JPH05130995A - Optical tomographinc imaging device using spatial difference - Google Patents

Abstract

PURPOSE:To obtain satisfactory tomographic images with high resolution by accurately suppressing scattered beam components while detecting light emitted from an intersection between the surface of a testee and the optical axis of irradiating beam light at all times. CONSTITUTION:A testee 1 is irradiated with the beam light from a light source 4, and the light transmitted through the testee 1 is detected by a photodetector (1) 5 arranged on the optical axis of this beam light and a photodetector (2) arranged on an axis at a prescribed angle to the optical axis of the beam light. At such a time, a light source 12 for ranging, line sensor 11 and controller 16 measures a distance between the photodetector 5/6 and the testee 1 and based on this distance, an X stage 9 is moved by a driving device 17. Then, the photodetectors 5 and 6 are displaced and therefore, the light from the intersection between the optical axis and the surface of the testee can be always detected by the respective detectors. Then, the tomographic images of the testee are reconstructed by a differential amplifier 20 and a computer 22 and displayed at a display device 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical tomographic imaging apparatus suitable for imaging information on tissues and organs inside a living body using light.

[0002]

2. Description of the Related Art Light in the red to near-infrared region is highly permeable to living tissues, and absorbs substances such as hemoglobin, myoglobin, and cytochrome oxidase, which are responsible for oxygen metabolism in the living body, and oxygen bonds of these substances. It has features such as a change in absorption spectrum corresponding to the state. US Pat. No. 4,223,680 discloses an apparatus for obtaining oxygen metabolism in a living body by utilizing such characteristics.

Further, recently, oxygen metabolism information in the living body is represented by images such as a tomographic image and a fluoroscopic image, and an effective method is shown for measuring the metabolic distribution of each organ in the living body and diagnosing cancer. For example, in Japanese Patent Laid-Open No. 60-72542, a two-dimensional tomographic image of oxygen concentrations of hemoglobin, myoglobin, and cytochrome oxidase in a living body is obtained by using an algorithm similar to X-ray CT, and organs such as blood circulation disorders are obtained. Devices useful for diagnosing sexual disorders are shown. Japanese Patent Publication No. 2-50733 discloses a device for diagnosing a breast cancer occurring in a human female breast by a near infrared spectrum.

By the way, when the measurement is performed from the outside using light and the inside of the living body is represented as a two-dimensional distribution image or as local information, tissue information inside the living body is obtained,
There is a problem that the irradiated light spreads over a wide range due to strong scattering by the epidermis and internal tissues of the living body, resulting in extremely poor spatial resolution. Therefore, the present applicant proposes a method of suppressing light scattering in Japanese Patent Application Nos. 2-81552 and 2-119468 in order to obtain a tomographic image with high spatial resolution.

The apparatus used in this method detects the light on the optical axis of the light beam with which the subject is irradiated, so that the beam optical axis is extended to the transmission side of the subject. The first photodetector arranged in the optical axis and the optical axis at the point where the detector-side surface of the subject intersects with the optical axis, so that the light scattered at a certain angle with the optical axis is detected. It comprises a second photodetector arranged at a predetermined angle, and means for suppressing the scattered component by making a difference between the respective light outputs of the photodetector. That is, the first detector detects a straight-ahead component that has passed straight through the subject and is slightly transmitted and a scattered component that has scattered inside the subject, and the second detector passes through the same optical path as the above-described scattered component. Since the scattered component is detected, the scattered component is removed by subtracting the components detected by the two detectors, and only the straight-ahead component can be detected.

[0006]

However, in the above-mentioned conventional apparatus, when the distance between the detection side surface of the object and the detector changes, the second photodetector changes the distance between the object detection side surface and the beam light. The light emitted from the point where the optical axes intersect cannot be detected. Therefore, there is a problem in that the scattering component detected by the first detector and the scattering component detected by the second detector do not coincide with each other, an error occurs, and the obtained tomographic image deteriorates. It was

The present invention has been made in view of the above circumstances, and detects the light emitted from the intersection of the surface of the subject and the optical axis of the irradiated beam light regardless of the distance between the subject and the detector. Therefore, it is an object of the present invention to provide an optical tomographic imaging apparatus capable of accurately suppressing a scattered light component and easily obtaining a good tomographic image with high resolution.

[0008]

An optical tomographic imaging apparatus according to the present invention is provided with a light source for generating a beam of light for irradiating a subject and an optical axis of the beam of light, which is transmitted through the subject of the beam of light. A first detector for detecting the reflected light or the light reflected from the inside of the object, and the light transmitted through the object of the beam light, which is arranged on an axis forming a predetermined angle with the optical axis of the light beam. A second detector that detects the light reflected from the inside of the subject, a distance measuring unit that measures the distance between the first and second detectors and the subject, and a distance measuring unit that detects the distance. Position control means for displacing the second detector so as to detect light from the intersection of the optical axis and the surface of the subject based on the distance;
Calculating the output of the detector and the output of the second detector,
And a tomographic image generation means for generating tomographic image information of the subject based on this.

[0009]

The object is irradiated with the light beam from the light source, the first detector is arranged on the optical axis of the light beam, and the first detector is arranged on the axis forming a predetermined angle with the optical axis of the light beam. The second detector detects the light of the light beam that has passed through the subject or the light reflected from the inside of the subject. At this time, the distance measuring means measures the distance between the first and second detectors and the object, and the position control means displaces the second detector based on the distance, and the respective detectors are displaced. Then, the light from the intersection of the optical axis and the surface of the subject is detected. Then, the tomographic image generation means calculates the output of the first detector and the output of the second detector, and based on this, tomographic image information of the subject is generated.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration explanatory view showing a configuration of an optical tomographic imaging apparatus according to a first embodiment of the present invention.

In the first embodiment, the subject 1 is placed on the X stage 2,
An example in which the tomographic image is obtained from the transmitted light by irradiating the subject 1 with the beam light from the light source (1) 4 is shown, which is arranged on the subject stage composed of the θ stage 3.

