JP2007264537A - Endoscopic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a spectral image where every kind of fine structure or the like is expressed without depending on an individual difference in terms of spectral transmission characteristic or the like of an endoscope and to provide useful image information of a body to be observed serviceable to diagnosis or the like. <P>SOLUTION: The endoscopic device has: first to third light sources (LED) 14a to 14c emitting light beams whose wavelength regions are different; a light composing part 12 composing the light beams from the three light sources 14a to 14c; and first to third light source driving circuits 15a to 15c driving the light sources 14a to 14c independently and also variably adjusting output intensity of each of the light beams. By radiating three kinds of synthetic illuminating light beams, whose output intensity is variably adjusted, from the light sources 14a to 14c, arithmetic operation parts 25 and 26 perform matrix arithmetic operation for obtaining the spectral image based on image data of three frames and data on the output intensity of the light obtained by an imaging part 18. The spectral image is formed by selecting the wavelength region thereof or selecting the output intensity of the light sources 14a to 14c. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an endoscope apparatus, and more particularly to a configuration for forming and displaying a spectral image made up of image information in a specific wavelength range, which is used in the medical field.

In recent years, in an electronic endoscope apparatus using a solid-state imaging device, spectral imaging combined with a narrow-band bandpass filter based on a spectral reflectance in a digestive organ (such as gastric mucosa), that is, an electronic endoscope apparatus with a narrow-band filter. (Narrow
Band Imaging-NBI) is attracting attention. This device is provided with three narrow (wavelength) band-pass filters instead of the surface sequential R (red), G (green), and B (blue) rotary filters. By sequentially performing the same processing as in the case of the R, G, B (RGB) signals while changing the weighting of the three signals obtained with these illumination lights, the spectral image is output. Is formed. According to such a spectroscopic image, it is possible to clearly observe a fine structure or the like that was previously unclear in digestive organs such as the stomach and the large intestine.

On the other hand, instead of using the above-described narrow-band bandpass filter, it is not a surface sequential type, but as shown in Japanese Patent Application Laid-Open No. 2003-93336, in a simultaneous type in which a fine mosaic color filter is arranged in a solid-state image sensor, white light It has been proposed to form a spectral image by arithmetic processing based on the image signal obtained in (1). This is a matrix data (coefficient set) for the relationship between the RGB color sensitivity characteristics converted into numerical data and the spectral characteristics of a specific narrowband bandpass converted into numerical data. An equivalent to a spectral image signal obtained through a narrow-band bandpass filter can be obtained by calculation with an RGB signal. When a spectral image is formed by such an operation, it is not necessary to prepare a plurality of filters corresponding to a desired wavelength region, and replacement arrangement of these is unnecessary, so that the apparatus can be prevented from being enlarged and reduced in size. Cost can be reduced.
JP 2003-93336 A

  However, in the above-mentioned Patent Document 1, calculation data (matrix data) indicating the relationship between the RGB color sensitivity characteristics converted into numerical data and the spectral characteristics of a specific narrowband bandpass converted into numerical data is used. However, such calculation data depends on the spectral transmission characteristics of the objective optical system, the spectral transmission characteristics of the imaging system, etc., and it is necessary to consider the type of endoscope and individual differences in the spectral transmission characteristics. There is complexity. The present invention proposes an endoscope apparatus of a new technique that has not been conventionally available and can obtain a spectral image without depending on the spectral transmission characteristics of the objective optical system and the imaging system.

  On the other hand, in the spectroscopic image of the endoscope apparatus, for example, depict various fine structures such as relatively thick blood vessels, capillaries, or deep blood vessels, shallow blood vessels, cancer tissues with different degrees of progression, In addition, for example, it is expected that a difference between specific substances such as a difference between oxyhemoglobin and deoxyhemoglobin is drawn as a target. It is possible to provide useful object image information useful for diagnosis and the like.

  The present invention has been made in view of the above problems, and its purpose is to provide a spectral image in which various microstructures are rendered in a manner that does not depend on individual differences such as spectral transmission characteristics of the objective optical system and the imaging system. It is an object of the present invention to provide an endoscope apparatus that can be formed and can provide useful object image information useful for diagnosis and the like.

