JP2001314366A - Method and apparatus for displaying fluorescent image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an S/N and a contrast of a calculated image in a method and an apparatus for displaying a fluorescent image for displaying the calculated image based on a self-fluorescent image generated from an organism tissue by emitting an exciting light. SOLUTION: The exciting light is radiated from a GaN semiconductor laser 114 to the organism tissue 10. The self-fluorescent image Zj generated from the tissue 10 is transmitted through an optical transmission filter 303 and detected as two fluorescent images having different wavelength bands by an image detecting unit. An image calculating unit 400 adds an offset value to the each image, then calculates to standardize to generate the calculated image and displays the image on a monitor unit 600. The S/N and the contrast of the calculated image are remarkably improved by adding the predetermined offset value to the each image before the calculation for standardizing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescence image display method and apparatus for measuring fluorescence generated from a living tissue by irradiating excitation light and displaying the image as information representing information on the living tissue.

[0002]

2. Description of the Related Art Conventionally, when a living tissue is irradiated with excitation light in the excitation light wavelength region of a dye existing in a living body, normal tissues and diseased tissues have different fluorescence intensities. There has been proposed a technique of irradiating excitation light in a predetermined wavelength region and receiving fluorescence emitted from a dye in a living body to display the localization and infiltration range of a diseased tissue as a fluorescence image.

Normally, when excitation light is irradiated, strong fluorescence is emitted from normal tissue as shown by a solid line in FIG. 1 and weak fluorescence is emitted from a diseased tissue as shown by a broken line. By doing so, it is possible to determine whether the living tissue is normal or in a pathological state.

When displaying the intensity of the fluorescence by the excitation light as an image, the intensity of the excitation light received by the living tissue changes due to a difference in the irradiation angle and the distance of the excitation light applied to the living tissue. The intensity of the fluorescence generated from the living tissue changes due to the difference in the received light intensity. Therefore, the tissue properties of the living tissue cannot be accurately identified only from the fluorescence intensity information. Therefore, the ratio between the intensity of the excitation light received by the living tissue and the intensity of the fluorescence generated from the living tissue by receiving the excitation light, that is, a value that is not affected by the distance or angle at which the excitation light is irradiated. A method has been proposed in which a value reflecting the fluorescence yield is obtained and displayed on an image to identify the tissue property of the living tissue.

As a method of obtaining a value reflecting the fluorescence yield and displaying an image, a method of displaying a calculated image by performing a normalization calculation by obtaining a ratio of two types of fluorescence intensities obtained from different wavelength bands, or Irradiating the living tissue with near-infrared light that is uniformly absorbed by various living tissues as reference light, and detects a reference image of light reflected by the living tissue that has been irradiated with the reference light. Then, a method of displaying a calculated image by performing a normalization calculation by obtaining a ratio with the fluorescence image has been proposed.

[0006]

However, since the fluorescence intensity from the living tissue is very weak, the S / N of the measured fluorescence image is very low. Therefore, when a normalization operation is performed using such a fluorescence image, the S / N of the operation image based on the obtained operation value also becomes extremely low, and it becomes very difficult to distinguish between a normal tissue and a diseased tissue.

In view of the above-mentioned problems of the prior art, the present invention provides an apparatus and a method for displaying a calculated image by performing a normalization calculation by obtaining a ratio of the fluorescence intensities of the different wavelength bands. An apparatus and method for displaying a computed image by performing a standardized computation by determining a ratio between an image and a reference image, wherein the S / N of the computed image and the contrast between the computed images are improved, and images of normal tissue and diseased tissue are improved. It is an object of the present invention to provide an apparatus and a method capable of performing identification at a higher accuracy.

[0008]

A fluorescence image display method according to the present invention detects fluorescence images of different wavelength bands from fluorescence generated from a living tissue by irradiation of excitation light, and displays the fluorescence images of different wavelength bands. In a fluorescent image display method for generating a calculated image by performing a normalization operation by calculating the ratio and displaying the calculated image, a desired offset is added to the fluorescent images in different wavelength bands before performing the normalization operation. It is characterized by doing.

The ratio of the fluorescent images means the ratio of each pixel value on the same coordinates in each image of the fluorescent images of different wavelength bands, and the normalization calculation means the same coordinates. It means that division or similar operation is performed by each pixel value above, and the operation image means an image in which a value obtained by normalization operation is used as a pixel value for each pixel.

