JP2810717B2 - Endoscope for fluorescence observation - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an endoscope for fluorescence observation capable of detecting fluorescence together with a normal observation image.

[Problems to be solved by conventional technology and invention] In recent years, by inserting an elongated insertion portion into a body cavity,
2. Description of the Related Art Endoscopes capable of observing organs in a body cavity and the like and performing various treatments using a treatment tool inserted into a treatment tool channel as necessary are widely used.

Also, various electronic endoscopes using a solid-state imaging device such as a charge-coupled device (CCD) as an imaging unit have been proposed.

By the way, recently, a diagnostic technique for finding a tumor part with an endoscope using fluorescence has been proposed. For example, a fluorescent agent is labeled (chemically conjugated) to a monoclonal antibody that has an ability to accumulate in a tumor and administered to a living body (intravenous injection, intracavity dispersion), and the living body is irradiated with excitation light such as laser light. When excitation light is applied to the fluorescent-labeled monoclonal antibody collected in the tumor, the antibody (= tumor part) emits fluorescence. By detecting this fluorescence, a tumor is found. The wavelength of the excitation light is determined depending on the type of the fluorescent agent, and the fluorescent agent emits fluorescence by applying light including the wavelength light.

However, the fluorescence emitted by the fluorescent agent is very weak light, and the emission time is only a certain level of the remaining fluorescence only during the application of the excitation light or only for an extremely short time. Therefore, since the fluorescence is weak, it is difficult to see the fluorescence while observing the affected part with the naked eye with an endoscope, and the positional relationship between the normally observed image and the part emitting the fluorescence is not known, and the fluorescence is emitted. There is a problem that the site cannot be accurately grasped.

To cope with this, JP-A-61-122421 discloses that a test site is irradiated by switching between excitation light and normal observation light, and a fluorescence image and a normal observation image corresponding to each light are separately stored in a memory. And superimpose both images on the same screen.

However, in this case, a means for switching the illumination light, a means for synthesizing the image, and the like are required, and the configuration of the apparatus becomes complicated.

The present invention has been made in view of the above circumstances, and has as its object to provide a fluorescence observation endoscope that can detect fluorescence together with a normal observation image with a simple configuration.

[Means for Solving the Problems] A fluorescence observation endoscope according to the present invention is provided with illumination means for irradiating an object to be inspected with observation illumination light including at least excitation light, and illumination light emitted by the illumination means. The imaging means for receiving light from the object to be inspected, and the illuminating means, wherein the light amount of a wavelength region near the excitation light in the entire wavelength region of the illumination light is compared with the light amount of another wavelength region. Pump light increasing means for increasing the intensity.

[Operation] In the present invention, the illumination unit irradiates the inspection object containing the fluorescent agent with illumination light including excitation light of the fluorescent agent. By increasing the amount of light in the wavelength region near the excitation light of the fluorescent agent in the entire wavelength region of the illumination light compared to the amount of light in the other wavelength regions, the amount of fluorescence emitted by the fluorescent agent increases. Normal,
In the spectral reflection characteristic of the inspection object of the endoscope, the component in the wavelength region (short wavelength side) near the excitation light of the fluorescent agent is small,
The color does not change much.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

1 to 8 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing a configuration of an endoscope apparatus, FIG. 2 is a side view showing the entire endoscope apparatus, FIG. FIG. 4 is a characteristic diagram showing a transmission wavelength region of each filter of the rotary filter. FIG. 4 is a timing chart showing a light amount of each wavelength region of illumination light. FIG. 5 is a characteristic diagram showing absorption and fluorescence characteristics of a fluorescent material. Figure 6
FIG. 7 is a characteristic diagram showing a spectral sensitivity characteristic of the CCD, FIG. 7 is a block diagram showing a main part of a signal processing circuit in a modification of the present embodiment,
FIG. 8 is an explanatory diagram showing characteristics of the nonlinear amplifier circuit of FIG.

