JP4804980B2 - Infrared observation system - Google Patents

Description

  The present invention relates to an infrared observation system that obtains an image of a blood vessel by irradiating pulsed infrared light.

In recent years, observation systems using endoscopes have been widely used in the medical field. As a conventional technique, for example, as shown in FIG. 13, a method of observing using the hemoglobin absorption characteristics of near infrared light having a wavelength shorter than 1 μm from the visible region is disclosed in, for example, Japanese Patent Laid-Open No. 2000-2000 as a first conventional example. No. 411942.
Hemoglobin has a light absorption characteristic as shown in FIG. 13, and the curve labeled “Hb” in the figure represents the characteristic of hemoglobin not bound to oxygen, and the curve labeled “HbO 2” represents oxygen. Shows the properties of hemoglobin bound to. In some cases, observation is performed at wavelengths near 750 nm and 900 nm in FIG.

However, when such a wavelength region is used, it is difficult to observe a blood vessel on the deep side from the surface of the living tissue because the transmission characteristics of the living tissue are not sufficient (absorption is high or attenuation is large).
Japanese Patent Laid-Open No. 6-22968 as a second conventional example discloses an apparatus for obtaining an image of a blood vessel inside a subject by performing pulse irradiation.
This second conventional example discloses an image picked up by reflected light from a blood vessel wall while suppressing scattering and reflection in blood.
Japanese Patent Laid-Open No. 2000-41942 JP-A-6-22968

  In the second conventional example, pulse irradiation is performed and imaging is performed in synchronization with this pulse irradiation, and there is a possibility that the influence of continuous irradiation can be reduced. However, image generation with very short single pulse irradiation is possible. Therefore, it is difficult to obtain a good observation image for a blood vessel in a deep part of the living tissue.

(Object of invention)
The present invention has been made in view of the above-described points, and an object of the present invention is to provide an infrared observation system capable of obtaining a good observation image even with respect to a deep blood vessel of a living tissue.

Infrared observation system of the present invention, pulse irradiation means for irradiating biological tissue with pulsed infrared light, infrared imaging means for imaging biological tissue irradiated with the infrared light at the time of pulse irradiation,
With a pulse irradiation stop time formed by the infrared imaging means, a plurality of output signals imaged at the time of pulse irradiation at different times are used for blood vessels in the living tissue, blood in the blood vessels, and infrared light. Image generating means for generating an image corresponding to a temperature difference with other biological tissue having different optical characteristics;
It is provided with.
In the above configuration, an image based on a plurality of imaging outputs obtained at the time of pulse irradiation at different times in a state where a pulse irradiation stop time is formed and the influence of a decrease in imaging signal output due to continuous irradiation is reduced by pulse irradiation. By generating, a good image can be obtained for an image of a blood vessel in a deep part of a living tissue.

  According to the present invention, an effect similar to temperature saturation is achieved.

  Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 10 relate to Example 1 of the present invention, FIG. 1 shows the overall configuration of an infrared observation system of Example 1 of the present invention, and FIG. 2 shows scattering / absorption in a living tissue in the visible to near infrared region. FIG. 3 shows the characteristics of the measurement results of the transmittance of muscles, fats, blood vessels, blood, etc. of the living body in the infrared wavelength region used in this embodiment, and FIG. Indicates the water content in the organ.
5 shows the configuration of the sampling processing circuit, FIG. 6 shows an explanatory diagram for detecting the temperature difference by the sampling processing circuit, FIG. 7 shows the overall configuration of the infrared observation system during infrared observation, and FIG. Shows the timing of pulse irradiation and infrared imaging during infrared observation, FIG. 9 shows a flowchart of the operation during infrared observation, and FIG. 10 shows an example of a blood vessel image obtained by this embodiment.

