JP2002336187A - Method and apparatus for forming normalized fluorescent image - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the S/N ratio of a normalized fluorescent image and stably perform a normaling operation for the fluorescent image by dividing the fluorescent image based on the fluorescence which is emitted from an observation part by irradiation with exciting light, by the normalized image based on the re-radiated light emitted from the observation part. SOLUTION: In the normalized fluorescent image forming means 403, the narrow-band fluorescent image picked up by an image pickup element 311 is divided by the wide-band fluorescent image picked up by an image pickup element 306 to calculate a normalizing operation value and the normalized fluorescent image is formed by an image synthesizing device 405. Low-pass filter processing is applied to the standardized image obtained before division is performed by a low-pass filter circuit 317. Since the pixel value of the wide- band fluorescent image can be two-dimensionally averaged by this processing, the pixel value of the image becoming a denominator at the time of division is hard to become a minus value, a zero value or a value near to zero and the S/N ratio of the normalized fluorescent image is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for acquiring a fluorescence image based on fluorescence emitted from an observation unit by irradiation of excitation light, and for standardizing the image based on re-radiated light emitted from the observation unit by irradiation of light. The present invention relates to a method and apparatus for generating a standardized fluorescent image by acquiring an image and dividing the fluorescent image by the standardizing image to generate a standardized fluorescent image.

[0002]

2. Description of the Related Art Conventionally, when a living tissue is irradiated with excitation light in an excitation wavelength region of an in-vivo dye, a normal tissue and a diseased tissue have different fluorescence intensities. There has been proposed a fluorescence detection device that irradiates excitation light in a wavelength region and detects fluorescence emitted from a dye in a living body to recognize the localization and infiltration range of a diseased tissue.

Normally, when excitation light is irradiated, strong fluorescence is emitted from normal tissue as shown by a solid line in FIG. 4, and weaker fluorescence than that emitted from normal tissue is emitted from a diseased tissue as shown by a broken line in FIG. Therefore, by measuring the fluorescence intensity, it is possible to determine whether the living tissue is normal or in a pathological state.

Further, there has been proposed a method of determining whether a living tissue is normal or in a diseased state by imaging fluorescence by excitation light with an image sensor or the like and displaying a fluorescence image corresponding to the intensity of the fluorescence. I have. In this technique, since the living tissue has irregularities, the intensity of the excitation light applied to the living tissue is not uniform, and the intensity of the fluorescent light emitted from the living tissue is the square of the distance between the light source and the living tissue. Decrease proportionally. In addition, the intensity of the received fluorescent light decreases in proportion to the square of the distance between the fluorescence detecting means and the living tissue. Therefore, from diseased tissue nearer than normal tissue far from the light source or detection means,
In some cases, strong fluorescence is received, and it is not possible to accurately identify the tissue properties of the living tissue only with information on the intensity of the fluorescence due to the excitation light. In order to reduce such problems,
Different wavelength bands (narrow band around 480 nm and 430 nm
The ratio of the fluorescence image based on the two types of fluorescence intensity obtained from the vicinity (a broad band around 730 nm from the vicinity) is obtained by division,
A method of generating a normalized fluorescence image based on the divided value,
Irradiating the living tissue with near-infrared light that is uniformly absorbed by various living tissues as reference light, and acquiring a reference image based on the intensity of the reflected light from the living tissue due to the irradiation of the reference light, The ratio of the narrow-band fluorescence image and the reference image is obtained by division, and a method of generating a normalized fluorescence image based on the division value, that is, based on the difference in the shape of the fluorescence spectrum that reflects the tissue properties of the living body A standardized fluorescent image generation method has been proposed. Also, by assigning color information to the divided values of the fluorescent images in different wavelength bands, a method of indicating the lesion state of the living tissue as a color image due to the difference in the color, and further, by assigning luminance information to the above-described reference image, A method has also been proposed in which the obtained luminance image is combined with the above-mentioned color image, so that an image having a sense of unevenness, which reflects the shape of the biological tissue in the image, has been proposed.

[0005]

By the way, when the above-mentioned fluorescence image or standardization image is acquired, dark noise is corrected by subtracting the dark noise image from the acquired image. Usually, a dark noise image for correction is formed by an average value of a plurality of dark noise images.However, it is difficult to accurately reflect the value of dark noise in the pixel value of the dark noise image for correction. In some cases, a pixel value larger than the actual dark noise value is set. Therefore, if the pixel value of the acquired image is small, the image after dark noise correction has a negative value, 0
In some cases, a pixel value close to a value or 0 value exists. If the normalization image serving as a denominator when performing the above-described standardized fluorescent image generation processing contains many such negative values, 0 values, or pixel values close to 0 values, the generated standard There is a problem that the S / N of the structured fluorescent image is reduced. Further, when there is a zero value in the pixel value of the standardization image serving as a denominator when performing division, there is a case where division by zero occurs, and there is a problem that the operation becomes unstable.

In view of the above-mentioned problems of the prior art, the present invention obtains a fluorescence image based on fluorescence emitted from an observation unit by irradiation of excitation light, and re-generates a fluorescence image emitted from the observation unit by irradiation of light. In the standardized fluorescent image generating method and apparatus for obtaining a standardized image based on radiation light and dividing the fluorescent image by the standardized image to generate a standardized fluorescent image, the standardized fluorescent image generated It is an object of the present invention to provide a standardized fluorescence image generation method and apparatus capable of improving the S / N of the above and performing a stable standardization operation.

