JP5663240B2 - 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 using an OCT probe having a plurality of light guiding means and an operating method thereof .

  Conventionally, when acquiring an optical tomographic image of a living tissue, an optical tomographic image acquisition apparatus using OCT (Optical Coherence Tomography) may be used. This optical tomographic image acquisition apparatus divides low-coherent light emitted from a light source into measurement light and reference light, and then reflects or backscatters light from the measurement object when the measurement light is applied to the measurement object. The light and the reference light are combined, and a tomographic image (optical tomographic image) is acquired based on the intensity of the interference light between the reflected light and the reference light.

Conventionally, probes having the following configurations are known as probes (OCT probes) used for OCT measurement as in Patent Documents 1 and 2 . O CT probe is rotary optical Fiber及 beauty torque transmission coil together with the inserted arrangement, deflection and optical lens for focusing light is disposed at the distal end of the rotary optical Fiber in Sea scan . When the measuring light is supplied to the rotary optical Fiber from instrumentation Okimoto body (OCT processor), the measuring light is emitted from the tip of the rotary optical Fiber, relative to the longitudinal axis of the thus OCT probe optical lens predetermined angle inclined by a radial direction (e.g., approximately 90 degrees) is deflected is irradiated to the measurement object to be positioned in the radial direction, the returning light is adapted to be incorporated into the rotation side optical fiber through the optical lens Te Yes. The optical rotary join preparative more rotary optical Fiber Contact and torque transmission coil optical lens is rotated by being rotated in a predetermined direction, the emission direction of the optical lens or these measurement light OCT probe Rotating about the longitudinal axis of the lens, radial scanning is performed.

Also, when generating a three-dimensional volume data, the optical lens by the axial movement drive (output position of the measurement light) is moved to the end of the movable range of the first direction, tomographic information in the radial direction by the radial scan While acquiring (tomographic image), it moves in the other direction by a predetermined amount, or moves to the end of the movable range while alternately repeating the acquisition of radial tomographic information and the predetermined amount of movement in the other direction.

Thus for the measurement Target by acquiring tomographic information in the desired range, it is possible to generate a three-dimensional volume data based on the acquired tomographic information.

That is, the interference signal by obtains the tomographic information of the measurement subject to the depth direction (first direction), the emission direction of measurement light is rotated in a predetermined direction against the measurement Target (circumferential Sea scan) by radial scanning, the measurement subject to the depth direction (first direction), to acquire the tomographic information of the scan surface consisting the direction (second direction) substantially orthogonal to the deep direction can, furthermore, by moving the scan surface along the direction (third direction) substantially orthogonal to the scan plane, the fault for generating a three-dimensional volume data in a predetermined three-dimensional region of the measurement Target Information can be acquired.

JP 2010-043994 A JP 2009-232960 A

  The present applicant has proposed the following OCT probe in Japanese Patent Application No. 2009-117655 in order to eliminate the drawbacks of the conventional OCT probe as described above. According to this, in the sheath of the OCT probe, a reflecting surface body having a plurality of reflecting surfaces with each pyramid surface (side surface) of the polygonal frustum as a reflecting surface has a central axis (symmetric axis) as the longitudinal axis of the sheath (OCT). It is arranged toward the direction of the longitudinal axis of the probe. Then, a plurality of optical fibers that guide measurement light and return light with the position facing each pyramid surface of the reflecting surface body as a tip are arranged in an annular shape around the central axis of the reflecting surface body. A GRIN lens for condensing is provided at the tip of the optical fiber. As a result, when the measurement light is emitted from the tip of each optical fiber, the measurement light is reflected and deflected by each reflection surface of the reflection surface body, and is emitted in the radial direction. Are emitted in an angular direction having a uniform angular interval (an angular interval obtained by dividing 360 ° by the number of pyramid surfaces) over 360 ° around the longitudinal axis. In addition, the return light for each measurement light is taken into the same optical fiber from which the measurement light is emitted via a reflecting surface.