As shown in FIG. 1, the infrared observation system 1 according to the first embodiment of the present invention is equipped with, for example, an optical endoscope 3 inserted into a patient 2 and a camera head (television camera) 4 incorporating an imaging means. A TV camera external endoscope (simply abbreviated as “endoscope”) 5, a light source device 6 that supplies illumination light to the optical endoscope 3, and a camera that performs signal processing on an imaging means built in the camera head 4 A control unit (abbreviated as CCU) 7 and a monitor 8 that displays an endoscopic image captured by the imaging means when a standard video signal output from the CCU 7 is input.
The optical endoscope 3 includes, for example, a rigid insertion portion 11, a grip portion 12 provided at the rear end of the insertion portion 11, and an eyepiece portion 13 provided at the rear end of the grip portion 12. The light guide cable 14 is connected to the base of the grip portion 12.

A light guide 15 that transmits illumination light is inserted into the insertion portion 11, and the light guide 15 is provided at an end portion thereof via a light guide cable 14 connected to a base on the side of the grip portion 12. A connector 16 is detachably connected to the light source device 6.
In the light source device 6, for example, a normal light lamp 19 a and an infrared lamp (abbreviated as IR lamp) 19 b are attached to a rotating plate 18 rotated by a motor 17, and the lamps arranged on the optical path can be switched. I am doing so.
In the light source device 6, a lamp lighting / pulse lighting circuit having a function of lighting the normal light lamp 19a with power supplied from the power circuit 21 and a function of lighting the IR lamp 19b in a predetermined cycle. 22 and a motor control circuit (rotary plate control circuit) 23 for switching the position of the rotary plate 18 by rotating the motor 17 is provided.

  The normal light lamp 19a generates visible light such as a xenon lamp. Further, the IR lamp 19b emits light in an infrared light region, for example, in a wavelength band of 1 μm to 14 μm.

The light of the lamp 19i (i = a or b) is condensed by the condenser lens 24 arranged on the illumination optical path, and the illumination light is incident on the incident end face of the light guide 15 of the light guide connector 16 part. The light guide 15 transmits the light to the distal end surface (exit end surface) of the insertion portion 11.
And it radiates | emits from the front end surface of the said light guide 15, and irradiates illumination light to the observation object site | part 25 in the biological tissue in the patient's 2 body cavity.
An objective lens 27 is attached to the observation window provided adjacent to the illumination window at the distal end of the insertion portion 11 to connect the illuminated optical image of the observation target region 25. The formed optical image is transmitted to the rear end face side by a relay lens system 28 serving as an image guide.

The optical image can be enlarged and observed by an eyepiece lens 29 provided on the eyepiece 13. When the camera head 4 is attached to the eyepiece 13, an optical image transmitted through the imaging lens 31 in the camera head 4 is formed.
In the camera head 4, a normal image sensor 33 a and an IR image sensor 33 b are attached to the rotating plate 32, and the image sensor disposed on the imaging optical path can be switched by operating the switching lever 34. I can do it. The user can switch the image sensor disposed on the imaging optical path by driving the motor 35 by operating the switching lever 34, for example.
The normal image sensor 33a is configured by an image sensor having sensitivity to normal light (visible light) such as a CCD.

On the other hand, the IR imaging element 33b has sensitivity in, for example, an infrared wavelength region from a wavelength of 1.2 μm (1200 nm) to around 2.5 μm, for example, Ex. This is an imaging element formed using a semiconductor detection element (photovoltaic semiconductor detection element) such as InGaAs, InAs, or InSb. These semiconductor detection elements have sensitivity to at least a wavelength band from 1 μm to around 2.5 μm. Note that InAs and InSb also have sensitivity in a long wavelength region longer than 2.5 μm and longer than 3.0 μm.
A biological tissue generally exhibits scattering / absorption characteristics as shown in FIG. Note that (A) on the upper side in FIG. 2 schematically shows a region that scatters and absorbs when light having a wavelength from visible to near-infrared is incident on the surface of a living tissue. (B) shows the wavelength dependence of the scattering / series coefficient of biological tissue.