[0010] The technique of adding a desired offset to the fluorescent images of different wavelength bands means adding an offset value to each pixel value of each image. By adding an offset value to each image, variations in the pixel values of the calculated image after the normalization calculation are reduced, and the S / S of the calculated image is reduced.
N can be improved. The portion to which the offset value is added does not have to be the entire image, and may be added to only a portion where the image is dark, that is, only a portion having a low S / N. That is, when the normalization operation is performed based on the ratio of each image, the offset is large enough to improve the S / N of the operation image so that the accuracy of discriminating between normal tissue and diseased tissue is improved. Just add a value.

Here, the normalization operation based on the ratio of the fluorescence images in the different wavelength bands is called an NF operation.

Assuming that the fluorescence images in the different wavelength bands are the fluorescence image 1 and the fluorescence image 2, NF operation value = (fluorescence image 1 + offset value) / (fluorescence image 2 + offset value) (1) The fluorescent image 1 and the fluorescent image 2 mean each pixel value in each image.

Further, a constant offset value can be added to each of the entirety of the fluorescence images in the different wavelength bands. The whole of each image means all pixels of each image. At this time, it is not always necessary to add the same offset value to each image, but by adding the offset value, the S / N becomes sufficiently large when the normalization operation is performed based on the ratio of each image. In addition, it is necessary to add a sufficiently large offset value to each pixel value.

As a method of generating a calculation image,
A method can be adopted in which different colors can be assigned to respective pixels according to the magnitude of the NF operation value. Here, the method of assigning different colors according to the magnitude of the NF calculation value may be any method as long as the diseased tissue and the normal tissue can be distinguished. Specifically, for example, a method is provided in which a reference value is provided in advance, binary determination is performed based on whether the NF operation value is large or small, and two types of colors are assigned to the binary value. The hue (Hue) in the Munsell color system is directly used as the magnitude of the NF operation value.
Can be used.

The reference value can be a value calculated in advance from a living tissue that is apparently a normal tissue or a diseased tissue.

The fluorescent image display apparatus according to the present invention comprises: an irradiating means for irradiating a living tissue with excitation light; and a fluorescent light for detecting fluorescent images in mutually different wavelength bands from fluorescent light generated from the biological tissue by irradiating the exciting light. Image detecting means, means for performing a normalization operation based on the ratio of the fluorescence images of the different wavelength bands to generate an operation image, and a fluorescent image display device comprising a display means for displaying the operation image, Before performing the normalization operation, a means for adding a desired offset to each of the fluorescence images in the mutually different wavelength bands is provided.

The means for adding a desired offset to the fluorescent images in the different wavelength bands does not have to add the offset value to the entire image. In particular, the image has dark portions, that is, low S / N. It may be added only to the part.

Further, a fixed offset value may be added to each of the entirety of the fluorescence images in the different wavelength bands. At this time, it is not always necessary to add the same offset value to each image,
By adding an offset value, a sufficiently large offset value is added to each pixel value so that the S / N becomes sufficiently large when a normalization operation is performed based on the ratio of each image. It is necessary to be.

Further, the means for generating the calculation image may include means for allocating different colors to respective pixels according to the magnitude of the NF calculation value.

Further, the fluorescent image display method according to the present invention comprises:
A fluorescence image is detected from fluorescence generated from the living tissue by irradiation of the excitation light, a reference image is detected by reflected light reflected from the living tissue by the irradiation of the reference light, and a ratio between the fluorescence image and the reference image is detected. A fluorescent image display method for generating a calculated image by performing a normalization calculation based on the calculated image, and adding a desired offset to the fluorescence image and the reference image before performing the normalization calculation It may be.

The ratio between the fluorescent image and the reference image means the ratio of each pixel value on the same coordinates in each image. Here, the normalization calculation based on the ratio between the fluorescence image and the reference image is referred to as AF calculation.

Further, the fluorescent image display device according to the present invention
Irradiation means for irradiating living tissue with excitation light and reference light,
Fluorescence image detection means for detecting a fluorescence image from fluorescence generated from the living tissue by irradiation of the excitation light, and reference image detection means for detecting a reference image by reflected light reflected from the living tissue by irradiation of the reference light A means for performing a normalization operation based on a ratio between the fluorescence image and the reference image to generate an operation image; and a display means for displaying the operation image. Means for adding a desired offset to the fluorescence image and the reference image before performing.

