JP4098402B2 - Fluorescent imaging device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fluorescence imaging apparatus that irradiates an observation target site of a living tissue with an excitation light and obtains a fluorescence image by the excitation light.
[0002]
[Prior art]
In recent years, excitation light is irradiated to a site to be observed in a living tissue, and autofluorescence directly generated from the living tissue by this excitation light or fluorescence of a drug that has been injected into the living body is detected as a two-dimensional image. Techniques for diagnosing disease states such as the degeneration of biological tissue, the type of cancer, and the infiltration range from images are being used. In recent years, the subject (subject) is irradiated with visible light, and the subject image is displayed by the reflected light. Also for an endoscope displayed on the means, a fluorescence observation apparatus having a function of fluorescence observation has been proposed.
[0003]
In fluorescence observation, autofluorescence is generated in a wavelength band longer than the excitation wavelength when a living tissue is irradiated with blue or ultraviolet light. The fluorescence spectrum is different between normal tissue and abnormal tissue (precancerous tissue, cancerous tissue).
For example, when light of 437 nm is irradiated to the digestive tract tissue, the green autofluorescence of the abnormal tissue is attenuated compared to the autofluorescence of the normal tissue, whereas the red autofluorescence of the abnormal tissue is changed to the autofluorescence of the normal tissue. It doesn't attenuate much. Japanese Patent Laid-Open No. 9-327433 discloses a transendoscopic fluorescence observation apparatus that utilizes this principle to image the green and red autofluorescence and show the presence of abnormal tissue.
[0004]
In this conventional example, the excitation light is irradiated into the body cavity endoscopically, and the autofluorescence of the green and red regions generated from the tissue is detected and imaged. Then, means for adjusting the ratio of the video signal corresponding to the green and fluorescence intensity and the video signal corresponding to the red fluorescence intensity is shown so that the normal tissue has a specific color tone. In this means, the doctor first looks at the color tone of the normal part and adjusts the ratio so that it becomes a specific color tone. Next, after adjusting the color tone, other parts are observed. Then, the normal part is displayed with a specific color tone adjusted, and the lesion part is displayed with a color tone different from that of the normal part due to the attenuation of the green signal. The lesioned part can be specified by the difference between the color tone of the lesioned part and the color tone of the normal part. In this conventional example, the ratio is adjusted so that the normal portion is shown in cyan and the lesion is shown in red.
[0005]
[Problems to be solved by the invention]
However, in the above-described conventional example of Japanese Patent Laid-Open No. 9-327433, the color tone of the normal part is adjusted based on the judgment of the individual doctor. For this reason, since the color tone set by the doctor is slightly different, there is a problem that it is difficult to make an objective diagnosis.
[0006]
The present invention has been made in view of the above circumstances, and by performing a simple operation during normal tissue observation, the normal tissue is adjusted to a specific color tone and displayed, so that the color tone of the lesion is always specified. It is an object of the present invention to provide a fluorescence imaging apparatus in which the color tone of a lesion is not changed due to a doctor's difference or the like.
[0007]
[Means for Solving the Problems]
The fluorescent imaging device of the present invention is a fluorescent imaging device that captures a fluorescent image of a subject excited by excitation light,
A first imaging unit that images the subject in a first wavelength band, a second imaging unit that images the subject in a second wavelength band, and a first output output from the first imaging unit A computing means for calculating a first maximum value of a signal level histogram in the signal and a second maximum value of a signal level histogram in the second output signal output from the second imaging means, and the computing means Control means for controlling the ratio of the signal level of the first output signal and the second output signal based on the first maximum value and the second maximum value obtained in step (b), and the control means Display means for displaying the subject image based on the first output signal and the second output signal whose ratios are controlled.