As can be seen from FIG. 2, the longer wavelength reaches the deep side of the living tissue and is suitable for obtaining information on the deep side. In the present embodiment, infrared imaging is performed with infrared light having good permeability with respect to a living tissue on a longer wavelength side than the wavelength region shown in FIG.
FIG. 3 shows the characteristics of the measurement results of transmittance in each case of the muscle, fat, blood vessel, blood, bladder, and liver of the living body in the infrared wavelength region used in this example.
As shown in FIG. 3, the transmittance in the living tissue is better when irradiated with infrared light having a wavelength of 1 μm or more, and the infrared light reaches a deep blood vessel in the living tissue.
The reason why the transmittance is improved is that, as shown in FIG. 2, the longer the wavelength, the smaller the scattering and absorption in the living tissue, and the light is transmitted to the deep living tissue.

FIG. 4 shows the water content in the tissues and organs of the living body.
Although blood vessels are made of almost the same tissue as muscles, the blood inside the blood vessels contains nearly 90% of water, as can be seen from FIG. The content differs greatly. Further, blood differs from other organs as living tissues, for example, a liver having a water content of about 70, by about 20% in terms of water content.
For this reason, in this embodiment, the reflected light is imaged using the light absorption characteristics of blood different from other biological tissues with respect to infrared light, and infrared image information reflecting blood vessels including blood is used. Obtain image information of temperature difference.
As can be seen from FIG. 3, the light absorption characteristics of water have peaks at 1.45 μm and 1.9 μm.

In the present embodiment, as will be described later, imaging is performed under pulse irradiation with infrared light by an IR imaging device 33b, and image information relating to blood vessels is generated. In this case, when infrared light is constantly or continuously irradiated, infrared absorption or temperature saturation of a living tissue such as an organ or a blood vessel is likely to occur, and the level of a detected imaging signal (detection signal) decreases. It becomes difficult to detect. For this reason, the present embodiment employs pulse irradiation, and a pulse stop time is formed so that a decrease in the level of the imaging signal due to continuous irradiation can be suppressed by this pulse irradiation. And the image by the infrared imaging of the blood vessel is produced | generated effectively using the several imaging signal obtained at the time of the pulse irradiation of a different time.
The image sensors 33a and 33b illustrated in FIG. 1 are connected to the CCU 7 via the changeover switch 36. The operation of the switching lever 34 can switch the image sensor used for imaging via the switch 36. In FIG. 1, for simplification, only the output signal side of the image sensor is switched. Note that the input signal side of the image sensor may be switched.

As described above, the image sensors 33 a and 33 b in the camera head 4 are connected to the CCU 7 via the changeover switch 36 and the signal line in the camera cable 37.
In the CCU 7, an image sensor driving circuit 38 that drives the image sensor 33 i, a signal processing circuit 39 that performs signal processing by inputting an image signal from the image sensor 33 i, and an output signal of the signal processing circuit 39 On the other hand, in the case of pulse lighting, a sampling processing circuit 40 that performs sampling processing is provided.
The observation mode switching instruction signal by the switching lever 34 is input to the signal processing circuit 39 in the CCU 7 and further input from the CCU 7 to the motor control circuit 23 and the lamp lighting / pulse lighting circuit 22 in the light source device 6. Switching between illumination light and lamp lighting / pulse lighting is performed.
Further, when the lamp lighting / pulse lighting circuit 22 operates by pulse lighting, the lamp lighting / pulse lighting circuit 22 uses the timing signal Sp synchronized with the pulse lighting as an image sensor driving circuit 38, a signal processing circuit 39, and the like in the CCU 7. The signals are output to the sampling processing circuit 40, and each of them operates in synchronization with the pulse lighting timing.

