JP5653087B2 - Optical tomographic imaging apparatus and operating method thereof - Google Patents

Description

The present invention relates to an optical tomographic imaging apparatus and an operating method thereof , and more particularly to an optical tomographic imaging apparatus capable of clearly rendering an image of a layer structure of interest such as a mucosal muscle plate and an operating method thereof .

  In recent years, for example, in the medical field, optical coherence tomography (OCT) measurement has been used as one of non-invasive methods for obtaining a tomographic image inside a living body. This OCT measurement has an advantage that the resolution is about 10 μm higher than that of ultrasonic measurement, and a detailed tomographic image inside the living body can be obtained. A three-dimensional tomographic image can be obtained by acquiring a plurality of images while shifting the position in a direction perpendicular to the tomographic image.

  Currently, there is a demand for acquiring a detailed tomographic image of a living body for purposes such as cancer diagnosis. As a method therefor, “Time domain OCT” has been proposed in which a light output from a low coherence light source is scanned to obtain a tomographic image of a subject (Patent Document 1).

  In addition, in recent years, an improvement that solved the problems that the optimum signal / noise ratio (S / N ratio), which is a disadvantage of “Time domain OCT”, was not obtained, the imaging frame rate was low, and the penetration depth (observation depth) was poor. Frequency domain OCT (Frequency domain OCT) (Patent Document 2, Non-Patent Document 1), which is a type of OCT, is used.

  On the other hand, frequency domain OCT (Frequency domain OCT) is used in other diagnostic areas and is widely used in clinical practice.

  In addition, with respect to an OCT tomographic image, there is a technique for specifying a pixel position corresponding to a layer boundary by applying a differential filter in the depth direction after performing preprocessing (smoothing, averaging, etc.) on image data. (Patent Document 3 and Patent Document 4).

  As a typical apparatus configuration for performing frequency domain OCT (Frequency domain OCT) measurement, there are two types, that is, an SD-OCT (Spectral Domain OCT) apparatus and an SS-OCT (Swept Source OCT).

  The SD-OCT apparatus uses broadband low-coherent light such as SLD (Super Luminescence Diode) or ASE (Amplified Spontaneous Emission) light source, white light as a light source, and uses a Michelson interferometer to generate broadband low-coherent light. After splitting into measurement light and reference light, the measurement light is irradiated onto the measurement object, the reflected light returned at that time interferes with the reference light, and this interference light is decomposed into frequency components using a spectrometer. By measuring the interference light intensity for each frequency component using a detector array in which elements such as photodiodes are arranged in an array, the resulting spectral interference intensity signal is Fourier-transformed by a computer, and optical tomography An image is constructed.

  On the other hand, the SS-OCT apparatus uses a laser that temporally sweeps the optical frequency as a light source, causes reflected light and reference light to interfere at each wavelength, and measures the time waveform of the signal corresponding to the temporal change of the optical frequency. An optical tomographic image is constructed by Fourier-transforming the spectral interference intensity signal thus obtained with a computer.

  By the way, OCT measurement is a method for acquiring an optical tomographic image of a specific region as described above. Under an endoscope, for example, a cancer lesion is observed by observation with a normal illumination light endoscope or a special light endoscope. By finding and performing OCT measurement of the region, it is possible to determine how far the cancerous lesion has infiltrated. Further, by scanning the optical axis of the measurement light two-dimensionally, three-dimensional information can be acquired together with depth information obtained by OCT measurement.

  By combining OCT measurement and three-dimensional computer graphic technology, it is possible to display a three-dimensional structure model composed of structure information of a measurement object having a resolution of the order of micrometers. Hereinafter, this three-dimensional structure model by OCT measurement is referred to as three-dimensional volume data.

JP 2000-131222 A Special table 2007-510143 gazette JP 2008-206684 A JP 2008-209166 A

Optics Express, Vol.11, Issue22, pp.2953-2963 “High-speed optical frequency-domain imaging”

  However, in general, in the diagnosis of cancer, for example, whether the cancer has infiltrated the mucosal muscle layer or not is largely related to the treatment policy. However, in the conventional OCT such as Non-Patent Document 1, the intensity of reflected light is grayscale. In addition, there is a problem that identification is difficult only by displaying using index colors.

  On the other hand, in the conventional techniques such as Patent Document 3 and Patent Document 4 used in the ophthalmologic region, the fundus layer structure is extracted, but in this diagnostic field, for observation in a relatively shallow observation depth range. Even if the image data once imaged is subjected to processing such as smoothing and average processing, the layer structure can be easily extracted, but it is required to depict, for example, a mucosal muscle plate existing in a deep part In the OCT for digestive organs, since the S / N is poor in the deep part, it is difficult to depict the mucosal muscle plate by the same method.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an optical tomographic imaging apparatus capable of clearly drawing an image of a layer structure of interest such as a mucosal muscle plate and an operating method thereof. To do.

In order to achieve the object, the optical tomographic imaging apparatus according to claim 1 divides light emitted from a wavelength swept light source into measurement light and reference light, and irradiates the measurement object with the measurement light. The reflected light from the measurement object and the reference light are combined, the interference light when the reflected light and the reference light are combined is detected as an interference signal, and the tomogram of the measurement object is detected using the interference signal An optical tomographic imaging apparatus for acquiring an image, comprising: Fourier transform means for Fourier transforming the interference signal to generate tomographic information of the measurement object; and logarithmic transformation of the tomographic information of the measurement object to obtain input image data A first logarithmic conversion unit and a first frequency filter having a lower center frequency among at least two types of frequency filters having different center frequencies are used to perform a filtering process on the input image data. By performing a filtering process on the input image data using a first filtering means for generating intermediate image data and a second frequency filter having a higher center frequency among the at least two types of frequency filters. Second filtering means for generating second intermediate image data; and AND processing means for generating output image data by extracting an overlap portion between the first intermediate image data and the second intermediate image data; Image generating means for generating an image to be displayed on the monitor means from the output image data, and center frequency changing means for changing the center frequency of the first or second frequency filter according to the type of the measurement object. Measuring object identifying means for identifying the type of the measuring object, and the center frequency changing means is configured to identify the measuring object. Based on the results identified by the stage, and changing the center frequency of the first or second frequency filter.

  According to the present invention, the first intermediate image data generated by the filtering process using the first frequency filter (low frequency filter) and the second image generated by the filtering process using the second frequency filter (high frequency filter). By performing a process (AND process) for extracting an overlap portion with the intermediate image data, an image in which a high-frequency noise component is removed and an attention layer structure such as a mucosal muscle plate is clearly extracted is obtained. be able to.

As in the optical tomographic imaging apparatus according to claim 2, an optical tomographic imaging apparatus according to claim 1, wherein the center frequency changing means, the measurement target center frequency of the first frequency filter It is preferable to determine the thickness based on the thickness of the target layer structure and the thickness of the adjacent layer of the target layer structure.

As in the optical tomographic imaging apparatus according to claim 3, an optical tomographic imaging apparatus according to claim 1 or 2, wherein the center frequency changing means, the center frequency of the second frequency filter It is preferable to determine based on the thickness of the target layer structure to be measured.

The optical tomographic imaging apparatus according to any one of claims 1 to 3 , as in the optical tomographic imaging apparatus according to claim 4 , wherein the measurement object identifying means is inserted into a subject. It is preferable to identify the type of the measurement object based on the identification ID given to the endoscope insertion portion.

