JP5616626B2 - 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 that generates an optical tomographic image by OCT (Optical Coherence Tomography) measurement and an operating method thereof.

  Conventionally, it has been proposed to use an optical tomographic image acquisition apparatus using OCT measurement when acquiring an optical tomographic image of a living tissue. For example, in addition to acquiring tomographic images of the fundus, anterior segment, and skin, observation of an arterial blood vessel wall using an OCT probe (optical probe), observation of a digestive tract in which an OCT probe is inserted from a forceps channel of an endoscope It is applied to various parts. In this optical tomographic image acquisition apparatus, after the low-coherent light emitted from the light source is divided into measurement light and reference light, reflected light from the measurement object when the measurement light is irradiated to the measurement object, or backscattering The light and the reference light are combined, and an optical tomographic image is acquired based on the intensity of the interference light between the reflected light and the reference light. Hereinafter, the reflected light and the backscattered light from the measurement object are collectively referred to as reflected light.

  The OCT measurement is roughly divided into two types: TD-OCT (Time domain OCT) measurement and FD-OCT (Fourier Domain OCT) measurement. In TD-OCT (Time domain OCT) measurement, reflected light corresponding to a position in the depth direction of a measurement target (hereinafter referred to as a depth position) is measured by measuring the intensity of interference light while changing the optical path length of the reference light. This is a method for obtaining an intensity distribution.

  On the other hand, in the FD-OCT measurement, the interference light intensity is measured for each spectral component of the light without changing the optical path length of the reference light, and the spectral interference intensity signal obtained here is represented by Fourier transform using a computer. This is a method of acquiring a reflected light intensity distribution corresponding to a depth position by performing frequency analysis. In recent years, it has attracted attention as a technique that enables high-speed measurement by eliminating the need for mechanical scanning existing in TD-OCT. As a typical apparatus configuration for performing FD-OCT measurement, there are two types, that is, an SD-OCT (Spectral Domain OCT) apparatus and an SS-OCT (Swept source OCT).

  The OCT measurement technique has high expectations for optical biopsies (biopsy) that perform non-invasive specification of a lesion site by measurement at the cellular level. However, the resolution of the current OCT is about 10 μm, which is insufficient for observation of a cell level as large as 10 to 20 μm, and further higher resolution is desired.

  The axial resolution Δz of OCT is determined by the spectral width and center wavelength of the light source used according to the following equation (1).

Δz = (2 · ln2 / π) · (λ ² / Δλ) (1)
Δλ: Spectral width, λ: Center wavelength It is necessary to widen the spectral width of the light source in order to increase the resolution of OCT, and research and development of Ti: sapphire light source and the like are underway. However, at present, these broadband light sources are expensive and do not have mass productivity.

  In order to solve this problem, in recent years, high resolution has been studied by creating a pseudo broadband light source using an SLD having a plurality of wavelength bands. The problem with this pseudo-broadbanding is that the spectral bands are separated because the SLD light sources having center wavelengths of 1.0 μm and 1.3 μm that are generally used for living bodies cannot cover the entire spectral band. Spectral band separation discontinuously divides the interference signal, causing artifacts in the OCT image. In particular, in the TD system, the acquired signal becomes an OCT image itself, and it is difficult to prevent these artifacts.

  Thus, as a combined OCT technique using the FD method, for example, a technique of combining a plurality of OCT systems using a plurality of light sources is disclosed (Patent Document 1).

  However, in the FD method, since the optical path difference between the detection light and the reference light is expressed as the frequency of the interference signal, even if the same object is measured, the conventional multiplexing of a configuration in which two or more systems are simply connected. In the OCT technology, there is a problem that the frequency of the interference signal varies depending on the distance to the reference plane in each system, and the positioning of the distance to the reference plane with high accuracy is required. That is, since the OCT image itself has a resolution of 10 μm or less, it is necessary to adjust the distance to the reference surface with the resolution or less.

  In order to cope with such a problem (positioning of the distance to the reference surface with high accuracy), for example, as a calibration method using a low reflector, there is a method of correcting variation in length when the probe is replaced. (Patent Document 2).