The sampling processing circuit 40 is configured as shown in FIG. 5, for example. The video signal from the signal processing circuit 39 is input to a changeover switch 42 which is switched under the control of the CPU 41, and when the contact b is selected, it passes through an A / D converter 43 to a RAM 44 as a memory means in a two-dimensional manner. Are stored. The RAM 44 has a storage area for storing two-dimensional image data for a plurality of frames.
In the normal observation mode, the contact point a is selected, and the video signal from the signal processing circuit 39 passes through the sampling processing circuit 40 and is output to the monitor 8.
The RAM 44 is connected via a bus to a CPU 41 that performs a function of temperature difference calculation (detection) processing 41a, a ROM 45 that stores a processing program executed by the CPU 41, and a D / A converter 46 that performs D / A conversion. Has been. The CPU 41 also has a function of a temperature gradient calculation process 41b.

When the infrared observation mode is set by operating the switching lever 34, the CPU 41 reduces or suppresses noise on the image data of a plurality of frames stored in the RAM 44 in time series by, for example, FFT processing, thereby Processing for calculating the temperature or calculating the temperature difference between the portion and the living tissue other than the blood vessel is performed.
In addition, since the characteristic with respect to infrared light differs between the blood vessel part and other biological tissue parts other than the blood vessel as described above, it is possible to obtain temperature difference information having different temperature values.
Then, as shown in FIG. 6, the CPU 41 calculates the luminance level, that is, the temperature or temperature difference information when the blood vessel part and the other biological tissue part are imaged in the infrared. FIG. 6A shows a state in which an image (output signal) captured by the IR imaging device 33b at a frame rate synchronized with pulse irradiation is captured (schematically shown by a pulse waveform portion).

Then, the CPU 41 detects (calculates) time-series infrared luminance levels, that is, temperature information, from the sampled image data, as shown on the upper side of FIG. In this illustrated example, the temperature information changes, for example, in a sine wave shape.
This temperature information is an example of data detected in time series from the same position when reflected light from a portion where a blood vessel exists is imaged. When the blood vessel does not exist, the temperature change is small and low as compared with FIG. 6A, and information on the temperature difference corresponding to the blood vessel portion is obtained by the difference.
The CPU 41 calculates information such as the temperature amplitude ΔT from the temperature information that changes in time series as shown in FIG.

Each value of the temperature information calculated in FIG. 6 (A) actually varies due to noise or the like as shown in FIG. 6 (B). Therefore, the CPU 41 performs, for example, fast Fourier transform (FFT) processing on the time-series imaging data (image data) at the same position as described above, and each temperature as a signal component in which noise is reduced (suppressed). Extract information. That is, this FFT processing function is a function of noise reduction processing or noise suppression processing.
Then, the CPU 41 further calculates a temperature gradient as a temperature amplitude ΔT, an average temperature at a short time interval, or a temporal temperature change rate.

In the example of FIG. 6B, the difference between the maximum value and the minimum value is shown as the temperature amplitude ΔT with respect to the same position in the signal (data) obtained by pulse irradiation and time-series infrared imaging in synchronization with the pulse irradiation. ing.
Including the case where such periodic characteristics are not shown, a temperature gradient is calculated per appropriate time or as a temporal temperature change rate.
The CPU 41 calculates the temperature amplitude ΔT and the temperature gradient from the data after the noise recommendation process. Note that the temperature gradient changes in a cosine shape in the case of FIG.
Then, after calculating the temperature amplitude ΔT or the temperature gradient, the CPU 41 images the data of a plurality of frames used to calculate the temperature average, for example, an average value of the average temperature and the temperature gradient. That is, the CPU 41 converts the data of the temperature amplitude ΔT obtained by adding and averaging the data at each position or the average value of the temperature gradient into an image signal (video signal) via the D / A converter 46 and outputs the image signal to the monitor 8. . In this case, the image data of a plurality of frames to be subjected to the FFT processing is updated in time series one by one or a plurality of frames, and converted into a moving image.

