Endoscopy system

Abstract

This invention provides an endoscopic system that can irradiate excitation light with different excitation wavelengths using a simple configuration. [Solution] An endoscope system 1 irradiates a fluorescent drug in which the peak of the fluorescence wavelength of the fluorescence emitted when the excitation light is irradiated and the peak of the excitation light wavelength are within 20 nm, comprising a light source device 20 that outputs excitation light, a light guide probe 61 inserted through the forceps channel of an endoscope 30 and propagating the excitation light output from the light source device 20, and a light cut filter that cuts the excitation light. The light cut filter is a short-wavelength cut filter that partially cuts the fluorescence emitted when the excitation light is irradiated onto the fluorescent drug.

Description

Technical Field

[0001] The present invention relates to an endoscope system capable of irradiating excitation light. Cross-reference to related applications

[0002] This application is based on Japanese Patent Application No. 2020-206826 filed on December 14, 2020, claims the benefit of its priority, and all of the contents of the patent application are incorporated herein by reference.

Background Art

[0003] Conventionally, an endoscope system has been known that irradiates light of a specific wavelength as excitation light onto a biological tissue and observes fluorescence emitted from the biological tissue (Patent Document 1). Also, an endoscope system is known that administers a fluorescent agent that accumulates in a lesion to a subject and observes the lesion by irradiating the fluorescent agent with excitation light (Patent Document 2). Recently, a method of treating a lesion by irradiating excitation light to a fluorescent agent that has accumulated in the lesion has also been studied.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

[0005] There are multiple types of fluorescent agents used in various applications as described above, and various fluorescent agents will be developed in the future, so it is necessary to irradiate excitation light suitable for the fluorescent agent. However, it is costly to prepare an endoscope system for each fluorescent agent. In particular, manufacturing an endoscope equipped with a specific excitation wavelength light source and manufacturing an endoscope system that can observe only the fluorescence wavelength by passing the received light through a filter on the processor side of the endoscope is expensive.

[0006] In endoscopic fluorescence observation, one possible method is to attach a hood equipped with a light-cutting filter to the tip of the endoscope to cut off the excitation light and observe the fluorescence wavelength. However, when attaching a light-cutting filter to the tip of the endoscope, selecting a filter that allows for clear fluorescence imaging has not been easy. Furthermore, while light-cutting filters that cut off the excitation wavelength are used when performing fluorescence observation, selecting a light-cutting filter that allows for clear fluorescence imaging has not been easy.

[0007] Therefore, in view of the above background, the present invention aims to provide an endoscope system that can irradiate excitation light with different excitation wavelengths with a simple configuration.

[0008] The present invention relates to an endoscope system that irradiates a fluorescent drug administered to a subject with excitation light, comprising: a light source device that outputs excitation light from one light source selected from a plurality of light sources with different wavelengths; a light guide probe inserted through the forceps channel of the endoscope and propagating the excitation light output from the light source device; and a hood that has a light cut filter facing the objective lens of the endoscope and is detachable from the tip of the endoscope, wherein the hood is configured to be selected from a plurality of types of hoods having different light cut filters, corresponding to the wavelength of the excitation light.

[0009] According to the present invention, by changing the hood attached to the tip of the endoscope according to the selected light source, fluorescence-based observation can be appropriately performed in response to various excitation lights.

[0010] Furthermore, the endoscope system of the present invention is an endoscope system that irradiates a fluorescent agent with excitation light, wherein the peak of the fluorescence wavelength of the fluorescence emitted when the excitation light is irradiated and the peak of the wavelength of the excitation light are within 20 nm, and comprises a light source device that outputs excitation light, a light guide probe inserted through the forceps channel of the endoscope and propagating the excitation light output from the light source device, and a light cut filter that cuts the excitation light, wherein the light cut filter has the configuration of a short-wavelength cut filter that partially cuts the fluorescence emitted when the excitation light is irradiated onto the fluorescent agent. [Brief explanation of the drawing]