  In this patent document 2, the offset amount according to the length position of the probe is read from the signal of the low reflector and used to move the position of the reference surface. The reference when the probe length is different depending on the signal from the low reflector. It can be applied to automatic surface position movement.

JP 2008-128708 A JP 2006-215006 A

  However, in the case of applying the calibration method of Patent Document 2 in a plurality of OCT systems using a plurality of light sources, if an intermediate spectrum estimation process is actually performed using an average value or the like, the phase between two interference signals This discrepancy causes artifacts.

  That is, since a plurality of OCT systems using a plurality of light sources use light sources having different center wavelengths, it is necessary to match the optical distance, not the physical distance, and the refraction due to the bending of the fiber itself or the environment. Even if the rate changes, it causes a reduction in resolution, so calibration in real time is necessary.

The present invention has been made in view of such circumstances, and does not require high-precision alignment of a reference surface, and uses a interference signal obtained from a plurality of light sources to produce a high-definition OCT image that does not have a reduction in resolution. It is an object of the present invention to provide an optical tomographic imaging apparatus and an operating method thereof.

In order to achieve the above object, the optical tomographic imaging apparatus according to the first aspect of the present invention is a light source unit that emits a plurality of light fluxes, each having a different wavelength band and sweeping a wavelength within the predetermined wavelength band. And a light dividing means for dividing the plurality of light beams emitted from the light source unit into measurement light and reference light, respectively, and means for irradiating the measurement object with the plurality of measurement lights divided by the light dividing means An optical fiber that guides the measurement light, and a measurement light that is fixed to the distal end of the optical fiber and that deflects the measurement light emitted from the distal end of the optical fiber toward the measurement object. irradiating means, wherein disposed between the distal optical system and the measurement object, and the reference reflecting means for over-permeability of another part reflects part of the measurement light, the measurement light is irradiated to the measurement object Before A reference light reflected from the measurement reflected light and the reference reflecting means from the measurement object, the respective interference light signal with the reference light and a plurality of interference light detecting means for detecting for each of the light beam, the interference light detecting means Peak position extraction means for detecting a peak position of optical tomographic image data obtained by Fourier transforming the interference light signal for each of the light beams detected in this manner, and optical tomographic image data for one of the plurality of light beams The peak information calculation means for calculating the difference between the peak position of the light beam and the peak position of the optical tomographic image data for the other light flux as peak information, and the optical tomographic image data for the other light flux is corrected based on the peak information The optical tomographic image data correcting means, the optical tomographic image data for the one light beam, and the optical tomographic image data corrected by the optical tomographic image data correcting means are reversed. It comprises a interference light reconstructing means for reconstructing the respective interference light signal for each of the light beams, a and Rie conversion.

According to the first aspect of the present invention, when the plurality of interference light detection means is irradiated with the measurement light, the measurement reflected light from the measurement object and the reference reflected light from the reference reflection means, By detecting each interference light signal with the reference light for each light beam, it is not necessary to align the reference surface with high accuracy, and there is no reduction in resolution using interference signals obtained from a plurality of light sources. It is possible to obtain a fine OCT image.

The optical tomographic imaging apparatus according to a second aspect of the present invention is the optical tomographic imaging apparatus according to the first aspect, wherein the peak position extraction means has a predetermined threshold value for the optical tomographic image data with respect to the measurement light irradiation direction by the measurement light irradiation means. The position that is beyond and closest to the tip optical system is detected as the peak position.

The optical tomographic imaging apparatus according to a third aspect of the present invention is the combined interference light obtained by synthesizing the interference light signal reconstructed for each of the light beams by the interference light reconstruction means in the first aspect or the second aspect. And a combined interference light signal generating means for generating a signal, and an optical tomographic image information generating means for generating optical tomographic image information of the measurement object from the combined interference light signal.

The optical tomographic imaging apparatus according to the fourth aspect of the present invention is the optical tomography apparatus according to any one of the first to third aspects, wherein the wavelength sweep periods of the plurality of light beams are synchronized.