[0007]

According to the present invention, there is provided a method for generating a standardized fluorescent image, comprising obtaining a fluorescent image based on fluorescence emitted from an observation unit by irradiation of excitation light, and emitting the fluorescent image from the observation unit by irradiation of light. In a standardized fluorescent image generating method for obtaining a standardized image based on re-radiated light and dividing the fluorescent image by the standardized image to generate a standardized fluorescent image, a low-pass filter is applied to the standardized image. Or performing a recursive filter process, and performing the division using the standardized image that has been subjected to the filter process.

In another aspect of the present invention, there is provided a method for generating a standardized fluorescent image, comprising obtaining a fluorescent image based on fluorescence emitted from an observation unit by irradiation with excitation light, and re-radiating the image from the observation unit by irradiation with light. Obtaining an image for normalization based on light, in the standardized fluorescent image generating method of generating a standardized fluorescent image by dividing the fluorescent image by the standardizing image, when obtaining the standardizing image Exposure time,
The exposure time is longer than the exposure time for acquiring the fluorescent image.

The standardized fluorescence image generating apparatus of the present invention irradiates an observation section with excitation light, and obtains a fluorescence image based on fluorescence emitted from the observation section by the irradiation of the excitation light; Irradiating the observation unit with light, a standardization image acquisition unit that acquires a standardization image based on re-radiated light emitted from the observation unit by the irradiation of the light, and the fluorescence image is used as the standardization image. In a normalized fluorescence image generating apparatus comprising a standardized fluorescent image generating means for generating a standardized fluorescent image by dividing by, a filter means for performing a low-pass filter process or a recursive filter process on the normalization image, The normalized fluorescence image generating means,
The division is performed using the standardized image that has been subjected to the filter processing.

The "low-pass filter" averages the pixel values of an image two-dimensionally, and the "recursible filter" averages the pixel values of an image on a time axis. is there.

Another standardized fluorescence image generating apparatus according to the present invention is a fluorescence image acquisition means for irradiating an observation section with excitation light and acquiring a fluorescence image based on fluorescence emitted from the observation section by irradiation of the excitation light. Irradiating the observation unit with light, a standardization image acquisition unit that acquires a standardization image based on re-radiated light emitted from the observation unit by the irradiation of the light, and the normalization of the fluorescence image A standardized fluorescent image generating unit that generates a standardized fluorescent image by dividing the image by the standard image, wherein the standardizing image obtaining unit obtains the standardizing image. The exposure time is set to be longer than the exposure time when the fluorescent image obtaining means obtains the fluorescent image.

The term "exposure time" refers to the time during which the fluorescence image acquiring means or the normalizing image acquiring means substantially acquires each image (fluorescence or fluorescence) when the observation section is irradiated with excitation light or light. (The time during which the re-radiated light is substantially received). The `` extended exposure time '' refers to simply extending the exposure time, or performing multiple exposures and integrating the exposure time when acquiring the standardization image, the fluorescence image. Means longer than the exposure time when acquiring

[0013] The term "re-radiated light" means light emitted from the observation section when irradiated with light, and specifically, fluorescence emitted from the observation section or reflection reflected on the observation section. It means light or scattered light that is scattered near the surface of the observation unit and then emitted.

If the fluorescent image is a narrow-band fluorescent image based on narrow-band fluorescent light in the fluorescent light, the normalizing image is obtained by irradiating the observation unit with excitation light. A broadband fluorescence image based on fluorescence in a wide wavelength band among the fluorescences emitted from the observation unit can be obtained. Note that the narrow-band fluorescence image and the broadband fluorescence image may be obtained from the fluorescence emitted from the observation unit with the same excitation light. For example, by using a filter or a prism or the like to extract narrow-band fluorescent light and wide-band fluorescent light from fluorescent light emitted by excitation light irradiation, to obtain a narrow-band fluorescent image and a broad-band fluorescent image. Cut off.

[0015]

According to the method and the apparatus for generating a standardized fluorescent image according to the present invention, a fluorescent image based on the fluorescent light emitted from the observation section by the irradiation of the excitation light is obtained and emitted from the observation section by the irradiation of the light. In a standardized fluorescent image generating method for obtaining a standardized image based on re-radiated light and dividing the fluorescent image by the standardized image to generate a standardized fluorescent image, a low-pass filter is applied to the standardized image. Processing or recursive filter processing, and the division is performed using the standardized image subjected to this filter processing, so that the pixel values of the standardized image are two-dimensionally averaged. (For low-pass filter),
Alternatively, since the pixels are averaged on the time axis (in the case of a recursible filter), the pixel values of this normalization image rarely become a negative value, a zero value, or a value close to zero. The S / N of the fluorescence image is improved, and a stable normalization operation can be performed.