  In addition, the reflecting surface is rotated by a flexible shaft with the central axis as the center of rotation. By emitting measuring light from the tip of each optical fiber while rotating the reflecting surface, the emission direction of each measuring light is also rotated. It is supposed to be. Then, when the angle ranges of the emission directions in which each measurement light is emitted during the rotation of the reflecting surface body are matched, when each pyramid surface is rotated to a position where it overlaps the adjacent pyramid surface (360 degrees is divided by the number of pyramid surfaces). Measurement light is emitted in the direction of the entire angular range (the entire circumference) around the longitudinal axis of the sheath.

Therefore, according to this OCT probe, minute number of pyramidal surface of the reflecting face piece compared to conventional OCT probe, acquisition time tomographic information becomes faster over the entire circumference during the radial scan, also, as in the prior art In addition, since it is not necessary to rotate the optical fiber together with the reflecting surface, it is possible to increase the radial scanning speed. Further, since an optical rotary joint for rotatably connecting the optical fiber of the OCT probe to the optical fiber on the OCT processor side is not required, the loss of the amount of measurement light and return light in the optical rotary joint that affects the image quality. And deterioration of S / N can be eliminated.

  However, as described above, in the OCT probe that simultaneously emits a plurality of measurement lights via a plurality of optical fibers, it is necessary to divide the measurement light from the light source into each optical fiber, and the amount of the measurement light is reduced accordingly. In addition, the acquired tomographic image may be deteriorated in image quality. Although it is possible to increase the number of light sources by the number of optical fibers, in that case, the cost increases.

  On the other hand, when the measurement target is a living tissue having a large lumen such as the large intestine or stomach, the measurement target is close to only a part of the peripheral surface of the OCT probe, and the one around the longitudinal axis of the OCT probe. In many cases, there is no measurement object that can acquire tomographic information effectively only in the direction of the angular range of the part.

  In such a case, among the plurality of measurement lights emitted from the plurality of optical fibers of the OCT probe, the measurement light emitted in the direction of the angle range where the tomographic information cannot be acquired effectively is wasted. If such measurement light is not supplied to the optical fiber, the amount of measurement light supplied to the other optical fiber can be increased correspondingly, and the image quality of the tomographic image can be improved.

The present invention has been made in view of such circumstances, and is effective in an optical tomographic imaging apparatus that obtains a tomographic image by applying measurement light to an optical probe including a plurality of optical fibers (light guiding means). It is an object of the present invention to provide an optical tomographic imaging apparatus and an operation method thereof for suppressing the reduction in the amount of measurement light that can acquire a tomographic image and improving the quality of the tomographic image.

In order to achieve the above object, an optical tomographic imaging apparatus according to claim 1 is a longitudinal optical probe having a plurality of light guides, and light emitted from a light source among the plurality of light guides. A switch means for switching the light guide means to be given to one of the light guide means, and a light guide means for giving light from the light source by the switch means among the plurality of light guide means, and sequentially switching along the circumferential direction of the optical probe A pre-scanning unit that acquires a tomographic image over the entire region, and a light-guiding unit that provides light from the light source among the plurality of light-guiding units based on the tomographic image acquired by the pre-scanning unit Among the plurality of light guide means, the light guide means for providing light from the light source by the switch means is sequentially switched to only the light guide means determined by the determination means, and the light Main scanning means for acquiring a tomographic image of only a part of the region along the circumferential direction of the lobe and acquiring the three-dimensional volume data by moving the region for acquiring the tomographic image in the longitudinal axis direction of the optical probe The optical probe includes a plurality of light guides in an elongated cylindrical sheath, and the light emitted from the light guides is different in a region along the circumferential direction. A polyhedral mirror having a plurality of light deflecting surfaces deflecting in the direction, and rotating the polyhedral mirror at the time of tomographic image acquisition to change the deflection direction of each light emitted from the plurality of light guide means Further, it is characterized in that it is changed within a range that is within each of a plurality of regions that divide all regions of the region along the circumferential direction .