An optical tomographic imaging device operating method according to a fifth aspect of the present invention includes: a light source unit that emits a plurality of light fluxes each having a different wavelength band and sweeping a wavelength within a predetermined wavelength band; and the light source unit A light dividing means for dividing each of the plurality of light beams emitted from the light into measurement light and reference light, and means for irradiating the measurement object with the plurality of measurement lights divided by the light dividing means, Measuring light irradiation means comprising: an optical fiber that guides measurement light; and a tip optical system that is fixed to the tip of the optical fiber and deflects the measurement light emitted from the tip of the optical fiber toward the measurement object; and A reference reflecting means that is disposed between the tip optical system and the measurement object, reflects a part of the measurement light and transmits the other part, a plurality of interference light detection means, a peak position extraction means, a peak information Means leaving, an optical tomographic image data correcting means, a method of operating an optical tomography system including the interference light reconstructing means, wherein the plurality of interference light detecting means, the irradiation the measurement light to the measurement target When the measured reflected light from the measurement object and the reference reflected light from the reference reflecting means, and the interference light signal of the reference light is detected for each of the luminous flux, the peak position extracting means, A peak position of optical tomographic image data obtained by Fourier transforming the interference light signal for each light beam is detected, and the peak information calculation means is a peak position of optical tomographic image data for one light beam among the plurality of light beams. When the difference between the peak position of the optical tomographic image data for the other light beam is calculated as the peak information, the optical tomographic image data correcting means, optical disconnection of the other light beam on the basis of the peak information Correcting the image data, the interference light reconstructing means, optical tomographic image data, and the light flux of each of the coherent light signal an optical tomographic image data by performing inverse Fourier transform after pre Kiho positive for the one light beam Rebuild every time .

  As described above, according to the present invention, there is an effect that a high-definition OCT image free from artifacts can be obtained using interference signals obtained from a plurality of light sources.

Schematic diagram showing a preferred embodiment of an optical tomographic imaging apparatus The figure which shows the structure of the principal part of the optical probe of FIG. The block diagram which shows the structure of the calculating part of FIG. Diagram showing interference signals due to different reference planes of the two systems The figure explaining the calibration of the interference signal of two systems of FIG. FIG. 4 is a flowchart for explaining a processing flow of the arithmetic unit in FIG. 3. The figure explaining the peak position detection in the reflected light L3a in the process of FIG. The figure explaining the peak position detection in the reflected light L3b in the process of FIG. The figure which shows the diagnostic imaging apparatus used together with the endoscope apparatus which can apply the OCT probe of the optical tomographic imaging apparatus of FIG.

Hereinafter, an optical tomographic imaging apparatus and an operation method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic diagram showing a preferred embodiment of an optical tomographic imaging apparatus. FIG. 2 is a diagram showing a configuration of a main part of the optical probe of FIG.

  The optical tomographic imaging apparatus 1 according to the present embodiment acquires a tomographic image of a measurement target such as a living tissue or a cell in a body cavity by SS-OCT (Swept source OCT) measurement, as shown in FIG. In addition, the light source unit 2, the light splitting units 3A and 3B as the light splitting means, the multiplexing units 6A and 6B, the interference light detection units 8A and 8B as the interference light detection means, the peak information detection means, the difference calculation means, and the interference information It has the calculating part 20 as a correction means, and the display apparatus 11. In addition, the calculating part 20 is comprised by a personal computer etc., for example.

  The light source unit 2 emits a plurality of light beams La and Lb having wavelength bands Δλa and Δλb separated from each other. Specifically, the light source unit 2 includes a first light source 2A that emits laser light while sweeping the wavelength in the wavelength band Δλa, and a laser beam that sweeps the wavelength in the wavelength band Δλb. Has a second light source 2B. Accordingly, the light sources 2A and 2B emit light beams La and Lb having wavelength bands Δλa and Δλb, respectively, when the wavelength is swept for one period.

  The light splitting units 3A and 3B are composed of, for example, a 2 × 2 optical coupler having a branching ratio of 90:10. The light splitting unit 3A splits the light beam La into measurement light L1a and reference light L2a, and the light splitting unit 3B splits the light beam Lb into measurement light L1b and reference light L2b. At this time, the light dividing units 3A and 3B divide at a ratio of measurement light: reference light = 90: 10. Here, the measurement lights L1a and L1b are guided to the optical probe 600 via the circulators 4A and 4B and the multiplexing / demultiplexing unit 12.