The light source (1) 4 is adapted to generate a beam of light having a wavelength having a high optical transparency to the subject 1, for example, a near infrared region in the case of living tissue, and irradiate the subject 1. , At a position facing the light source (1) 4 across the subject 1,
A photodetector (1) 5 and a photodetector (2) 6 for detecting the light transmitted through the subject 1 are provided.

Photodetector (1) 5, photodetector (2) 6
Immediately before the above, a collimator (1) 7 and a collimator (2) 8 are provided to limit the incident angle in order to remove extraneous light such as extraneous light. The photodetector (1) 5, the photodetector (2) 6, the collimator (1) 7, and the collimator (2) 8 are movable in the optical axis direction of the light beam emitted from the light source (1) 4. It is arranged on the X stage 9 for various detectors. Further, the photodetector (1) 5 is arranged on the optical axis of the light beam, and the photodetector (2) 6 is arranged on the axis forming a predetermined angle with the optical axis of the light beam. Further, a lens 10 and a line sensor 11 are provided on the X stage 9, and a light source (2) 12 for distance measurement is used to detect the subject from the photodetector (1) 5 and the photodetector (2) 6. Distance measuring means for measuring the distance to the transmission side of 1 is configured.
Reference numeral 13 is the optical axis of the light source (1) 4 and the light source (2) 12
It is a half mirror or a dichroic mirror for matching the optical axis of. An optical filter (1) 14 for removing the light of the distance measuring light source (2) 12 is provided in front of the collimator (1) 7 and the collimator (2) 8, and the light of the light source (1) 4 is provided in front of the lens 10. The optical filters (2) 15 for removing the light are respectively arranged.

A control device 16 for controlling the positions of the photodetectors (1) 5 and (2) 6, and the photodetectors (1) 5 and 5.
(2) Driving device for driving X stage 9 including 6 (3)
A position control means composed of 17 is provided,
The control device 16 detects the distance between the subject 1 and the photodetectors (1) 5 and (2) 6 from the signal obtained from the line sensor 11, and drives the drive signal so as to keep this distance constant. It outputs to the device (3) 17 and drives the X stage 9 to displace the positions of the photodetectors (1) 5 and (2) 6.

On the other hand, on the output side of the photodetector (1) 5 and the photodetector (2) 6, an amplifier (1) for weighting the angle formed by the detector with respect to each output and correcting the sensitivity is provided. 18, an amplifier (2) 19 and a difference amplifier 20 that suppresses a light scattering component and detects a rectilinear component by taking a difference between the outputs of the amplifier (1) 18 and the amplifier (2) 19. There is. The output terminal of the difference amplifier 20 is connected to a computer 22 that performs each process for reconstructing an optical tomographic image via an A / D converter 21, and outputs light from the straight-ahead component obtained by the difference amplifier 20. The tomographic image is reconstructed and displayed on the display device 23.

Further, a driving device (1) 24 and a driving device (2) 25 for moving and rotating the subject 1 to measure the data necessary for reconstruction of the optical tomographic image are provided, and each of them is driven. It is connected to the X stage 2 and the θ stage 3 for the subject.

Next, the operation of this embodiment will be described.
First, when the near-infrared light generated from the light source (1) 4 is applied to the subject 1 of the biological tissue, the near-infrared light is diffused by the tissue and is transmitted. The transmitted light, which is spatially spread in this way, is at a predetermined angle with respect to the intersection of the photodetector (1) 5 that is correctly aligned on the optical axis and the optical axis and the transmission side surface of the subject 1. Arranged photodetector (2) 6
When detected by and, the photodetector (1) 5 on the optical axis detects a rectilinear component that has traveled straight inside the subject and a scattered component that has been scattered, and the photodetector (2) 6 will also scatter. Only the component is detected.

Then, after the outputs of the respective photodetectors are weighted by the amplifier (1) 18 and the amplifier (2) 19 according to the detection angle, and then they are differentiated by the differential amplifier 20, the scattered component is canceled and the object of the subject is detected. Only the straight-ahead component corresponding to the absorbance on the optical axis is detected. Further, the computer 22 controls the drive unit (1) 24 and the drive unit (2) 25,
By moving and rotating the subject 1 to detect the straight-ahead components from all directions of the subject 1, and by using an image reconstruction algorithm similar to X-ray CT, a near-infrared optical tomographic image of the subject, that is, a living body is obtained. Obtainable.

By the way, since the shape of the subject 1 is usually not circular, when the subject is moved and rotated, the photodetectors (1) 5,
(2) The distance between 6 and the subject 1 changes. Therefore, the distance is made constant by the distance measuring means and the position control means.

The light emitted from the light source (2) 12 for distance measurement is different from the near-infrared light emitted from the light source (1) 4, and has a wavelength that has low permeability to the subject, for example, the second YAG light. High frequency green light is used. The dichroic mirror 13 makes this light coincide with the optical axis of the light source (1) 4 and irradiates the subject 1 from the detector side. Then, the near-infrared light from the light source (1) 4 is removed by the optical filter (2) 15, and the green scattered light on the surface of the subject is imaged by the imaging lens 10 in the line sensor 1.
Image on 1. Imaging lens 10 and line sensor 1
1 is arranged so that the image of the scattered light moves on the line sensor 11 with respect to the movement of the green scattered light in the optical axis direction. When the scattered light moves in the optical axis direction, the line sensor 1 corresponds to this. The image formation position of the scattered light on 11 changes. Therefore, the control device 16 feedback-controls the drive device (3) 17 so that the light distribution detected by the line sensor 11, that is, the position is constant, and drives the X stage 9. As a result, the distance between the photodetectors (1) 5, (2) 6 and the subject 1 is always kept constant.

As described above, according to the present embodiment, even when the distance between the subject and the detector changes, the detector and the subject are displaced by displacing the detector according to the change. The distance can be kept constant at all times. For this reason,
Since the light emitted from the intersection of the surface of the subject and the optical axis of the irradiated beam light can be detected at all times, the scattering component can be suppressed with high accuracy, and a tomographic image with high image quality can be reconstructed.