The endoscope apparatus according to the present embodiment includes an electronic endoscope 1 as shown in FIG. The electronic endoscope 1 has a slender, for example, flexible insertion section 2, and a large-diameter operation section 3 is connected to the rear end of the insertion section 2. A flexible universal cord 4 extends laterally from a rear end of the operation unit 3, and a connector 5 is provided at an end of the universal cord 4. The electronic endoscope 1 is connected via the connector 5 to a video processor 6 having a light source device and a signal processing circuit built therein. further,
The video processor 6 is connected to a monitor 7.

On the distal end side of the insertion portion 2, a rigid distal end portion 9 and a bending portion 10 which can be bent rearward adjacent to the distal end portion 9 are sequentially provided. By rotating a bending operation knob 11 provided on the operation section 3, the bending section 10 is rotated.
Can be bent in the horizontal direction or the vertical direction. The operation section 3 is provided with an insertion port 12 communicating with a treatment instrument channel provided in the insertion section 2.

As shown in FIG. 1, a light guide 14 for transmitting illumination light is inserted into the insertion section 2 of the electronic endoscope 1. The distal end surface of the light guide 14 is arranged at the distal end 9 of the insertion section 2 so that illumination light can be emitted from the distal end 9. The light guide 14 has an incident end inserted through the universal cord 4 and connected to the connector 5. Further, an objective lens system 15 is provided at the distal end portion 9, and a solid-state image sensor, for example, a CCD 16 is provided at an image forming position of the objective lens system 15. This CCD16
As shown in FIG. 6, in the spectral sensitivity characteristic of, the sensitivity is lower on the shorter wavelength side in the visible region. Signal lines 26 and 27 are connected to the CCD 16. The signal lines 26 and 27 are inserted through the insertion section 2 and the universal cord 4 and connected to the connector 5.

On the other hand, the video processor 6 includes a pulse lighting device 22.
Is connected to the lamp 21. The pulse lighting device 22 can light the lamp 21 in pulses and change the amount of each pulse light based on the timing from the clock driver 24.
A rotary filter 30 driven by a motor 23 is disposed in front of the lamp 21. In the rotary filter 30, filters that transmit light in each wavelength region of red (R), green (G), and blue (B) are arranged along the circumferential direction. FIG. 3 shows the transmission characteristics of each filter of the rotary filter 30.

The rotation of the motor 23 is controlled by a motor driver 25 to be driven.

The light that has passed through the rotary filter 30 and has been separated in time series into light in each of the R, G, and B wavelength regions is incident on the incident end of the light guide 14, and the light guide 14 has 9 and is emitted from the tip 9 to illuminate the observation site.

The light from the observation site illuminated by this illumination light,
An image is formed on the CCD 16 by the objective lens system 15 and photoelectrically converted. A drive pulse from a driver circuit 31 in the video processor 6 is applied to the CCD 16 via the signal line 26, and reading and transfer are performed by the drive pulse. this
The video signal read from the CCD 16 is input to the preamplifier 32 provided in the video processor 6 or the electronic endoscope 1 via the signal line 27. The video signal amplified by the preamplifier 32 is input to a process circuit 33, subjected to signal processing such as γ correction and white balance, and converted into a digital signal by an A / D converter. The digital video signal is supplied to the memory (1) 36a, the memory (2) 36b, and the memory (3) 36c corresponding to, for example, each color of red (R), green (G), and blue (B) by the selection circuit 35. It is selectively stored. The memory (1) 36a,
The memory (2) 36b and the memory (3) 36c are read out at the same time, converted to analog signals by the D / A converter 37, output as R, G, and B color signals.
8 and output from this encoder 38 as an NTSC composite signal.

Then, the R, G, B color signals or the NTSC composite signals are input to a color monitor 7, and the color monitor 7 displays the observation region in color.

In the video processor 6, a timing generator 28 for generating the timing of the entire system is provided, and the timing generator 28 synchronizes the motor driver 25, the driver circuit 31, the clock driver 24, and other circuits. ing.