  According to the present invention, even when the optical probe has a plurality of light guide means, the light (measurement light) from the light source is not branched and given to these light guide means, but any one light guide means is provided. Since it is given only to the optical member, the amount of measurement light is not reduced. Further, the measurement light is not given to the light guide means that cannot effectively acquire the tomographic image, but the measurement light is sequentially switched and given only to the light guide means that can effectively acquire the tomographic image along the circumferential direction of the optical probe. In order to acquire the tomographic image of the region, the region where the tomographic image cannot be acquired effectively is scanned when the region for acquiring the tomographic image is moved in the longitudinal direction of the optical probe to acquire the three-dimensional volume data. Therefore, the scanning speed can be increased.

An 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 main scanning unit rotates the polyhedral mirror around a longitudinal axis of the optical probe while the plurality of light guiding units and The polyhedral mirror is moved in the longitudinal axis direction of the optical probe to generate three-dimensional volume data constructed from a plurality of tomographic images.

An optical tomographic imaging apparatus according to a third aspect is the invention according to the first or second aspect , wherein the determining means has a pixel value at each position of the tomographic image acquired by the pre-scanning means equal to or greater than a predetermined threshold value. Or not, and the light guide means related to the acquisition of the tomographic image in the area larger than the predetermined threshold is determined as the light guide means for providing the light from the light source.

An optical tomographic imaging apparatus according to a fourth aspect is the invention according to the first, second, or third aspect, wherein the polyhedral mirror is a planar n-gon (where n is a natural number of 3 or more). In the n-pyramid, the top apex side is cut at a predetermined height to form n light deflection surfaces from the n-pyramidal surface, and the n-shaped pyramid has the longitudinal axis of the sheath as the center of rotation. Each of the light deflection surfaces is configured to be rotatable.

The operation method of the optical tomographic imaging apparatus according to claim 5 includes a plurality of light guiding means and a plurality of light deflecting each of the light emitted from the plurality of light guiding means in different directions in a region along the circumferential direction. A longitudinal optical probe having a polyhedral mirror having a light deflection surface, and a switch unit that switches the light guide unit that gives light emitted from the light source to any one of the plurality of light guide units , a prescanning means, determining means, and a main scan unit, by rotating the front Symbol polyhedral mirror together given a light emitted from the light source to the light guiding means of the optical probe, the plurality of light guide Optical tomographic imaging for obtaining a tomographic image by changing the deflection direction of each light emitted from the means within a range of each of a plurality of regions dividing the entire region along the circumferential direction. a method of operating a device It said prescanning means, acquires a tomographic image over the entire area of the region along the circumferential direction of the sequentially switch and the optical probe light guide means for providing the light from the light source by the switch means of the plurality of light guide means a prescan step of the determining means, on the basis of the press tomographic image acquired by the scanning unit, among the plurality of light guide means, a determination step of determining a light guide means for providing light from said light source, The main scanning means sequentially switches the light guiding means for applying light from the light source by the switch means to the light guiding means determined by the determining means among the plurality of light guiding means, and the circumferential direction of the optical probe. A tomographic image of only a part of the region along the line is acquired and the region for acquiring the tomographic image is moved in the longitudinal direction of the optical probe to A main scan step of acquiring Mudeta, is characterized by comprising a.

The operation method of the optical tomographic imaging apparatus according to a sixth aspect is the invention according to the fifth aspect, wherein the determining step includes determining whether a pixel value at each position of the tomographic image acquired by the pre-scanning unit is a predetermined threshold value or more. The light guide means related to the acquisition of the tomographic image in the area larger than the predetermined threshold is determined as the light guide means for providing the light from the light source.

According to a seventh aspect of the present invention, in the operation method of the optical tomographic imaging apparatus according to the sixth aspect of the invention, the determining step displays the tomographic image acquired by the pre-scan unit on the image display unit, When a region to be scanned is designated by the input unit based on the tomographic image, a light guide unit that provides light from the light source is determined based on the designated region.

  According to the present invention, it is possible to improve the quality of a tomographic image by suppressing a reduction in the amount of measurement light that can effectively acquire a tomographic image.