[0011] [Figure 1] This is a diagram showing the configuration of the endoscope system according to the embodiment. [Figure 2] This is a diagram showing the external appearance of an endoscope. [Figure 3A] This diagram shows an example of a configuration in which one light source is selected from multiple light sources. [Figure 3B] This diagram shows another example of a configuration in which one light source is selected from multiple light sources. [Figure 4A] This is a perspective view of food. [Figure 4B] These are side, top, and cross-sectional views of the hood. [Figure 5] This is an example of data stored in the memory unit that shows the relationship between the light source, excitation wavelength, and hood. [Figure 6A] This diagram illustrates the cut-off wavelength of an optical cut-off filter, showing an example where the excitation wavelength and fluorescence wavelength are sufficiently far apart. [Figure 6B] This diagram illustrates the cut-off wavelength of an optical cut-off filter, showing an example where the excitation wavelength and fluorescence wavelength are close together. [Figure 7A] This figure shows an example of a screen where the user selects a light source. [Figure 7B] This figure shows an example of a screen that displays the food to be selected. [Figure 8] This diagram shows a white reflector, which is a means of guiding the excitation light to the objective lens. [Figure 9A] An example of a screen for starting the check of hood attachment. [Figure 9B] An example of a screen showing the check result of hood attachment. [Figure 10] A diagram showing the characteristics of the optical cut filter used in the experiment. [Figure 11A] A diagram for explaining the observation region when the wavelength uses the cut filter of the present case. [Figure 11B] A diagram for explaining the observation region when the wavelength uses the comparative cut filter.

Mode for Carrying Out the Invention

[0012] The endoscope system of the present embodiment is an endoscope system that irradiates excitation light to a fluorescent agent administered to a subject, and includes a light source device that outputs excitation light from one light source selected from a plurality of light sources having different wavelengths, a light guide probe inserted into the forceps port of the endoscope for propagating the excitation light output from the light source device, and a hood that is detachable from the tip of the endoscope and has an optical cut filter facing the objective lens of the endoscope. The hood has a configuration selected corresponding to the wavelength of the excitation light from among a plurality of types of hoods having different optical cut filters.

[0013] According to the present embodiment, by replacing the hood attached to the tip of the endoscope, even if the excitation wavelength is changed, the excitation light can be appropriately cut and observation based on fluorescence can be performed.

[0014] In the endoscope system of the present embodiment, the optical fiber bundle of the light guide probe may be composed of a material capable of guiding excitation light of any of a plurality of wavelengths.

[0015] With this configuration, no matter which of the plurality of wavelengths is selected, the light guide probe does not need to be changed, so the convenience is high.

[0016] The endoscope system of this embodiment includes an image signal processing unit that displays images captured by the endoscope on a monitor, and the image signal processing unit may change the display range of the images according to the light cut filter.

[0017] When light enters the light cut filter at an angle, the performance of the light cut filter is not guaranteed, and excitation light may be mixed into the edges of the displayed image, causing the image to blur. However, according to this embodiment, by changing the display range of the image according to the light cut filter, the observation area can be displayed clearly.

[0018] The endoscope system of this embodiment may include a storage unit that stores information identifying the wavelength of excitation light and the corresponding hood, a selection unit that allows the user to select the wavelength of excitation light, and an output unit that reads information identifying the hood corresponding to the wavelength selected by the selection unit from the storage unit and outputs it to the user.

[0019] This configuration allows users to easily select a hood suitable for their excitation light, as selecting the wavelength of the excitation light will output information about the corresponding hood.

[0020] The endoscope system of this embodiment may include a determination unit that determines whether the intensity of the light input by means for guiding the excitation light output from the tip of the endoscope to the objective lens of the endoscope meets a predetermined standard, and determines that the hood is properly attached if it is determined that the predetermined standard is met.