 Next, the operation of the present embodiment will be described.

For example, a fluorescent material called fluorescein, which has absorption and fluorescence characteristics as shown in FIG. 5, is labeled (chemically conjugated) to a monoclonal antibody that has an ability to accumulate in a tumor and administered to a living body (intravenous injection). , Intraluminal spray), the fluorescently labeled monoclonal antibodies collect in the tumor. As shown in FIG. 5, the fluorescein absorbs and excites light in a wavelength region of approximately B, and emits fluorescence in a wavelength region of approximately G.

When the test site containing the fluorescent agent is observed by the electronic endoscope 1 to detect the fluorescence, the lamp 21 is used.
Is turned on at the timing when each filter of the rotary filter 30 is interposed in the illumination light path, and as shown in FIG. 4, only at the timing of B, the amount of light is smaller than at the timing of G and R. Increase. Therefore, the R, G, and B lights transmitted through the rotary filter 30 are radiated in time series to the test site, but the light amount of B is larger than the light amounts of G and R. Then, light from the test site illuminated with such illumination light is received by the CCD 16, and a color image of the test site is obtained.

As described above, since the fluorescein absorbs light in the B wavelength region and emits fluorescence at the timing of B, the fluorescence is processed as a change in the B image regardless of the wavelength of the fluorescence. Will be That is, in the part emitting the fluorescence, the B component in the color image increases due to the fluorescence.

In the present embodiment, since the light amount of B is larger than the light amounts of G and R, the amount of fluorescence also increases as compared with the case where the light amount of B is not increased. In a living body, which is an observation site by an endoscope, the B component is generally small and the sensitivity of the CCD 16 is low on the B side as shown in FIG. The return light is not too large.
On the other hand, the fluorescence is not actually the light in the B wavelength region, but is light on the longer wavelength side. Therefore, from the sensitivity characteristics of the CCD 16, it is detected to be larger than the return light of the B component of the living body. As described above, without inserting a sharp cut filter in the illumination system and the observation system, curing that irradiates the excitation light more can be obtained from the characteristics of the illumination light, and from the characteristics of the CCD 16,
The same effect as a filter that reduces reflected light (B) from a living body and increases fluorescence (G) can be obtained. Moreover, in the case of an endoscopic image, the color tone does not change much even if the B illumination light is increased.
Therefore, in a normal color image in the visible light region, the color tone of only the portion that emits fluorescence changes.

As described above, according to the present embodiment, with a simple configuration, weak fluorescence can be more clearly detected together with a normal image,
It is possible to accurately grasp a part emitting fluorescence in a normal image.

In addition, when the B illumination light is increased, the B signal is accordingly processed by the signal processing.
When the signal level is lowered, an image closer to the color tone of the normal observation image can be obtained. In this case, as shown in FIG.
Non-linear amplifier circuit 39 for B signal from A converter 37
By performing a non-linear conversion process by
The B signal level based on the component is reduced,
It is possible to increase the signal level. That is,
As shown in FIG. 8, the B signal level based on the B component of the living body is distributed on the smaller side, and the B signal level based on the fluorescence is distributed on the larger side. Therefore, as shown in FIG. 8, by setting the amplification degree of the non-linear amplifier 39 to be smaller on the lower level side and higher on the higher level side, the B signal based on the B component of the living body is obtained. The level decreases, the image becomes closer to the color tone of the normal observation image, the B signal level based on the fluorescence increases, and only the fluorescence is enhanced, and a fluorescent image with a good SN can be obtained.

9 to 12 relate to a second embodiment of the present invention, FIG. 9 is a block diagram showing a configuration of an endoscope device, FIG. 10 is a characteristic diagram showing spectral characteristics of illumination light, and FIG. Is an explanatory diagram of a color filter array, and FIG. 12 is a characteristic diagram showing transmission characteristics of each filter of the color filter array.

The electronic endoscope 1 in this embodiment is of a simultaneous type using a CCD 41 having a color filter array 40 on the front surface.