According to another method and apparatus for generating a normalized fluorescence image according to the present invention, a fluorescence image based on fluorescence emitted from an observation section by irradiation with excitation light is acquired, and emitted from the observation section by irradiation with light. Obtaining the standardization image based on the re-emitted light, and obtaining the standardization image in a standardized fluorescence image generation method of dividing the fluorescence image by the standardization image to generate a standardization fluorescence image In this case, the exposure time is set to be longer than the exposure time when the fluorescent image is obtained, so that the pixel value of the normalization image is a negative value, 0 value, or a value close to 0. , The S / N of the generated normalized fluorescence image is improved, and a stable normalization operation can be performed.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a first embodiment of a fluorescent endoscope to which a standardized fluorescent image generating apparatus that performs a standardized fluorescent image generating method of the present invention is applied.

The fluorescent endoscope according to the present embodiment is an endoscope insertion portion 100 inserted into a site suspected of a lesion of a patient.
And an image signal processing unit 1 for processing information obtained from the living tissue by the endoscope insertion unit 100 as an image signal, and a monitor 600 for displaying the signal processed by the image signal processing unit 1 as a visible image. Is done.

The image signal processing section 1 includes a normal image white light L
w, an illumination unit 110 including three light sources that respectively emit the excitation light Lr for the auto-fluorescence image and the reference light Ls for the reference image, and an auto-fluorescence image Zj generated from the living tissue 9 by irradiation of the excitation light. An image detection unit 300 that captures a reference image Zs generated from the living tissue 9 by the irradiation of the reference light, converts the image into a digital value, and outputs the image as two-dimensional image data, and an autofluorescence image output from the image detection unit 300. Performs a normalization operation from two-dimensional image data,
Color information is assigned to the normalized operation value, luminance information is assigned to two-dimensional image data of the reference image, an image operation unit 400 that combines and outputs two pieces of image information, and a normal image is converted to a digital value. A display signal processing unit 500 that converts the two-dimensional image data and the output signal of the image operation unit 400 into a video signal and outputs the two-dimensional image data, and a control computer that is connected to each unit and controls operation timing and the like 200, and a foot switch 2 for switching between a normal image display state and a composite image display state described later.

The endoscope insertion section 100 includes a light guide 101 extending to the distal end therein, and an image fiber 102. An illumination lens 103 is provided at the distal end of the light guide 101, that is, at the distal end of the endoscope insertion section 100. The image fiber 102 is a multi-component glass fiber, and is provided with an excitation light filter 104 and a condenser lens 105 at the tip. Light guide 101
Is a multi-component glass fiber white light light guide 1
The light guide 101a and the excitation light guide 101b, which are quartz glass fibers, are bundled and integrated into a cable. The white light guide 101a and the excitation light guide 101b are connected to the illumination unit 110. Note that the excitation light light guide 101b is also a light guide that guides the reference light. One end of the image fiber 102 is connected to the image detection unit 300.

The illuminating unit 110 includes a GaN-based semiconductor laser 111 for emitting excitation light Lr for auto-fluorescence image,
A semiconductor laser power supply 112 electrically connected to the N-based semiconductor laser 111, a white light source 114 for emitting white light Lw for normal images, a white light power supply 115 electrically connected to the white light source 114, a reference image Light source 117 which emits reference light Ls for reference, power supply 118 for reference light source electrically connected to reference light source 117, and excitation light Lr output from GaN-based semiconductor laser 111 are transmitted therethrough.
The dichroic mirror 120 is configured to reflect the reference light Ls output from the mirror 17 at right angles.

An image fiber 102 is connected to the image detecting unit 300, and a collimating lens 301 for forming an autofluorescence image, a normal image, and a reference image transmitted by the image fiber 102, and a normal image transmitted through the collimating lens 301. Totally reflected at right angles, collimating lens 3
The movable mirror 302 that moves and passes the fluorescent image and the reference image that have passed through 01 and the dichroic mirror 30 that reflects the fluorescent image (light having a wavelength of 750 nm or less) that has passed through the collimating lens 301 in a right angle direction.
3. A half mirror 308 that transmits 50% of the light amount of the auto-fluorescent image reflected by the dichroic mirror 303 and reflects 50% in a right angle direction, and a fluorescent image that reflects the auto-fluorescent image transmitted through the half mirror 308 in a right angle direction Mirror 313,
A broadband fluorescent image condensing lens 304 for forming an autofluorescent image reflected in a direction perpendicular to the fluorescent image mirror 313, and 4 from the autofluorescent image transmitted through the broadband fluorescent image condensing lens 304.
A wideband bandpass filter 305 for selecting a wavelength of 30 nm to 730 nm, a high-sensitivity image sensor 306 for a wideband fluorescent image for capturing an autofluorescence image transmitted through the wideband bandpass filter 305, and a high-sensitivity image sensor 30 for a wideband fluorescent image
A / D converter 307, which converts the autofluorescence image captured by the camera 6 into a digital value and outputs it as two-dimensional image data
A low-pass filter circuit 317 that subjects the two-dimensional image data of the broadband auto-fluorescence output from the D converter 307 to low-pass filtering and outputs the narrow-band fluorescence image that forms an auto-fluorescence image that is reflected at right angles to the half mirror 308. 430 nm to 530 nm from the auto-fluorescent image formed by the condensing lens 309 for narrow band fluorescent image and the condensing lens 309 for narrow band fluorescent image
Are picked up by the narrow-band bandpass filter 310 for extracting the wavelength of light, the narrow-band fluorescence image high-sensitivity image sensor 311 for capturing the autofluorescence image transmitted through the narrow-band bandpass filter 310, and the narrow-band fluorescence image high-sensitivity image sensor 311. A / D converter 312 for converting the autofluorescent image into a digital value and outputting it as two-dimensional image data, dichroic mirror 3
The reference image condensing lens 314 that forms the reference image transmitted through the reference image 03, the reference image imaging element 315 that captures the reference image formed by the reference image condensing lens 314, and the reference image imaging element 315. An AD converter 316 that converts the captured reference image into a digital value and outputs the digital value as two-dimensional image data is provided.