As the distance measuring means, a device that uses ultrasonic waves instead of light, that is, a device that measures the distance from the time difference between the reflected echo signals of the ultrasonic waves may be used. Further, the light source (1) 4 and the light source (2) 12 may be sequentially irradiated when detecting the straight-ahead component from the subject. In this case, the optical filter (1) 14 and the optical filter (2) 15 are not required.

2 and 3 relate to a second embodiment of the present invention, FIG. 2 is a structural explanatory view showing the constitution of an optical tomographic imaging apparatus, and FIG. 3 shows respective reflected light components detected by a detector. It is a waveform diagram.

The second embodiment is an example of an apparatus for irradiating a subject with pulsed light and obtaining a tomographic image from the reflected light.

As shown in FIG. 2, the optical tomographic imaging apparatus includes a pulse laser 31 for generating picosecond-order pulsed light with light having a wavelength in the near-infrared region that is highly transparent to a living body,
Half mirror 32 for superimposing the pulsed light on the irradiation detection optical axis
And a lens 34 that guides the pulsed light to a light guide (1) 33, and a straight component and scattering that irradiate the subject 1 with the pulsed light and reflect on the same optical axis as the irradiation optical axis. A collimator (1) 35 arranged to detect light containing a component, and a collimator (1) 35 arranged on an axis forming a predetermined angle with the irradiation optical axis to detect only a scattered component of the reflected light of the pulsed light. A collimator (2) 36, a light guide (2) 37 connected to the collimator (2) 36 and transmitting the reflected light of the pulsed light, the collimator (1) 35, the collimator (2) 36 and the light guide (1). ) 33, (2) 37, streak camera 38 for measuring the time-resolved waveforms of the respective pulsed lights
It has and.

The collimators (1) 35, (2) 36,
And the front ends of the light guides (1) 33, (2) 37 are
It is arranged on an XYZ stage 39 that is movable in the XYZ directions. Further, the distance between the subject 1 and the collimator is detected from the rise time of the pulsed light obtained from the streak camera 38, and the positions of the collimator (1) 35 and the collimator (2) 36 are set so that this distance becomes constant. A control device 39 for controlling the movement of the collimator 1 in the optical axis direction and a drive device 40 for driving the XYZ stage 39 by the drive signal of the control device 39 and displacing the collimator (1) 35 and the collimator (2) 36 are provided. .. Here, since the position of detecting the reflected pulsed light is determined by the positions of the collimator (1) 35, the light guide (1) 33, the collimator (2) 36, and the light guide (2) 37, the collimator (1) 35, ( 2) The distance between 36 and the subject 1 is proportional to the distance between the detector and the subject.

Further, the time-resolved waveforms of the respective pulsed lights obtained from the streak camera 38 are arithmetically processed to cancel the scattered components, and the reflected pulsed lights with little scattering corresponding to the absorbance on the optical axis of the subject 1. A signal processing device 41 for obtaining the signal is provided and is connected to the computer 42. The computer 42 reconstructs an optical tomographic image from the signal of the reflected pulsed light obtained by the signal processing device 41,
The information is displayed on the display device 43.

The pulse laser 3 is used to synchronize the sweep timing of the streak camera 38 with the pulsed light.
Beam sampler 4 arranged on the optical path of the light emitted from
4 and a photodiode 45 for converting the pulsed light detected by the beam sampler 44 into an electric pulse, which are connected to a streak camera 38.

Next, the operation of this embodiment will be described.
First, the near-infrared pulsed light generated by the pulse laser 31 is applied to the half mirror 32, the lens 34, and the light guide (1) 3.
3. When the subject 1 is irradiated with light through the collimator (1) 35, the pulsed light is widely spread due to scattering by the tissue, while partly transmitting and partly reflecting. The collimator (1) 35 and the light guide (1) in which the pulsed light reflected while spreading is correctly aligned on the irradiation optical axis.
It is detected by the streak camera 38 through 33. Also,
On the other hand, the streak camera 38 detects pulsed light that forms an angle with the irradiation optical axis through the collimator (2) 36 and the light guide (2) 37. Streak camera 3
Each reflected pulsed light detected in 8 is shown in FIG.
And as shown in FIG.

In FIG. 3A, the pulse waveform at the time zero position is the waveform immediately after the pulse laser 31 is emitted, and the subsequent waveforms are the object 1 and the collimator (1) 35.
And a pulse waveform on the optical axis that rises with a time delay T corresponding to the distance from the light guide (1) 33, reflects on the surface of the subject and inside, and spreads in time. Also, FIG.
(B) is a reflection pulse waveform detected by the collimator (2) 36 and the light guide (2) 37 which are arranged at a position forming an angle with the optical axis. Here, the time delay T in FIG. 3A corresponds to the optical path length of the light that is irradiated to the subject 1 and reflected on the surface, that is, the distance between the subject 1 and the collimator and the front end face of the light guide. The XYZ stage 39 is controlled to move in the optical axis direction by the driving device 39 and the driving device 40 so that the time delay T becomes constant, and the collimator (1)
35, (2) 36 and light guides (1) 33, (2)
By displacing 37, the distance between the subject and the detector can be made constant at all times.

Then, the time-resolved waveforms thus obtained by the streak camera 38 are arithmetically processed by the signal processing device 41 at each time, so that the scattered component is canceled and the reflected pulse having a small influence of scattering is generated. Light is obtained. FIG. 3C shows a time waveform of the reflected pulsed light in which the scattered component is canceled. In addition, the XYZ stage 39
Is moved on a plane perpendicular to the optical axis, the time-resolved waveform similar to the above is obtained at each point, an optical tomographic image of the inside of the subject is constructed by the computer 42, and displayed on the display device 43.