In order to achieve the above object, an invention according to claim 1 emits light having different wavelength ranges in an endoscope apparatus that images an object to be observed irradiated with illumination light with an imaging element mounted on the endoscope. A light source unit that synthesizes the light from these three light sources and outputs the illumination light, and independently drives the three light sources of the light source unit and outputs each light source light. A light source driving circuit for variably adjusting the intensity, a control circuit for controlling the light source driving circuit, and forming a plurality of types of combined illumination light in which the output intensities of the respective wavelength band lights of the three light sources are variably adjusted; An arithmetic circuit for performing a matrix operation for obtaining a spectral image based on a plurality of image data obtained by the imaging device by irradiation of the plurality of types of synthetic illumination light and output intensity data of the three light source lights is provided. It is characterized by that.
The invention of claim 2 is provided with wavelength selection means for selecting a wavelength range of the spectral image, and the control circuit outputs the output intensities of the three light sources based on the wavelength range selected by the wavelength selection means. Is variably set.
According to a third aspect of the present invention, there is provided light intensity selection means for selecting the output intensity of the three light sources, and the control circuit determines the output intensity of the three light sources based on the output from the light intensity selection means. It is characterized by variable setting.

  According to said structure, the light from which a wavelength range and intensity differ from each of the 1st thru | or 3rd light source, and the light which synthesize | combined these will be irradiated to a to-be-observed body as illumination light, This synthetic | combination illumination An image (video) of the object to be observed is picked up by the image pickup device with light. Then, a spectral image is formed by performing a spectral matrix calculation based on, for example, three (for example, three frames) image data obtained by irradiation with three types of synthetic illumination light having different intensities in the wavelength region.

In the following, using mathematical formulas, it is possible to form three types of combined illumination light by changing the intensities of three light sources having different wavelength ranges, and to form a spectral image based on image data for three frames photographed with this combined illumination light. I will explain.
Here, the three independent light sources output an intensity proportional to the injected current, and the spectral spectrum waveform (shape) of each light source in this case is constant regardless of the intensity, and the light from the three light sources is constant. It is assumed that the spectrum and intensity of the light synthesized by can be expressed by its linear sum.

First, spectrums of first to third light sources composed of LEDs (light emitting diodes) or the like (assuming that their intensities are normalized) are expressed as S ₁ (λ), S ₂ (λ), S ₃ (λ). When the intensity of each light source is represented by α, β, γ by an injection current that is driven and controlled, the spectral spectra S _c1 (λ), S _c2 (λ), S _c3 ( λ) is expressed by Equation 1 below.

Now, the spectral reflection characteristics of a living body observing R (lambda), the spectral transmission characteristic of the objective optical system and L (lambda), the spectral transmission characteristic of the imaging system _{D 1 (λ), D 2} (λ), D 3 (Λ) (each corresponding to RGB). At this time, the last three stimulus values (r, g, b) obtained from the imaging system are generally expressed by the following formula 2 [S (λ) means a general light source].

この数式３により上記数式１での３通りの合成照明光より得られる最終刺激値（ｒ_１，ｇ_１，ｂ_１，ｒ_２，ｇ_２，ｂ_２，ｒ_３，ｇ_３，ｂ_３：３フレーム分の３波長域の画像データ）は、以下の数式４のように表される。

Then, Formula 1 is expanded into Formula 2 and defined as Formula 3 below.

The final stimulus values (r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ , r ₃ , g ₃ , b ₃ : 3 obtained from the three types of synthesized illumination light in the above formula 1 by this formula 3 The image data in the three wavelength regions for the frame) is expressed as the following Equation 4.

On the other hand, since the final stimulus value and the current value injected into each of the first to third light sources are known, the entire system of the electronic endoscope apparatus used and the object to be observed shown in Equation 3 above are used. A specific factor S _ij determined by the reflectance characteristic of a certain living body can be obtained by the calculation of the following Expression 5.

Next, since an arbitrary spectral image desired to be displayed by the endoscope apparatus may be irradiated with irradiation synthesized light with a light source having arbitrary spectral spectral characteristics, the spectral spectrum corresponding to this spectral image is defined as S ₀ (λ). , S ₀ (λ) = α ₀ S ₁ (λ) + β ₀ S ₂ (λ) + γ ₀ S ₃ (λ), the relationship of Equation 6 below is established in a pseudo manner.

例えば、この数式７の上記Ｓ_０（λ），Ｓ_１（λ），Ｓ_２（λ），Ｓ_３（λ）を、波長４００〜７００ｎｍで５ｍｍ毎の要素からなる列ベクトルとして表記すると、６１×１の列ベクトルとなる。従って、この上記行列Ａの６１×１、行列Ｂは６１×３の構成をとることになる。このようにすれば、係数（α_０，β_０，γ_０）、次の数式８で近似される。

Since Equation 5 above cannot be solved as it is, in order to obtain the coefficients (α ₀ , β ₀ , γ ₀ ) related to the final stimulus value of Equation 6, the pseudo equation is solved and the optimum approximation coefficient is obtained as follows: Ask. That is, the light source spectrum is expressed as Equation 7 as n column vectors.