The image processing unit 400 stores the autofluorescence image memory 401 for storing digitized autofluorescence image signal data, the reference image memory 402 for storing reference image signal data, and the autofluorescence image memory 401. A standardized fluorescence image generating unit 403 that calculates a standardized operation value for each pixel of the autofluorescent image in the two wavelength bands thus obtained,
Color image calculation means 40 for assigning color information to the normalized calculation value calculated by the normalized fluorescence image generation means 403
5. Luminance image calculation means 40 for allocating luminance information to each pixel value of the reference image stored in reference image memory 402
An image synthesizing unit for generating and outputting a synthesized image by synthesizing an image signal having color information output from the color image arithmetic unit 405 and an image signal having luminance information output from the luminance image arithmetic unit 406 407 is provided.

The auto-fluorescence image memory 401 is composed of a broadband auto-fluorescence image storage area and a narrow-band auto-fluorescence image storage area (not shown). ,
After the low-pass filter circuit 317 performs the low-pass filter processing, the narrow-band fluorescence image stored in the broadband auto-fluorescence image storage area and captured by the high-sensitivity imaging device 311 for the narrow-band fluorescence image is stored in the narrow-band fluorescence image storage area. Is stored in

The standardized fluorescent image generating means 403 calculates a standardized operation value for each pixel by dividing the pixel value of the narrow band fluorescent image by the pixel value of the wide band fluorescent image for each corresponding pixel.

The color image calculation means 405 assigns color information according to the magnitude of the standardized calculation value calculated by the standardized fluorescence image generation means 403 to generate a color image.

The luminance image calculation means 406 allocates luminance information in accordance with the magnitude of the pixel value stored in the reference image memory 402 and generates a luminance image.

The image synthesizing means 407 includes the color image calculating means 4
The color image output from the luminance image calculation unit 406 and the luminance image output from the luminance image calculation unit 406 are combined and output to a video signal processing circuit 506 of a display signal processing unit 500 described later.

The display signal processing unit 500 includes a normal image mirror 501 that reflects the normal image reflected by the movable mirror 302 in a perpendicular direction, and a normal image collection that forms a reference image reflected by the normal image mirror 501. An optical lens 502, a normal image pickup device 503 for picking up a normal image formed by the normal image condensing lens 502, and a reference image picked up by the normal image pickup device 503 is converted into a digital value to be a two-dimensional image. A / D converter 504 for outputting data, and a normal image memory 50 for storing digitized normal image signals
5. A video signal processing circuit 5 that converts the normal image signal output from the normal image memory 505 and the synthesized image signal output from the image synthesis unit 405 into a video signal and outputs the video signal.
06. The monitor 600 switches and displays a normal image and a composite image.

Next, the operation of the fluorescent endoscope in the above embodiment will be described. First, an operation of capturing an autofluorescence image and a reference image in two different wavelength bands, and generating and displaying a composite image from these images will be described.

At the time of displaying the composite image, the semiconductor laser power supply 11 is controlled based on a signal from the control computer 200.
2, the excitation light Lr is emitted from the GaN-based semiconductor laser 111, and the excitation light Lr transmits through the excitation light condenser lens 113, transmits through the dichroic mirror 120, enters the excitation light light guide 101b, and enters the endoscope. Insertion part 100
After being guided to the tip of the living tissue 9, the living tissue 9 is irradiated from the illumination lens 103. The auto-fluorescence image from the living tissue 9 generated by the irradiation of the excitation light Lr is condensed by the condenser lens 105, passes through the excitation light cut filter 104, is incident on the tip of the image fiber 102, passes through the image fiber 102, The light enters the collimator lens 301. The excitation light cut filter 104 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 9 is cut by the excitation light cut filter 104. The auto-fluorescent image transmitted through the collimating lens 301 is reflected by the dichroic mirror 303 in a direction perpendicular to the direction. Then, the light passes through the half mirror 308 at a transmittance of 50%, and is reflected at a reflectance of 50%. The auto-fluorescent image transmitted through the half mirror 308 is the fluorescent image mirror 3
13 is reflected at right angles to the broadband fluorescent light condensing lens 30.
4 and transmitted through the broadband fluorescent light condensing lens 304, is converted into a broadband bandpass filter 305.
And is imaged by the high-sensitivity image sensor 306 for broadband fluorescent image, and the high-sensitivity image sensor 306 for broadband fluorescent image
Is input to an AD converter 307 and digitized, and then subjected to a low-pass filter process in a low-pass filter circuit 317 to obtain an auto-fluorescent image memory 401.
In the broadband autofluorescence image storage area. Since the broadband autofluorescence image is two-dimensionally averaged by the low-pass filter circuit 317, a negative value, a zero value, or a zero value is obtained.
There are almost no pixel values close to the value. FIG. 2 shows a case where the same image is subjected to low-pass filtering (b).
FIG. 7A is a diagram comparing a case where the low-pass filter processing is not performed (a). As shown in this figure, in the image (b) that has been subjected to the low-pass filter processing, the gradation of the image is smooth, and the pixel value at or near the zero value has almost disappeared.