[0023]

According to the present invention, an offset value is added to each image before the normalization operation is performed by calculating the ratio of the two images. It is possible to achieve an effect that a very low S / N can be increased. Hereinafter, the reason will be discussed.

The S / N ratio of the calculated image when the calculated image is calculated by performing the NF calculation by adding a fixed offset value to each of the whole fluorescent images in the different wavelength bands.
Are shown in Table 1.

Fluorescent images in wavelength bands different from each other typically have an average pixel value of 1 and a standard deviation of 1 in each image.
Is assumed. It can be said that this schematic image has a very poor S / N.

[0026]

[Table 1] In Table 1, the variation represents the standard deviation of the NF operation value,
The average value is the average value of the NF operation values, and the S / N is the average value /
It means variation.

From Table 1, it can be seen that the S / N ratio of the NF operation value to which a large offset value is added is significantly improved.

Further, each image of the fluorescence images in the mutually different wavelength bands is schematically assumed based on the conditions in Table 2, and an NF operation is performed by adding an offset value to each image to calculate an operation image. FIG. 2 shows the result of calculating the contrast of the computed image as the degree of separation.

[0029]

[Table 2] In Table 2, the numerator value 1 of the calculation condition 1 is the average value of the pixel values in the fluorescence image 1 of the diseased tissue, the denominator value 10 of the calculation condition 1 is the average value of the pixel values in the fluorescence image 2 of the diseased tissue, and the calculation condition The variation 1 of 1 is a value schematically representing the standard deviation of the pixel values in the fluorescence image 1 and the fluorescence image 2 of the diseased tissue.

The numerator value 10 in the calculation condition 2 is the average value of the pixel values in the fluorescent image 1 of the normal tissue, the denominator value 25 in the calculation condition 2 is the average value of the pixel values in the fluorescent image 2 of the normal tissue, and the calculation condition 2 Variation 1 is a value that schematically represents the standard deviation of the pixel values in the fluorescent image 1 and the fluorescent image 2 of the normal tissue.

The offset of the calculation condition 1 and the calculation condition 2 is obtained by changing the offset value from 5 to 1000
It means that the operation was performed and the degree of separation was calculated. Note that the fluorescent image 1 and the fluorescent image 2 are fluorescent images in different wavelength bands. The degree of separation is defined by equation (3).

Degree of separation = (Ave ₂ −Ave ₁ ) ² / (SD ₂ + SD ₁ ) ² (3) Ave ₁ is obtained by adding an offset to the fluorescent image 1 and the fluorescent image 2 of the diseased tissue and performing NF calculation 5 shows the average value of the NF calculation values. Ave ₂ indicates the average value of the NF calculation values when the NF calculation is performed by adding an offset to the fluorescence images 1 and ₂ of the normal tissue. SD ₁ is the NF obtained by performing an NF operation by adding an offset to the fluorescent image 1 and the fluorescent image 2 of the diseased tissue.
Indicates the standard deviation of the calculated value. SD2 indicates the standard deviation of the NF calculation value when the NF calculation is performed by adding an offset to the fluorescence image 1 and the fluorescence image ₂ of the normal tissue. In other words, the larger the value of the degree of separation, the higher the contrast between the computed images of the diseased tissue and the normal tissue.

Further, each of the fluorescent images in the different wavelength bands is schematically assumed based on the conditions shown in Table 2 and displayed as images, and an NF operation is performed by adding an offset value to each image to calculate a calculated image. 3 (a) to 3 (c) and FIGS. 4 (a) to 4 (h)
Shown in

FIG. 3A shows the fluorescent image 1 displayed. The upper image schematically shows the fluorescent image 1 of the diseased tissue, and the lower image shows the fluorescent image 1 of the normal tissue. This is a schematic display of the fluorescent image 1. FIG.
(B) is a display of the fluorescent image 2, wherein the upper image is a schematic display of the fluorescent image 2 of the diseased tissue, and the lower image is the fluorescent image 2 of the normal tissue. This is schematically displayed. FIG. 3C shows the fluorescence image 1
And a calculation image obtained by performing the NF calculation using the fluorescent image 2 and the fluorescence image 2. The offset value added at the time of this NF calculation is 5. FIGS. 4A to 4H schematically show an operation image obtained by performing the NF operation by changing the offset value from 5 to 1000 using the fluorescence image 1 and the fluorescence image 2. Things.