The light source unit in the video processor 6 includes a lamp 21, a pulse lighting device 22, a clock driver 24,
It includes a rotation filter 30, a motor 23, and a motor driver 25. The illumination light emitted from the light source unit is a time-series light in which the light quantity of B is larger than the light quantities of G and R, as in the first embodiment.

The optical image of the subject illuminated by the illumination light is formed on the imaging surface of the CCD 41 by the objective lens system 45. At that time, color separation is performed by the color filter array 40. As shown in FIG. 11, the color filter array 40
(Green), Cy (cyan), and Ye (yellow) are arranged in a mosaic of three color transmission filters. FIG. 12 shows the transmission characteristics of the G, C, y, and Ye filters.

The CCD 41 is read out by application of a drive signal from a driver 46 in the video processor 6, amplified by an amplifier 47 in the video processor 6, and then LPFs 48, 49 and BP
Passed through F50. The LPF48,49, for example 3 MHz, indicates a cutoff characteristic of 0.8 MHz, they each divided into a luminance signal Y _L of the signal passing through each luminance signal Y _H of the high-frequency low-band process circuit 51 , 52, respectively, and γ
Correction and the like are performed. Luminance signal Y _H of the high-frequency side through the process circuit 51 is subjected to horizontal contour correction by the horizontal correction circuit 53, a horizontal aperture correction or the like has been performed, are input to the color encoder 67.

Further, the luminance signal Y on the low frequency side through the process circuit 52 is output.
_L is input to a matrix circuit 54 for video display, and tracking correction is performed.

On the other hand, a color signal component is extracted by passing through a BPF50 having a pass band of 3.58 ± 0.5 MHz.
(1H delay line) 57, an adder 58 and a subtractor 59, which separate and extract the color signal components B and R. In this case, the output of 1HDL57 processes in the process circuit 52, further luminance signal Y _L of the vertical aperture correction, low frequency side in the vertical correcting circuit 60, are mixed in the mixer 61, the mixed output is the sum Input to the subtractor 58 and the subtractor 59. The color signals R color signal B and the subtractor 59 in adder 58, respectively, are input to the gamma correction circuit 62 and 63, gamma correction by using the luminance signal Y _L of through correction circuit 55 low frequency band The color signals B and R are input to demodulators 64 and 65, respectively, and are then input to a matrix circuit 54.

Further, the color difference signals RY, B
-Y is generated and then inputted to the color encoder 67, the luminance signal obtained by mixing the luminance signal Y _L and Y _H, color difference signals R-Y, the B-Y and a chroma signal orthogonal modulated subcarriers The mixed video signal is superimposed, and a composite video signal is output from the NTSC output terminal.

The driver 46 receives a synchronization signal from a synchronization signal generation circuit 69, and the driver 46 outputs a drive signal synchronized with the synchronization signal. The synchronization signal generation circuit 69 is input to the pulse generator 70,
70 outputs various timing pulses to be supplied to the clock driver 24, the motor driver 25, and the like.

The lamp 21 emits R, G, and B lights during the accumulation period of one frame of the CCD 41. Therefore, the spectral characteristics of the illumination light are as shown in FIG.

In the present embodiment configured as described above, as in the first embodiment, when a monoclonal antibody labeled with fluorescein is administered to a living body, and this is observed with the electronic endoscope 1,
The fluorescence is observed as a change in the color tone on the G side. B in living body
Since the component is small and the sensitivity of the CCD is low on the B side, even if the light amount of B is increased, the return light of the B component of the living body does not become too large, but the fluorescence increases the excitation light and CCD1
6 is larger than the sensitivity characteristic.