The operation of the present embodiment having such a configuration will be described. As shown in FIG. 1, the endoscope 5 is connected to the light source device 6 and the CCU 7, and the power is turned on. The state when the power is turned on is initially set to a normal observation mode state as shown in FIG. 1, for example.
In this normal observation mode state, the light source device 6 is provided with a normal light lamp 19 a on the illumination optical path as shown in FIG. 1, and this normal light lamp 19 a is lit from the lamp lighting / pulse lighting circuit 22. Electric power is supplied, and the normal light lamp 19a continuously emits normal light (visible light).
In this state, the normal imaging element 33a is arranged on the imaging optical path in the camera head 4, and normal light observation by the endoscope 5 is performed under the illumination light by the normal light. Can do.

Therefore, the surgeon inserts the insertion portion 11 of the endoscope 5 into the abdomen of the patient 2 and sets the observation target region 25 so as to be observed.
In the normal observation mode, an image sensor driving signal is applied from the image sensor driving circuit 38 to the normal image sensor 33a, and a video signal corresponding to the visible light image captured by the normal image sensor 33a is a signal. It is generated by the processing circuit 39 and displayed on the monitor 8. On the other hand, when the surgeon intends to observe the blood vessel 51 in the observation target region 25, the switching lever 34 is operated to switch the observation mode to the infrared observation mode.
Then, the motor 17 in the light source device 6 and the motor 35 in the camera head 4 are rotated by the switching signal from the switching lever 34, and the infrared observation system 1 performs infrared light observation as shown in FIG. Switch to the operating state of the mode.

In this infrared light observation mode, as shown in FIG. 7, in the infrared light observation mode, the IR lamp 19b is disposed on the illumination optical path, and this IR lamp 19b is supplied with pulse lighting power from the lamp lighting / pulse lighting circuit 22. The IR lamp 19b is pulse-lit as shown in FIG. 8A, and infrared light is pulsed from the front end surface via the light guide 15.
That is, as shown in step S <b> 1 of FIG. 9, infrared light is pulse-irradiated on the observation target region 25 side in the patient 2. Further, an IR imaging element 33 b is arranged on the imaging optical path in the camera head 4 by the operation by the switching lever 34.
Then, as shown in FIG. 8B, infrared imaging is performed in synchronization with the pulse lighting in FIG. That is, as shown in step S2 of FIG. 9, in synchronization with pulse lighting (pulse irradiation), the IR imaging element 33b performs infrared imaging by sampling in synchronization with a predetermined period of pulse irradiation.

The imaging signal imaged by the IR imaging element 33b is read at a high speed as shown in FIG. The read image signal is subjected to signal processing by the signal processing circuit 39, converted into a video signal, and input to the sampling processing circuit 40.
As shown in FIG. 5, the CPU 41 in the sampling processing circuit 40 switches the changeover switch 42 so that the contact b is turned on as shown in FIG. 5 when the pulse lighting timing signal Sp is input. The video signal input from the signal processing circuit 39 is converted into digital signal data by the A / D converter 43 and stored in the RAM 44 at, for example, an address of a clock pulse timing (not shown) synchronized with the timing signal Sp. Is done. FIG. 6A shows an example of data obtained by sampling infrared imaging synchronized with pulse irradiation when a blood vessel 51 is present inside the living tissue surface of the observation target region 25. The sampled data is stored in the RAM 44 as shown in step 3 of FIG. 8D and FIG.

The time-series data stored in the RAM 44 is FFT processed by the CPU 41 in the next step S4. That is, as shown in FIG. 6B, actually, the measured values vary, but the CPU 41 performs FFT on the pixel data at the same coordinate position in the image data for several frames or several tens of frames. By performing the processing, it is possible to extract signal components having the same frequency component with respect to the sampling period, and it is possible to reduce or eliminate noise components generated almost independently of the sampling period.
By this FFT processing, the CPU 41 calculates information on the temperature amplitude ΔT and information on the temperature gradient as a temporal temperature change rate in the next step S5. Note that instead of the FFT processing, for example, signal components may be extracted by suppressing noise by wavelet transform processing.