The auto-fluorescent image reflected by the dichroic mirror 303 and reflected by the half mirror 308 is formed by the narrow-band fluorescent light condensing lens 309, passes through the narrow-band band-pass filter 310, and becomes narrow-band. The image signal is picked up by the high-sensitivity image sensor for fluorescent image 311, and the video signal from the high-sensitivity image sensor for narrow-band fluorescent image 311 is input to the AD converter 312, digitized, and then converted to the narrow band of the auto-fluorescent image memory 401. It is stored in the private area fluorescent image area. Note that the high-sensitivity image sensor 306 for the broadband fluorescent image
The digital data of the auto-fluorescent image captured by the camera and the digital data of the auto-fluorescent image captured by the narrow band fluorescent image high-sensitivity image sensor 311 are stored in different areas. At this time, it is assumed that the movable mirror 302 is positioned at a broken line parallel to the optical axis of the autofluorescent image.

The reference light source 117 emits reference light Ls from the reference light source 117, and the reference light Ls
Is transmitted through the reference light condensing lens 119, is reflected by the dichroic mirror 120 in a right angle direction, is incident on the excitation light guide 101 b, and is guided to the end of the endoscope. The tissue 9 is irradiated. A reference image from the living tissue 9 generated by the irradiation of the reference light Ls is condensed by the condensing lens 105 and the condensing lens 10
5 passes through the excitation light cut filter 104, enters the tip of the image fiber 102, passes through the image fiber 102, and passes through the collimator lens 301.
Incident on. The excitation light cut filter has a wavelength of 420 nm.
This is a long-pass filter that transmits the above-described reference image. The reference image transmitted through the collimating lens 301 is transmitted through the dichroic mirror 303, and the reference image condensing lens 314.
And an image is picked up by the reference image pickup device 315, and the video signal from the reference image pickup device 315 is AD
After being input to the converter 316 and digitized, it is stored in the reference image memory 402. At this time, it is assumed that the movable mirror 302 is positioned at a broken line parallel to the optical axis of the reference image.

The auto-fluorescence image of the two wavelength bands stored in the auto-fluorescence image memory 401 is converted into a narrow-band auto-fluorescence image by a standardized fluorescence image generating means 403 for each pixel. A normalized operation value divided by the value is calculated.

Then, color information is assigned to each pixel by the color image calculation means 405 based on the standardized calculation value, and is output to the image synthesis means 407 as a color image signal. On the other hand, in the reference image stored in the reference image memory 402, luminance information is assigned to each pixel value by the luminance image calculation means 406, and a luminance image signal is generated and output. 2 output from the color image calculation means 405 and the luminance image calculation means 406
The two image signals are combined by the image combining means 407. The combined image combined by the image combining unit 407 is input to the monitor 600 after DA conversion by the video signal processing circuit 506, and the combined image is displayed.

Next, the operation when a normal image is displayed will be described. First, the white light source 11 is supplied by the white light source power supply 115 based on a signal from the control computer 200.
4, the white light Lw is emitted. The white light Lw is incident on the white light light guide 101 a through the white light condensing lens 116, is guided to the distal end of the endoscope insertion unit 100, and then is illuminated by the illumination lens. Irradiation is applied to the living tissue 9 from 103. The reflected light of the white light Lw is condensed by the condenser lens 105, passes through the excitation light filter 104, is incident on the tip of the image fiber 102, and is incident on the collimator lens 301 via the image fiber 102. The excitation light cut filter 104 is a long-pass filter that transmits visible light having a wavelength of 420 nm or more. Collimating lens 3
01 is reflected by the movable mirror 302 and the normal image mirror 501, and is reflected by the normal image condenser lens 502.
Is incident on. The normal image transmitted through the normal image condenser lens 502 is formed on a normal image pickup device 503. The video signal from the normal image pickup device 503 is supplied to the AD converter 50.
4, digitized, and stored in the normal image memory 505. The normal image signal stored in the normal image memory 505 is output to the video signal processing circuit 50.
6, the data is input to the monitor 600 after the DA conversion, and displayed on the monitor 600 as a visible image.

A series of operations relating to the operation of the composite image display and the operation of the normal image display are performed by the control computer 2.
00. The switching between the composite image display state and the normal image display state is performed by pressing the foot switch 2.

As is apparent from the above description, according to the fluorescence endoscope in the above-described embodiment to which the standardized fluorescent image generating method and apparatus according to the present invention are applied, a wideband autofluorescent image which is an image for standardization is obtained. A low-pass filter process is performed, and division is performed using the filtered broadband autofluorescence image to obtain a normalized operation value.Therefore, the pixel value of the broadband autofluorescence image serving as a denominator of the division operation is calculated. The two-dimensionally averaged values are less likely to be a negative value, a zero value or a value close to zero, and the S / N of the standardized fluorescent image generated based on the standardized operation value is improved. Also, in the above division operation, division by zero is not performed, and a stable normalization operation can be performed.