  The optical probe 600 guides the measurement lights L1a and L1b incident through the optical rotary connector 18 to the measurement target S and irradiates the same part of the measurement target S simultaneously. Further, the optical probe 600 guides the reflected lights L3a and L3b from the measurement object S when the measurement light L1a and L1b are irradiated on the measurement object S.

  As shown in FIG. 2, the optical probe 600 is connected to the optical rotary connector 18 by a motor (not shown), and has a configuration in which a fiber part FB1 having a ball lens 680 provided at the tip covered with a transparent sheath 601 rotates. It has become. As a result, the optical probe 600 can scan the light beam radially on the measurement target S via the sheath 601 (arrow R in FIG. 2) and measure a two-dimensional tomographic image. Furthermore, the optical probe 600 is moved forward and backward (arrows D1 and D2 in FIG. 2) in a direction perpendicular to the plane formed by the scanning circle of the optical path by a motor (not shown). Measurement of dimensional tomographic images is also possible.

  Further, in the optical probe 600, a reflection member 700 that reflects a part of the light beam from the ball lens 680 is provided on the entire outer surface or the inner peripheral surface of the sheath 601.

  The reflecting member 700 is made of a low reflecting member such as glass having a predetermined reflectance with respect to the wavelength of the measurement light.

  Returning to FIG. 1, the optical tomographic imaging apparatus 1 includes the multiplexing / demultiplexing unit 12 in the optical path between the optical dividing unit 3 </ b> A and the optical probe 600 and in the optical path between the optical dividing unit 3 </ b> B and the optical probe 600. The multiplexing / demultiplexing unit 12 has a function of multiplexing and demultiplexing light according to a set cutoff wavelength, and is configured by, for example, a WDM (Wavelength Division Multiplexing) coupler.

  The multiplexing / demultiplexing unit 12 multiplexes the measurement lights L1a and L1b incident from the light splitting units 3A and 3B, respectively, and emits them to the optical probe 600 side, and the reflected lights L3a and L3b incident from the optical probe 600 side. Are demultiplexed and emitted to the multiplexing sections 6A and 6B, respectively.

  The reflected light L3a is combined with the reference light L2a in the combining unit 6A, and the reflected light L3b is combined with the reference light L2b in the combining unit 6B.

  A reflection type optical path length adjustment unit 7A having a reference surface such as a reflection mirror (not shown) is provided in the optical path of the reference light L2a from the light dividing unit 3A to the multiplexing unit 6A via the circulator 5A. A reflection type optical path length adjustment unit 7B having a reference surface such as a reflection mirror (not shown) is provided in the optical path of the reference light L2b from the light splitting unit 3B to the multiplexing unit 6B via the circulator 5B. The optical path length adjusting units 7A and 7B change the optical path lengths of the reference lights L2a and L2b, respectively, in order to adjust the position where the tomographic image acquisition is started.

  The multiplexing units 6A and 6B are composed of, for example, a 2 × 2 optical fiber coupler with a branching ratio of 50:50. The multiplexing unit 6A combines the reflected light L3a and the reference light L2a, and emits the interference light L4a generated at this time to the interference light detection unit 8A. The multiplexing unit 6B combines the reflected light L3b and the reference light L2b, and emits the interference light L4b generated at this time to the interference light detection unit 8B.

  In the optical tomographic imaging apparatus 1, the multiplexing units 6A and 6B bisect the interference lights L4a and L4b, respectively, and emit them to the interference light detection units 8A and 8B, and the interference light detection units 8A and 8B are bisected. The detected interference lights L4a and L4b are each subjected to balance detection using two photodetectors. By this balance detection mechanism, the influence of light intensity fluctuation can be suppressed and a clearer image can be obtained.

  The interference light detectors 8A and 8B have a function of photoelectrically converting the interference lights L4a and L4b, respectively, and detecting them as a plurality of interference signals ISa and ISb for the wavelength bands Δλa and Δλb of the light beams La and Lb. Here, the interference light detection units 8A and 8B recognize the corresponding light flux by synchronizing with the wavelength sweep trigger signals 9A and 9B from the light sources 2A and 2B. At this time, the interference light detection units 8A and 8B observe the interference signals ISa and ISb of each light beam La and Lb. The interference signals ISa and ISb are output to the calculation unit 20.