As described above, according to this embodiment, when the straight traveling component of the reflected pulsed light from the subject is obtained, the distance between the subject and the detector is always constant as in the first embodiment. Since it is possible to always detect the light emitted from the intersection between the surface of the subject and the optical axis of the irradiated beam light, it is possible to suppress the scattering component with high accuracy.

The distance between the subject and the detector may be measured using the distance measuring means shown in the first embodiment.

FIG. 4 is a structural explanatory view showing the structure of the main part of an optical tomographic imaging apparatus according to the third embodiment of the present invention.

In the third embodiment, instead of the means for changing the position of the detector shown in the first embodiment, the detection angle of the second detector (of the collimator (2) 8 and the photodetector (2) 6 is changed). This is an example in which a means for changing the angle is provided so that the light emitted from the intersection of the surface of the subject and the irradiated pulsed light optical axis can be detected.

As shown in FIG. 4, immediately before the collimator (2) 8, an A / O polarizer (acoustic oscilator polarizer) whose polarization angle can be changed by vibrating a vibrator.
45 are arranged. Further, the control device 46 for controlling the polarization angle of the A / O polarizer 45 based on the distance between the object 1 and the photodetector measured by the distance measuring means similar to the first embodiment, and the A A drive device 47 that outputs a drive signal to the / O polarizer 45 is provided. Others are the same as those in the first embodiment, the same reference numerals are given and the description thereof is omitted.

The scattered light of the light emitted from the distance measuring light source (2) 12 to the subject 1 is imaged on the line sensor 11, and at this time, the subject 1 and the photodetector (1). 5, (2)
The image of the scattered light on the line sensor 11 moves corresponding to the distance from the line sensor 6. Then, the control device 46 calculates the distance between the subject 1 and the detector based on the light intensity distribution on the line sensor 11, and the control device 4 is based on the distance data.
6, A / O polarizer 45 is driven by the drive device 47,
The polarization angle of the / O polarizer 44 is changed. This allows
The detection angle of the photodetector (2) 6 is made to coincide with the intersection of the optical axis of the irradiated light beam and the surface of the subject.

Then, the beam light components detected by the photodetectors (1) 5 and (2) 6 are supplied to the amplifier (1) 18 and the amplifier (2) 19, respectively, and the target components are received in the same manner as in the first embodiment. A tomographic image of the specimen is generated. At this time, the amplifier (2) 1
At 9, the photodetector output is weighted according to the change in the detected angle.

As described above, according to this embodiment, by changing the detection angle of the second detector, it is possible to always detect the light emitted from the intersection of the surface of the subject and the optical axis of the irradiated beam light. Therefore, it is possible to accurately suppress the scattering component and obtain a good tomographic image with good resolution.

FIG. 5 is a structural explanatory view showing the structure of the main part of an optical tomographic imaging apparatus according to the fourth embodiment of the present invention.

The fourth embodiment is an example of an apparatus having means for mechanically keeping the distance between the object and the detector constant.

As shown in FIG. 5, the optical tomographic imaging apparatus has a cylindrical fixed portion 51 and is movable in the axial direction of the fixed portion 51. The photodetector (1) 5 and the photodetector (2 )
6, and a tip forming portion 52 in which the collimator (1) 7 and the collimator (2) 8 are provided. The photodetector (1) 5, the photodetector (2) 6, and the collimator (1)
7. The collimator (2) 8 is fixed at a predetermined position in the tip forming section 52, and a transparent member 53, which is made of, for example, optical glass, which transmits light is arranged on the tip side of the tip forming section 52. .. The front end surface of the transparent member 53 is located at the intersection of the optical axes of the collimator (1) 7 and the collimator (2) 8. The rear end surface of the tip forming portion 52 and the fixed portion 5
An elastic member 54 for urging the tip forming portion 52 forward is provided between the elastic member 54 and the first member 1. That is, in this apparatus, the transparent member 53 is brought into contact with the subject 1 with a constant force, and the tip forming portion 52 is moved in accordance with the shape of the surface of the subject 1 to bring the transparent member 53 into contact with the subject 1. Surface (Subject 1
The surface) is always the intersection of the optical axes of the collimator (1) 7 and the collimator (2) 8. Further, the fixing portion 51 includes the tip forming portion 52 and the subject 1
On the other hand, it is mounted on a moving stage (not shown) for moving and scanning. The photodetector (1) 5 and the photodetector (2) 6 are connected to the amplifier (1) 18 and the amplifier (2) 19, respectively, and the other configurations are the same as in the first embodiment.

With the above construction, the surface of the subject 1 is always the intersection of the optical axes of the collimator (1) 7 and the collimator (2) 8, and therefore the photodetectors (1) 5 and 5.
The photodetector (2) 6 can always detect the light emitted from the intersection of the surface of the subject and the optical axis of the irradiated beam light. Therefore, the scattered component can be suppressed with high accuracy, and a good tomographic image with good resolution can be obtained. Also, the subject 1
The transparent member 53 and the transparent member 53 are brought into contact with each other to keep the distance between the subject and the detector constant, so that the above-mentioned effect can be easily and inexpensively provided without providing a special electric circuit or a driving device. Can be realized.

FIG. 6 is a structural explanatory view showing the structure of an optical tomographic imaging apparatus according to the fifth embodiment of the present invention.

The applicant of the present invention filed Japanese Patent Application No. 2-259 previously filed.
No. 914 proposes a device for obtaining a tomographic image of the inside of a body cavity organ using light. The fifth embodiment is an example in which the spatial difference method using reflected light shown in the second embodiment is applied to an endoscope configured by a fiber bundle having a small diameter that can be inserted into a body cavity organ.

As shown in FIG. 6, the optical tomographic imaging apparatus illuminates an endoscope 57 having an elongated insertion portion 56 to be inserted into a body cavity organ 55 and pulsed light, and an optical tomographic image is obtained from the reflected light. And an analysis device 58 for determining The same components as those in the second embodiment are designated by the same reference numerals and the description thereof will be omitted.