The optical tomographic imaging apparatus according to any one of claims 1 to 3 , as in the optical tomographic imaging apparatus according to claim 5 , wherein the measurement object identifying unit is configured to perform the measurement from an endoscopic image. It is preferable to identify the type of measurement object.

As in the optical tomographic imaging apparatus according to claim 6, an optical tomographic imaging apparatus according to any one of claims 1 to 5, wherein the first filtering means, the input image data On the other hand, it is preferable that the first intermediate image data is generated by performing a binarization process after performing a filtering process by the first frequency filter.

As in the optical tomographic imaging apparatus according to claim 7, an optical tomographic imaging apparatus according to any one of claims 1 to 6, wherein the second filtering means, the input image data On the other hand, it is preferable to generate the second intermediate image data by performing a binarization process after performing a filtering process by the second frequency filter.

The optical tomographic imaging apparatus according to any one of claims 1 to 7 , as in the optical tomographic imaging apparatus according to claim 8 , wherein the image generated by the image generating means and the tomographic image It is preferable that image synthesis means for generating a synthesized image by adding at a preset ratio is provided.

In order to achieve the above object, the operation method of the optical tomographic imaging apparatus according to claim 9 divides the light emitted from the wavelength swept light source into measurement light and reference light, and measures with the measurement light. Irradiate the object, combine the reflected light from the measurement object and the reference light, detect the interference light when the reflected light and the reference light are combined as an interference signal, and use the interference signal An operation method of an optical tomographic imaging apparatus for acquiring a tomographic image of a measurement object, wherein the optical tomographic imaging apparatus includes a Fourier transform unit, a logarithmic transform unit, a first filtering unit, and a second filtering unit. Means, AND processing means, image generation means, center frequency changing means, and measurement object identification means, and the Fourier transform means Fourier-transforms the interference signal to generate tomographic information of the measurement object Fourier transform step And flop, said logarithmic conversion means, and the logarithmic conversion step of generating an input image data of the tomographic information of the object to be measured logarithmic transformation, the first filtering means, the center frequency of at least two different frequency filters A first filtering step of generating first intermediate image data by performing a filtering process on the input image data using a first frequency filter having a lower center frequency, and the second filtering. Means for generating second intermediate image data by performing a filtering process on the input image data using a second frequency filter having a higher center frequency of the at least two types of frequency filters. and second filtering step, the aND processing means, and the first intermediate image data wherein An AND processing step of generating output image data by extracting the overlapping portion between the second intermediate image data, the image generation step of the image generating unit generates an image to be displayed on the monitor means from the output image data A center frequency changing step in which the center frequency changing means changes the center frequency of the first or second frequency filter according to the type of the measurement object; and the measurement object identification means is the type of the measurement object. A measuring object identifying step for identifying, wherein the center frequency changing step changes the center frequency of the first or second frequency filter based on the result identified by the measuring object identifying step. And

  According to the present invention, the first intermediate image data generated by the filtering process using the first frequency filter (low frequency filter) and the second image generated by the filtering process using the second frequency filter (high frequency filter). By performing a process (AND process) for extracting an overlap portion with the intermediate image data, an image in which a high-frequency noise component is removed and an attention layer structure such as a mucosal muscle plate is clearly extracted is obtained. be able to.

As a method of operating an optical tomographic imaging apparatus according to claim 10, a method of operating an optical tomographic imaging apparatus according to claim 9, wherein the center frequency changing step, the first frequency filter The center frequency is preferably determined based on the thickness of the target layer structure to be measured and the thickness of the adjacent layer of the target layer structure.

As a method of operating an optical tomographic imaging apparatus according to claim 11, a method of operating an optical tomographic imaging apparatus according to claim 9 or 10, wherein the center frequency changing step, the second frequency It is preferable to determine the center frequency of the filter based on the thickness of the target layer structure to be measured.

As a method of operating an optical tomographic imaging apparatus according to claim 12, a method of operating an optical tomographic imaging apparatus according to any one of claims 9 to 11, wherein the measurement object identification step, It is preferable to identify the type of the measurement object based on the identification ID given to the endoscope insertion portion inserted into the subject.

As a method of operating an optical tomographic imaging apparatus according to claim 13, a method of operating an optical tomographic imaging apparatus according to any one of claims 9 to 11, wherein the measurement object identification step, It is preferable to identify the type of the measurement object from an endoscopic image.

As a method of operating an optical tomographic imaging apparatus according to claim 14, a method of operating an optical tomographic imaging apparatus according to any one of claims 9 to 13, wherein the first filtering step It is preferable that after the filtering process is performed on the input image data by the first frequency filter, the first intermediate image data is generated by further performing a binarization process.

As a method of operating an optical tomographic imaging apparatus according to claim 15, a method of operating an optical tomographic imaging apparatus according to any one of claims 9 to 14, wherein the second filtering step It is preferable that the second intermediate image data is generated by performing a binarization process after performing a filtering process on the input image data by the second frequency filter.

As a method of operating an optical tomographic imaging apparatus according to claim 16, a method of operating an optical tomographic imaging apparatus according to any one of claims 9 to 15, wherein the optical tomographic imaging apparatus It is preferable that the image synthesizing unit further includes an image synthesizing step of generating a synthesized image by adding the image generated by the image generating step and the tomographic image at a preset ratio. .

  According to the present invention, the first intermediate image data generated by the filtering process using the first frequency filter (low frequency filter) and the second image generated by the filtering process using the second frequency filter (high frequency filter). By performing a process (AND process) for extracting an overlap portion with the intermediate image data, an image in which a high-frequency noise component is removed and an attention layer structure such as a mucosal muscle plate is clearly extracted is obtained. be able to.

1 is an external view showing an image diagnostic apparatus using an optical tomographic imaging apparatus according to a first embodiment. The block diagram which shows the internal structure of the OCT processor of FIG. Sectional view of the OCT probe of FIG. The figure which shows the scanning surface of a tomographic image in case optical scanning is radial scanning with respect to the measuring object S of FIG. The figure which shows the three-dimensional volume data constructed | assembled by the tomographic image of FIG. The figure which shows a mode that a tomographic image is acquired using the OCT probe derived | led-out from the forceps opening | mouth of the endoscope of FIG. The figure which shows the structure which performs a sector scan with respect to the measuring object S of FIG. 2, and acquires a tomographic image The figure which shows the three-dimensional volume data constructed | assembled by the tomographic image of FIG. The block diagram which shows the structure of the signal processing part of FIG. A figure showing an example of an input image (original image) The figure which showed the image obtained when low frequency band pass filtering was performed with respect to the input image of FIG. The figure which showed the image obtained when performing the high frequency band pass filtering with respect to the input image of FIG. 11 is a diagram showing an image obtained when AND processing is performed on the image shown in FIG. 11 and the image shown in FIG. A diagram showing the relationship between the normal mucosa of the main digestive system and the thickness of the mucosal fascia The figure which showed an example of the screen displayed on a monitor device It is the flowchart figure which showed an example of the method of identifying a measurement region | part based on an endoscopic image. The block diagram which shows the structure of the signal processing part which concerns on 2nd Embodiment.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[First Embodiment]
First, a first embodiment of the present invention will be described.

<Appearance of diagnostic imaging equipment>
FIG. 1 is an external view showing an image diagnostic apparatus using the optical tomographic imaging apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, the diagnostic imaging apparatus 10 mainly includes an endoscope 100, an endoscope processor 200, a light source device 300, an OCT processor 400 as an optical tomographic imaging device, and a monitor device 500. . Note that the endoscope processor 200 may be configured to incorporate the light source device 300.