1 is an external view showing an image diagnostic apparatus using an optical tomographic imaging apparatus according to an embodiment of the present invention. The figure which shows the structure of the OCT probe connected to the OCT processor of FIG. The figure which shows the detailed structure of the polyhedral mirror of FIG. The figure which shows the structure of the 1st modification of the polyhedral mirror of FIG. The figure which shows the structure of the 2nd modification of the polyhedral mirror of FIG. The figure which shows the structure of the 3rd modification of the polyhedral mirror of FIG. Block diagram showing the configuration of the OCT processor of FIG. The block diagram which shows the structure of the kth channel interference part in the interference part of FIG. The figure which shows the structural example of the optical path length correction | amendment part of FIG. The figure which illustrated the tomographic image acquired by giving measurement light to all the optical fibers of the OCT probe of FIG. The figure explaining operation of radial scanning in case measurement light is given to only one of the n-channel fibers of the OCT probe The block diagram which showed this Embodiment of the OCT processor Flow chart showing the procedure from setting the effective channel to starting the main scan Explanatory diagram used to explain effective channel settings The figure explaining the operation | movement of the radial scan at the time of the main scan of the OCT processor of FIG.

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

  FIG. 1 is an external view showing an image diagnostic apparatus using an optical tomographic imaging apparatus according to an 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 apparatus, and an image display unit 500 that is a monitor device. It consists of and. 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 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 155 via a forceps channel (not shown) provided in the insertion portion 114. Has been. In the diagnostic imaging apparatus 10, the OCT probe 600 as an optical probe is inserted from the forceps insertion portion 138, and the OCT probe 600 is led out from the forceps port 156. The OCT probe 600 is inserted from the forceps insertion part 138 and inserted from the forceps port 156, an operation part 604 for the operator to operate the OCT probe 600, and the OCT processor 400 via the connector 410. It consists of a cable 606 to be connected.

  At the distal end portion 155 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) (inserted into the cable 116 of the endoscope 100). 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 via the cable 116 of the endoscope 100 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.

  2 is a diagram showing a configuration of an OCT probe connected to the OCT processor 400 of FIG. 1, and FIG. 3 is a diagram showing a detailed configuration of the polyhedral mirror of FIG. 4 to 6 are diagrams showing the configuration of a modification of the polyhedral mirror of FIG. In FIG. 3, illustration of components such as a flexible shaft is omitted to explain the positional relationship between the optical fiber and the polyhedral mirror.

  As shown in FIG. 2, the OCT probe 600 is entirely covered with a flexible and slender and transparent substantially cylindrical sheath 620 whose tip is closed, and within the sheath 620, the tip of the flexible shaft 622 is covered. A polyhedral mirror 621 having n (n is an integer greater than or equal to 3) reflecting surfaces (hereinafter also referred to as light deflecting surfaces), n optical fibers 623 (1) to 623 (n), etc. Insertion is arranged. Hereinafter, in order to simplify the description, it is assumed that n = 6.

  As shown in FIG. 3, the polyhedral mirror 621 has a hexagonal pyramid shape in which the head apex side is cut at a predetermined height in a regular hexagonal pyramid having a planar regular hexagon as a bottom surface 621 a. There are six light deflection surfaces 640 (1) to 640 (6). Each of the light deflection surfaces 640 (1) to 640 (6) is formed with an inclination of, for example, 45 degrees with respect to the bottom surface 621a. On the bottom surface 621a side of the polyhedral mirror 621, as shown in FIG. 2, a shaft portion 621b protruding in a cylindrical shape is integrally formed, and the shaft portion 621b is pivotally supported by a holding frame 660. . The holding frame 660 is disposed in contact with the inner surface of the sheath 620 in a state where displacement in a direction orthogonal to the probe longitudinal axis is restricted, whereby the polyhedral mirror 621 has its central axis (symmetric axis). It is arranged in the sheath 620 in a state substantially aligned with the probe longitudinal axis, and is rotated in a stable state around the probe longitudinal axis. That is, the polyhedral mirror 621 has a configuration in which the six light deflection surfaces 640 (1) to 640 (6) are rotatably arranged with the probe longitudinal axis as the center of rotation. The polyhedral mirror 621 has a rotationally symmetric shape with the probe longitudinal axis as the center.