[0008]
According to this configuration, when the fluorescent image of the subject is displayed on the display means, the color tone of the normal tissue is adjusted to a specific color tone, and the color tone of the lesioned part is normal after being adjusted to this specific color tone. Since it is displayed for the tissue, the color tone of the lesion does not change depending on the doctor.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
1 to 3 relate to an embodiment of the present invention, FIG. 1 is an explanatory diagram showing a schematic configuration of a fluorescence imaging apparatus, FIG. 2 is a histogram showing the frequency of green and red image signal levels, and FIG. 3 is normal It is a flowchart which shows the operation | work which sets a structure | tissue to a specific color tone.
[0010]
As shown in FIG. 1, the fluorescence imaging apparatus 1 according to the present embodiment irradiates a living body with a light source device 2 including a lamp 21 that generates excitation light, and the excitation light from the light source device 2, while the excitation light. The first image in corresponding to the green color which amplifies the fluorescent images of the different wavelength bands of green and red obtained by the endoscope 3 and detects the fluorescent image by the endoscope 3 and transmits it to the outside of the living body. Tensifier (hereinafter abbreviated as II) 41 and second I.I corresponding to red. I. 42 and this first I.D. I. CCD 43, which is a first image pickup means for picking up the fluorescent image amplified at 41, and a second I.D. I. The camera 4 provided with the CCD 44 as the second image pickup means for picking up the fluorescent image amplified at 42, the first output signal output from the first CCD 43 of the camera 4 and the output from the second CCD 44. The second output signal is processed into an image signal, a pseudo color image signal is generated from each image signal, and the normal part is adjusted to a specific color tone. A calculation unit 51 which is a calculation means for calculating a value and the I.S. I. The image processing device 5 including a control unit 52 that is a control unit that adjusts and controls the amplification ratios 41 and 42, and a display unit that displays a pseudo color image signal that is a subject image generated by the image processing device 5. It is mainly comprised with the monitor 6 which is.
[0011]
In order to generate excitation light having a specific wavelength, the light source device 2 transmits light having a specific wavelength of 350 to 450 nm, for example, with a lamp 21 such as a metal halide lamp, a xenon lamp, a mercury lamp, or a mercury xenon lamp. And an interference filter 22.
[0012]
The endoscope 3 has an elongated insertion portion 31 that is inserted into a living body, and a light guide 32 that transmits excitation light from the light source device 2 to the distal end of the insertion portion and the light in the insertion portion 31. An illumination optical system having an illumination window 33 that illuminates the observation site with excitation light transmitted through the guide 32, and an eyepiece lens 35 that is arranged on the eyepiece 34 on the proximal side of the insertion portion for the fluorescence image of the observation site An observation optical system having an observation window 36 that captures a fluorescence image of an observation site to be transmitted and an image guide 37 that transmits the fluorescence image captured through the observation window 36 is configured.
[0013]
The camera 4 is detachably connected to the eyepiece 34 of the endoscope 3.
The camera 4 includes a dichroic mirror 45 that divides a fluorescent image incident on the camera 4 through the eyepiece 35 into light of a long wavelength side and a short wavelength side at a certain wavelength, for example, 580 nm, and the dichroic mirror 45. Of the short wavelength light that has traveled straight through the light, for example, a first band pass filter 46 that transmits a wavelength band of 480 to 520 nm, which is a wavelength band for detecting green fluorescence, and the long wavelength side reflected by the dichroic mirror 45 and the mirror 47 The second band-pass filter 48 that transmits, for example, 630 nm or more, which is a wavelength band for detecting red fluorescence, and the first I that amplifies the fluorescence image that has passed through the first band-pass filter 46. . I. 41 and a second I.D. amplifying fluorescent image transmitted through the second band-pass filter 48. I. 42 and the first I.S. I. The first CCD 43 that picks up the output image from the first I. 41 and the second I.D. I. And a second CCD 44 that captures an output image from 42.