  The endoscope 100 includes a hand operation unit 112 and an insertion unit 114 that is connected to the hand operation unit 112. The surgeon grasps and operates the hand operation unit 112 and performs observation by inserting the insertion unit 114 into the body of the subject.

  The hand operation part 112 is provided with a forceps insertion part 138, and the forceps insertion part 138 communicates with the forceps port 156 of the distal end part 144. In this embodiment, the OCT probe 600 is led out from the forceps opening 156 by inserting the OCT probe 600 from the forceps insertion portion 138. The OCT probe 600 is inserted into the OCT processor 400 via the insertion portion 602 inserted from the forceps insertion portion 138 and led out from the forceps opening 156, the operation portion 604 for the operator to operate the OCT probe 600, and the connector 610. It consists of a cable 606 to be connected.

<Configuration of endoscope, endoscope processor, and light source device>
[Endoscope]
At the distal end portion 144 of the endoscope 100, an observation optical system 150, an illumination optical system 152, and a CCD (not shown) are disposed.

  The observation optical system 150 forms an image of a subject on a light receiving surface (not shown) of the CCD, and the CCD converts the subject image formed on the light receiving surface into an electric signal by each light receiving element. The CCD of this embodiment is a color CCD in which three primary color red (R), green (G), and blue (B) color filters are arranged for each pixel in a predetermined arrangement (Bayer arrangement, honeycomb arrangement). is there.

  Reference numeral 154 denotes a cleaning nozzle for supplying cleaning liquid and pressurized air toward the observation optical system 150.

[Light source device]
The light source device 300 causes visible light to enter a light guide (not shown). One end of the light guide is connected to the light source device 300 via the LG connector 120, and the other end of the light guide faces the illumination optical system 152. The light emitted from the light source device 300 is emitted from the illumination optical system 152 via the light guide, and illuminates the visual field range of the observation optical system 150.

[Endoscope processor]
An image signal output from the CCD is input to the endoscope processor 200 via the electrical connector 110. The analog image signal is converted into a digital image signal in the endoscope processor 200, and necessary processing for displaying on the screen of the monitor device 500 is performed.

  In this manner, observation image data obtained by the endoscope 100 is output to the endoscope processor 200, and an image is displayed on the monitor device 500 connected to the endoscope processor 200.

<Internal configuration of OCT processor and OCT probe>
FIG. 2 is a block diagram showing an internal configuration of the OCT processor of FIG.

[OCT processor]
An OCT processor 400 and an OCT probe 600 shown in FIG. 2 are for obtaining an optical tomographic image of a measurement object by an optical coherence tomography (OCT) measurement method, and emit a light La for measurement. One light source unit (first light source unit) 12 and light La emitted from the first light source unit 12 are branched into measurement light (first light beam) L1 and reference light L2, and measurement is performed on the subject. An optical fiber coupler (branching / combining unit) 14 that generates the interference light L4 by combining the return light L3 from the target S and the reference light L2, and the measurement light L1 branched by the optical fiber coupler 14 is guided to the measurement target. And an OCT probe 600 including a rotation-side optical fiber FB1 that guides the return light L3 from the measurement target, and guides the measurement light L1 to the rotation-side optical fiber FB1 and rotates the rotation-side optical fiber. The fixed side optical fiber FB2 that guides the return light L3 guided by the bar FB1 and the rotation side optical fiber FB1 are rotatably connected to the fixed side optical fiber FB2, and the measurement light L1 and the return light L3 are transmitted. The optical connector 18, the interference light detection unit 20 that detects the interference light L 4 generated by the optical fiber coupler 14 as an interference signal, and the interference signal detected by the interference light detection unit 20 to process the optical tomographic image ( Hereinafter, the signal processing unit 22 is also obtained. Further, the optical tomographic image acquired by the signal processing unit 22 is displayed on the monitor device 500.

  Further, the OCT processor 400 adjusts the optical path length of the second light source unit (second light source unit) 13 that emits aiming light (second light flux) Le for indicating a mark of measurement, and the reference light L2. An optical path length adjusting unit 26, an optical fiber coupler 28 that splits the light La emitted from the first light source unit 12, and detectors 30a and 30b that detect return lights L4 and L5 combined by the optical fiber coupler 14. And an operation control unit 32 that inputs various conditions to the signal processing unit 22, changes settings, and the like.

  In the OCT processor 400 shown in FIG. 2, various lights including the above-described emission light La, aiming light Le, measurement light L1, reference light L2, return light L3, and the like are guided between components such as optical devices. Various optical fibers FB (FB3, FB4, FB5, FB6, FB7, FB8, etc.) including the rotation side optical fiber FB1 and the fixed side optical fiber FB2 are used as light paths for wave transmission.

  The first light source unit 12 emits light for OCT measurement (for example, laser light having a wavelength of 1.3 μm or low-coherence light), and the first light source unit 12 has a frequency of a constant period. For example, the light source emits a laser beam La centered at a wavelength of 1.3 μm, for example, in the infrared region while being swept with a laser beam. The first light source unit 12 includes a light source 12a that emits laser light or low-coherence light La, and a lens 12b that condenses the light La emitted from the light source 12a. Further, as will be described in detail later, the light La emitted from the first light source unit 12 is divided into the measurement light L1 and the reference light L2 by the optical fiber coupler 14 via the optical fibers FB4 and FB3, and the measurement light L1 is Input to the optical connector 18.

  The second light source unit 13 emits visible light so as to make it easy to confirm the measurement site as the aiming light Le. For example, red semiconductor laser light with a wavelength of 0.66 μm, He—Ne laser light with a wavelength of 0.63 μm, blue semiconductor laser light with a wavelength of 0.405 μm, or the like can be used. Therefore, the second light source unit 13 includes, for example, a semiconductor laser 13a that emits red, blue, or green laser light, and a lens 13b that condenses the aiming light Le emitted from the semiconductor laser 13a. The aiming light Le emitted from the second light source unit 13 is input to the optical connector 18 through the optical fiber FB8.

  In the optical connector 18, the measurement light L 1 and the aiming light Le are combined and guided to the rotation side optical fiber FB 1 in the OCT probe 600.

  The optical fiber coupler (branching / combining unit) 14 is composed of, for example, a 2 × 2 optical fiber coupler, and is optically connected to the fixed-side optical fiber FB2, the optical fiber FB3, the optical fiber FB5, and the optical fiber FB7, respectively. ing.

  The optical fiber coupler 14 divides the light La incident from the first light source unit 12 via the optical fibers FB4 and FB3 into measurement light (first light flux) L1 and reference light L2, and the measurement light L1 is fixed. The light is incident on the optical fiber FB2, and the reference light L2 is incident on the optical fiber FB5.

  Furthermore, the optical fiber coupler 14 is incident on the optical fiber FB5, is subjected to frequency shift and optical path length change by the optical path length adjusting unit 26 described later, and is returned by the optical fiber FB5 and acquired by the OCT probe 600 described later. Then, the light L3 guided from the fixed side optical fiber FB2 is multiplexed and emitted to the optical fiber FB3 (FB6) and the optical fiber FB7.