For example, when S ₀ (λ), S ₁ (λ), S ₂ (λ), and S ₃ (λ) in Expression 7 are expressed as column vectors composed of elements every 5 mm at wavelengths of 400 to 700 nm, 61 A x1 column vector. Therefore, 61 × 1 and matrix B of the matrix A have a 61 × 3 configuration. In this way, the coefficients (α ₀ , β ₀ , γ ₀ ) are approximated by the following formula 8.

この数式９において、右辺の諸量は、全て既知の値であるから、最終刺激値（ｒ_０，ｇ_０，ｂ_０）は一意に求まり、この最終刺激値が分光画像の最終刺激値、即ち求めるべき３つの波長域の画像データとなる。なお、上記数式１に代表されるα，β，γの値の全ては非負であるが、上記数式８に代表されるα_０，β_０，γ_０は、少なくとも１つが非負であればよい。 Therefore, the final stimulus values (r ₀ , g ₀ , b ₀ ) when irradiated with a light source having the spectral spectrum S ₀ (λ) characteristic corresponding to the spectral image are expressed as The following equation 9 is estimated.

In Equation 9, since the quantities on the right side are all known values, the final stimulus value (r ₀ , g ₀ , b ₀ ) is uniquely determined, and this final stimulus value is the final stimulus value of the spectral image, that is, This is image data of three wavelength ranges to be obtained. Note that all the values of α, β, and γ represented by Equation 1 are non-negative, but at least one of α ₀ , β ₀ , and γ ₀ represented by Equation 8 may be non-negative.

As described above, as shown in Expression 9, the final stimulus value (each wavelength region image data) (r ₀ , g ₀ , b ₀ ) of the spectral image is the three image data (r ₁ , g ₁ , b ₁ , r ₂ , g ₂ , b ₂ , r ₃ , g ₃ , b ₃ : image data of 3 wavelength ranges for 3 frames) and 3 types of combined illumination light in each wavelength range The light intensity (α ₁ , β ₁ , γ ₁ , α ₂ , β ₂ , γ ₂ , α ₃ , β ₃ , γ ₃ ) and the coefficient (α ₀ , β ₀ , γ ₀ ). As can be seen from Equation 9, the final stimulus value (r ₀ , g ₀ , b ₀ ) does not depend on the spectral transmission characteristic L (λ) of the objective optical system or the spectral transmission characteristic D (λ) of the imaging system. It is a value, and formation of a spectral image is not influenced by individual differences of endoscopes.

  In the present invention, wavelength selection means is provided, and when the wavelength range of the spectral image is selected by the wavelength selection means, the control circuit includes first to third light sources for obtaining a spectral image of this wavelength range. Is output to the light source driving circuit, and the intensity of the output light of the first to third light sources is set by this light source driving circuit. Furthermore, a light intensity selection means may be provided, and according to this light intensity selection means, the intensity of the output light of the first to third light sources can be directly selected and set. The light intensity data of the first to third light sources selected and set in this way is used as operation data with image data for three frames, thereby forming a spectral image.

  According to the endoscope apparatus of the present invention, various types of microstructures and the like can be drawn regardless of individual differences such as the spectral transmission characteristics of the objective optical system and the imaging system, that is, regardless of the type of endoscope and individual differences. A good spectral image can be formed, and on the endoscopic image, a relatively thick blood vessel, a capillary blood vessel, a deep blood vessel, a shallow blood vessel, a fine structure such as a cancer tissue having a different degree of progression, etc. It can be observed, and a difference between specific substances such as a difference between oxyhemoglobin and deoxyhemoglobin can be observed, and there is an advantage that useful object image information useful for diagnosis and the like can be obtained.

  FIG. 1 shows a configuration block of an electronic endoscope apparatus according to the embodiment, and FIG. 2 shows a configuration of a light source unit. In this electronic endoscope apparatus, an endoscope tip portion and the like are shown. As shown in FIG. 1, the light source unit provided in the first to third light sources 14a, 14b, 14c and the first to third light source driving circuits 15a including an irradiation window 11, a light combining unit 12, LEDs (light emitting diodes). , 15b, 15c are provided. That is, as shown in FIG. 2, in the light source unit of the embodiment, for example, a dichroic (dichroic) prism is disposed as the light combining unit 12, and the first light source 14 a on the back side of the light combining unit 12 of this dichroic prism. A second light source 14b is disposed on the upper surface side, and a third light source 14c is disposed on the lower surface side. Each of the first, second, and third light sources 14a to 14c has a different emission wavelength range, for example, R (red), It consists of G (green) and B (blue) LEDs. The first light source 14a is driven by the first light source drive circuit 15a, the second light source 14b is driven by the second light source drive circuit 15b, and the third light source 14c is driven by the third light source drive circuit 15c, and the intensity of the output light. Is variably adjusted by current (or voltage) control.