Further, in the next step S6, the CPU 41 performs processing for calculating, for example, an average value of the temperature amplitude ΔT (may be an average value of the temperature gradient at an appropriate time) from the information of the temperature amplitude ΔT, and further shows in step S7. Thus, for example, the addition average value is output to the monitor 8 via the D / A converter 46 and imaged.
In addition, when performing the addition averaging process, by imaging as a difference amount obtained by subtracting the entire average value, more information on the temperature difference based on the difference in characteristics in the infrared between the blood vessel 51 and other living tissue can be obtained. You may make it image-form clearly.
For example, a blood vessel image as shown in FIG. 10 can be obtained on the monitor 8. In FIG. 10, the solid line shows an image of the blood vessel 51 according to the present embodiment, and the dotted line schematically shows an image in which the blood vessel 51 is blurred when, for example, infrared light is continuously irradiated.

When infrared irradiation is not pulse irradiation but continuous irradiation, the data obtained based on the IR imaging device 33b is blood and biological tissue in the blood vessel 51 than the waveform example shown in FIG. Infrared absorption causes temperature saturation or the lattice vibration mode involved in infrared absorption to be easily saturated, or the temperature is transmitted to the surrounding tissue, and the temperature becomes uniform. The difference in data obtained between living tissues is reduced.
For this reason, in the case of continuous irradiation, when imaged, as shown by the dotted line in FIG. 10, the reflected light image of the infrared light between the blood vessel portion and the other biological tissue, that is, the blurred outline with little influence of the temperature difference. It becomes an image.

On the other hand, in this embodiment, the imaging signal obtained at the time of each pulse irradiation by the pulse irradiation is easily affected by noise because the amount of illumination light itself is small, but the blood in the blood vessel 51 It is possible to minimize the effects similar to temperature saturation due to infrared absorption due to IR and temperature saturation due to infrared absorption in other living tissues. For example, as shown in the schematic example of FIG. 6A, by adopting pulse irradiation, a pulse irradiation stop period is formed. Therefore, data with a large temporal change amount can be obtained. And the data by the temperature difference of a biological tissue and the blood vessel 51 can be detected more faithfully.
Then, noise having no correlation amount such as FFT processing is suppressed for a plurality of frames in these data, and a signal component having a high correlation amount (substantially the same) is extracted as a signal component. Temperature or temperature difference information can be calculated with a high S / N. And by imaging, the information of the temperature difference between a biological tissue and a blood vessel can be extracted more faithfully, and a clear blood vessel observation image can be obtained as shown in FIG.

As described above, according to the present embodiment, it is possible to observe an image of a blood vessel in a deep part of a living tissue by performing imaging under pulse irradiation of infrared light. Therefore, according to the present embodiment, it is possible to smoothly perform an operation or the like under endoscopic observation.
Further, according to the present embodiment, the operator can perform endoscopic observation in a desired observation mode by switching between the normal observation mode and the infrared observation mode by infrared pulse lighting by operating the switching lever 34. Can do.
Next, a modification according to this embodiment will be described. Regarding the temperature gradient, for example, when information close to the period shown in FIG. 6A is obtained, the CPU 41 determines the number of data to be used for generating an image of one screen using the information.

More specifically, the number of data to be used for generating an image of one screen is determined by using, for example, about 1/4 of one period of the temperature gradient as a unit. In other words, if data of about 1/4 of one cycle is used as a unit, the average value can be reproduced even when the temperature gradient changes, and the temporal change of the imaged scene can be dealt with. .
Then, the user may be able to select and set how many times the number of data used for generating one screen is this unit.
In this case, if the multiple is increased, the followability to the movement is lowered, but the S / N can be increased. In other words, the user can appropriately set the multiple according to the degree of priority given to the tracking of the motion and the S / N in the moving image having the trade-off relationship by the selection setting of multiples.

According to this modification, it is possible to appropriately set the number of data actually used when an image of one screen is generated from temperature gradient information.
In the present embodiment, the period in the case of pulse irradiation is assumed to be constant, and although not specifically mentioned, the period may be variably set based on temperature gradient information and the like as described in the second embodiment. .