The insertion section 56 irradiates the internal cavity 55 with irradiation pulse light and detects the reflected light, so that one tip side has a concentric two-layer structure and the other analysis apparatus side has two layers of each layer. Y-shaped light guide 59 divided into the fiber bundles and the tip portion 56a of the insertion portion for the irradiation pulse light.
In order to irradiate the light in the circumferential direction, the prism 61 fixed to the disk-shaped gear 60 is rotatably provided. The gear 60 meshes with a gear 63 that is continuously provided at the tip of a rotary shaft that extends from the motor 62.
Is rotated so that the prism 61 is rotated and the irradiation pulse light is scanned in the circumferential direction of the tip portion 56a. An encoder 64 is connected to the motor 62, and a rotation amount and a rotation position value of the motor 62 are input to a control device 65 connected to the encoder 64.

Between the light guide 59 and the prism 61, a focusing lens 66 having a variable focal length for detecting the light which is irradiated to the internal organ 55 in the body cavity and reflected on the surface and inside thereof, and the reflection lens A collimator 67 for limiting the solid angle at which light is detected is provided. The focusing lens 66 is used for the internal organ 55 of the body cavity.
Is arranged on a rack-and-pinion mechanism 69 that moves the focal position of the focusing lens 66 in accordance with the distance between the light-emitting surface 68 and the light-emitting surface 68. The rack-and-pinion mechanism 69 has a rotation extended from a motor 70. The axis is connected. That is, the focusing lens 66 is displaced by the rotation of the motor 70, and the focal length is changed. The motor 7 has an encoder 7
1, the encoder 71 is connected to the control device 65 in the same manner as described above, and the rotation amount and the rotation position value of the motor 70 are input.

Further, the analysis device 58 includes a control device 65 for measuring the distance between the light emitting surface 68 and the internal organ 55 in the body cavity from the pulse waveform obtained from the streak camera 38, and a drive signal from the control device 65. Motor 62, 70
Drive the prism 61 and the focusing lens 6
Drive devices 72 and 73 for displacing 6 are provided.

Further, although not shown, this apparatus is provided with a light source for observing an endoscopic image, a light guide, an objective lens, an image guide, and an eyepiece lens.

Next, the operation of this embodiment will be described.
The pulsed light emitted from the pulse laser 31 is guided to the fiber bundle 59a on the central side of the concentric two-layer structure light guide 59, and is irradiated to the body cavity organ 55 as shown by the solid line in the figure. The irradiated pulsed light spreads spatially greatly due to scattering by the organ tissue. Here, the reflected light of the pulsed light is received by the light guide 59 having the concentric two-layer structure through the focusing lens 66 and the collimator 67, and among the light scattered and reflected inside the organ, as shown by the solid line in the figure. The light reflected on the optical axis is detected by the fiber bundle 59a on the center side, and the light off the optical axis is detected by the fiber bundle 59b on the outer circumference side as shown by the broken line in the figure. These detected reflected lights are guided to the analyzer 58, and the time-resolved waveform of each pulsed light is measured. At this time, the solid angle that can be detected by the central fiber bundle 59a and the solid angle that can be detected by the peripheral fiber 59b are set to be the same.

Then, the control device 65 measures the time delay of the rising portion of the reflected pulsed light, and calculates the distance between the light emitting surface 68 and the internal organ 55 in the body cavity from this. In accordance with the detected distance, the driving device 73 displaces the focus position of the focusing lens 66 so as to be on the surface of the internal organ in the body cavity, so that the surface of the internal organ in the body cavity and the irradiation pulsed light optical axis always intersect. Light is detected.

Further, the driving device 72 drives the motor 62 to rotate the prism 61, so that the pulsed light is scanned in the circumferential direction of the insertion portion 56. A computer 42 reconstructs a tomographic image based on the time-resolved waveform of the reflected pulsed light in each direction obtained by this scanning, and displays it on the display device 43.

As described above, the focus position of the focusing lens 66 is controlled so as to be on the surface of the internal organ in the body cavity, and the light from the intersection of the surface of the internal organ in the body cavity and the optical axis of the irradiation pulse light is detected. Similar to the example, the influence of light scattering can be removed with high accuracy, and an optical tomographic image with high resolution can be obtained. Further, according to the present embodiment, since the approach can be made from the inside of the body cavity, the applicable range can be expanded to a wide range such as the brain, heart, stomach and intestine.

FIG. 7 is a structural explanatory view showing the structure of an optical tomographic imaging apparatus according to the sixth embodiment of the present invention.

The sixth embodiment is an example of an apparatus which suppresses a light scattering component by using modulated light instead of the pulsed light of the second embodiment and by subtracting a phase difference signal of the modulated light.

As shown in FIG. 7, the optical tomographic imaging apparatus includes a light source 81 for generating continuous light in the near infrared region and an optical modulator 82 for temporally changing the intensity of the light from the light source 81. And an oscillator 83 for generating a reference signal for modulating in the optical modulator 82 at an extremely high cycle, for example, a cycle of 1 GHz. The optical modulator 8
The modulated light emitted from 2 is reflected by the half mirror 13 and applied to the subject 1 as in the first embodiment. In order to detect the reflected light from the subject 1, photodetectors (1) 84 and (2) 85 which respond in a time sufficiently shorter than the modulation period are provided, and a collimator (1) is provided in front of these detectors. ) 7, and a collimator (2) 8 are arranged.

The photodetectors (1) 84 and (2) 85 are
Phase detector (1) 86 and phase detector (2) 87 for detecting the phase of the light detected in synchronization with the oscillator 83.
Respectively connected to. These phase detectors (1) 86 and (2) 87 are signal processing devices 8 that suppress scattered components by performing arithmetic processing on the output signals that have been phase detected.
The computer 42 is configured to reconstruct a tomographic image based on the output of the signal processing device 88 and display the tomographic image on the display device 43.