[0014]
The image processing device 5 controls the first CCD 43 and generates a first camera control unit (hereinafter abbreviated as CCU) 53 for generating an electric signal transmitted from the CCD 43 as an image signal. A first analog-to-digital converter (abbreviated as A / D converter) 54 for converting an image signal generated by the CCU 53 into a digital signal, and the digital data into a first I.D. I. 41 and a first lookup table 55 (hereinafter abbreviated as LUT) 55 that is corrected in accordance with the sensitivity characteristics of the first CCD 43 and the second CCD 44, and an electrical signal transmitted from the CCD 44 is used as an image signal. A second CCU 56 to be generated, a second A / D converter 57 for converting an image signal generated by the second CCU 56 into a digital signal, and the digital data to a second I.D. I. 42 and a second LUT 58 that is corrected in accordance with the sensitivity characteristics of the second CCD 44, a video processor 59 that generates data corrected by the LUTs 55 and 58 into a pseudo color image signal, and image signals of the LUTs 55 and 58. The calculation unit 51 for calculating the frequency (histogram) of the luminance level, the ratio of the peak of the histogram distribution of the green and red signals obtained by the calculation unit 51 is obtained, and the ratio is a value corresponding to the color tone of the normal part. As described above, the I.S. I. The control unit 52 is configured to adjust and control the amplification ratios 41 and 42. Further, the image processing apparatus 5 outputs an instruction signal for starting the adjustment of the amplification ratio described above to the control unit 52. The color tone adjustment switch 10 to be connected is connected.
[0015]
The operation of the fluorescence imaging apparatus 1 configured as described above will be described.
First, of the broadband light generated from the lamp 21 of the light source device 2, ultraviolet or blue excitation light passes through the interference filter 22 and is condensed on the base end surface of the light guide 32 of the endoscope 3. The excitation light condensed on the base end face of the light guide 32 is transmitted to the illumination window 33 through the light guide 32 inserted through the endoscope 3 and is observed from the illumination window 33 in the living body. Irradiated towards. Fluorescence is generated from the observation site by the irradiated excitation light, and the fluorescence image is transmitted to the eyepiece 34 on the hand side through the observation window 36 and the light guide 37 of the endoscope 3, and the camera is passed through the eyepiece 35. 4 is incident.
[0016]
Next, the fluorescent image incident on the camera 4 is divided by the dichroic mirror 45 into a short wavelength side and a long wavelength side with 580 nm as a boundary. The short-wavelength fluorescent image travels straight through the dichroic mirror 45, and only the green fluorescent image is transmitted by the first band-pass filter 46. I. After being amplified at 41, the image is picked up by the first CCD 43. On the other hand, the long-wavelength fluorescent image is reflected by the dichroic mirror 45 and the mirror 47, and only the red fluorescent image is transmitted by the second bandpass filter 48. I. After being amplified at 42, the image is picked up by the second CCD 44.
[0017]
Next, the green fluorescent image picked up by the first CCD 43 is converted into an image signal by the first CCU 53, converted into a digital signal by the first A / D converter 54, and this digital data is converted into the first signal. I. I. 41 and the first CCD 43 are corrected to correct sensitivity characteristics by the first LUT 55 in which correction data matching the sensitivity characteristics of the first CCD 43 is recorded. The red fluorescent image picked up by the second CCD 44 is converted into an image signal by the second CCU 56, converted into a digital signal by the second A / D converter 57, and this digital data is converted into the second signal. I. I. Corrected sensitivity characteristics are corrected by the second LUT 58 in which correction data matching the sensitivity characteristics of the 42 and the second CCD 44 is recorded.
[0018]
The digital signal corrected by the LUTs 55 and 58 is generated as a pseudo color image signal by the video processor 59 and displayed on the screen of the monitor 6 as a fluorescent image of the observation site. The color tone of the fluorescent image displayed on the monitor 6 corresponds to the ratio of digital data to the green and red fluorescent images output from the LUTs 55 and 58. That is, as shown in the conventional example, when the green digital data is larger than the red color of the normal tissue, it is displayed in cyan, and the red digital data is larger than the green color of the abnormal tissue such as the cancer tissue. In some cases, it is displayed in red. At this time, the first I.D. I. 41, a second I.A. I. If the ratio of 42 is high, the normal tissue becomes whitish in cyan and the abnormal tissue is displayed in red. On the other hand, the second I.D. I. When the ratio of 42 is low, the normal tissue is more cyan and the abnormal tissue is displayed in a blackish color.