  On the other hand, at the distal end of the scope, an imaging unit 18 having an objective optical system 17 shown in FIG. 1 and a CCD that is a solid-state imaging device is provided. As this CCD, for example, Mg (magenta), Ye on the imaging surface is provided. A complementary color type having color filters of (yellow), Cy (cyan) and G (green) or a primary color type having color filters of R (red), G (green) and B (blue) is arranged. The imaging unit 18 is provided with an imaging signal processing circuit 20 that performs predetermined image (video) processing (correlated double sampling, automatic gain control, γ correction, etc.) based on a signal output from the CCD. The output of the signal processing circuit 20 is supplied to the display system 21. The display system 21 is provided with, for example, a normal image monitor 21a and a spectral image monitor 21b, and the normal image and the spectral image are displayed in parallel (these images are divided into one monitor screen). May be displayed).

Then, after the imaging signal processing circuit 20, video data [for example, Y (luminance) / C (color difference) signal, etc.] output from the imaging signal processing circuit 20, image data [for example, R (Red, G (green), B (blue) color signal data)] image 1 (r ₁ , g ₁ , b ₁ ), image 2 (r ₂ , g ₂ , b ₂ ), image 3 ( r ₃ , g ₃ , b ₃ ), an image processing unit 24 for forming and outputting, a first calculation unit 25 for performing the calculation of Equation 5, and a second calculation unit 26 for performing the calculation of Equation 9 are provided. The spectral image signal formed by the calculation unit 26 is supplied to the display system 21.

  The electronic endoscope apparatus includes a control unit (such as a microcomputer) 28 that controls each circuit in the apparatus and performs control for spectral image formation, a memory 29 that stores the spectral calculation information and programs, A keyboard 30 is provided as input means for wavelength and light intensity for generating a spectral image, and the keyboard 30 and the display system 21 constitute wavelength selection means and light intensity selection means. That is, a wavelength selection menu, a light intensity selection menu, a selection menu for a specific structure to be drawn and a difference between specific substances are displayed on the monitor of the display system 21, and the wavelength and light intensity are selected with the keyboard 30 in this menu. Can be set. An operation switch or the like for selecting a wavelength, light intensity, or a specific structure may be provided on the operation panel.

The embodiment has the above-described configuration. First, the wavelength of a desired spectral image and the light intensity of each of the light sources 14a to 14c are selected using the keyboard 30 by each menu displayed on the display system 21 of FIG. However, for example, when calculating and displaying a spectral image when illumination is performed with a light source having the spectrum described in FIG. 3D, that is, wavelengths of 470 nm (b ₀ ), 500 nm (g ₀ ), and 670 nm (r ₀ ) In the case of a region (center wavelength), the control unit 28 determines the light intensities of the light sources 14a to 14c of the first to third combined illumination lights as shown in FIGS. These light intensities are set by current control of the first to third light source driving circuits 15a to 15c. That is, in the first combined illumination light in FIG. 3A, the intensity of the light S ₁ of the first light source 14a (corresponding to r ₁ in the above arithmetic expression) is α ₁ (instead of the intensity parameter of the above arithmetic expression). The intensity of the light S ₂ of the second light source 14b (corresponding to g ₁ in the above arithmetic expression) is β ₁ , and the intensity of the light S ₃ of the third light source 14c (corresponding to b ₁ in the above arithmetic expression) is γ _1. made of synthetic light Sc, and the 3 second combined illumination light (B) is ₂ intensity of light _{S 1} of the first light source 14a is alpha, the intensity of light _{S 2} of the second light source 14b is beta _2, 3 combined light Sc next to the intensity of light _{S 3} of the light source 14c is formed of gamma _2, 3 third combined illumination light (C), the intensity of the light _{S 1} of the first light source 14a is alpha _3, the second light source 14b ₃ the intensity of the light _{S 2} is beta, the combined light Sc next to the intensity of light _{S 3} of the third light source 14c is made of gamma _3, these first combined illumination light 3 Synthesis illumination light is sequentially irradiated to the observation target.