FIGS. 2 and 4A to 4H show that as the offset value increases, the degree of separation increases and the contrast between the upper image and the lower image is improved.

From FIGS. 2 and 4 (a) to 4 (h), when the offset value is about 10, the degree of separation is 0, and the contrast of the calculated image is reversed with the offset value as a boundary. The offset value at which the degree of separation becomes zero is determined based on the numerator value, denominator value, and variation value of the calculation conditions 1 and 2, and is predicted in advance. It is desirable to specify an offset value that is sufficiently larger than the value.

From the above results, it can be seen that by performing the NF operation by adding an offset to the fluorescent images in the different wavelength bands, the S / N and the contrast of the operation image based on the NF operation value are greatly improved.

The same applies to the case where AF calculation is performed with an offset added to each of the fluorescent image and the reference image.

According to the fluorescence image display method apparatus or method of the present invention configured as described above, the NF calculation is performed based on the ratio of the fluorescence images in different wavelength bands to generate and display the calculated image. By performing the NF operation by adding an offset to the fluorescence images in the different wavelength bands, the S / N of the operation image based on the NF operation value and the contrast between the images can be improved.
Normal tissue and diseased tissue can be detected with higher accuracy.

In addition, when performing the NF calculation by adding an offset to the fluorescence images of different wavelength bands, the calculation process can be simplified by adding a constant offset value to each image as a whole.

Further, in generating an operation image based on the NF operation value, different colors are assigned according to the magnitude of the operation value obtained by performing the NF operation, so that the normal tissue and the diseased tissue can be more clearly distinguished. Can be.

Further, an AF operation is performed based on the ratio between the fluorescent image and the reference image, and an offset is added to the fluorescent image and the reference image to generate and display the calculated image.
By performing the F calculation, the S / N and contrast of the calculation image based on the AF calculation value can be improved, so that the normal tissue and the diseased tissue can be detected with higher accuracy.

Also, in this case, similarly to the above, when performing an AF operation by adding an offset to the fluorescence image and the reference image, the arithmetic processing is simplified by adding a constant offset value to each image as a whole. be able to.

Further, in generating a calculation image based on the AF calculation value, by assigning different colors according to the size of the calculation value obtained by performing the AF calculation, it is possible to more clearly distinguish normal tissues from lesion tissues. Can be.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 5 is a diagram showing a schematic configuration in which a fluorescent image display device that performs the fluorescent image display method of the present invention is applied to a fluorescent endoscope device.

The fluorescence endoscope apparatus according to the present embodiment emits an endoscope 100 inserted into a suspected lesion of a patient, a white light Lw for a normal image, and an excitation light Lr for an autofluorescence image. Lighting unit 11 with two light sources
0, an image detection unit 300 that captures an auto-fluorescence image Zj generated from the living tissue 10 by the auto-fluorescence, converts the auto-fluorescence image into a digital value, and outputs it as two-dimensional image data, and two-dimensional image data output from the image detection unit 300 Image calculation for adding a specified offset to each pixel, calculating an operation image using the image to which the offset has been added, comparing with a reference value stored in advance, and outputting a signal corresponding to the comparison result. A display signal processing unit 50 for converting a normal image into a digital value to obtain two-dimensional image data, converting the two-dimensional image data and an output signal of the image operation unit 400 into a video signal, and outputting the video signal;
0, a fluorescence diagnostic apparatus 1 connected to each unit and comprising a control computer 200 for controlling operation timing, and a monitor unit 600 for displaying a signal processed by the display signal processing unit 500 as a visible image. ing.

The endoscope 100 includes a light guide 101, a CCD cable 102, and an image fiber 103 that extend to the distal end. Light guide 1
An illumination lens 104 and an objective lens 105 are provided at the end of the endoscope 100 and the end of the CCD cable 102, that is, at the end of the endoscope 100. The image fiber 103 is a silica glass fiber, and has a condenser lens 106 at the tip. A normal image pickup device 107 is connected to the distal end of the CCD cable 102, and the normal image pickup device 107 has a reflecting prism 10.
8 is attached. The light guide 101 is a multi-component glass fiber white light light guide 101a.
Light guide 1 made of quartz and silica glass fiber
The white light guide 101a and the excitation light guide 101b are connected to the illumination unit 110.
One end of the CCD cable 102 is connected to the display signal processing unit 500, and one end of the image fiber 103 is connected to the image detection unit 300.