[0021] Since the excitation light is cut off by the light cut filter, if the correct light cut filter is installed, the light intensity will be significantly reduced. If the light cut filter installed in the hood does not match the excitation wavelength of the excitation light, the excitation light will not be cut off. According to the configuration of this embodiment, if the light intensity of the excitation light is below a predetermined threshold or below a predetermined percentage of the original intensity, it can be determined that the hood is correctly installed on the endoscope, and if the predetermined criteria are not met, it can be determined that the wrong hood is installed. This configuration helps in selecting the appropriate hood when using the endoscope.

[0022] In the endoscope system of this embodiment, the light cut filter in each of the multiple types of hoods is a filter that sufficiently cuts the wavelength band of the excitation light. When the wavelength band (or peak of the wavelength band) of the excitation light and the wavelength band (or peak of the wavelength band) of the fluorescence that is emitted are separated by more than a predetermined standard (they do not overlap), a filter that sufficiently cuts the wavelength band (or peak of the wavelength band) of the excitation light is used.

[0023] If the excitation light wavelength peak and the fluorescence wavelength peak are closer than a predetermined reference (e.g., 20 nm), the light cut filter may be a short-wavelength cut filter that partially cuts the fluorescence wavelength as well, or a short-wavelength cut filter that cuts the fluorescence wavelength peak. For example, a short-wavelength cut filter may cut light in the range up to wavelengths 26 nm or longer than the excitation light wavelength peak. Furthermore, it may be a bandpass type filter that cuts not only the short wavelength side but also the long wavelength side of the fluorescence wavelength region simultaneously. This makes it possible to observe only the fluorescence wavelength.

[0024] A light cut filter basically guarantees the ability to cut out light of a specific wavelength for light incident perpendicularly. In the case of a short-wavelength cut filter, the wavelength at which light is cut shifts to the shorter wavelength side as the angle of incidence of light increases. According to this embodiment, even at the edges of the screen where the angle of incidence of light is large, the excitation wavelength of light can be cut out, so the observation area for fluorescence can be kept wide.

[0025] To determine whether the excitation wavelength peak and the fluorescence wavelength peak are close together, one can use the distance between the excitation wavelength and fluorescence wavelength peaks, or use the spectra of the excitation wavelength and fluorescence wavelength. For example, if the excitation wavelength peak and the fluorescence wavelength peak are within 20 nm of each other, they can be considered close together. As another example, one can determine that they are close together based on whether the wavelength band in the excitation wavelength range where the light intensity is more than half of the peak (spectral FWHM) overlaps with the wavelength band in the fluorescence wavelength range where the light intensity is more than half of the peak (spectral FWHM).

[0026] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 shows the configuration of the endoscope system 1 according to the embodiment. The endoscope system 1 comprises an endoscope 30 that is inserted into the body of a subject and a main unit 10 that displays images captured by the endoscope 30. The endoscope system 1 has the function of observing the inside of the body using visible light, similar to a normal endoscope system.

[0027] Furthermore, the endoscope system 1 is equipped with a light source device 20 that irradiates fluorescence into the body of the subject through the forceps channel of the endoscope 30. When irradiating with fluorescence using the light source device 20, a fluorescent agent is administered to the subject in advance. The fluorescent agent is a drug that accumulates in the lesion and emits fluorescence when irradiated with excitation light of a predetermined wavelength. By observing the fluorescence emitted from the fluorescent agent, the endoscope system 1 can appropriately observe lesions that are difficult to distinguish with visible light. In other words, by performing both observation using visible light and observation using fluorescence, it becomes possible to perform highly accurate diagnoses (qualitative diagnoses).

[0028] Furthermore, the endoscopic system 1 can also be used to destroy lesions by irradiating the fluorescent agent with excitation light to raise the temperature of the fluorescent agent.