The object to be observed irradiated with the first to third combined illumination lights is imaged by the imaging unit 18 via the objective optical system 17, and the video signal output from the imaging unit 18 is the imaging signal processing circuit 20. A predetermined process is performed, and the output of the imaging signal processing circuit 20 is supplied to a display system 21 and an image processing unit 24 for forming a spectral image. That is, in the imaging signal processing circuit 20, a normal video signal is formed as in the conventional case, and a normal object image is displayed on the normal image monitor 21 a of the display system 21. On the other hand, in the image processing unit 24, image data of three wavelength regions suitable for spectral calculation is formed, and an image 1 (image obtained by the first combined illumination light) composed of signal data of r ₁ , g ₁ , b ₁ is formed. _{), r 2, g 2,} b 2 of the signal data from the composed image 2 (image obtained by the second synthetic illumination _{light), r 3, g 3,} b composed of _three signal data image 3 (the (Images obtained with three combined illumination light) are sequentially output.

Then, in the spectral calculation, using the data of the images 1 to 3 for the above three frames, the first calculation unit 25 performs the calculation of the above formula 5, and the second calculation unit 26 outputs the output of the first calculation unit 25. A matrix image (r ₀ , g ₀ , b ₀ ) is formed by performing the matrix operation of the above formula 9 that multiplies the coefficients (α ₀ , β ₀ , γ ₀ ) of the final stimulus value of the formula 8. The As shown in FIG. 3D, the spectral image has image data in a wavelength range (b ₀ ) centered at 470 nm, image data in a wavelength range (g ₀ ) centered at 500 nm, and centered at 670 nm. an image consisting of image data in the wavelength range (r ₀₎ to, the spectral image is displayed on the spectral image monitor 21b of the display system 21. In the formation and display of the spectral image, the spectral image can be displayed using only one or two image data in the three wavelength ranges.

Such spectral images are obtained by comparing the intensity (α ₁ , β ₁ , γ ₁ , α ₂ ) of the light sources 14a to 14c in the first to third synthesized illumination light from the first synthesized illumination light in FIGS. 3 (A) to 3 (C). , Β ₂ , γ ₂ , α ₃ , β ₃ , γ ₃ ) can also be formed and displayed in the same manner by setting with the keyboard 30.

In the embodiment, a menu for selecting a specific structure such as a thick blood vessel, a capillary blood vessel, a deep blood vessel, a shallow blood vessel, a cancer tissue having a different degree of progression, or the difference between oxyhemoglobin and deoxyhemoglobin, for example. In order to draw the difference between these specific structures and specific substances by selecting the menu for specific structures and differences between specific substances, etc. By setting the intensity of the first to third light sources 14a to 14c from the wavelength range (r ₀ , g ₀ , b ₀ ) (or the intensity may be set directly), the specific structure and the specific substance A spectral image depicting the difference is formed and displayed.
In the above-described embodiment, the case where three types of combined illumination light are used has been described. However, the combined illumination light may be two types or four or more types.

It is a block diagram which shows the structure of the electronic endoscope apparatus which concerns on the Example of this invention. It is a figure which shows the structure of the light source part of an Example. It is a wave form diagram which shows an example of the wavelength range of the spectral image obtained by the 1st thru | or 3rd synthetic | combination illumination light set in an Example, and these illumination light.

Explanation of symbols

12 ... Photosynthesis part, 14a-14c ... 1st thru | or 3rd light source part,
15a to 15c: first to third light source driving circuits,
17 ... Objective optical system, 18 ... Imaging unit,
21 ... Display system (monitor), 24 ... Image processing unit,
25 ... 1st calculating part, 26 ... 2nd calculating part,
28 ... Control unit, 29 ... Memory,
30 ... Keyboard.

Claims (3)

In an endoscope apparatus that images an object to be observed irradiated with illumination light with an imaging element mounted on the endoscope,
A light source unit having three light sources that emit light having different wavelength ranges, and combining the light from the three light sources and outputting the light as the illumination light;
A light source driving circuit that independently drives the three light sources of the light source unit and variably adjusts the output intensity of each light source light; and
A control circuit for controlling the light source driving circuit to form a plurality of types of combined illumination light in which the output intensities of the respective wavelength band lights of the three light sources are variably adjusted;
An arithmetic circuit for performing a matrix operation for obtaining a spectral image based on a plurality of image data obtained by the imaging device by irradiation of the plurality of types of synthetic illumination light and output intensity data of the three light source lights is provided. An endoscope apparatus characterized by that. Provide a wavelength selection means for selecting the wavelength range of the spectral image,
2. The endoscope apparatus according to claim 1, wherein the control circuit variably sets the output intensities of the three light sources based on the wavelength range selected by the wavelength selection means. A light intensity selecting means for selecting the output intensity of the three light sources;
The endoscope apparatus according to claim 1, wherein the control circuit variably sets the output intensities of the three light sources based on the output from the light intensity selecting means.

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