  The OCT probe 600 is connected to the fixed optical fiber FB2 via the optical connector 18, and the measurement light L1 combined with the aiming light Le is rotated from the fixed optical fiber FB2 via the optical connector 18. The light enters the side optical fiber FB1. The measurement light L1 combined with the incident aiming light Le is transmitted by the rotation side optical fiber FB1, and is irradiated to the measurement object S. Then, the return light L3 from the measuring object S is acquired, the acquired return light L3 is transmitted by the rotation side optical fiber FB1, and is emitted to the fixed side optical fiber FB2 via the optical connector 18.

  The optical connector 18 combines the measurement light (first light beam) L1 and the aiming light (second light beam) Le.

  The interference light detection unit 20 is connected to the optical fibers FB6 and FB7, and uses the interference lights L4 and L5 generated by combining the reference light L2 and the return light L3 by the optical fiber coupler 14 as interference signals. It is to detect.

  Here, the OCT processor 400 is provided on the optical fiber FB6 branched from the optical fiber coupler 28. The detector 30a detects the light intensity of the interference light L4, and the light of the interference light L5 on the optical path of the optical fiber FB7. And a detector 30b for detecting the intensity.

  The interference light detection unit 20 generates an interference signal based on the detection results of the detectors 30a and 30b.

  The signal processing unit 22 generates image data from the interference signal detected by the interference light detection unit 20, and outputs an image obtained by performing various processes on the image data to the monitor device 500.

  The optical path length adjustment unit 26 is disposed on the emission side of the reference light L2 of the optical fiber FB5 (that is, the end of the optical fiber FB5 opposite to the optical fiber coupler 14).

  The optical path length adjustment unit 26 includes a first optical lens 80 that converts the light emitted from the optical fiber FB5 into parallel light, a second optical lens 82 that condenses the light converted into parallel light by the first optical lens 80, and The reflection mirror 84 that reflects the light collected by the second optical lens 82, the base 86 that supports the second optical lens 82 and the reflection mirror 84, and the base 86 are moved in a direction parallel to the optical axis direction. The optical path length of the reference light L2 is adjusted by changing the distance between the first optical lens 80 and the second optical lens 82.

  The first optical lens 80 converts the reference light L2 emitted from the core of the optical fiber FB5 into parallel light, and condenses the reference light L2 reflected by the reflection mirror 84 on the core of the optical fiber FB5.

  The second optical lens 82 condenses the reference light L2 converted into parallel light by the first optical lens 80 on the reflection mirror 84 and makes the reference light L2 reflected by the reflection mirror 84 parallel light. Thus, the first optical lens 80 and the second optical lens 82 form a confocal optical system.

  Further, the reflection mirror 84 is disposed at the focal point of the light collected by the second optical lens 82 and reflects the reference light L2 collected by the second optical lens 82.

  As a result, the reference light L2 emitted from the optical fiber FB5 becomes parallel light by the first optical lens 80 and is condensed on the reflection mirror 84 by the second optical lens 82. Thereafter, the reference light L2 reflected by the reflection mirror 84 becomes parallel light by the second optical lens 82 and is condensed by the first optical lens 80 on the core of the optical fiber FB5.

  The base 86 fixes the second optical lens 82 and the reflecting mirror 84, and the mirror moving mechanism 88 moves the base 86 in the optical axis direction of the first optical lens 80 (the direction of arrow A in FIG. 2). .

  By moving the base 86 in the direction of arrow A with the mirror moving mechanism 88, the distance between the first optical lens 80 and the second optical lens 82 can be changed, and the optical path length of the reference light L2 can be adjusted. Can do.

  The operation control unit 32 includes input means such as a keyboard and a mouse, and control means for managing various conditions based on input information, and is connected to the signal processing unit 22. The operation control unit 32 inputs, sets, and changes various processing conditions and the like in the signal processing unit 22 based on an operator instruction input from the input unit.

  Note that the operation control unit 32 may display the operation screen on the monitor device 500, or may provide a separate display unit to display the operation screen. Further, the operation control unit 32 controls the operation of the first light source unit 12, the second light source unit 13, the optical connector 18, the interference light detection unit 20, the optical path length, the detectors 30a and 30b, and sets various conditions. You may do it.

[OCT probe]
FIG. 3 is a cross-sectional view of the OCT probe of FIG.

  As shown in FIG. 3, the distal end portion of the insertion portion 602 has a probe outer cylinder 620, a cap 622, a rotation side optical fiber FB 1, a spring 624, a fixing member 626, and an optical lens 628. .

  The probe outer cylinder (sheath) 620 is a flexible cylindrical member and is made of a material through which the measurement light L1 combined with the aiming light Le and the return light L3 are transmitted in the optical connector 18. The probe outer cylinder 620 is a tip through which the measurement light L1 (aiming light Le) and the return light L3 pass (the tip of the rotation side optical fiber FB1 opposite to the optical connector 18, hereinafter referred to as the tip of the probe outer cylinder 620). It is only necessary that a part of the side is made of a material that transmits light over the entire circumference (transparent material), and parts other than the tip may be made of a material that does not transmit light.

  The cap 622 is provided at the distal end of the probe outer cylinder 620 and closes the distal end of the probe outer cylinder 620.

  The rotation side optical fiber FB1 is a linear member, is accommodated in the probe outer cylinder 620 along the probe outer cylinder 620, is emitted from the fixed side optical fiber FB2, and is emitted from the optical fiber FB8 by the optical connector 18. The measurement light L1 combined with the aiming light Le is guided to the optical lens 628, and the measurement object L is irradiated with the measurement light L1 (aiming light Le) to return from the measurement object S acquired by the optical lens 628. The light L3 is guided to the optical connector 18 and enters the fixed optical fiber FB2.

  Here, the rotation-side optical fiber FB1 and the fixed-side optical fiber FB2 are connected by the optical connector 18, and are optically connected in a state where the rotation of the rotation-side optical fiber FB1 is not transmitted to the fixed-side optical fiber FB2. ing. The rotation-side optical fiber FB1 is arranged so as to be rotatable with respect to the probe outer cylinder 620 and movable in the axial direction of the probe outer cylinder 620.

  The spring 624 is fixed to the outer periphery of the rotation side optical fiber FB1. The rotation side optical fiber FB1 and the spring 624 are connected to the optical connector 18.

  The optical lens 628 is disposed at the measurement-side tip of the rotation-side optical fiber FB1 (tip of the rotation-side optical fiber FB1 opposite to the optical connector 18), and the tip is measured from the rotation-side optical fiber FB1. In order to collect the light L1 (aiming light Le) with respect to the measuring object S, it is formed in a substantially spherical shape.

  The optical lens 628 irradiates the measurement target S with the measurement light L1 (aiming light Le) emitted from the rotation side optical fiber FB1, collects the return light L3 from the measurement target S, and enters the rotation side optical fiber FB1. .

  The fixing member 626 is disposed on the outer periphery of the connection portion between the rotation side optical fiber FB1 and the optical lens 628, and fixes the optical lens 628 to the end portion of the rotation side optical fiber FB1. Here, the fixing method of the rotation side optical fiber FB1 and the optical lens 628 by the fixing member 626 is not particularly limited, and the fixing member 626, the rotation side optical fiber FB1 and the optical lens 628 are bonded and fixed by an adhesive. Alternatively, it may be fixed with a mechanical structure using a bolt or the like. The fixing member 626 may be any member as long as it is used for fixing, holding or protecting the optical fiber such as a zirconia ferrule or a metal ferrule.