Although not shown in the figure, the object 1 and the photodetectors (1) 84, (2) 85 are similar to the above-described embodiment.
Position control means is provided for controlling the position of the detector so that the distance between and is constant.

As in the device shown in the first embodiment,
It may be configured to detect the light transmitted through the subject.

First, the oscillator 83 generates a reference signal of about 1 GHz. The optical modulator 8 based on this reference signal
When 2 is driven, the continuous beam light emitted from the light source 81 is intensity-modulated at about 1 G hertz. When the subject 1 is irradiated with this modulated light, the phases of the reflected light and the transmitted light are shifted due to light scattering. This phase-shifted light is detected by the photodetectors (1) 84 and (2) 85 arranged in the same manner as in the above-described embodiment, and the respective phase delays are detected by the phase detector (1) 8
6, (2) 87 performs phase detection and detection.

Here, if the phase delay detected by the phase detector is, for example, 10 degrees, the distance of the light traveling during that time is 1
It is 8.75 mm. That is, by detecting the phase of the modulated light, the same effect as that of the embodiment using the pulsed light can be obtained. Then, each phase detector (1) 86,
(2) The scattering component is suppressed by performing the arithmetic processing on the phase obtained in 87 by the signal processing device 88, and only the phase corresponding to the irradiation optical axis is measured. Based on this, the computer 42 reconstructs a tomographic image.

As described above, even when the modulated light is used, the scattered component can be suppressed with high accuracy as in the case where the pulsed light is used.

FIG. 8 is a structural explanatory view showing the structure of an optical tomographic imaging apparatus according to the seventh embodiment of the present invention.

Conventionally, when measuring the oxygen saturation of hemoglobin, myoglobin, cytochrome, etc., the absorbance of near-infrared light of 2 to 4 kinds of wavelengths is obtained, and the simultaneous equations are solved for each absorbance. .. The seventh embodiment is an example of an optical tomographic imaging apparatus suitable for measuring the hemoglobin and the like by using pulsed light of two wavelengths.

As shown in FIG. 8, the optical tomographic imaging apparatus uses, as a light source, a pulse laser 91 for generating pulsed light on the order of picoseconds, and the pulsed light (wavelength λ0) as excitation light and a wavelength different from that of the excitation light. And a dye laser (1) 92 (wavelength .lambda.1) and a dye laser (2) 93 (wavelength .lambda.2) which generate pulsed light. Further, in front of the pulse laser 91, a half mirror 94 that divides the pulsed light of the wavelength λ0 into two is disposed, and the dye laser (2)
In front of 93, a dichroic mirror 95 for superposing pulsed lights of λ1 and λ2 so as to coincide with each other both temporally and spatially is arranged. Reference numeral 96 in the figure is a total reflection mirror in which aluminum or the like is vapor-deposited. The pulsed lights of the respective wavelengths are applied to the subject 1 with the optical axis and the temporal rise matched.

A collimator 97 composed of a lens and a pinhole for detecting the transmitted light of the pulsed light at a certain light receiving angle, at a position facing the irradiated pulsed light with the subject 1 in between.
A dichroic mirror 98 for separating the transmitted light into wavelengths λ1 and λ2 again is arranged. Then, each of the divided transmitted lights is detected, and one end has a concentric two-layer structure so that the light on the optical axis and the light off the optical axis are separated, and the other end is divided into two fiber bundles in each layer. The Y-shaped light guide (1) 99 and the light guide (2) 100 are arranged so that the incident optical axes thereof are orthogonal to each other. Here, the fiber lengths of the light guide (1) 99 and the light guide (2) 100 are made equal so that the detected pulsed light does not deviate in time.

In addition, the streak camera 38 for measuring the time-resolved waveform of each detected pulsed light is
The configuration is similar to that of the embodiment, and the same reference numerals are given and the description thereof is omitted.

In this embodiment, first, the pulse laser 91
Generates pulsed light of wavelength λ 0. This pulsed light is divided into two by a half mirror 94, one is applied to a dye laser (1) 92 and the other is applied to a dye laser (2) 93, and pulsed light λ1 of a near infrared wavelength different from the wavelength λ0 is obtained.
And excite λ 2. Then, the pulsed lights of λ1 and λ2 are overlapped by a dichroic mirror 95 so as to match in time and space, and when this pulsed light is irradiated to the subject 1, the pulsed light is scattered due to light scattering by a tissue or the like. It spreads both spatially and temporally. The spread light is detected by the collimator 97 arranged on the transmission side of the irradiation pulse light, and separated again by the dichroic mirror 98 into wavelengths λ1 and λ2. Further, for each wavelength of light, a light guide (1) having a concentric two-layer structure is provided so as to separate and detect light on an optical axis including a straight component and a scattered component and light off the optical axis of only the scattered component. ) 99 and light guide (2) 10
The light is received at 0, and this light is guided to the streak camera 38. Four light pulse time-resolved waveforms are simultaneously obtained in the streak camera 38, and the respective waveforms are processed by the processing device 41 to suppress the scattered component and obtain information on the oxygen saturation level such as hemoglobin locally. ..

As described above, by using the pulsed light of two wavelengths, it is possible to obtain the local oxygen saturation such as hemoglobin. Further, as in the above-described embodiment, by providing the position control means for displacing the collimator 97 and the like according to the distance from the subject 1, the scattered component can be suppressed with high accuracy.

The detectors such as the collimator and the light guide may be arranged on the opposite side so as to detect the reflected light from the subject 1.

By the way, the refractive index of living tissue is in air (n
= 1.0), which is a large value of about n = 1.4. Therefore, when light is used to reconstruct a tomographic image of a subject such as biological tissue in the air, light refraction and reflection occur at the boundary between the air and the subject, and a large false image is generated at the tomographic image boundary surface. There was a problem that occurs. In order to solve the occurrence of such a false image, the present applicant discloses in Japanese Patent Application No. 3-60801 that a light transmitting member such as a buffer solution having a refractive index substantially equal to that of the subject is provided around the subject. A device capable of reducing refraction when transmitting light is proposed. less than,
An example in which the means for reducing the false image due to the change in the refractive index is applied to the above-described optical tomographic imaging apparatus will be shown.