  On the other hand, the distal end of the flexible shaft 622 that transmits rotational torque is connected to the top vertex side of the polyhedral mirror 621 with the longitudinal axis thereof aligned with the central axis of the polyhedral mirror 621. The flexible shaft 622 is integrally connected to a motor 625 having a longitudinal axis as a rotation axis on the base end side. Accordingly, by driving the motor 625, the rotational torque is transmitted to the polyhedral mirror 621 via the flexible shaft 622, and the polyhedral mirror 621 rotates about the probe longitudinal axis.

  The six optical fibers 623 (1) to 623 (6) (hereinafter also referred to as 6-channel fibers) are provided with a GRIN lens 624 as a condensing means on the tip surface, and a holding frame 660 at the tip portion. And is arranged annularly at equiangular intervals (60 degrees) around the longitudinal axis of the flexible shaft 622, that is, the probe longitudinal axis. The tip surfaces of the optical fibers 623 (1) to 623 (6) are arranged to face the light deflection surfaces 640 (1) to 640 (6) of the polyhedral mirror 621. The holding frame 660 is also a member that supports the shaft portion 621b of the polyhedral mirror 621, and as described above, abuts against the inner surface of the sheath 620 and regulates the position of the tip portion of the 6-channel fibers 623 (1) to 623 (6). In addition, the positions of the polyhedral mirror 621 and the 6-channel fibers 623 (1) to 623 (6) are held in a predetermined positional relationship.

  Further, the 6-channel fibers 623 (1) to 623 (6) are entirely covered with an elongated, substantially cylindrical endothelium 661 having flexibility similar to the sheath 620, and the tip of the endothelium 661 is the holding frame. 660 is fixed. Accordingly, the polyhedral mirror 621, the 6-channel fibers 623 (1) to 623 (6), the flexible shaft 622, the holding frame 660, and the endothelium 661 contained in the sheath 620 are in the probe longitudinal axis direction as sheath containing members. The at least one of the 6-channel fibers 623 (1) to 623 (6), the flexible shaft 622, and the endothelium 661 is advanced / retracted as an advancing / retreating drive means for advancing / retreating in the longitudinal axis direction. It is connected to the mechanism part 631. For example, the flexible shaft 622 is connected to the advance / retreat drive mechanism 631 via a motor 625 installed at the proximal end thereof, and the proximal end of the inner skin 661 is connected to the advance / retreat drive mechanism 631. The advance / retract drive mechanism 631 is configured by a ball screw (not shown) or the like, and is configured to drive the sheath-containing member forward / backward in the probe longitudinal axis direction by converting the rotational drive force of the motor 626 to the advance / retreat drive force. ing.

  According to the OCT probe 600 configured as described above, when measurement light is given from the OCT processor 400 to each of the 6-channel fibers 623 (1) to 623 (6), the 6-channel fibers 623 (1) to 623 (6 ) Of the polyhedral mirror 621 facing the each of the 6-channel fibers 623 (1) to 623 (6), which is emitted by the GRIN lens 624 under the light collecting action. The measurement light reflected and deflected by the deflection surfaces 640 (1) to 640 (6) and deflected by the respective light deflection surfaces 640 (1) to 640 (6) is a predetermined angle (for example, the probe longitudinal axis direction). (90 degrees) Inclined radial direction is transmitted through the sheath 620 and emitted to the outside, and each measurement light is equiangularly spaced over a 360-degree range around the probe longitudinal axis. It is emitted to the 60 degree intervals) and a angular direction. In addition, the return light from the measurement object irradiated with each measurement light is passed through the polyhedral mirror 621 to each optical fiber of the same 6-channel fibers 623 (1) to 623 (6) as the original measurement light. It is captured.