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 11 shows an infrared observation system 1B according to the second embodiment of the present invention. This infrared observation system 1B is a band pal filter that transmits, for example, a wavelength band that is a peak wavelength of absorption in the moisture absorption characteristic before the IR lamp 19b in the infrared observation system 1 shown in FIG. 60 is provided.
In this embodiment, the CPU 41 (see FIG. 5) in the sampling processing circuit 40 sends a control signal Sc to the pulse generation circuit 22 a built in the lamp lighting / pulse lighting circuit 22 in the light source device 6. The pulse generation circuit 22a changes the period of pulses generated when performing pulse lighting, etc., according to the control signal Sc.

FIG. 12 shows the transmission wavelength band of the band-pass filter 60 set to the transmission characteristics of blood or the like shown in FIG. Among these transmission characteristics, the transmittance of water (similar to the characteristics of blood) is the lowest, that is, a wavelength band of 1.45 μm ± 0.15 μm where the absorption reaches a peak (the band is indicated by the symbol Ra), The transmission band of the band pass filter 60 is set to 9 μm ± 0.2 μm (indicated by the symbol Rb). Note that the transmission wavelength band of the bandpass filter 60 is not limited to the absorption peak wavelength band of moisture transmittance, and may be set to a wavelength band in which the transmittance between blood and other living tissue is greatly different.
Other configurations are the same as those of the first embodiment. Next, the operation of this embodiment will be described.
The present embodiment has the same operation as that of the first embodiment with respect to the normal observation mode.

When the mode is switched to the infrared light observation mode, infrared light in a wavelength band that has passed through the bandpass filter 60 is used on the observation target region 25 side, so that the transmittance of living tissue such as fat, blood, and blood vessels can be obtained. The difference can be increased. For this reason, it is possible to obtain an image due to a temperature difference of the blood vessel with a better contrast than in the case of the first embodiment.
In addition to the operations described in the first embodiment, the present embodiment has the following operations. As described in the first embodiment, the monitor 8 displays an image picked up under pulse irradiation. In this case, the user uses the mouse 61 to indicate a region of interest considered to be, for example, a blood vessel portion in the image displayed on the monitor 8.
In response to this instruction, the CPU 41 reads data corresponding to the region of interest from the RAM 44 and displays it in time series as shown in FIG. 6A, for example. When performing this data display, noise reduction processing may be performed by FFT processing.

The user does not have to change the pulse lighting cycle or the like when the temperature change as shown in FIG. 6A, that is, a periodic temperature gradient is formed. In this case, the operation is the same as that of the first embodiment. On the other hand, for example, if the lighting time in pulse lighting is too long, the temperature change or the temperature gradient is small compared to FIG. .
When such a characteristic is displayed, the user operates the mouse 61 to instruct the CPU 41 to shorten the pulse lighting cycle. In response to this instruction, the CPU 41 sends a control signal Sc to the pulse generation circuit 22a built in the lamp lighting / pulse lighting circuit 22 to shorten the pulse lighting cycle. That is, the period of pulse irradiation is changed. By shortening the pulse lighting cycle, it is possible to reduce an influence similar to temperature saturation and obtain an image that allows a blood vessel to be observed more clearly.

Note that the CPU 41 may perform the instruction operation for changing the pulse lighting cycle instead of the user. In this case, the CPU 41 changes the pulse lighting cycle in comparison with the reference temperature gradient characteristic data stored in the ROM 45 in advance. When the characteristic of temporal change of the temperature gradient actually obtained is small compared to the reference characteristic data, the pulse lighting cycle is shortened. Alternatively, the period is kept constant, and at least the pulse irradiation time ratio is reduced or the stop time ratio is increased. By doing in this way, the influence similar to temperature saturation can be reduced.
Thus, according to the present embodiment, imaging is performed by pulse irradiation of infrared light in a wavelength band in which the difference between the transmittance of blood and other living tissue is large. It is also possible to obtain a blood vessel image with good contrast.
Note that the pulse lighting cycle may be changed and set by the user at any time, not only when the pulse lighting cycle is changed and set after the temperature gradient information is obtained.
In addition, since the period of pulse irradiation (pulse lighting) is set to be changeable, infrared observation can be performed by setting a more appropriate pulse irradiation state even when the site and conditions to be observed are different. effective.