9 and 10 show an example of an apparatus suitable for diagnosing a luminal organ such as an intestine or a blood vessel. FIG. 9 shows the configuration of the distal end portion of the insertion portion that performs optical imaging scanning.

A donut-shaped elastic film 1 made of a transparent elastic member having a high light-transmitting property is provided on the distal end side of the insertion portion distal end portion 111.
12 is provided, and the inside surrounded by the elastic film 112 is filled with a buffer solution 114 made of a transparent liquid having a refractive index equal to that of the luminal organ 113 so as to be adjustable. Then, at the time of measurement, the buffer solution 114 is increased to increase the elastic film 11.
By inflating 2 and bringing it into close contact with the luminal organ 113, the refractive index between the light emitting surface 115 and the luminal organ surface 116 is made equal to that of the luminal organ 113. With this configuration, the refraction of light by the organ surface is reduced, and the occurrence of false images is reduced, so that a good tomographic image can be obtained. The light emitting surface 115 is set to be perpendicular to the optical axis, and an antireflection film is applied to prevent light reflection.

Next, the details of this example will be described with reference to FIG. FIG. 10 is a cross-sectional view showing the internal structure of the distal end portion 111 of the insertion portion.

The inside of the insertion portion distal end portion 111 has the same structure as that of the fifth embodiment shown in FIG. 6, and the same reference numerals are given to omit the description. The distal end side of the insertion portion distal end portion 111 is covered with a transparent member 117 so that light can pass therethrough.

As described above, the elastic film 112 is provided outside the transparent member 117, and this elastic film 112 is provided.
Has a pressing plate 119 at the front end and a thread 120 at the rear end.
It is fixed to the insertion portion distal end portion 111 by. In addition, the tube 12 for sending the buffer solution 114 into the elastic film 112.
1 is inserted through the inside of the insertion portion, and the tip side is open in the elastic film 112. A water tank 12 is provided on the rear end side of the tube 121.
2 is provided and is filled with the buffer solution 114.
A pump 123 is connected to the water tank 122, and the buffer solution 114 in the elastic film 112 is increased or decreased by operating the pump 123.

At the time of insertion into the luminal organ, the buffer solution 114 inside the elastic film 112 is sucked by the pump 123 to facilitate insertion, and the light emitting surface 115 and the elastic film 112 are brought into close contact with each other to have a small diameter. At the time of measurement, the buffer solution 1 in the water tank 122
14 is pumped into the elastic film 112 through the tube 121 by the pump 123, and the buffer solution 114 is supplied to the elastic film 112 and the light emitting surface 1 until the elastic film 112 comes into close contact with the luminal organ 113.
Fill between 15 and. Thus, the surface of the luminal organ 116
When there is no gap between the elastic film 112 and the elastic film 112, that is, when light is irradiated in a state where the change in the refractive index between the light emitting surface 115 and the surface 116 of the luminal organ is small, the light reflected and scattered inside the luminal organ. Progresses without being affected by the refractive index. Therefore, it is possible to accurately detect the light on the optical axis and the light off the optical axis.

The applicant of the present invention filed Japanese Patent Application No. 2-259916.
In the above issue, a device suitable for measuring an optical tomographic image of a body cavity organ is proposed. FIG. 11 shows an example in which the means for reducing the false image due to the change in the refractive index described above is applied to an optical tomographic imaging apparatus suitable for a non-tubular organ such as a stomach or a ventricle.

The optical tomographic imaging apparatus of this example has an elongated insertion portion 131 to be inserted into an organ in a body cavity, and this insertion portion 13.
1 is connected, and an analysis device 132 that reconstructs an optical tomographic image from the detected reflected light, and a scan drive that scans the distal end 133 of the insertion unit 131 to measure the data necessary to reconstruct the tomographic image A device 134, a light source device 135 for endoscopic observation, and a display device 136 connected to the analysis device 132 and displaying an optical tomographic image are provided.

The insertion portion 131 is elongated and flexible so that it can be inserted into an organ in a body cavity, and an elastic film 137 is provided so as to cover the tip portion 133 thereof, and the elastic film 137.
A buffer solution 114 having the same refractive index as that of the organ is filled inside. Further, at the tip portion 133, an observation window 139 for normal endoscope observation, an illumination window 140, a measurement window 141 for measuring an optical tomographic image, the buffer solution 114.
A channel 142 for ejecting and sucking is provided.
The channel 142 communicates with the tube 143 inserted through the insertion portion 131. The other end of the tube 143 has a water tank 144 filled with the buffer solution 114 and a pump 1
It is connected to a buffer solution increasing / decreasing device 146 constituted by 45 and.

A light guide 147 is provided on the illumination window 140.
Are connected, and the light guide 147 is inserted into the insertion portion 131 and connected to the light source device 135. The light source device 135 includes a lamp 148 that emits illumination light and a lens 149 that guides the illumination light to the light guide 147. Further, an objective lens (not shown) is provided in the observation window 139, and the front end face of the image guide 150 is arranged at the image forming position of the objective lens. The image guide 150 is inserted through the insertion portion 131 and is connected to an eyepiece portion 152 having an eyepiece lens 151 inside.

A fiber 15 for light transmission is provided in the measurement window 141.
3 and one end of the light receiving fiber 154 are connected, and the other end of the light transmitting fiber 153 is connected to the picosecond laser 156 that generates pulsed light via the lens 155 and the light receiving fiber 154.
The other end of each is connected to a streak camera 158 that measures light by time resolution through a lens 157. The streak camera 158 is connected to the processing device 159, and the time-resolved waveform obtained by the streak camera 158 is arithmetically processed by the processing device 159 to reconstruct a tomographic image. A control device 160 for controlling scanning when reconstructing a tomographic image is provided, and the picosecond laser 15 is provided.
6. The processing device 159 and the scan driving device 134 are controlled to measure data necessary for reconstructing a tomographic image.