[0019]
The surgeon observing the fluorescent image displayed on the screen of the monitor 6 now observes the normal tissue in order to objectively determine the normal part and the lesion part and identify the lesion part. When the color tone adjustment switch 10 is pressed. Then, when the color tone adjustment switch 10 is pressed, the color tone adjustment is automatically started so that the normal part of the tissue is displayed in the cyan color tone.
[0020]
This automatic color tone adjustment will be described below.
A second I. amplifying red fluorescence. I. The gain of 42 is the I.D. I. 41.
[0021]
R (G) = aG ² + bG + c (1)
Here, R is the second I.D. I. 42, and G is the first I.D. I. A gain of 41. a, b, and c are constants. I. The constant b is a term for correcting individual differences in the gain characteristics of 41 and 42. I. This is a term for correcting the relative gain of 41 and 42. That is, the color tone can be adjusted by adjusting the value of the term b. The constant c is an offset value.
[0022]
Here, for the sake of simplicity in the following description of the color tone adjustment procedure, the method of adjusting the color tone by adjusting the value of the term b with the value of the term a and the value of the term c being 0 is shown in FIGS. Will be described with reference to FIG.
First, when the normal tissue is being observed, the color tone adjustment switch 10 is pressed as described above. Then, the value of the term b in the equation (1) is set to 1 as shown in step S1. Then, in this relative gain state of b = 1, green and red fluorescent images are taken, the digital data of the green and red fluorescent images at that time are taken out from the LUTs 55 and 58, and the process proceeds to step S2.
[0023]
Next, in step S2, as shown in FIG. 2, the histogram of each digital data is measured and the process proceeds to step S3, where the green maximum value HG and the red maximum value HR are calculated from the histograms for green and red. And the process proceeds to step S4. In step S4, a ratio R (HG / HR) between the maximum green value HG and the maximum red value HR is obtained.
[0024]
Next, the process proceeds to step S5, and it is compared whether or not the value of the ratio R obtained in step S4 is smaller than the first value R1. At this time, if the value of the ratio R is smaller than the first value R1, the process proceeds to step S6, the value of the term b is increased by, for example, 0.1, and the relative gain state of b = 1.1. The process from step S2 is performed again. Accordingly, the processing from step S2 to step S5 is repeated until the value of the ratio R becomes larger than the first value R1 as shown in step S5. When the value of the ratio R becomes larger than the first value R1, the process proceeds to step S7.
[0025]
In this step S7, it is compared whether or not the value of the ratio R larger than the first value R1 obtained in step S5 is larger than the second value R2. At this time, if the value of the ratio R is larger than the second value R2, the process proceeds to step S8, the value of the term b is decreased by, for example, 0.1, and the processing from step S2 to step S5 and step S7 is performed again. Do. Then, until the value of the ratio R is larger than the first value R1 as shown in step S5 and the value of the ratio R is smaller than the second value R2 as shown in step S7, That is, the value b is repeatedly increased or decreased until the ratio R is between the first value R1 and the second value R2. Then, the processing is completed when the value of the ratio R is between the first value R1 and the second value R2. The interval between the first value R1 and the second value R2 is set to a reasonably wide value as compared with the change in step S6 in step S6 and step S8.
[0026]
At this time, in the fluorescent image displayed on the screen of the monitor 6, the normal tissue is displayed in a cyan color tone that is most easily recognized as being a normal tissue. Then, the structure of the abnormal portion is displayed in a dark red tone that is easily recognized as the most abnormal with respect to the cyan color tone. Thus, the surgeon can objectively determine whether the tissue is a normal part tissue or a lesion part tissue, and can specify the lesion part.