As a modified example of the fluorescence endoscope apparatus of the first embodiment, an apparatus using a recursive filter circuit instead of the low-pass filter circuit 317 can be considered. By averaging the pixel values of the broadband autofluorescence image on the time axis by the recursible filter circuit, it is unlikely that the value becomes a negative value, a zero value, or a value close to zero. N can be improved, and a stable normalization operation can be performed.

Next, a description will be given of a second embodiment of a fluorescent endoscope to which a standardized fluorescent image generating apparatus for implementing the standardized fluorescent image generating method of the present invention is applied. FIG. 3 is a diagram showing a schematic configuration of the present embodiment. Note that, in the present embodiment, the same elements as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted unless necessary.

The fluorescence endoscope according to the present embodiment has a configuration in which reference light is not used in the first embodiment.

The image signal processing section 3 outputs the white light L for normal image.
w, an illumination unit 120 provided with two light sources for respectively emitting the excitation light Lr for auto-fluorescence image, and an auto-fluorescence image Zj generated from the living tissue 9 by the irradiation of the excitation light, and converted into a digital value. An image detection unit 310 for outputting as two-dimensional image data, and an image detection unit 31
An image operation unit 410 that performs a normalization operation from the two-dimensional image data of the autofluorescence image output from 0, assigns color information to the normalized operation value, and outputs the color information as a color image signal.
And converts the normal image into a digital value to obtain two-dimensional image data, the two-dimensional image data and the image operation unit 41.
A display signal processing unit 500 that converts an output signal of 0 to a video signal and outputs the video signal; a control computer 210 that is connected to each unit and controls operation timing and the like;
It comprises a foot switch 2 for switching between a normal image display state and a composite image display state described later.

The illuminating unit 120 includes a GaN-based semiconductor laser 121 for emitting excitation light Lr for auto-fluorescence image,
The semiconductor laser 111 includes a semiconductor laser power supply 122 electrically connected to the N-based semiconductor laser 111, a white light source 124 for emitting white light Lw for normal images, and a white light power supply 125 electrically connected to the white light source 124. You.

An image fiber 102 is connected to the image detection unit 310, and the autofluorescent image transmitted by the image fiber 102, the collimating lens 311 for forming a normal image, and the normal image transmitted through the collimating lens 311 are perpendicularly transmitted. The fluorescent image that has been totally reflected and transmitted through the collimating lens 311 moves to the position shown by the broken line and is 50% of the amount of light of the autofluorescent image (light having a wavelength of 750 nm or less) transmitted through the collimating lens 311.
Half mirror 3 that transmits light and reflects 50% in the perpendicular direction
23, a narrow-band fluorescent image condensing lens 324 for forming an auto-fluorescent image transmitted through the half mirror 323, and 4 from the auto-fluorescent image formed by the narrow-band fluorescent image condensing lens 324.
A narrow band-pass filter 325 for extracting a wavelength of 30 nm to 530 nm, a high-sensitivity image sensor 326 for a narrow-band fluorescent image that captures an autofluorescent image transmitted through the narrow-band band-pass filter 325, and a high-sensitivity image sensor 32 for a narrow-band fluorescent image
An A / D converter 327 that converts the auto-fluorescent image captured by the camera 6 into a digital value and outputs the digital value as two-dimensional image data, and a mirror for a fluorescent image that reflects the auto-fluorescent image reflected by the half mirror 323 at right angles again. 318, a broadband fluorescent image condensing lens 319 for forming an autofluorescent image reflected in a direction perpendicular to the fluorescent image mirror 318, and 430 nm from the autofluorescent image transmitted through the broadband fluorescent image condensing lens 319.
A broadband bandpass filter 320 for selecting a wavelength of up to 730 nm, a high-sensitivity image sensor 321 for a wideband fluorescent image for capturing an autofluorescence image transmitted through the wideband bandpass filter 320, and a high-sensitivity image sensor 321 for a wideband fluorescent image
Auto-fluorescence image captured by a
An AD converter 322 for outputting as two-dimensional image data is provided. The exposure time when the control computer 210 captures a fluorescent image in the high-sensitivity image sensor 321 for a broadband fluorescent image is the exposure time when the fluorescent image is captured in the high-sensitivity image sensor 326 for a narrow-band fluorescent image. High-sensitivity image sensor 321 for broadband fluorescence image so as to be doubled
In addition, the operation timing of the high-sensitivity image sensor 326 for the narrow band fluorescent image is controlled.

The image calculation unit 410 includes a broadband autofluorescence memory 411 for storing digitized broadband autofluorescence image signal data, a narrowband autofluorescence memory 412 for storing narrowband autofluorescence image signal data, and a broadband autofluorescence memory 412. A standard for calculating, for each pixel of the two fluorescent images stored in the fluorescent memory 411, the pixel value of the narrow-band auto-fluorescent image by the pixel value of the broad-band auto-fluorescent image to calculate a normalized operation value of each pixel. And a color image calculation means 415 for allocating color information to the normalized operation value calculated by the normalized fluorescence image generation means 413 and outputting a color image signal.

Next, the operation of the fluorescent endoscope in the above embodiment will be described. First, an operation in a case where autofluorescence images of two different wavelength bands are captured, and a color image is generated and displayed from these images will be described.