  The arithmetic unit 20 processes the interference signals ISa and ISb, and displays a tomographic image on the display device 11.

  FIG. 3 is a block diagram showing the configuration of the calculation unit of FIG. As shown in FIG. 3, the calculation unit 20 of the optical tomographic imaging apparatus 1 includes a first interference wave data storage unit 21, a second interference wave data storage unit 22, a first optical tomographic image data generation unit 23, and a second light. A tomographic image data generation unit 24, a peak position extraction unit 25 as a peak information detection unit and a difference calculation unit, a second optical tomographic image data correction unit 26 as an interference information correction unit, a first interference wave data reconstruction unit 27, a first 2 includes an interference wave data reconstruction unit 28, a combined interference wave generation unit 29 as a combined interference light signal generation unit, and an FFT unit 30 as an optical tomographic image information generation unit.

  The first interference wave data storage unit 21 stores digital data of the interference signal ISa on the light beam La side, and the second interference wave data storage unit 22 stores digital data of the interference signal ISb on the light beam Lb side. Is.

  The first optical tomographic image data generation unit 23 generates first optical tomographic image data by performing FFT (Fast Fourier Transform) on the digital data of the interference signal ISa stored in the first interference wave data storage unit 21. is there.

  The second optical tomographic image data generation unit 24 performs FFT on the digital data of the interference signal ISb stored in the second interference wave data storage unit 22 to generate second optical tomographic image data.

  The peak position extraction unit 25 is configured to receive the first optical tomographic image data obtained by the first optical tomographic image data generation unit 23 and the second optical tomographic image data obtained by the second optical tomographic image data generation unit 24, respectively. From the data, the peak position on the optical tomographic image of the peak indicating the reflecting member 700 is detected, and the difference (AB) between the peak position A of the first optical tomographic image data and the peak position of the second optical tomographic image data B is detected. ) As peak information.

  The second optical tomographic image data correction unit 26 corrects the second optical tomographic image data generated by the second optical tomographic image data generation unit 24 based on the peak information (AB).

  Details of the peak position extraction unit 25 and the second optical tomographic image data correction unit 26 will be described later.

The first interference wave data reconstruction unit 27 reconstructs the interference signal ISa by performing IFFT (inverse fast Fourier transform) on the first optical tomographic image data. Hereinafter, the reconstructed interference signal is denoted as ISa ′.

  The second interference wave data reconstruction unit 28 performs IFFT on the second optical tomographic image data corrected by the second optical tomographic image data correction unit 26 to reconstruct the interference signal ISb. Hereinafter, the reconstructed interference signal is referred to as ISb ′.

  The combined interference wave generation unit 29 combines the digital data of the interference signal ISa ′ and the digital data of the interference signal ISb ′ for each wavelength band to generate a combined interference wave (synthesized interference signal).

  The FFT unit 30 generates a tomographic image information (OCT image) of the measurement target S by performing FFT on the synthetic interference wave (synthetic interference signal), and causes the display device 11 to display the OCT image.

  Next, the calculation unit 20 in the optical tomographic imaging apparatus 1 of the present embodiment configured as described above will be described.

  FIG. 4 is a diagram illustrating interference signals due to different reference surfaces of the two systems, and FIG. 5 is a diagram illustrating calibration of interference signals of the two systems in FIG.

The signal obtained by the interference light detection unit has a frequency that depends on the optical distance difference between the measurement light and the reflected light and the reference light reflected by the reference surface of the optical path length adjustment unit 7 as follows: causing interference signal I _D as shown in).

Z _R : Reference surface position, Z _Sn : Measurement object position, R _R : Reference surface reflectance, R _Sn : Measurement object reflectance When the same object is measured by two systems as in this embodiment The interference signal obtained from each system depends on the position of the respective reference plane. That is, the signals obtained by the interference light detection units 8A and 8B are the measurement light L1a and L1 and the reflected light L3a and L3b, and the reference light L2a and L2b reflected by the reference surfaces of the optical path length adjustment units 7A and 7B. Interference signals I _D1 and I _D2 as shown in the following formulas (2) and (3) having a frequency that depends on the difference in optical distance from the above are generated.