[0029] Figure 2 shows the external appearance of the endoscope 30. The endoscope 30 comprises an intracavitary insertion section 31 which is formed to be elongated for insertion into a body cavity, an angle knob 32 for bending the tip of the intracavitary insertion section 31, an operating section 35 equipped with two switches 33, 34, etc., a light guide flexible tube 36 for connecting the operating section 35 and the main body 10, and a connector 37 provided at the base end of the light guide flexible tube 36. A signal cable 38 is connected to the connector 37.

[0030] Furthermore, the intracavitary insertion section 31 has a forceps channel formed therein for inserting various types of forceps and allowing their tips to protrude from the tip surface of the intracavitary insertion section 31. The base end of this forceps channel is a forceps port 39 that protrudes from the side of the operating section 35. In the endoscope system 1 of this embodiment, a light guide probe 61 is inserted into the forceps port 39. As shown in Figure 1, the light guide probe 61 is connected to a light source device 20, and excitation light for exciting a fluorescent agent is input through the light guide probe 61.

[0031] The main unit 10 includes an image signal processing unit 11 that processes image signals captured and transmitted by the endoscope 30, and a touch panel monitor 12 that displays images based on the image signals processed by the image signal processing unit 11. The touch panel monitor 12 constitutes the interface with the user and has the function of receiving various instructions from the user. The main unit 10 further includes a selection unit 13, a storage unit 14, and a determination unit 15, the functions of which will be described later. The main unit 10 is originally equipped with a light source for visible light, and visible light observation can be performed when fluorescence observation is not being performed.

[0032] The light source device 20 has multiple light sources with different wavelengths and has the function of outputting excitation light from one of the multiple light sources selected from among them. A light guide probe 61 is connected to the light source device 20. The light guide probe 61 may be detachable from the light source device 20. The light guide probe 61 is inserted through the forceps channel 39 of the endoscope 30 and protrudes from the tip surface of the endoscope 30. The excitation light output from the light source device 20 is propagated to the tip of the endoscope 30 through the light guide probe 61. A collimator 62 is attached to the tip of the light guide probe 61, which focuses the optical path of the light output from the light guide probe 61 and irradiates the excitation light in a predetermined direction.

[0033] Figures 3A and 3B illustrate an example of a configuration for selecting one light source from multiple light sources. In the example shown in Figure 3A, a light guide probe 61 and a collimator 62 are provided as a set for each of the multiple light sources, and the desired light source is selected. In this example, the collimator 62 is sized to pass through the forceps channel. Because the collimator 62 passes through the forceps channel, the light guide probe 61 and collimator 62 can be replaced and used as a set when selecting a light source.

[0034] In the example shown in Figure 3B, a light guide probe (e.g., a multimode fiber) 61 is used, in which the optical fiber bundle is made of a material capable of guiding excitation light of any of multiple wavelengths. This light guide probe 61 and connection probes 63 for multiple light sources are switchedly connected by an FC / PC connector 64. With this configuration, the desired excitation light can be selected simply by switching the connector 64. In this case, it is necessary to attach a collimator 62 corresponding to the selected light source to the tip of the light guide probe 61.

[0035] Next, the hood 50 used in this embodiment will be described. As shown in Figure 1, the hood 50 is attached to the tip of the endoscope 30. Figure 4A is a perspective view of the tip 31a of the endoscope 30 and the hood 50 attached to the tip 31a, and Figure 4B is a side view, top view, and cross-sectional view of the hood 50. The tip surface of the endoscope 30 has an objective lens 41, illumination windows 42a and 42b that allow illumination light to pass through to illuminate the inside of the body, a cleaning nozzle 43, and the end of the forceps channel 44.

[0036] The hood 50 has a light cut filter 51 that cuts out excitation light. In this embodiment, the light cut filter 51 is a short-wavelength cut filter that cuts out light below a specific wavelength. The hood 50 is attached to the endoscope 30 with the light cut filter 51 facing the objective lens 41 of the endoscope 30. The user visually aligns the light cut filter 51 with the objective lens 41, but alignment marks may be placed on the tip of the endoscope 30 and the hood 50 to facilitate this alignment.