[0027]
In this way, by operating the color tone adjustment switch connected to the control unit of the image processing apparatus, the amplification ratio is adjusted via the control unit and the calculation unit, so that the color tone of the normal part is the most normal tissue. By automatically adjusting to the cyan color tone that is easily recognized as being present, and making the tissue of the abnormal part a dark red color tone that is most likely to be recognized as being abnormal, the surgeon can detect from the fluorescent image displayed on the monitor screen. It is possible to objectively judge normal tissue and abnormal tissue, and to quickly and accurately diagnose a disease state such as the presence of a lesion and the range of a lesion. As a result, the color tone does not change due to different operators, and anyone can easily determine the difference in color tone between the normal part and the lesioned part.
[0028]
It should be noted that the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.
[0029]
[Appendix]
According to the embodiment of the present invention as described above in detail, the following configuration can be obtained.
[0030]
(1) In a fluorescence imaging apparatus that captures a fluorescence image of a subject excited by excitation light,
In a fluorescence imaging device that captures a fluorescence image of a subject excited by excitation light,
First imaging means for imaging the subject in a first wavelength band;
Second imaging means for imaging the subject in a second wavelength band;
The first maximum value of the histogram of the signal level in the first output signal output from the first imaging means and the second value of the histogram of the signal level in the second output signal output from the second imaging means. Computing means for calculating the maximum value of
Control means for controlling a signal level ratio between the first output signal and the second output signal based on the first maximum value and the second maximum value obtained by the calculating means;
Display means for displaying the subject image based on the first output signal and the second output signal whose signal level ratio is controlled by the control means;
A fluorescence imaging apparatus comprising:
[0031]
(2) The fluorescence imaging apparatus according to appendix 1, wherein the relative gain is adjusted so that a ratio between the first maximum value and the second maximum value falls within a specific value range.
[0032]
(3) The fluorescent image device according to appendix 1, wherein the color tone of a normal tissue of a subject image displayed on the monitor is adjusted to a cyan color tone.
[0033]
【The invention's effect】
As described above, according to the present invention, the normal tissue is adjusted to a specific color tone and displayed, so that the color tone of the lesion is always displayed with respect to the normal tissue color tone adjusted to the specific color tone. Therefore, it is possible to provide a fluorescence imaging apparatus in which the color tone of a lesioned part does not change due to a difference in doctors.
[Brief description of the drawings]
FIG. 1 to FIG. 3 relate to an embodiment of the present invention, FIG. 1 is an explanatory diagram showing a schematic configuration of a fluorescence imaging apparatus, and FIG. 2 is a histogram showing frequency of green and red image signal levels. FIG. 3 is a flowchart showing an operation for setting a normal tissue to a specific color tone.
DESCRIPTION OF SYMBOLS 1 ... Fluorescence image apparatus 2 ... Light source device 3 ... Endoscope 4 ... Camera 5 ... Image processing apparatus 6 ... Monitor 41 ... 1st I.D. I.
42 ... The second I.D. I.
43 ... 1st CCD
44 ... Second CCD
51 ... Calculation unit 52 ... Control unit

Claims (1)

In a fluorescence imaging device that captures a fluorescence image of a subject excited by excitation light,
First imaging means for imaging the subject in a first wavelength band;
Second imaging means for imaging the subject in a second wavelength band;
The first maximum value of the histogram of the signal level in the first output signal output from the first imaging means and the second value of the histogram of the signal level in the second output signal output from the second imaging means. Computing means for calculating the maximum value of
Control means for controlling a signal level ratio between the first output signal and the second output signal based on the first maximum value and the second maximum value obtained by the calculating means;
Display means for displaying the subject image based on the first output signal and the second output signal whose signal level ratio is controlled by the control means;
A fluorescence imaging apparatus comprising:

Images