  The rotation side optical fiber FB1 and the spring 624 are connected to a rotation cylinder 656, which will be described later. By rotating the rotation side optical fiber FB1 and the spring 624 by the rotation cylinder 656, the optical lens 628 is moved to the probe outer cylinder 620. On the other hand, it is rotated in the direction of arrow R2. The optical connector 18 includes a rotary encoder, and detects the irradiation position of the measurement light L1 from the position information (angle information) of the optical lens 628 based on a signal from the rotary encoder. That is, the measurement position is detected by detecting the angle of the rotating optical lens 628 with respect to the reference position in the rotation direction.

  Further, the rotation side optical fiber FB1, the spring 624, the fixing member 626, and the optical lens 628 are moved through the probe outer cylinder 620 in the arrow S1 direction (forceps opening direction) and the S2 direction (probe outer cylinder 620) by a driving unit described later. It is configured to be movable in the direction of the tip.

  Further, the left side of FIG. 3 is a diagram showing an outline of a drive unit such as the rotation side optical fiber FB1 in the operation unit 604 of the OCT probe 600.

  The probe outer cylinder 620 is fixed to a fixing member 670. On the other hand, the rotation side optical fiber FB1 and the spring 624 are connected to a rotating cylinder 656, and the rotating cylinder 656 is configured to rotate via a gear 654 in accordance with the rotation of the motor 652. The rotary cylinder 656 is connected to the optical connector 18, and the measurement light L1 and the return light L3 are transmitted between the rotation side optical fiber FB1 and the fixed side optical fiber FB2 via the optical connector 18.

  Further, the frame 650 containing these includes a support member 662, and the support member 662 has a screw hole (not shown). A forward and backward movement ball screw 664 is engaged with the screw hole, and a motor 660 is connected to the forward and backward movement ball screw 664. Therefore, the frame 650 can be moved forward and backward by rotationally driving the motor 660, whereby the rotation side optical fiber FB1, the spring 624, the fixing member 626, and the optical lens 628 can be moved in the S1 and S2 directions in FIG. It has become.

  The OCT probe 600 is configured as described above, and the measurement side light L1 emitted from the optical lens 628 is obtained by rotating the rotation-side optical fiber FB1 and the spring 624 in the direction of the arrow R2 in FIG. (Aiming light Le) is irradiated to the measuring object S while scanning in the arrow R2 direction (circumferential direction of the probe outer cylinder 620), and the return light L3 is acquired. The aiming light Le is irradiated to the measuring object S as, for example, blue, red, or green spot light, and the reflected light of the aiming light Le is also displayed as a bright spot on the observation image displayed on the monitor device 500.

  Thereby, the desired site | part of the measuring object S can be caught correctly in the perimeter of the circumference direction of the probe outer cylinder 620, and the return light L3 which reflected the measuring object S can be acquired.

  Furthermore, when acquiring a plurality of tomographic images for generating three-dimensional volume data, the optical lens 628 is moved to the end of the movable range in the direction of the arrow S1 by the drive unit, and a predetermined amount is acquired while acquiring the tomographic images. Move to the end of the movable range while moving in the S2 direction or alternately repeating tomographic image acquisition and a predetermined amount of movement in the S2 direction.

  Thus, a plurality of tomographic images in a desired range can be obtained for the measurement object S, and three-dimensional volume data can be obtained based on the acquired plurality of tomographic images.

  FIG. 4 is a diagram showing a scan plane of a tomographic image when the optical scanning is radial scan with respect to the measurement target S of FIG. 2, and FIG. It is. A tomographic image in the depth direction (first direction) of the measurement target S is acquired from the interference signal, and the measurement target S is scanned (radial scan) in the direction of arrow R2 in FIG. 3 (circumferential direction of the probe outer cylinder 620). As a result, as shown in FIG. 4, a tomographic image on the scan plane composed of the first direction and the second direction orthogonal to the first direction can be acquired. Furthermore, by moving the scan plane along a third direction orthogonal to the scan plane, a plurality of tomographic images for generating three-dimensional volume data can be acquired as shown in FIG.

  FIG. 6 is a diagram illustrating a state in which a tomographic image is obtained using the OCT probe derived from the forceps opening of the endoscope of FIG. As shown in FIG. 6, the tomographic image is obtained by bringing the distal end portion of the insertion portion 602 of the OCT probe close to a desired portion of the measurement target S. When acquiring a plurality of tomographic images in a desired range, it is not necessary to move the OCT probe 600 main body, and the optical lens 628 may be moved within the probe outer cylinder 620 by the drive unit described above.

  Although the measurement light L1 (aiming light Le) is radially scanned on the measurement object S, the present invention is not limited to this. FIG. 7 is a diagram illustrating a configuration in which a tomographic image is acquired by performing sector scanning on the measurement target S in FIG. 2, and FIG. 8 is a diagram illustrating three-dimensional volume data constructed from the tomographic image in FIG. . As shown in FIG. 7, the present invention can also be applied to a configuration in which a galvano mirror 900 is used and a sector scan is performed from above the measurement target S to acquire a tomographic image. As shown, a plurality of tomographic images for generating three-dimensional volume data can be acquired.

[Signal processing section]
FIG. 9 is a block diagram showing a configuration of the signal processing unit 22 of FIG.

  As illustrated in FIG. 9, the signal processing unit 22 according to the present embodiment is a processing unit that performs signal processing for generating an image output to the monitor device 500 from the interference signal input from the interference light detection unit 20. , Mainly including a Fourier transform unit 410, a logarithmic transform unit 420, a low frequency filtering unit 430, a high frequency filtering unit 440, an AND unit 450, an AND image construction unit 460, and a control unit 490. The control unit 490 controls each unit of the signal processing unit 22 based on the operation signal from the operation control unit 32.

  The interference light detection unit 20 is obtained when the light emitted from the first light source unit 12 serving as a wavelength swept light source is divided into measurement light and reference light, and the measurement light S is irradiated from the OCT probe 600 to the measurement target S. The interference light when the reflected light and the reference light are combined is input. The interference light detection unit 20 converts an input interference light (optical signal) into an interference signal (electric signal), and converts the interference signal generated by the interference signal generation unit 20a from an analog signal to a digital signal. It comprises an AD conversion unit 20b that converts it into a signal.

  In the AD conversion unit 20b, for example, conversion from an analog signal to a digital signal is performed with a sampling rate of about 80 MHz and a resolution of about 14 bits. However, the value is not particularly limited to these values. The interference signal converted into a digital signal by the AD conversion unit 20 b is input to the Fourier transform unit 410 of the signal processing unit 22.

  The Fourier transform unit 410 performs frequency analysis by FFT (Fast Fourier Transform) on the interference signal converted into a digital signal in the AD conversion unit 20b of the interference light detection unit 20, and the reflected light L3 at each depth position of the measurement target S. Intensity, that is, reflection intensity data (tomographic information) in the depth direction.

  The logarithmic conversion unit 420 performs logarithmic conversion of the data (tomographic information) Fourier-transformed by the Fourier transform unit 410 to generate image data (input image data) that is original data of an image displayed on the monitor device 500. The image data generated by the logarithmic conversion unit 420 is input to the low frequency filtering unit 430 and the high frequency filtering unit 440, respectively.

  The low frequency filtering unit 430 includes a low frequency band pass filter unit (low frequency BPF unit) 432 and a binarization processing unit 434.

  The low-frequency BPF unit 432 includes a low-frequency bandpass filter (not shown), and performs filtering (low-frequency bandpass filtering) on the image data input from the logarithmic conversion unit 420 using the low-frequency bandpass filter.