At the time of displaying the color image, the semiconductor laser power supply 122 is controlled based on a signal from the control computer 200.
As a result, the excitation light Lr is emitted from the GaN-based semiconductor laser 121, the excitation light Lr passes through the excitation light condenser lens 123, enters the excitation light light guide 101 b, and is guided to the distal end of the endoscope insertion section 100. After being illuminated, illumination lens 1
03 to the living tissue 9. The auto-fluorescence image from the living tissue 9 generated by the irradiation of the excitation light Lr is condensed by the condensing lens 105, and the excitation light cut filter 104
And is incident on the tip of the image fiber 102,
After passing through the image fiber 102, the collimator lens 31
Incident on 1. The excitation light cut filter 104 has a wavelength of 4
It is a long-pass filter that transmits all fluorescence of 20 nm or more. Since the wavelength of the excitation light Lr is 410 nm, the excitation light reflected by the living tissue 9 is cut by the excitation light cut filter 104. The autofluorescent image transmitted through the collimator lens 311 is transmitted by the half mirror 313 at a transmittance of 50%, and is reflected at a reflectance of 50%. The auto-fluorescent image reflected by the half mirror 313 is the fluorescent image mirror 3
18 is reflected in a right angle direction, and the broadband fluorescent light condensing lens 31 is reflected.
9 and transmitted through the broadband fluorescent light condensing lens 319, is converted into a broadband bandpass filter 320.
And is imaged by the high-sensitivity image sensor 321 for the broadband fluorescent image, and the high-sensitivity image sensor 321 for the broadband fluorescent image
Are input to the AD converter 322, digitized, and stored in the wideband autofluorescence memory 411.

The auto-fluorescent image transmitted through the half mirror 313 is formed by the narrow-band fluorescent light condensing lens 314, transmitted through the narrow-band band-pass filter 315, and sent to the high-sensitivity image sensor 316 for narrow-band fluorescent image. The video signal from the high-sensitivity image sensor 316 for narrow-band fluorescent image is input to the AD converter 317, digitized, and stored in the narrow-band auto-fluorescent memory 412. The digital data of the auto-fluorescence image captured by the high-sensitivity imaging device 321 for the broadband fluorescence image and the digital data of the auto-fluorescence image captured by the high-sensitivity imaging device 316 for the narrow-band fluorescence image are stored in different areas of the common memory. May be stored.

At this time, it is assumed that the movable mirror 312 is positioned at a broken line parallel to the optical axis of the autofluorescent image. At the time of the above imaging, the control computer 210
Accordingly, the exposure time when capturing a fluorescent image in the high-sensitivity image sensor 321 for broadband fluorescent image is twice as long as the exposure time when capturing a fluorescent image in the high-sensitivity image sensor 326 for narrow-band fluorescent image. . For this reason, the pixel value of the broadband fluorescence image stored in the broadband autofluorescence memory 411 rarely becomes a negative value, a zero value, or a value close to zero.

The auto-fluorescence image of the two wavelength bands stored in the auto-fluorescence image memory 411 is converted into a narrow-band auto-fluorescence image by the normalized fluorescence image generating means 413 for each pixel. A normalized operation value divided by the value is calculated. Then, color information is assigned to each pixel by the color image calculation means 415 based on the standardized calculation value, and a color image signal is generated. The color image signal is converted by the video signal processing circuit 506 from DA conversion to the monitor 60.
0 is input and a color image is displayed. Other operations are the same as those in the first embodiment.

As is apparent from the above description, the exposure time when capturing a fluorescent image in the high-sensitivity image sensor 321 for a broadband fluorescent image is different from the exposure time when capturing a fluorescent image in the high-sensitivity image sensor 326 for a narrow-band fluorescent image. , The pixel value of the broadband fluorescent image serving as a denominator when performing the division in the normalization operation is a negative value, 0
Values or values close to 0 are rare. Therefore, the S / N of the generated normalized fluorescence image is improved, and a stable normalization operation can be performed.

In the first and second embodiments, the composite image and the normal image or the color image and the normal image are switched and displayed on one monitor, but are displayed on separate monitors. It may be.
Also, the method of switching with one monitor may be automatically performed in a time series by the control computer without using the foot switch as in the above embodiment.

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. The excitation light source may have any wavelength of about 400 nm to 420 nm.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment of a fluorescence endoscope to which a standardized fluorescence image generating method and apparatus according to the present invention is applied.

FIG. 2 is a diagram showing an image subjected to a low-pass filter process and an image not subjected to the low-pass filter process;

FIG. 3 is a schematic configuration diagram of a second embodiment of a fluorescence endoscope to which a standardized fluorescence image generating method and apparatus according to the present invention is applied;