[0037] Furthermore, the hood 50 has irradiation windows 52a and 52b positioned opposite the irradiation windows 42a and 42b, and an opening 53 positioned opposite the cleaning nozzle 43. In this embodiment, there is not just one type of hood 50, but a plurality of hoods 50 corresponding to different wavelengths of excitation light. That is, the endoscope system has a plurality of hoods equipped with light cut filters with different cut wavelengths. Each hood 50 has a different light cut filter 51, but the other configurations are the same.

[0038] Figure 5 shows an example of data stored in the memory unit 14 that illustrates the relationship between the light source, the excitation wavelength, and the hood 50. As shown in Figure 5, the excitation wavelength of light source A is 410 nm, and the hood corresponding to this excitation wavelength is hood a. The excitation wavelength of light source B is 685 nm, and the hood corresponding to this excitation wavelength is hood b. In this figure, "excitation wavelength" refers to the peak of the excitation wavelength. As shown in Figure 5, in this embodiment, multiple hoods 50 equipped with optical cut filters 51 corresponding to each excitation light are provided.

[0039] Figures 6A and 6B show the excitation light spectrum and fluorescence spectrum, respectively. In Figures 6A and 6B, α [nm] represents the peak wavelength of the excitation light, and β [nm] represents the peak wavelength of the fluorescence. As shown in Figure 6A, when the excitation light wavelength and the fluorescence wavelength are sufficiently far apart and do not overlap, a clear fluorescence image can be obtained by using a filter that sufficiently cuts the excitation light wavelength band. For example, the excitation light wavelength peak of the fluorescent substance 5-Aminolevulinic acid (5-ALA) is 410 nm, and the fluorescence wavelength peak is 635 nm, and the distance between the two is sufficiently far. In such a case, by using a filter that cuts out wavelengths that are sufficiently longer than the excitation light peak wavelength, for example, light below 440 nm, only the fluorescence wavelength can be sufficiently received, and a clear image can be obtained with a field of view of approximately 75°.

[0040] On the other hand, as shown in Figure 6B, when the distance between the excitation wavelength peak α and the fluorescence wavelength peak β (β>α) is short, the cut filter needs to partially cut the fluorescence wavelength as well. For example, the excitation wavelength peak of the fluorescent substance IRDye700 is 685 nm and the fluorescence wavelength peak is 700 nm. The range of light cut by the light cut filter 51 built into the hood covers the excitation light wavelength band and extends to wavelengths longer than β-α beyond the fluorescence wavelength peak β. Specifically, when the excitation wavelength peak is 685 nm and the fluorescence wavelength peak is 700 nm, for example, a light cut filter 51 that cuts light below 725 nm is used.

[0041] When the distance between the excitation wavelength peak and the fluorescence wavelength peak is short, the optical cut-off filter 51, which cuts off light over a range longer than the fluorescence wavelength peak β, is used to appropriately cut off the excitation light even at the edges of the screen where the angle of incidence of light is large, thereby widening the observation area by fluorescence. Ideally, since we do not want to cut off the light of the fluorescence wavelength peak that we want to observe, an optical cut-off filter that does not cut off the fluorescence wavelength peak β would be used. However, the inventor focused on maintaining a wide observation area by fluorescence and used a cut-off filter 51 that includes the wavelength range that also cuts off the fluorescence wavelength spectrum peak β.

[0042] Next, the main unit 10 will be described. The image signal processing unit 11 has the function of displaying the image captured by the endoscope 30 on the monitor 12. In addition to the normal image obtained by irradiating with visible light, the image signal processing unit 11 processes the image signal obtained by fluorescence excited by excitation light and displays it on the monitor 12. The image signal processing unit 11 in this embodiment has the function of changing the display range of the image according to the light cut filter 51 used. Examples of changing the display range of the image include cropping the edges of the displayed image, or enlarging the cropped image to fit the monitor.

