pixel addition may be performed as necessary, and a method of ensuring the necessary sensitivity at the expense of resolution is possible. Needless to say.

  In the above description, a repetition period of 200 frames is used for calculation for measurement. However, any value may be used as long as blood flow measurement is possible, and it is not fixed but variable in consideration of calculation efficiency. It is good. Moreover, although the application example to the rigid endoscope was shown, it is needless to say that the present invention is not limited to this and may be applied to a surgical microscope.

  In addition, the energy efficiency is improved by using a laser light source for illumination. Furthermore, even if hemoglobin or erythrocytes are not captured by texture, of course, if the amount is directly known to each individual, there is no problem even if it is directly detected, but it seems rather accurate. In order to directly observe hemoglobin and erythrocytes, a camera with higher sensitivity or a camera with higher definition may be used.

  As described above, according to the present invention, by using near infrared light for illumination, the inside of a living body can be observed non-invasively.

  Further, according to the present invention, it is possible to observe a blood flow with a high flow velocity by using a high-speed imaging means.

  In addition, according to the present invention, it is possible to perform observation simultaneously with image display by detecting a change in luminance while imaging.

  Furthermore, according to the present invention, by using laser illumination for illumination, light can be efficiently transmitted / irradiated to a subject.

DESCRIPTION OF SYMBOLS 1 Visible light emission control part 2 Visible light emission part 3 Near-infrared light emission control part 4 Near-infrared light emission part 5 Illumination mixing part 6 Delivery fiber 7 Rigid mirror 8 Illumination emitting part 9 Illumination irradiation range example 10 Objective lens 11 Adapter lens 12 Camera head Block 13 Visible image processing unit 14 Near-infrared image processing unit 15 Image display unit 16 Control unit 28 Notch filter 35 Comparison unit

Claims (8)

A medical imaging device,
Illumination means for emitting light in a wavelength band including near infrared to irradiate a subject;
High-speed imaging means that uses the illuminating means to capture a light image from a subject in a wavelength band including near infrared at high speed;
Image processing means for performing signal processing for observing the fluid flowing in the subject together with the imaging of the image of the subject based on the image captured by the high-speed imaging means,
The image processing means includes
Brightness detection means for detecting brightness from an image captured by the high-speed imaging means;
An image pickup apparatus comprising: a movement amount detection unit that detects a movement amount of the luminance detected by the luminance detection unit per unit time. The illumination means emits light in a wavelength band including near-infrared excitation light for a fluorescent contrast agent and irradiates the subject,
The high-speed imaging means uses the illuminating means to capture a light image in a wavelength band including near-infrared fluorescence at a high speed,
The imaging apparatus according to claim 1, wherein the image processing unit performs signal processing for observing a fluid flowing in a subject using fluorescence image information obtained from a fluorescent contrast agent. The illumination means includes
First illumination means for emitting light in the visible light band;
Second illumination means for emitting near-infrared excitation light for the fluorescent contrast agent,
The high-speed imaging means uses the first illuminating means and the second illuminating means, and images a light image in a wavelength band including near-infrared fluorescence at a high speed,
The imaging apparatus according to claim 1, wherein the image processing unit performs signal processing for observing a fluid flowing in a subject using fluorescence image information obtained from a fluorescent contrast agent. The imaging device according to claim 1, wherein the illumination unit uses a laser light source. The illumination means uses a wavelength band that is minimally invasive to the living body as the near-infrared light,
The imaging apparatus according to claim 1, wherein the image processing unit performs signal processing for observing a fluid flowing in a subject without using a fluorescent contrast agent. The illumination means includes
First illumination means for emitting light in the visible light band;
Second illumination means for emitting near-infrared light,
The second illumination means uses a wavelength band that is minimally invasive to the living body as the near-infrared light,
The high-speed imaging means uses the first illuminating means and the second illuminating means, and images a light image in a wavelength band including near infrared at high speed,
The imaging apparatus according to claim 1, wherein the image processing unit performs signal processing for observing a fluid flowing in a subject without using a fluorescent contrast agent. The imaging apparatus according to claim 5, wherein the illumination unit uses a laser light source. The image pickup apparatus according to claim 1, wherein the high-speed image pickup unit uses an image pickup device having a high-definition pixel number exceeding that of high definition.

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