FIG. 4 is an explanatory diagram showing an intensity distribution of a fluorescence spectrum of a living tissue of a normal part and a lesion part.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Fluorescence diagnostic apparatus 2 Foot switch 9 Living tissue 100 Endoscope insertion part 101 Light guide 101a White light light guide 101b Excitation light light guide 102 Image fiber 103 Illumination lens 104 Excitation light cut filter 105 Objective lens 110, 120 Illumination unit 111, 121 GaN-based semiconductor laser 112, 122 Power supply for semiconductor laser 113, 123 Condensing lens for excitation light 114, 124 White light source 115, 125 Power supply for semiconductor laser 116, 126 Condensing lens for white light 200, 210 Control computer 300, 310 Image detection unit 301, 311 Fluorescent collimating lens 302, 312 Movable mirror 303 Dichroic mirror 304, 319 Broadband fluorescent image condensing lens 305, 320 Broadband bandpass Filter 306, 321 High-sensitivity image sensor for broadband fluorescence image 307, 312, 316, 322, 327, 504
A / D converters 308, 323 Half mirrors 309, 324 Narrow band fluorescent image mirrors 310, 325 Narrow band pass filters 311, 326 Narrow band fluorescent image high-sensitivity image pickup device 313 Fluorescent image mirror 314 Reference image condensing lens 315 Reference image pickup device 317 Low-pass filter circuit 400 Image calculation unit 401 Autofluorescence image memory 402 Reference image memory 403,413 Normalized fluorescence image generation means 405,415 Color image calculation means 406 Luminance image calculation means 407 Image synthesis means 500 Display signal processing unit 501 Normal image mirror 502 Normal image condensing lens 503 Normal image imaging element 505 Normal image memory 506 Video signal processing circuit 600 Monitor unit

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G06T 5/00 100 G06T 5/00 100 5C024 5/20 5/20 C 5C054 H04N 1/04 H04N 5/225 C 5C072 5/225 5/321 5/321 5/335 Z 5/335 7/18 M 7/18 1/04 EF term (reference) 2G043 AA03 BA16 CA05 DA01 EA01 FA01 GA08 GA21 GB21 HA01 HA02 HA05 HA09 JA03 KA09 LA03 NA01 2H040 BA00 CA04 CA09 CA10 CA11 CA12 CA27 DA12 GA01 GA11 4C061 CC06 HH51 QQ04 RR02 SS18 SS21 WW17 5B057 AA07 BA02 CA08 CA12 CA16 CB12 CB16 CC01 CE05 CE11 5C022 AA09 AB15 AC42 AC54 AC75 5C024 AX01 AX01 AX01 AX01 AX01 AX01 AX01 AX01 AX01 AX01 AX01 5C054 AA01 CA04 CC02 CD03 CE08 EA01 EA05 ED07 EG01 FC04 FC12 FC15 FE09 GA04 HA12 5C072 AA01 BA11 CA02 DA02 DA04 DA09 EA04 UA20 VA01

Claims (6)

[Claims] 1. A fluorescence image based on fluorescence emitted from an observation unit by irradiation with excitation light is obtained, and a standardization image based on re-radiated light emitted from the observation unit by irradiation with light is obtained. In a standardized fluorescent image generating method for generating a standardized fluorescent image by dividing a fluorescent image by the standardizing image, a low-pass filter process or a recursive filter process is performed on the standardized image, and the filter process is performed. And performing the division using the standardized image. 2. Obtaining a fluorescence image based on fluorescence emitted from an observation unit by irradiation of excitation light, acquiring a standardization image based on re-radiation light emitted from the observation unit by irradiation of light, In a standardized fluorescent image generating method for generating a standardized fluorescent image by dividing a fluorescent image by the standardized image, an exposure time for obtaining the standardized image, an exposure time for obtaining the fluorescent image A method for generating a standardized fluorescent image, wherein the time is longer than the time. 3. The fluorescence image is a narrow-band fluorescence image based on narrow-band fluorescence in the fluorescence, and the normalization image is obtained by irradiating the observation unit with excitation light. 3. The standardized fluorescence image generation method according to claim 1, wherein the image is a broadband fluorescence image based on fluorescence in a wide wavelength band among the fluorescences emitted from the unit. 4. A fluorescence image acquisition unit that irradiates an observation unit with excitation light, acquires a fluorescence image based on fluorescence emitted from the observation unit by the irradiation of the excitation light, and irradiates the observation unit with light. A standardization image acquisition unit that acquires a standardization image based on the re-radiated light emitted from the observation unit by the light irradiation, and divides the fluorescence image by the standardization image to obtain a standardized fluorescence image. In the standardized fluorescent image generating apparatus comprising: a standardized fluorescent image generating unit that generates; a filter unit that performs a low-pass filter process or a recursive filter process on the standardizing image; A normalized fluorescence image generating apparatus, wherein the division is performed using the normalized image subjected to the filter processing. 5. A fluorescence image acquiring means for irradiating an observation section with excitation light, and acquiring a fluorescence image based on fluorescence emitted from the observation section by the irradiation of the excitation light, and irradiating the observation section with light; A standardization image acquisition unit that acquires a standardization image based on the re-radiated light emitted from the observation unit by the light irradiation, and divides the fluorescence image by the standardization image to obtain a standardized fluorescence image. In the standardized fluorescent image generating apparatus comprising a standardized fluorescent image generating unit that generates, the standardizing image obtaining unit, the exposure time when obtaining the standardizing image, the fluorescent image obtaining unit, A standardized fluorescent image generation apparatus characterized in that the exposure time is longer than the exposure time for acquiring a fluorescent image. 6. The fluorescence image is a narrow-band fluorescence image based on narrow-band fluorescence in the fluorescence, and the normalization image is obtained by irradiating the observation unit with excitation light. The standardized fluorescence image generating apparatus according to claim 4 or 5, wherein the image is a broadband fluorescence image based on fluorescence in a wide wavelength band among the fluorescences emitted from the unit.