[0043] In this embodiment, the wavelength of the light cut filter 51 is designed to prevent excitation light from entering the peripheral area of ​​the light cut filter 51. However, it is still possible that excitation light may be mixed into the edges of the displayed image, causing the image to blur. The endoscope system 1 of this embodiment can display the observation area clearly by changing the display range of the image according to the light cut filter 51. This display range setting may be done automatically or manually.

[0044] The selection unit 13 has the function of allowing the user to select the wavelength of excitation light. Specifically, it displays a screen like the one shown in Figure 7A on the touch panel monitor 12 to allow the user to select the light source to be used. As shown in Figure 7A, the peak excitation wavelengths of each light source are displayed. Therefore, selecting a light source and selecting an excitation wavelength are essentially the same thing. When a light source is selected by input to the touch panel monitor 12, the selection unit 13 reads information from the storage unit 14 that identifies the hood 50 corresponding to the selected wavelength and outputs the information of the hood 50 to be used to the touch panel monitor 12.

[0045] Figure 7B shows a screen that indicates which hood 50 should be attached. As shown in Figure 7B, the selected light source and its corresponding hood 50 are displayed. In the example shown in Figure 7B, the message "Please attach hood a" is displayed, allowing the user to know which hood to attach.

[0046] With the above configuration, the user is instructed on the data of the hood 50 to be used for the excitation wavelength of the light source, allowing for easy selection of the hood 50. While this example shows the user selecting the light source by displaying the excitation wavelength peak, the user may instead select a fluorescent agent, and the endoscope system 1 may output information on the hood 50 to be used according to the fluorescent agent. This is because once the fluorescent agent is determined, the corresponding light source is also determined. In this case, the correspondence between the fluorescent agent and the hood needs to be stored in the memory unit 14.

[0047] The determination unit 15 has the function of determining whether the correct hood 50 is attached or not. When checking the hood 50, the tip of the endoscope 30 is inserted into the white reflector 70, as shown in Figure 8. The white reflector 70 is a component that totally reflects and outputs incident light, and its role is to guide the excitation light output from the tip of the endoscope 30 to the objective lens 41 of the endoscope 30. An integrating sphere may be used instead of the white reflector 70.

[0048] In this state, the endoscope 30 outputs excitation light, and the intensity of the light received through the objective lens 41 is measured. The determination unit 15 determines whether the intensity of the incident light meets a predetermined standard. An example of a predetermined standard is whether or not it is below a predetermined threshold. The threshold may be defined as an absolute value, or as the attenuation rate from the light intensity at the peak of the excitation wavelength. If the intensity of the incident light is below the predetermined threshold, it is determined that the light cut filter 51 (i.e., the hood 50) is properly installed because the excitation light is being appropriately cut off by the light cut filter 51.

[0049] Figure 9A shows an example of the screen used to start the check for the attachment of the hood 50. Pressing the "Start Test" button on the screen shown in Figure 9A will begin the check. Pressing the "Back" button will return you to the previous screen. Above the buttons is a display area for showing the captured images.

[0050] Figure 9B shows an example of a screen displaying the results of the hood 50 attachment check. If the intensity of the incident light is below a predetermined threshold, the message "The appropriate filter has been selected" is displayed. The display area shows a dark image where the light has been cut off. By checking the attachment of the hood 50 with the determination unit 15 in this way, it is possible to prevent the inconvenience of starting observation with the endoscope 30 with the hood 50 incorrectly attached. [Examples]

[0051] Here, we describe an example in which we experimented to see how the fluorescence observation image changes depending on the type of light cut filter when the excitation light wavelength peak and the fluorescence wavelength peak are close, as with the IRDye700.

[0052] (Example 1) [Experimental conditions and methods] Fluorescence images were captured by reacting cell aggregates, which had been treated with a fluorescently labeled probe containing an antibody specific to tumor cells, with light at a peak wavelength of 685 nm as excitation light. A hood equipped with short-wavelength cut filters with different wavelength ranges was attached to the tip of an endoscope and detached. As the short-wavelength cut filter, Sigma Koki Co., Ltd.'s long-pass filter LOPF-25C-715C (hereinafter referred to as "the cut filter") was used, and for comparative experiments, Solab Japan Co., Ltd.'s long-pass filter FELH0700 (hereinafter referred to as "the comparison cut filter") was used.