  The low-frequency bandpass filter is configured by a generally known Gaussian filter, DOG filter, or the like. The center frequency of the low frequency band filter is assumed to be lower than the center frequency of the high frequency band pass filter provided in the high frequency BPF 442 described later.

  Here, the noise suppression performance of the low-frequency bandpass filter becomes higher as the center frequency is lower. However, if the center frequency is too low, the layer structure of interest (for example, the mucosal muscle plate) and the adjacent layer cannot be distinguished. May end up.

For this reason, in this embodiment, it is preferable that the center frequency of the low-frequency bandpass filter is determined according to the layer structure of interest and the thickness of the adjacent layer. For example, when the measuring object S is the large intestine, the thickness of the normal mucosal layer is generally 450 [μm], and the thickness of the mucosal muscle plate is 10 to 50 [μm]. As the filter, for example, a band-pass filter having a center frequency of 4.16 [mm ⁻¹ ] (half cycle 120 [μm]) is preferably used.

  The binarization processing unit 434 performs binarization processing on the image data subjected to the low frequency bandpass filtering by the low frequency BPF unit 432 by comparison with a predetermined threshold value. The image data (first intermediate image data) binarized by the binarization processing unit 434 is input to the AND unit 450.

  The binarization processing unit 434 extracts image data that exceeds the threshold (or image data that is less than the threshold) from among the image data as a candidate region for the mucosal muscle. However, as the threshold value is larger (or smaller), the noise component included in the image data after the binarization processing is reduced. Conversely, when the threshold value is too large (or too small), it is originally extracted. In some cases, the candidate region of the mucosal muscle to be performed is also excluded. For this reason, the binarization processing unit 434 needs to use a threshold value optimized through experiment or experience. For example, the threshold value may be statistically determined based on a conventional measurement image. Further, the threshold value may be handled as a fixed parameter, or may be changed manually according to the intention of the operator (observer).

  The high frequency filtering unit 440 includes a high frequency band pass filter unit (high frequency BPF unit) 442 and a binarization processing unit 444.

  The high frequency BPF unit 442 includes a high frequency band pass filter (not shown) having a higher center frequency than the above-described low frequency band pass filter, and the image data input from the logarithmic conversion unit 420 is filtered by the high frequency band pass filter. (High-frequency bandpass filtering) is performed. Note that the high-frequency bandpass filter is configured by a Gaussian filter, a DOG filter, or the like, similarly to the low-frequency bandpass filter.

In the present embodiment, it is preferable that the center frequency of the high-frequency bandpass filter is determined according to the thickness of the layer structure of interest (for example, the mucosal muscle plate). For example, when the measurement target S is the large intestine, the thickness of the mucosal muscle plate in the normal large intestine is 10 to 50 [μm] as described above. Therefore, as the high-frequency bandpass filter, for example, the center frequency is 10 [mm ^−1. ] (Half-cycle 50 [μm]) band-pass filter is preferably used.

  The binarization processing unit 444 performs binarization processing on the image data that has been subjected to high-frequency bandpass filtering by the high-frequency BPF unit 442 by comparison with a predetermined threshold. Image data (second intermediate image data) binarized by the binarization processing unit 444 is input to the AND unit 450.

  Note that the threshold value used in the binarization processing unit 444 is the same as that of the binarization processing unit 434 described above, and it is necessary to use a threshold value optimized through experimentation or experience. For example, the threshold value is statistically determined based on a conventional measurement image. Further, the threshold value may be handled as a fixed parameter, or may be changed manually according to the intention of the operator (observer).

  The AND unit 450 performs a logical product of the image data (first intermediate image data) input from the low frequency filtering unit 430 and the image data (second intermediate image data) input from the high frequency filtering unit 440, that is, Then, AND processing (overlapping portion extraction processing) for extracting overlapping portions of each image data is performed to generate AND image data (output image data). The AND image data generated by the AND unit 450 is input to the AND image construction unit 460.

  The AND image construction unit 460 constructs an AND image based on the input AND image data in accordance with the monitor device 500 and its display method. Specifically, the AND image is constructed by adjusting the brightness and contrast, resampling in accordance with the display size, coordinate conversion in accordance with a scanning method such as radial scanning and sector scanning. At that time, a pseudo color may be applied as necessary, or superimposition with a tomographic image may be performed as in a second embodiment described later.

  Next, the operation of the present embodiment configured as described above will be described.

  First, when the interference signal generated by the interference light detection unit 20 is input to the signal processing unit 22, the Fourier transform unit 410 performs frequency analysis by FFT (Fast Fourier Transform). Thereby, reflection intensity data (tomographic information) in the depth direction of the measuring object S is generated.

  Next, the tomographic information generated by the Fourier transform unit 410 is logarithmically converted by the logarithmic conversion unit 420. As a result, image data (input image data) serving as an original image displayed on the monitor device 500 is generated. The image data generated in this way is input to the low frequency filtering unit 430 and the high frequency filtering unit 440, respectively.

  The image data input to the low frequency filtering unit 430 is first subjected to low frequency bandpass filtering in the low frequency BPF unit 432, and then subjected to binarization processing in the binarization processing unit 434. Thereby, for example, a layer structure of interest such as a mucosal muscle plate is roughly extracted, but image data from which high-frequency noise components are removed (first intermediate image data) can be obtained. The image data obtained in this way is input to the AND unit 450.

  On the other hand, the image data input to the high frequency filtering unit 440 is first subjected to high frequency bandpass filtering in the high frequency BPF unit 442 and then subjected to binarization processing in the binarization processing unit 444. As a result, image data (second intermediate image data) in which a layer structure such as a mucosal muscle plate is clearly extracted is obtained although many high-frequency noise components are included. The image data obtained in this way is input to the AND unit 450.

  Next, AND processing (overlapping portion extraction processing) for extracting overlapping portions of two image data (first and second intermediate image data) input in the AND portion 450 is performed, and AND image data (output image data) ) Is generated. The AND image data generated in this way has the advantages of the two input image data (first and second intermediate image data), and the layer structure of interest such as a mucosal muscle plate is clearly shown. The extracted high frequency noise component is removed.

  Then, the AND image data is input to the AND image construction unit 460, and an AND image to be displayed on the monitor device 500 is generated based on the AND image data. The AND image generated by the AND image constructing unit 460 in this way is displayed on the monitor device 500 and can be diagnosed.

Here, as an example, an image (first image) obtained when low-frequency bandpass filtering (center frequency 4.16 [mm ⁻¹ ]) is performed on the input image (original image) shown in FIG. An intermediate image) is shown in FIG. 11, and an image (second intermediate image) obtained when high-frequency bandpass filtering (center frequency 10 [mm ⁻¹ ]) is performed is shown in FIG. FIG. 13 shows an image (AND image) obtained when AND processing is applied to the image shown in FIG. 11 and the image shown in FIG.

  The input image shown in FIG. 10 is the same as a tomographic image constructed by a tomographic image construction unit 470 (FIG. 17) described later, and this corresponds to a grace scale tomographic image obtained by conventional OCT signal processing. . Here, an image obtained when sector scanning is performed from above the subject (measurement target S) using the galvanometer mirror 900 described in FIG. 7 is shown.

  On the other hand, in the image shown in FIG. 11, although the noise of the high-frequency component is removed, the candidate region of the mucosal muscle plate is roughly extracted. There are drawbacks that the plate is detected in a connected state, or that the boundary between the mucosal muscle plate and the adjacent layer (mucosal layer) is not clear and is detected as one layer.