The illumination unit 110 is a white light source 111 that emits white light Lw for normal images, a white light source power supply 112 electrically connected to the white light source 111, and collects white light emitted from the white light source 111. Condensing lens 113 for white light, GaN-based semiconductor laser 114 emitting excitation light Lr for fluorescent image, and GaN-based semiconductor laser 1
Power supply 11 for semiconductor laser electrically connected to 14
5. It is provided with an excitation light condenser lens 116 for condensing the excitation light emitted from the GaN-based semiconductor laser.

An image fiber 103 is connected to the image detection unit 300. The collimating lens 301 for fluorescence guides the auto-fluorescent image propagated by the image fiber 103 to an image forming system. An excitation light cut filter 302 for cutting, an optical transmission filter 303 for cutting out a desired wavelength band from the autofluorescence image transmitted through the excitation light cut filter 302,
Filter rotation device 3 for rotating the optical transmission filter
04, a fluorescent light condensing lens 305 that forms an autofluorescent image transmitted through the optical transmission filter 303, a fluorescent image high-sensitivity image sensor 306 that captures an autofluorescent image formed by the fluorescent light condensing lens 305, An AD converter 3 that converts an auto-fluorescent image captured by the fluorescent-image high-sensitivity element 306 into a digital value and outputs the digital value as two-dimensional image data
07.

The optical transmission filter is composed of two types of optical filters 303a and 303b as shown in FIG.
The optical filter 303b is a band-pass filter that transmits light having a wavelength of up to 0 nm.
Is a band-pass filter that transmits the light.

The image calculation unit 400 is used to determine whether the tissue is a diseased tissue or a normal tissue based on the image data memory 401 for storing digitized autofluorescence image signal data and the data stored in the image data memory. A reference value memory 402 in which a reference value RE is stored in advance, a desired offset value is added to the data of each pixel in the image data memory, and a calculated image is calculated using the image data to which the offset value is added. And an inter-image calculation unit 403 for comparing the reference value RE of the reference value memory 402 to generate and output a calculation image according to the comparison result.

The reference value RE is a value previously set based on the data of each pixel of the autofluorescence image of the living tissue that is apparently a normal tissue or a diseased tissue.

The means for adding desired offsets to the auto-fluorescent images in the mutually different wavelength bands may be any means that adds an offset value to each pixel value of the auto-fluorescent image. Element 306
Means for giving DC light, that is, light of a constant intensity according to the offset value, means for setting an offset value in the image data memory 401, means for setting the offset value in the inter-image calculation unit 403, high-sensitivity imaging for fluorescent image Element 306 and A
When an amplifying unit is provided between the / D converters 307, a unit for applying a DC bias voltage corresponding to the offset value to the amplifying unit, a unit for applying a DC offset voltage corresponding to the offset value to the amplifying unit, and the like are used. Can be.

The display signal processing unit 500 includes an A / D converter 501 for digitizing the video signal obtained by the normal image pickup device 107, a normal image data memory 502 for storing the digitized normal image signal, and a normal image data memory 502 for storing the digitized normal image signal. A video signal processing circuit 503 is provided for converting the image signal output from the image data memory 502 and the operation image of the inter-image operation unit 403 into a video signal.

The monitor unit 600 includes a normal image monitor 601 and a computed image monitor 602.

Next, the operation of the endoscope apparatus to which the fluorescent image display device according to the present embodiment configured as described above is applied will be described. First, the operation at the time of displaying a normal image will be described.

When displaying a normal image, the control computer 2
The white light source power supply 112 is driven based on the signal from 00, and the white light source 111 emits white light Lw. The white light Lw is incident on the white light guide 101 a via the white light condensing lens 113, is guided to the end of the endoscope, and is then emitted from the illumination lens 104 to the living tissue 10.

The reflected light of the white light Lw is condensed by the objective lens 105, is reflected by the reflecting prism 108, and forms an image on the normal image pickup device 107. The video signal from the normal image pickup device 107 is input to the A / D converter 501 and digitized.
2 is stored. The normal image signal stored by the normal image data memory 502 is output to the video signal processing circuit 50.
After the DA conversion by 3, the image is input to the normal image monitor 601 and displayed as a visible image on the monitor 601.
The above series of operations are controlled by the control computer 200.