Z _R1 : Reference plane position of the optical path length adjustment unit 7A, Z _R2 : Reference plane position of the optical path length adjustment unit 7B, R _R1 : Reference plane reflectance of the optical path length adjustment unit 7A, R _R2 : Reference of the optical path length adjustment unit 7B Surface Reflectance As shown in FIG. 4, as a result, interference signals having different frequencies are obtained due to the difference ΔL in the position of the reference surface.

In other words, when trying to create a high resolution image from these two interference signals I _D1 and I _D2 , the signals come in different positions even though they are looking at the same thing, so they are expressed as waves of different frequencies. Become.

In this embodiment, when the measurement target is the reflection member 700 provided at the tip of the optical probe 600, the above-described interference signals I _D1 and I _D2 can always be obtained with respect to the position of the reflection member 700.

An optical tomographic image having peaks at Z _R1 -Z _Sn and Z _R2 -Z _Sn can be obtained by Fourier transforming the interference signals I _D1 and I _D2 .

The difference between the peak positions is Z _R1 −Z _Sn − (Z _R2 −Z _Sn ) = Z _R1 −Z _R2 (4)
Thus, it can be seen that this is the difference in the position of the reference plane between the systems (optical path length adjusting units 7A and 7B).

That is, when the two systems are systems A and B, as shown in FIG. 5, the interference signals I _D1 and I _D2 of the reflecting member 700 are used as calibration signals (A) and (B), and the calibration signal ( By detecting the peak positions of A) and (B), and shifting the OCT signal (B) by the difference between the positions to match the OCT signal (A), reference between systems (optical path length adjustment units 7A and 7B) is made. An interference signal having a surface position can be obtained.

  For the detection of the peak position of the reflecting member 700, the reflecting member 700 is arranged in front of the measuring object S, so that the peak position that is always closest to the position of the zero measurement light in the emission direction (see FIG. 2) is detected as a threshold. It is desirable to do.

  As described above, the calculation unit 20 of the present embodiment calibrates the difference between the reference planes in real time by detecting a signal that is always at the same position.

  Next, a specific processing flow of the calculation unit 20 in the present embodiment will be described. FIG. 6 is a flowchart for explaining the flow of processing of the arithmetic unit in FIG. 7 and 8 are diagrams for explaining peak position detection in the reflected lights L3a and L3b in the process of FIG.

  As shown in FIG. 6, the calculation unit 20 stores the digital data of the interference signal ISa in the first interference wave data storage unit 21 and stores the digital data of the interference signal ISb in the second interference wave data storage unit 22 ( Step S1).

  Then, the computing unit 20 generates the first optical tomographic image data by performing FFT on the digital data of the interference signal ISa stored in the first interference wave data storage unit 21 in the first optical tomographic image data generating unit 23. At the same time, the second optical tomographic image data generation unit 24 performs FFT on the digital data of the interference signal ISb stored in the second interference wave data storage unit 22 to generate second optical tomographic image data (step S2). ).

  Subsequently, the calculation unit 20 causes the peak position extraction unit 25 to obtain the first optical tomographic image data and the second light obtained by the first optical tomographic image data generation unit 23, as shown in FIGS. From the data of the second optical tomographic image data obtained by the tomographic image data generation unit 24, the peak position on the optical tomographic image indicating the reflecting member 700 is detected (step S3).

  Specifically, as shown in FIGS. 7 and 8, the peak position extraction unit 25 obtains each optical tomographic image obtained with respect to the measurement light emission direction position (see FIG. 2) in the reference lights L <b> 2 a and L <b> 2 b. The peak position whose emission direction position is closest to 0 is detected as the peak position of the reflecting member 700 based on the predetermined threshold value.

  The predetermined threshold is set to a level that is not sufficiently affected by noise. In addition, since the signal level of the reflection member 700 is seen from the reflection level before the measurement object S, it can be stably detected without depending on the measurement object S except for factors such as fluctuations in the light amount of the light source.

  Then, the calculation unit 20 calculates, in the peak position extraction unit 25, the difference (A−B) between the peak position A of the first optical tomographic image data and the peak position of the second optical tomographic image data B as peak information. (Step S4).