In addition, by lowering the B signal level in the signal processing by an amount corresponding to the increase in the amount of B light, an image closer to the color tone of the normal observation image is obtained. Unlike the case of the frame sequential method, in the simultaneous method, the fluorescence is detected as an increase in the signal level in the fluorescence wavelength region. Therefore, even if the B signal level is reduced, the signal level based on the fluorescence does not decrease. In the case of the simultaneous type, since the color filter array 40 is provided on the light receiving side, it is possible to cut the excitation light without using a special filter. That is, in the case of this embodiment, the Ye and G transmission filters function as excitation light cut filters, and even if the amount of B illumination light is increased, the increase in the reflected light of the B component of the living body is caused by the output of the Ye and G pixels. No contribution, only an increase in fluorescence can be detected. Although the output of the pixel of Cy increases with an increase in the amount of B illumination light, the effect of the increase in the amount of B illumination light can be eliminated by lowering the level by signal processing as described above.

As described above, by increasing the light amount only in the wavelength region near the excitation light on the illumination side, the fluorescence can be more clearly detected together with the normal image.

Instead of using the rotation filter 21, illumination may be performed with continuous illumination light having spectral characteristics as shown in FIG.

Other configurations, operations and effects are the same as those of the first embodiment.

The present invention is not limited to the above embodiments. For example, the fluorescent agent may be fluorescein, adreamycin,
Hematoporphyrin derivative, pheophorbide a, FITC
And so on.

Further, the present invention is also applicable to an eyepiece of an endoscope capable of observing the naked eye such as a fiberscope, or to an endoscope apparatus used by connecting to a television camera by replacing the eyepiece with the eyepiece. Can be.

[Effects of the Invention] As described above, according to the present invention, the amount of light in the wavelength region near the excitation light of the fluorescent agent in the entire wavelength region of the illumination light is increased as compared with the amount of light in other wavelength regions. In addition, since the amount of fluorescence increases without changing the color tone much, there is an effect that the fluorescence can be detected together with the normal observation image with a simple configuration.

[Brief description of the drawings]

1 to 8 relate to a first embodiment of the present invention.
FIG. 2 is a block diagram showing the configuration of the endoscope device, FIG. 2 is a side view showing the entire endoscope device, FIG. 3 is a characteristic diagram showing the transmission wavelength region of each filter of the rotary filter, and FIG. 5 is a timing chart showing the amount of illumination light for each wavelength region,
The figure is a characteristic diagram showing the absorption and fluorescence characteristics of the fluorescent material.
FIG. 7 is a characteristic diagram showing a spectral sensitivity characteristic of D, FIG. 7 is a block diagram showing a main part of a signal processing circuit in a modification of the present embodiment, FIG. 8 is an explanatory diagram showing characteristics of the nonlinear amplifier circuit of FIG. 9 to 12 relate to a second embodiment of the present invention, FIG. 9 is a block diagram showing a configuration of an endoscope device, FIG. 10 is a characteristic diagram showing spectral characteristics of illumination light, and FIG. Is an explanatory diagram of a color filter array, and FIG. 12 is a characteristic diagram showing transmission characteristics of each filter of the color filter array. 1 ... Electronic endoscope, 16 ... CCD 21 ... Lamp, 22 ... Pulse lighting device 30 ... Rotary filter

────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiro Kawashima 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside O-limpus Optical Industry Co., Ltd. (72) Inventor Koichiro Ishihara 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside the Olympus Optical Co., Ltd. (72) Kazuyuki Minami 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside the Olympus Optical Co., Ltd. (72) Eiichi Fuse 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (72) Inventor Masaaki Hayashi 2-43-2 Hatagaya, Shibuya-ku, Tokyo Inside Olympus Optical Co., Ltd. (56) References JP-A-63-122421 (JP, A) Sho 64-86933 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) A61B 1/00, 5/00

Claims (1)

(57) [Claims] An illumination unit configured to irradiate the inspection target with observation illumination light including at least excitation light; an imaging unit configured to receive light from the inspection target irradiated with the illumination light by the illumination unit; Excitation light increasing means for increasing the amount of light in a wavelength region near the excitation light in the entire wavelength region of the illumination light compared to the amount of light in other wavelength regions with respect to the illumination means. Endoscope for fluorescence observation.