Next, a description will be given of the operation in the case of displaying a calculated image using fluorescent images of different wavelength bands. At the time of displaying the calculation image, the excitation light source power supply 115 is driven based on the signal from the control computer 200, and the Ga
Excitation light Lr having a wavelength of 410 nm from the N-based semiconductor laser 114
Is injected. The excitation light Lr is supplied to the excitation light condenser lens 11.
6 and is incident on the excitation light guide 101b.
After being guided to the end of the endoscope, the living tissue 10 is irradiated from the illumination lens 104.

The auto-fluorescence from the living tissue 10 generated by the irradiation of the excitation light Lr is condensed by the condensing lens 106, is incident on the tip of the image fiber 103, passes through the image fiber 103, and passes through the excitation light cut filter. It is incident on 302.

The auto-fluorescence transmitted through the excitation light cut filter 302 enters the optical transmission filter 303. Note that the excitation light cut filter 302 is a long-pass filter that transmits all fluorescence having a wavelength of 420 nm or more. Since the wavelength of the excitation light Lr is 410 nm, the excitation light reflected by the living tissue 10 is applied to the excitation light cut filter 302.
And does not enter the optical transmission filter 303.

The filter rotation device 304 is driven by the control computer 200, and the auto-fluorescent image Zj is transmitted through the optical filter 303a or 303b in a plane-sequential manner, and then formed by the condensing lens 305 for fluorescent light to obtain a high sensitivity for fluorescent image. An image signal is picked up by the image pickup device 306, and a video signal from the high-sensitivity image pickup device 306 for fluorescent image
The data is converted into digital data and stored in the image data memory 401.

The operation unit 403 includes the image data memory 40
A desired offset value is added to each pixel value of each image stored in No. 1 and NF calculation is performed. The NF operation value of each pixel is
A comparison is made with a reference value RE stored in the reference value memory unit 402 in advance, a determination is made as to whether each pixel is a normal tissue or a diseased tissue, and an arithmetic image based on the determination is generated. The reference value RE stored in the reference value memory unit 402 is a pixel value calculated in advance from a living tissue that is apparently a normal tissue or a diseased tissue, and determines whether the tissue is a normal tissue or a diseased tissue. Is the reference value RE
Is performed depending on whether the NF operation value is large or small.

The operation image is displayed on the operation image monitor 602. By changing the display color of the measured area between the case where the NF calculation value is equal to or less than the reference value RE and the case where the calculation value is larger than the reference value RE, the measurer can instantly recognize the comparison result. .

Although the binary determination is made here, the magnitude of the NF calculation value is not changed and the hue (Hue) in the Munsell color system is used without performing the comparison determination between the reference value memory 402 and the calculation unit 403. To generate and display a calculated image, or display the NF calculated value as it is as an analog amount.

Hereinafter, a second specific embodiment of the present invention will be described. Since the configuration is almost the same as that of the specific first embodiment shown in FIGS. 5 and 6, only the different elements are indicated by the element numbers in FIGS. 5 and 6. The description of the same elements as those in the first embodiment is as follows.
Omitted unless otherwise required.

The fluorescence endoscope apparatus according to the present embodiment uses the white light source 111 of the first embodiment as a reference light source, and the image detection unit 700 uses an optical transmission filter 701 instead of the optical transmission filter 303. It is provided with. Since the white light Lw emitted from the white light source 111 includes light in a wavelength band that can be used as the reference light Ls, it can be used as a reference light source.

The optical transmission filter 701 is composed of a filter 701a that transmits a fluorescent image and a filter 701b that transmits a reference image.
Is a band-pass filter that transmits light having a wavelength of 430 nm to 730 nm, and an optical filter 701b.
Is 750 nm to 900 nm, which is the wavelength band of the reference light.
This is a bandpass filter that transmits light up to.

The operation in the case of displaying a calculation image using an autofluorescence image and a reference image will be described. At the time of displaying the calculation image, based on a signal from the control computer 200,
The white light source power supply 112 is driven to emit white light Lw. This white light Lw has a wavelength band of 750 nm to 9
Reference light Ls up to 00 nm is included. The white light Lw including the reference light Ls is transmitted through the lens 113, is incident on the white light guide 101a, is guided to the distal end of the endoscope, and is emitted from the illumination lens 104 to the living tissue 10.