  Next, the calculation unit 20 outputs the second optical tomographic image data generated by the second optical tomographic image data generation unit 24 based on the peak information (AB). The position is shifted by the peak information (A-B) and calibrated to the position in the emission direction of the first optical tomographic image data to generate corrected second optical tomographic image data (step S5).

In addition, the calculation unit 20 performs IFFT on the first optical tomographic image data in the first interference wave data reconstruction unit 27, reconstructs the interference signal ISa, generates the interference signal ISa ′, and generates the second interference wave. The data reconstruction unit 28 performs IFFT on the second optical tomographic image data corrected by the second optical tomographic image data correction unit 26, reconstructs the interference signal ISb, and generates the interference signal ISb ′. The arithmetic unit 20 then combines the digital data of the interference signal ISa ′ and the digital data of the interference signal ISb ′ for each wavelength band at the combined interference wave generation unit 29 to generate a combined interference wave (synthesized interference signal). (Step S6).

  Next, in the FFT unit 30, the calculation unit 20 performs fast Fourier transform (FFT) on the combined interference wave generated by the combined interference wave generation unit 29 to generate tomographic image information (OCT image) of the measurement target S. Then, the OCT image is displayed on the display device 11 (step S7).

  As described above, in this embodiment, (1) the peak position on the optical tomographic image indicating the reflecting member 700 is detected, and the peak position A of the first optical tomographic image data and the peak of the second optical tomographic image data B are detected. A difference (AB) from the position is calculated as peak information, and (2) emission of the second optical tomographic image data generated by the second optical tomographic image data generation unit 24 based on the peak information (AB) thereafter. Since the position of the direction is shifted by the peak information (AB) and calibrated to the position of the emission direction of the first optical tomographic image data, it is not necessary to align the reference plane with high accuracy, and thus obtained. With the combined interference wave, it is possible to obtain a high-definition OCT image without a reduction in resolution using interference signals obtained from a plurality of light sources.

  In addition, since the refractive index of optical fibers, probes, etc. changes due to stress such as bending, it is possible to construct a system that is resistant to external disturbances and environmental changes by always calibrating in real time with the signal of the reflecting member 700. is there.

  Note that the resolution of the OCT measurement may be increased by expanding the apparent frequency band using the synthetic interference wave, or may be used for the spectroscopic tomographic image by the difference of the optical tomographic image.

  Note that this embodiment can be applied to an image diagnostic apparatus used in combination with an endoscope apparatus. More specifically, as shown in FIG. 9, the diagnostic imaging apparatus 50 used in combination with the optical probe 600 and the endoscope apparatus of the present embodiment mainly includes an endoscope 100, an endoscope processor 200, a light source device 300, a living body. An OCT processor 400 serving as a tomographic image generation apparatus and an image display unit 500 serving as a monitor device serving as display means are included. 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 unit 112 is provided with a forceps insertion portion 138, and this forceps insertion portion 138 communicates with a forceps port 156 of the distal end portion 144 via a forceps channel (not shown) provided in the insertion portion 114. Has been. In the diagnostic imaging apparatus 10, the optical probe 600 is led out from the forceps opening 156 by inserting the optical probe 600 that is an OCT probe from the forceps insertion portion 138. The optical probe 600 is inserted from the forceps insertion portion 138 and inserted from the forceps port 156, the operation portion 604 for the operator to operate the optical probe 600, and the optical processor 400 via the connector 401. It consists of a cable 606 to be connected.

  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). It is.

  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.

  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 image display unit 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 image display unit 500 connected to the endoscope processor 200.