[0053] Figure 10 shows the characteristics of each light cut filter used in the experiment. Figure 10 also shows the wavelength characteristics of the fluorescent agent IR-700 used in the experiment. The cut filter in question cuts out light below 725 nm for light incident perpendicular to the filter, with a transmittance of <90% at 724 nm and <1% at 721 nm. On the other hand, the comparison cut filter cuts out light below 708 nm for light incident perpendicular to the filter, with a transmittance of <90% at 707 nm and <1% at 702 nm. Both light cut filters have a strong light blocking effect for light perpendicular to the filter.

[0054] [Experimental Results] When using the comparative cut filter, the image region free from excitation light interference was observed at a field of view of 40-45°. However, when using the present cut filter, this region expanded to a field of view of 60-65°. Although the light intensity was weaker compared to the case with the comparative cut filter, it did not hinder fluorescence observation.

[0055] Figures 11A and 11B are diagrams illustrating why the present cut filter is expected to produce sharp observation images over a wide range. Figure 11A shows an example using the present cut filter, and Figure 11B shows an example using a comparison cut filter. Here, the explanation assumes an excitation wavelength peak of 685 nm.

[0056] The performance of the light cut filter is guaranteed only for light incident perpendicular to the filter; in the peripheral areas of filter 51 (i.e., the peripheral areas of the imaging region), excitation light is also transmitted. Excitation light is much stronger than fluorescence, and it is difficult to observe fluorescence when light within approximately ±10 nm of the excitation wavelength peak of 685 nm is incident.

[0057] In Figure 11A, the central dotted line, representing region R1, is the area where light is incident perpendicularly to the filter. In this area, light with wavelengths shorter than 725 nm is cut off. Outside region R1, light is incident obliquely on the cut filter, and therefore the performance of the light cut filter cannot be guaranteed. Region R2 is the area where light shorter than approximately 700 nm can be cut, and the field of view of this region is 60-65°. The outermost region R3 is the field of view of the CCD, but in the endoscopic image, the surrounding area is automatically masked with black, so the area outside region R2 is masked and not visible. In other words, by using this cut filter, in combination with the masking function, a clear fluorescence image can be obtained throughout the entire endoscopic image.

[0058] In the case of the comparison filter, as shown in Figure 11B, the performance of the comparison cut filter is guaranteed in region R1, so excitation light is cut within region R1 and a clear fluorescence image can be obtained. However, in the case of the comparison filter, because light enters the filter at an angle, the region R2 into which light with wavelengths shorter than 700 nm enters is narrow, and the field of view is 40-45°. Therefore, excitation light enters between the masking area on the outside of the endoscope and the filter, and it is thought that the fluorescence observation image becomes blurred in the peripheral part of the endoscopic image.

[0059] As described above, this cut filter cuts out 700nm light, which is sufficiently larger than the excitation wavelength, up to a viewing angle of about 60-65°, even for light that would otherwise be transmitted due to being incident at an oblique angle on the filter. Therefore, it is expected that clear fluorescence observation images can be obtained even in the peripheral areas.

[0060] This fluorescence endoscopy system allows for the diagnosis of submucosal tumors hidden beneath the mucosa using molecular imaging techniques. Normally, submucosal tumors cannot be distinguished from malignant to benign tumors because tumor cells are not collected through biopsy with forceps. However, by administering a fluorescently labeled antibody against c-KIT, which is specifically expressed in gastrointestinal stromal tumors (GIST), a representative malignant submucosal tumor, this system makes it possible to easily diagnose GIST. Similarly, other fluorescent substances besides IRDye700 can also be observed using this endoscopy system with appropriate excitation light sources and cut filters.