  In the image shown in FIG. 12, the boundary (adjacent edge) with the mucosal layer adjacent to the mucosal muscle plate is clearly extracted, and the portion where the mucosal muscle plate is interrupted can be easily identified. However, there is a drawback that many high frequency noise components remain.

  Therefore, in the present embodiment, the images shown in FIG. 13 are generated by performing AND processing on these images in order to compensate for the defects of the images shown in FIGS. 11 and 12. According to this, the high-frequency noise component is removed, the image of the mucosal muscle plate as the layer structure of interest is clearly depicted, and the boundary (edge) between the mucosal muscle plate and its adjacent layer is also clearly separated. Is displayed.

  The images shown in FIGS. 11 to 13 are displayed in black and white due to the limitations of the drawings, but a pseudo color (red in this example) is applied to the portion that is actually displayed in light gray. This makes it easier to recognize the target structure.

  FIG. 14 is a diagram showing the relationship between the normal mucosal layer of the main digestive tract and the thickness of the mucosal muscle plate. As shown in FIG. 14, generally, the thickness of the mucosa layer and the mucosal muscle plate in the digestive tract varies depending on the region. Despite the fact that the thickness of the mucosal layer and mucosal fascia varies depending on the measurement site, if the center frequency of the low-frequency bandpass filter and the high-frequency bandpass filter is fixed uniformly, depending on the measurement site, the layer structure of interest May not be extracted properly or noise components may not be removed.

Therefore, in the present embodiment, it is desirable to change the center frequencies of the low-frequency bandpass filter and the high-frequency bandpass filter according to the measurement site (that is, the type of the measurement target S). Specifically, when the mucosal layer thickness at the measurement site is a [μm] and the mucosal muscle plate thickness is b [μm] (where a> b), the center frequency of the low-frequency bandpass filter is 1 ^{/ 2a~1 / 2b [mm -1]} ( half cycle b~a [μm]), the center frequency of the high frequency band pass filter be a 1 / 2b ^{[mm -1]} (half cycle b [μm]) preferable. In this way, by changing the center frequency of each filter according to the measurement site, the layer structure of interest such as the mucosal muscle plate can be accurately depicted without being affected by the thickness of the mucosal layer or mucosal muscle plate at the measurement site. It becomes possible to do.

  In the present embodiment, the method for identifying the measurement site is not particularly limited. For example, the following method is conceivable.

  In general, the endoscope 100 includes an upper endoscope and a lower endoscope depending on the purpose of examination and treatment, and the thickness of the insertion portion 114 differs depending on the type of measurement site. Therefore, an identification ID for identifying the measurement site is provided in the insertion unit 114 of the endoscope 100, and the signal processing unit 22 performs low-frequency bandpass based on the identification ID read by a reading device (not shown). The center frequency of the filter and the high-frequency bandpass filter is changed, and various processes are executed. It is assumed that the signal processing unit 22 stores the thickness of the mucosa layer and the mucosal muscle plate of the measurement site corresponding to the identification ID in a data table and stored in a storage unit (not shown). According to such an identification method, the measurement site is identified by performing a simple operation, and the center frequencies of the low-frequency bandpass filter and the high-frequency bandpass filter are automatically changed based on the result. The burden on the operator can be reduced.

  Further, for example, as shown in FIG. 15, the monitor device 500 displays an observation image (endoscope image) 510 obtained by the endoscope 100 on the left side of the display screen, and signals of the OCT processor 400 on the right side thereof. An image (OCT image) 520 generated by the processing unit 22 is displayed. Thus, it is conceivable to identify the type of the measurement site using the endoscope image 510 displayed on the monitor device 500 in this way.

  FIG. 16 is a flowchart illustrating an example of a method for identifying a measurement site based on an endoscopic image. As shown in FIG. 16, first, the signal processing unit 22 acquires an endoscopic image (step S12). For example, the endoscope image is acquired from the endoscope processor 200 that generates an endoscope image.

  Next, the signal processing unit 22 determines whether or not an annular structure exists in the acquired endoscopic image (step S14). When it is determined that no annular structure exists in the endoscopic image, the measurement site is identified as the stomach (step S16).

  On the other hand, when it is determined that an annular structure exists in the endoscopic image, it is further determined whether or not a pleat structure exists in the endoscopic image (step S18). If it is determined that no pleat structure exists in the endoscopic image, the measurement site is identified as the esophagus (step S20). On the other hand, if it is determined that a pleat structure exists in the endoscopic image, the measurement site is identified as the large intestine.

  Thereafter, the signal processing unit 22 reads out the thickness of the mucosa layer and the mucosal muscle plate of the measurement site specified as described above from the storage unit (not shown), and according to the thickness of the mucosa layer and the mucosal muscle plate of the measurement site. The center frequency of the low frequency band pass filter and the high frequency band pass filter is set, and the above-described various processes are executed.

  As described above, according to the present embodiment, the image data that has been subjected to the low-frequency filtering process (first intermediate image data) and the image data that has been subjected to the high-frequency filtering process (second intermediate image data) By performing the process (AND process) for extracting the overlapping parts of the above, it is possible to obtain an image in which the high-frequency noise component is removed and the layer structure of interest such as the mucosal muscle plate is clearly extracted. As a result, it is possible to more reliably determine whether or not the region where the mucosal muscle plate has not been extracted is due to the tear of the mucosal muscle plate. As a result, it becomes easier to determine whether the cancer has infiltrated the mucosal fascia.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. Hereinafter, description of parts common to the first embodiment will be omitted, and description will be made focusing on characteristic parts of the present embodiment.

  FIG. 17 is a block diagram illustrating a configuration of a signal processing unit according to the second embodiment. In FIG. 17, elements that are the same as or similar to those in FIG.

  As shown in FIG. 17, the signal processing unit 22B as the second embodiment further includes a tomographic image construction unit 470 and an image composition unit 480 in addition to the configuration of the first embodiment (see FIG. 9). Yes.

  The tomographic image construction unit 470 is a processing unit that constructs a normal tomographic image in the same manner as in the past, and the image data (input image data) generated by the logarithmic conversion unit 420 is input, and the monitor device 500 uses the image data. A tomographic image is constructed in accordance with the display method. Specifically, a tomographic image is constructed by adjusting brightness and contrast, resampling in accordance with the display size, coordinate conversion in accordance with a scanning method such as radial scanning and sector scanning.

  The image composition unit 480 synthesizes the tomographic image constructed by the tomographic image construction unit 470 and the AND image constructed by the AND image construction unit 460 and outputs the synthesized image to the monitor device 500.

The image composition method in the image composition unit 480 is preferably a method in which the tomographic image and the AND image are added and combined at a preset ratio. In particular,
(1) A method of adding an AND image at a fixed ratio β when a tomographic image is set to 1. Composite image = tomographic image + β × AND image (0 <β <1)
Or
(2) Method of adding both at a fixed ratio Composite image = (1-β) × tomographic image + β × AND image (0 <β <1)
There is. However, the image composition method is not limited to these, and any generally used method such as a method of superimposing an AND image on a tomographic image may be used. The synthesized image output from the image synthesizing unit 480 is displayed on the monitor device 500 and can be diagnosed.