As in the example of FIG. 10 described above, the buffer solution 11
By filling 4 in the elastic film 137, refraction of light is prevented. When inserting into the internal organ of the body cavity, the buffer solution 114 inside the elastic film 137 is sucked so that the elastic film 137 is easily inserted, and the elastic film 137 is in close contact with the tip portion 133 and has a small diameter.
On the other hand, at the time of measurement, the pump 145 causes the buffer solution 114 in the water tank 144 to flow into the elastic film 137 through the tube 143 and the channel 142, and is filled until the elastic film 137 is in close contact with the measurement site 161. And the measurement site 16
1 and the elastic film 137, there is no gap, that is, when light is irradiated and scanned in a state where the change in the refractive index between the measurement window 141 and the measurement site 161 is small, the light reflected and scattered inside the measurement site. Progresses without being affected by the refractive index. Therefore, it is possible to accurately detect the light on the optical axis and the light off the optical axis.

FIG. 12 shows an example of an apparatus in which only an optical fiber for obtaining an optical tomographic image is covered with an elastic film. In this example, the insertion portion 131 is provided with a channel 163 into which an optical fiber 162 for obtaining an optical tomographic image is inserted. Further, similarly to the example shown in FIG. 11, an observation window 139 and an illumination window 140 are provided. Inside the channel 163, one projects from the tip 133 and the other projects into the water tank 144.
A sheath 164 connected to the optical fiber 162 and an optical fiber 162 for transmitting and receiving the pulsed light inserted through the sheath 164 are arranged. Further, the distal end portion 13 of the sheath 164.
An elastic film 165 is provided at the portion protruding from the optical fiber 1
62 is provided so as to cover 62, and a buffer solution 114 is provided inside thereof.
Is satisfied.

According to this example, the observation window 139 has the elastic film 1
Since it is not surrounded by 65, the observation of the endoscopic image is easy, and it can be used as a normal endoscope by removing the sheath 164.

FIG. 13 shows an example of a device having no elastic film. As shown in the drawing, this example has the same configuration as the example of FIG. 11 except that the elastic film 137 is not provided.

When the measurement site 161 is a recessed site, the buffer solution 114 is directly filled around the measurement site 161 as in this example, and the tip portion 133 of the insertion portion is positioned so that the tip surface is located in the buffer solution 114. Are arranged and the optical tomographic image is measured in the same manner as described above.

According to this example, since the internal organs in the body cavity are directly filled with the buffer solution, there is no possibility that air causing refraction of light will enter between the measurement site and the light irradiation surface, and more accurate measurement can be performed. Is possible.

[0090]

As described above, according to the present invention, it is possible to detect the light emitted from the intersection of the surface of the subject and the optical axis of the irradiated beam light, regardless of the distance between the subject and the detector. Thereby, it is possible to accurately suppress the scattered light component,
There is an effect that a good tomographic image with good resolution can be easily obtained.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view showing a configuration of an optical tomographic imaging apparatus according to a first embodiment of the present invention.

2 and 3 relate to a second embodiment of the present invention, and FIG. 2 is a structural explanatory view showing a structure of an optical tomographic imaging apparatus.

FIG. 3 is a waveform diagram showing respective reflected light components detected by a detector.

FIG. 4 is a configuration explanatory view showing a configuration of a main part of an optical tomographic imaging apparatus according to a third embodiment of the present invention.

FIG. 5 is a configuration explanatory view showing a configuration of a main part of an optical tomographic imaging apparatus according to a fourth embodiment of the present invention.

FIG. 6 is a structural explanatory view showing the structure of an optical tomographic imaging apparatus according to a fifth embodiment of the present invention.

FIG. 7 is a structural explanatory view showing the structure of an optical tomographic imaging apparatus according to a sixth embodiment of the present invention.

FIG. 8 is a structural explanatory view showing the structure of an optical tomographic imaging apparatus according to a seventh embodiment of the present invention.

FIG. 9 is a structural explanatory view showing an example of an optical imaging scanning unit suitable for diagnosing a luminal organ.

FIG. 10 is an explanatory cross-sectional view showing the detailed configuration of the optical imaging scanning unit of FIG.

FIG. 11 is a structural explanatory view showing an example of an optical tomographic imaging apparatus having means for reducing the influence of a change in the refractive index, which is suitable for diagnosing a non-tubular organ.

FIG. 12 is a structural explanatory view showing an example of an apparatus in which only an optical fiber for obtaining an optical tomographic image is covered with an elastic film as a means for reducing the influence of a change in refractive index.

FIG. 13 is a structural explanatory view showing an example of an apparatus provided with means for reducing the influence of a change in the refractive index which does not have an elastic film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Object 4 ... Light source 5, 6 ... Photodetector 7, 8 ... Collimator 9 ... Detector X stage 11 ... Line sensor 12 ... Distance measuring light source 16 ... Control device 17 ... Drive device 18, 19 ... Amplifier 20 ... Differential amplifier 22 ... Computer 23 ... Display device

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[Procedure amendment]

[Submission date] January 20, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location G06F 15/62 390 B 9287-5L

Claims (1)

[Claims] 1. A light source for generating a beam of light for irradiating a subject, and a light arranged on the optical axis of the beam of light for detecting the light of the beam of light transmitted through the subject or reflected from the inside of the subject. And a second detector that is disposed on an axis that forms a predetermined angle with the optical axis of the light beam, and that detects the light of the light beam that has passed through the subject or reflected from the inside of the subject. Detector, distance measuring means for measuring the distance between the first and second detectors and the object, and the optical axis and the surface of the object based on the distance detected by the distance measuring means. Position control means for displacing the second detector so as to detect the light from the intersection point with, and the output of the first detector and the output of the second detector are calculated, and based on this And a tomographic image generating means for generating tomographic image information of the subject. An optical tomographic imaging apparatus using spatial difference characterized by the above.