[0061] (Example 2) We attempted fluorescence observation of talaporfin sodium (Laserphyrin®) (excitation wavelength peak 664 nm, fluorescence wavelength peak 672 nm), which is used in PDT (phototherapy) for esophageal cancer, lung cancer, and brain tumors. The cut filter cuts out light below 690 nm, including the fluorescence wavelength peak (672 nm), to prevent contamination due to the blue shift of the excitation light. Esophageal cancer cells (ESCC510) were transplanted into the buttocks of nude mice, and when they reached a size of 8 mm, talaporfin sodium was administered via the tail vein. Four hours later, excitation light at 664 nm was irradiated, and observation was performed using an endoscope with a cut filter (Tokai Optical CF650-675-0215-003). Sharp red fluorescence corresponding to the tumor was observed in a wide field of view. On the other hand, when observation was performed using an endoscope with a cut filter that cuts out light below 679 nm (Tokai Optical CF650-665-0215-003), excitation light was mixed into the peripheral part of the endoscopic image (blue shift), and the clearly visible fluorescence observation image was narrowed.

[0062] (Example 3) Similarly, fluorescence observation was possible using this endoscopic system by exciting ICG (excitation wavelength 774 nm, fluorescence wavelength 805 nm) at 785 nm and using a cut filter (Tokai Optical CF650-800-0215-003) that cuts out wavelengths below 819 nm. On the other hand, when observation was performed using an endoscope with a cut filter (Tokai Optical CF650-800-0215-003) that cuts out light below 799 nm, excitation light was mixed into the peripheral part of the endoscopic image (blue shift), and the fluorescence observation image, which appeared clear in the peripheral part, became narrower.

[0063] The experimental results for Examples 1-3 and their respective comparative examples are summarized below. Thus, this endoscopic system can observe fluorescent substances at various wavelengths. [Table 1] [Industrial applicability]

[0064] The present invention is useful as an endoscope system or the like that can irradiate with excitation light.

Claims

1. An endoscopic system that irradiates a fluorescent agent administered to a subject with excitation light, A light source device that outputs excitation light from one light source selected from multiple light sources with different wavelengths, A light guide probe is inserted through the forceps channel of the endoscope and propagates the excitation light output from the light source device, The endoscope has a light-cutting filter facing the objective lens, and a detachable hood attached to the tip of the endoscope. Equipped with, The aforementioned hood is an endoscope system in which a hood is selected from among several types of hoods having different light-cutting filters, corresponding to the wavelength of the excitation light.

2. The endoscopic system according to claim 1, wherein the optical fiber bundle of the light guide probe is made of a material capable of guiding excitation light of any of the multiple wavelengths.

3. It is equipped with an image signal processing unit that displays images taken with an endoscope on a monitor. The endoscope system according to claim 1 or 2, wherein the image signal processing unit changes the display range of the image according to the light cut filter.

4. A memory unit that stores information identifying the wavelength of the excitation light and the corresponding hood, A selection unit that allows the user to select the wavelength of the excitation light, An output unit reads information from the storage unit that identifies the hood corresponding to the wavelength selected in the selection unit and outputs it to the user. An endoscope system according to any one of claims 1 to 3, comprising:

5. The endoscope system according to any one of claims 1 to 4, further comprising a determination unit that determines whether the intensity of the light input by means for guiding the excitation light output from the tip of the endoscope to the objective lens of the endoscope meets a predetermined standard, and determines that the hood is properly attached if it is determined that the predetermined standard is met.

6. Each of the aforementioned multiple types of hoods has a light cut filter that cuts the wavelength of the corresponding excitation light, The endoscopic system according to any one of claims 1 to 5, wherein when the wavelength of the corresponding excitation light and the wavelength of the fluorescence emitted by the excitation are closer than a predetermined standard, the short-wavelength cut filter partially cuts not only the wavelength band of the excitation light but also the fluorescence.

Images