  Infrared light with high transmittance to living tissue is pulsed to reduce the effect of continuous irradiation, and due to differences in characteristics of blood vessels and other living tissue with respect to infrared light, However, a clear image can be obtained, and a surgical operation or the like under endoscopic observation can be performed smoothly.

FIG. 1 is an overall configuration diagram of an infrared observation system according to a first embodiment of the present invention. FIG. 2 is a diagram showing an outline of scattering / absorption characteristics in a living tissue in the visible to near-infrared region. FIG. 3 is a characteristic diagram of transmittance when the living tissue in the infrared wavelength region used in this embodiment is muscle, fat, blood vessel, blood, or the like. FIG. 4 is a diagram showing the water content in tissues and organs of a living body. FIG. 5 is a block diagram showing a configuration of a sampling processing circuit. FIG. 6 is an explanatory diagram for detecting a temperature difference by a sampling processing circuit. FIG. 7 is an overall configuration diagram of an infrared observation system during infrared observation. FIG. 8 is a diagram showing the timing of pulse irradiation and infrared imaging during infrared observation. FIG. 9 is a flowchart of the operation during infrared observation. FIG. 10 is a view showing an example of a blood vessel image obtained by this embodiment. FIG. 11 is an overall configuration diagram of an infrared observation system at the time of infrared observation in Example 2 of the present invention. FIG. 12 is a diagram showing a transmission wavelength band of a bandpass filter set on the transmittance characteristic. FIG. 13 is a diagram showing absorption characteristics in the visible and near-infrared regions with hemoglobin.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Infrared observation system 2 ... Patient 3 ... Optical endoscope 4 ... Camera head 5 ... Endoscope 6 ... Light source device 7 ... CCU
DESCRIPTION OF SYMBOLS 8 ... Monitor 11 ... Insertion part 19a ... Normal light lamp 19b ... IR lamp 22 ... Lamp lighting / pulse lighting circuit 33a ... Normal image sensor 33b ... IR image sensor 38 ... Image sensor drive circuit 39 ... Signal processing circuit 40 ... Sampling Processing circuit 41 ... CPU
41a ... temperature difference calculation processing 41b ... temperature gradient calculation processing 44 ... RAM
51 ... Blood vessels

Claims (6)

Pulse irradiation means for irradiating a living tissue with pulsed infrared light; and
Infrared imaging means for imaging the biological tissue irradiated with the infrared light at the time of pulse irradiation;
With a pulse irradiation stop time formed by the infrared imaging means, a plurality of output signals imaged at the time of pulse irradiation at different times are used for blood vessels in the living tissue, blood in the blood vessels, and infrared light. Image generating means for generating an image corresponding to a temperature difference with other biological tissue having different optical characteristics;
An infrared observation system characterized by comprising:   The image generation means synchronizes with the pulse irradiation, from a plurality of data obtained by sampling the output signal of the infrared imaging means in time series, the temperature as the temporal temperature change rate of the data for the same position at different times The infrared observation system according to claim 1, further comprising a temperature gradient calculation unit that calculates a gradient.   The apparatus according to claim 2, further comprising a control unit configured to perform setting control or data processing of the number of data used for the plurality of output signals used for generating the image based on a calculation result of the temperature gradient calculation unit. The described infrared observation system.   The infrared observation system according to claim 3, wherein the control unit performs data processing for noise suppression on a plurality of data used for generating the image.   The infrared observation system according to claim 1, wherein the wavelength of infrared light of the pulse irradiation is set in the vicinity of a moisture absorption peak.   The infrared observation system according to claim 1, further comprising cycle setting means for changing and setting the cycle of the pulse irradiation.

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