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 1 ... Optical tomographic imaging apparatus, 2 ... Light source unit, 2A, 2B ... Light source, 3A, 3B ... Light splitting part, 6A, 6B ... Multiplexing part, 8A, 8B ... Interference light detection part, 11 ... Display apparatus, 20 ... Calculation unit, 21 ... first interference wave data storage unit, 22 ... second interference wave data storage unit, 23 ... first optical tomographic image data generation unit, 24 ... second optical tomographic image data generation unit, 25 ... peak position Extraction unit 26 ... second optical tomographic image data correction unit 27 ... first interference wave data reconstruction unit 28 ... second interference wave data reconstruction unit 29 ... combined interference wave generation unit 30 ... FFT unit 600 ... Optical probe

Claims (5)

A light source unit that emits a plurality of light fluxes, each having a different wavelength band and sweeping a wavelength within a predetermined wavelength band;
A light splitting means for splitting the plurality of light beams emitted from the light source unit into measurement light and reference light, respectively;
A means for irradiating a measurement object with a plurality of the measurement lights divided by the light dividing means, and an optical fiber for guiding the measurement light, fixed to the tip of the optical fiber, and emitted from the tip of the optical fiber Measuring light irradiation means having a tip optical system that deflects the measuring light toward the measurement object;
Reference reflecting means that is disposed between the tip optical system and the measurement object, reflects a part of the measurement light and transmits the other part,
A plurality of interference light signals for each of the light fluxes, which are measured reflected light from the measuring object and the reference reflected light from the reference reflecting means when the measuring light is applied to the measuring object, and the reference light. Interference light detecting means,
Peak position extraction means for detecting a peak position of optical tomographic image data obtained by Fourier transforming the interference light signal for each of the light beams detected by the interference light detection means;
Peak information calculating means for calculating, as peak information, the difference between the peak position of the optical tomographic image data for one light beam among the plurality of light beams and the peak position of the optical tomographic image data for the other light beam;
Optical tomographic image data correction means for correcting optical tomographic image data for the other light flux based on the peak information;
Interfering light reconstruction for reconstructing each interference light signal for each light flux by inverse Fourier transforming the optical tomographic image data for the one light flux and the optical tomographic image data corrected by the optical tomographic image data correction means Means,
Optical tomography system characterized in that example Bei a. The peak position extraction means detects, as the peak position, a position where the optical tomographic image data exceeds a predetermined threshold and is closest to the tip optical system with respect to the measurement light irradiation direction by the measurement light irradiation means. The optical tomographic imaging apparatus according to claim 1 . Combined interference light signal generating means for generating a combined interference light signal obtained by combining the interference light signals reconstructed for each of the light beams by the interference light reconstructing means;
Optical tomographic information generating means for generating optical tomographic image information of the measurement object from the combined interference light signal;
Optical tomographic imaging apparatus according to claim 1 or 2, further comprising a. Wherein the plurality of wavelength sweep cycle of the light beam, the optical tomographic imaging apparatus according to any one of claims 1 to 3 characterized by being synchronized. A light source unit that emits a plurality of light fluxes, each having a different wavelength band and sweeping a wavelength within a predetermined wavelength band;
A light splitting means for splitting the plurality of light beams emitted from the light source unit into measurement light and reference light, respectively;
A means for irradiating a measurement object with a plurality of the measurement lights divided by the light dividing means, and an optical fiber for guiding the measurement light, fixed to the tip of the optical fiber, and emitted from the tip of the optical fiber Measuring light irradiation means having a tip optical system that deflects the measuring light toward the measurement object;
Reference reflecting means that is disposed between the tip optical system and the measurement object, reflects a part of the measurement light and transmits the other part,
An operation method of an optical tomographic imaging apparatus comprising a plurality of interference light detection means, peak position extraction means, peak information calculation means, optical tomographic image data correction means, and interference light reconstruction means,
The plurality of interference light detection means are interference lights of the measurement reflected light from the measurement object, the reference reflected light from the reference reflection means, and the reference light when the measurement light is irradiated onto the measurement object. A signal is detected for each luminous flux,
The peak position extraction means detects a peak position of the optical tomographic image data obtained by the interference light signal for each of the light beams by Fourier transform,
The peak information calculation means calculates as the peak information a difference between the peak position of the optical tomographic image data for light and the peak position of the tomographic image data, the other light beam for one of the light beams of the plurality of light beams,
The optical tomographic image data correcting means, an optical tomographic image data for the other light beam is corrected on the basis of the peak information,
The interference light reconstruction means, to rebuild the respective interference light signal for each of the beam optical tomographic image data, and an optical tomographic image data before and after Kiho forward and inverse Fourier transform for the one light beam method of operating an optical tomography system according to claim and this.

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