  According to the second embodiment, by combining the tomographic image and the AND image, information regarding the layer structure of interest such as the mucosal muscle plate is added to the composite image displayed on the monitor device 500. Thus, the attention layer structure can be easily identified. This makes it possible to more reliably determine whether or not the region where the mucosal muscle plate has not been extracted is due to the tear of the mucosal muscle plate. As a result, it becomes easier to determine whether the cancer has infiltrated the mucosal fascia.

  In each of the above-described embodiments, the SS-OCT (Swept Source OCT) apparatus has been described as the OCT processor 400. However, the present invention is not limited to this, and the OCT processor 400 is also applied as an SD-OCT (Spectral Domain OCT) apparatus. Is possible.

The optical tomographic imaging apparatus and the operation method thereof according to the present invention have been described in detail above. However, the present invention is not limited to the above examples, and various improvements and modifications can be made without departing from the gist of the present invention. Of course you can go.

  DESCRIPTION OF SYMBOLS 10 ... Diagnostic imaging apparatus, 20 ... Interference light detection part, 20a ... Interference signal generation part, 20b ... AD conversion part, 22 ... Signal processing part, 100 ... Endoscope, 200 ... Endoscope processor, 300 ... Light source device, 400 ... OCT processor, 410 ... Fourier transform unit, 420 ... logarithmic transform unit, 430 ... low frequency filtering unit, 432 ... low frequency BPF unit, 434 ... binarization processing unit, 440 ... high frequency filtering unit, 442 ... high frequency BPF unit 444, binarization processing unit, 450, AND unit, 460, AND image construction unit, 470, tomographic image construction unit, 480, image composition unit, 490, control unit, 500, monitor device

Claims (16)

The light emitted from the wavelength swept light source is divided into measurement light and reference light, irradiated to the measurement object with the measurement light, and the reflected light from the measurement object and the reference light are combined, and the reflected light and An optical tomographic imaging apparatus that detects interference light when the reference light is combined as an interference signal, and acquires the tomographic image of the measurement object using the interference signal,
Fourier transform means for Fourier transforming the interference signal to generate tomographic information of the measurement object;
Logarithmic conversion means for logarithmically converting the tomographic information to be measured to generate input image data;
A first intermediate image data is generated by performing a filtering process on the input image data using a first frequency filter having a lower center frequency among at least two types of frequency filters having different center frequencies. One filtering means;
Second filtering for generating second intermediate image data by performing filtering processing on the input image data using a second frequency filter having a higher center frequency among the at least two types of frequency filters. Means,
AND processing means for generating output image data by extracting an overlap portion between the first intermediate image data and the second intermediate image data;
Image generating means for generating an image to be displayed on the monitor means from the output image data;
Center frequency changing means for changing the center frequency of the first or second frequency filter according to the type of the measurement object;
A measuring object identifying means for identifying the type of the measuring object,
The optical tomographic imaging apparatus, wherein the center frequency changing unit changes a center frequency of the first or second frequency filter based on a result identified by the measurement object identifying unit . The center frequency changing means to claim 1, characterized in that determining the center frequency of the first frequency filter based on the thickness of the adjacent layer thickness and the noticed layer structure of interest layer structure of the measurement object The optical tomographic imaging apparatus described. The center frequency changing means, the optical tomographic imaging apparatus according to claim 1 or 2, characterized in that determining the center frequency of the second frequency filter based on the thickness of the target layer structure of the measurement object. The measurement target identification means, based on the endoscope imparted identification ID to the insertion portion to be inserted into a subject, any one of claims 1 to 3, characterized in that identifying the type of the measurement object 1 The optical tomographic imaging apparatus according to Item . The measurement target identification means, an optical tomographic imaging apparatus as set forth in the endoscopic image in any one of claims 1 to 3, characterized in that identifying the type of the measurement target. The first filtering means generates the first intermediate image data by performing a binarization process after performing a filtering process on the input image data by the first frequency filter. The optical tomographic imaging apparatus according to any one of claims 1 to 5 , wherein: The second filtering means generates the second intermediate image data by performing a binarization process after performing a filtering process on the input image data by the second frequency filter. The optical tomographic imaging apparatus according to any one of claims 1 to 6 . To any one of claims 1 to 7, characterized in that it comprises an image synthesizing means for generating a composite image by adding in the proportions set the tomographic image and the generated image by the image generating unit previously The optical tomographic imaging apparatus described. The light emitted from the wavelength swept light source is divided into measurement light and reference light, irradiated to the measurement object with the measurement light, and the reflected light from the measurement object and the reference light are combined, and the reflected light and An operation method of an optical tomographic imaging apparatus that detects interference light when the reference light is combined as an interference signal, and acquires the tomographic image of the measurement object using the interference signal,
The optical tomographic imaging apparatus includes a Fourier transform unit, a logarithmic transform unit, a first filtering unit, a second filtering unit, an AND processing unit, an image generating unit, a center frequency changing unit, and a measurement object. An identification means,
A Fourier transform step in which the Fourier transform means generates the tomographic information of the measurement object by Fourier transforming the interference signal;
A logarithmic conversion step in which the logarithmic conversion means logarithmically converts the tomographic information to be measured to generate input image data;
The first filtering means performs a filtering process on the input image data by using a first frequency filter having a lower center frequency among at least two types of frequency filters having different center frequencies. A first filtering step for generating intermediate image data of:
The second filtering means applies a filtering process to the input image data using a second frequency filter having a higher center frequency among the at least two types of frequency filters, thereby providing a second intermediate image. A second filtering step for generating data;
The AND processing means, and AND processing step of generating output image data by extracting the overlapping portion between the first intermediate image data and the second intermediate image data,
Wherein the image generation means, an image generating step of generating an image to be displayed on the monitor means from the output image data,
A center frequency changing step in which the center frequency changing means changes the center frequency of the first or second frequency filter according to the type of the measurement object;
The measurement object identification means includes a measurement object identification step for identifying the type of the measurement object,
The operation method of an optical tomographic imaging apparatus characterized in that the center frequency changing step changes the center frequency of the first or second frequency filter based on the result identified by the measurement object identifying step . The center frequency changing step, to claim 9, characterized in that determining the center frequency of the first frequency filter based on the thickness of the adjacent layer thickness and the noticed layer structure of interest layer structure of the measurement object A method of operating the described optical tomographic imaging apparatus . The center frequency changing step, the optical tomographic imaging apparatus according to claim 9 or 10, characterized in that determining the center frequency of the second frequency filter based on the thickness of the target layer structure of the measurement object Actuation method. The measurement target identification step, based on the identification ID given to the endoscope insertion portion to be inserted into a subject, any one of claims 9 to 11, characterized in that identifying the type of the measurement object 1 The operation | movement method of the optical tomographic imaging apparatus as described in an item . The method of operating an optical tomographic imaging apparatus according to claim 9, wherein the measuring object identifying step identifies the type of the measuring object from an endoscopic image. The first filtering step generates the first intermediate image data by performing a binarization process after performing a filtering process on the input image data by the first frequency filter. The method of operating an optical tomographic imaging apparatus according to any one of claims 9 to 13 . The second filtering step generates the second intermediate image data by performing a binarization process after performing a filtering process on the input image data by the second frequency filter. The method of operating an optical tomographic imaging apparatus according to any one of claims 9 to 14 , wherein: The optical tomographic imaging apparatus further comprises image synthesis means,
The image synthesizing means, the claims 9 to 15, characterized in that it comprises an image synthesizing step of generating a composite image by adding in the proportions set the tomographic image and the generated image by the image generating step in advance An operation method of the optical tomographic imaging apparatus according to claim 1.