The reflected light from the living tissue 10 generated by irradiating the white light Lw including the reference light Ls is condensed by the condensing lens 106,
Incident on the tip of
The light enters the excitation light cut filter 302.

The fluorescent light transmitted through the excitation light cut filter 302 enters the optical transmission filter 701.

The filter rotation device 304 is driven by the control computer, and the reference image Zs is
01b, the image is formed by the fluorescent light focusing lens 305, captured by the fluorescent image high-sensitivity image sensor 306, and the video signal from the fluorescent image high-sensitivity image sensor 306 is input to the A / D conversion circuit 307. After being converted into digital data, it is stored in the image data memory 401.
At this time, the optical filter 701b transmits only the reference image Zs by the reflected light reflected from the living tissue 10 by the irradiation of the reference light Ls included in the white light Lw. Further, the image data memory 401 stores the image in an area different from the area in which the auto-fluorescence image data is stored.

The operation unit 403 includes the image data memory 40
A desired offset value is added to each pixel value of each image stored in No. 1 and AF calculation is performed. The AF calculation value of each pixel is
A comparison is made with a reference value RE stored in the reference value memory unit 402 in advance, a determination is made as to whether each pixel is a normal tissue or a diseased tissue, and an arithmetic image based on the determination is generated.

The operation image is displayed on the operation image monitor 602. By changing the display color of the measured area between the case where the AF calculation value is equal to or less than the reference value RE and the case where the calculation value is larger than the reference value RE, the measurer can instantly recognize the comparison result. .

Although the binary determination is made here, the AF calculation value is assigned to the hue (Hue) in the Munsell color system without performing the comparison determination between the reference value memory 402 and the calculation unit 403. Generate and display images,
The AF calculation value can be displayed as it is as an analog amount.

Other operations are the same as those of the first embodiment.

The comparison performed by the arithmetic unit 403 is not limited to being performed on a pixel-by-pixel basis, but may be performed on a pixel-by-pixel basis corresponding to the binning process of the high-sensitivity image sensor for fluorescent image 306, or by using a computer. Alternatively, the measurement may be performed in arbitrary vertical and horizontal n × m pixel units desired by the measurer. Alternatively, the comparison may be performed only in the area specified by the measurer, or the comparison may be performed by appropriately thinning out the pixels in consideration of the calculation amount.

When there is an area for which the comparison process has not been performed, the comparison area can be clearly displayed by displaying the display color of the area in a predetermined color. For example, when the comparison pixels are thinned out, complementary display is performed based on the comparison result of the vicinity.

The method of displaying the calculated image is described in the monitor 601 for the normal image and the monitor 602 for the calculated image.
And are displayed separately, but they may be displayed on a single monitor. At this time, the method of switching between the normal image and the auto-fluorescence image depends on the control computer 2
00 may be performed automatically in chronological order, or may be arbitrarily switched by a measurer using appropriate switching means.

Although the GaN-based semiconductor laser 114 and the white light source 111 are configured separately, a single light source can be used for both the excitation light source and the white light source by using an appropriate optical transmission filter.

Although the image pickup device for normal image 306 is installed at the end of the endoscope, it may be installed in the fluorescence diagnostic apparatus 1 by using an image fiber. Further, the image fiber and the image sensor for the normal image and the fluorescent image may be shared. In this case, a filter means for obtaining a normal image by dividing the optical transmission filter 303 into three may be provided.

A mosaic filter having the same function as that of the optical transmission filter 303 is replaced with a high-sensitivity image sensor 3 for fluorescence.
If it is installed on the front surface of the imaging device 06, it becomes possible to use the image sensor for both the normal image and the fluorescent image.

Further, if the image sensor having the mosaic filter on chip as described above is installed at the end of the endoscope,
Similarly, both the normal image and the fluorescent image can be used.

The excitation light source has a wavelength of 400 nm.
To about 420 nm.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an intensity distribution of a fluorescence spectrum of autofluorescence.

FIG. 2 is a diagram illustrating a change in the degree of separation with respect to a change in an offset value.

FIG. 3 is a diagram showing an image in which autofluorescence images in different wavelength bands are schematically represented and a calculation image generated from the image.

FIG. 4 is a diagram showing a change in contrast of a calculated image with respect to a change in an offset value.

FIG. 5 is a schematic configuration diagram of an endoscope apparatus according to first and second specific embodiments to which the fluorescent display device according to the present invention is applied.

FIG. 6 is a schematic configuration diagram of an optical transmission filter used in the endoscope apparatus according to the first and second specific embodiments.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fluorescence diagnostic apparatus 10 Living tissue 100 Endoscope 101 Light guide 101a White light light guide 101b Excitation light light guide 102 CCD cable 103 Image fiber 104 Illumination lens 105 Objective lens 106 Condensing lens 107 Image sensor for normal image 108 Reflecting prism Reference Signs List 110 lighting unit 111 white light source 112 white light source power supply 113 white light condenser lens 114 GaN-based semiconductor laser 115 semiconductor laser power supply 116 excitation light condenser lens 200 control computers 300, 700 image detection unit 301 fluorescent collimating lens 302 Excitation light cut filter 303, 701 Optical transmission filter 303a, 303b, 701a, 701b Optical filter 304 Filter rotating device 305 Fluorescent light condensing lens 30 High-sensitivity image sensor for fluorescent image 307, 501 A / D converter 400 Image operation unit 401 Image data memory 402 Reference value memory 403 Image-to-image operation unit 500 Display signal processing unit 502 Normal image data memory 503 Video signal processing circuit 600 Monitor Unit 601 Monitor for normal image 602 Monitor for operation image

Claims (11)

[Claims] 1. A method for detecting fluorescence images in mutually different wavelength bands from fluorescence generated from a living tissue by irradiation with excitation light, and performing a normalization operation based on a ratio of the fluorescence images in the mutually different wavelength bands to calculate an operation image. Generating a fluorescence image and displaying the operation image, wherein before performing the normalization operation, a desired offset is added to each of the fluorescence images in the different wavelength bands. . 2. The fluorescent image display method according to claim 1, wherein a fixed offset value is added to each of the fluorescent images in the different wavelength bands. 3. A fluorescence image is detected from fluorescence generated from a living tissue by irradiation of excitation light, a reference image is detected by reflected light reflected from the living tissue by irradiation of reference light, and the fluorescence image and the reference are detected. In a fluorescent image display method for performing a normalization operation based on a ratio with respect to an image to generate an operation image and displaying the operation image, the fluorescence image and the reference image may be respectively displayed before performing the normalization operation. A fluorescent image display method, characterized by adding an offset. 4. The fluorescent image display method according to claim 3, wherein a predetermined offset value is added to each of the fluorescent image and the reference image. 5. The fluorescent image display method according to claim 1, wherein different colors are assigned according to the magnitude of the normalized operation value to generate an operation image. 6. Excitation light irradiating means for irradiating living tissue with excitation light, and fluorescence image detecting means for detecting fluorescence images in different wavelength bands from fluorescence generated from the living tissue by irradiation of the excitation light, respectively. A fluorescence image display device comprising: a means for performing a normalization operation based on a ratio of the fluorescence images in the different wavelength bands to generate an operation image; and a display means for displaying the operation image, wherein the normalization operation is performed. A fluorescent image display device comprising means for adding a desired offset to each of the fluorescent images in the different wavelength bands. 7. The fluorescent image display device according to claim 6, wherein the means for adding an offset to the fluorescent images of different wavelength bands adds a constant offset value to each of the images. . 8. Irradiation means for irradiating living tissue with excitation light and reference light, fluorescence image detection means for detecting a fluorescence image from fluorescence generated from the living tissue by irradiation of the excitation light, and irradiation of the reference light Reference image detecting means for detecting a reference image by reflected light reflected from the living tissue, and means for performing a normalization operation based on a ratio between the fluorescence image and the reference image to generate an operation image, A fluorescence image display device comprising: a display unit for displaying a calculation image; and a fluorescence device comprising: a unit for adding a desired offset to each of the fluorescence image and the reference image before performing the normalization calculation. Image display device. 9. The fluorescent image display device according to claim 8, wherein the means for adding an offset to the fluorescent image and the reference image adds a fixed offset value to each image. . 10. The apparatus according to claim 1, wherein the means for performing the normalization operation to generate an operation image includes means for assigning different colors according to the magnitude of the operation value obtained by performing the normalization operation. 10. The fluorescent image display device according to any one of items 6 to 9. 11. The fluorescent image display device according to claim 6, wherein said excitation light irradiation means is a GaN-based semiconductor laser.