  Further, since the 6-channel fibers 623 (1) to 623 (6) are fixed without rotating in the sheath 620, an optical rotary joint is not required, and the polyhedral mirror 621 is driven by the motor 625 via the flexible shaft 622. , And the light deflecting surfaces 640 (1) to 640 (6) are rotated to rotate the emission directions of the respective measurement lights emitted from the 6-channel fibers 623 (1) to 623 (6). .

  At this time, by rotating the polyhedral mirror 621 by 60 degrees (= 360 degrees × 1/6), radial scanning over the entire circumference is performed with six measurement light beams from the six-channel fibers 623 (1) to 623 (6). It becomes possible.

  That is, the n-channel fibers 623 (1) to 623 () are rotated by rotating the polyhedral mirror 621 having n reflection surfaces (light polarization surfaces) with respect to an integer n of 3 or more by “360 degrees × 1 / n”. It is possible to perform a radial scan over the entire circumference of 360 degrees with n light beams from n) at high speed.

  In the description of the OCT probe 600, n = 6 has been described as an example. However, the present invention is not limited thereto. For example, the bottom surface of the polyhedral mirror 621 may be a planar regular octagon as shown in FIG. As shown in FIG. 6, it may be a plane regular tetragon, or it may be a plane regular triangle as shown in FIG. 6, corresponding to the n light deflection surfaces 640 (1) to 640 (n) of the polyhedral mirror 621. The n-channel fibers 623 (1) to 623 (n) may be arranged.

  FIG. 7 is a block diagram showing a basic configuration of an OCT processor corresponding to the OCT probe 600 provided with a plurality of optical fibers (n-channel fibers 623 (1) to (n)). As shown in FIG. 7, the OCT processor 400 is for acquiring an optical tomographic image of the measuring object S by an optical coherence tomography (OCT) measurement method, and is a light source that emits light La for measurement. An OCT light source 12 as means, a branch coupler 13 that branches the light La emitted from the OCT light source 12 into n-channel light L1 to light Ln, and n-channel light L1 to light Ln are separated into measurement light and reference light. An interference unit 14 including first to n-th channel interference units 14 (1) to 14 (n) for detecting an interference wave and a first to n-th channel interference unit 14 (1) of the interference unit 14. The interference signal generation unit 15 that generates an interference signal from the interference waves from ˜14 (n), and the tomographic image and three-dimensional volume data of the measurement target S are generated based on the interference signal generated by the interference signal generation unit 15. And an image processing unit 17 for displaying these images on the composed image display unit 500.

  Hereinafter, in order to simplify the description, 1 to n are represented by k. FIG. 8 is a block diagram showing a configuration of the k-th channel interference unit in the interference unit 14 of FIG.

  As shown in FIG. 8, the k-th channel interference unit 14 (k) in the interference unit 14 branches the light Lk branched by the branch coupler 13 into the measurement light L1 (k) and the reference light L2 (k). 140, a circulator 141 that guides the measurement light L1 (k) to the k-channel fiber 623 (k) of the OCT probe 600, an optical path length correction unit 142 that corrects an optical path length for transmitting the reference light L2 (k), 50. The return light L3 (k) from the measurement target S via the circulator 141 from the k-channel fiber 623 (k) of the OCT probe 600 interferes with the reference light L2 (k) via the optical path length correction unit 142: 50 coupler 143, and balance detector 144 that balance-detects the interference light L 4 (k) interfered by the 50:50 coupler 143 and outputs it to the interference signal generator 15. Ete constructed.

  FIG. 9 is a diagram illustrating a configuration example of the optical path length correction unit 142 of FIG. The optical path length correction unit 142 of the reference light L2 (k) is provided for each channel of the first to n-th channel interference units 14 (1) to 14 (n) in order to adjust the zero path position of each n channel. As shown in FIG. 9, two optical path length (fine adjustment) adjusting means are used to change the spatial length with respect to the collimated light Lc between the collimating lenses 142a and 142b using two collimating lenses 142a and 142b. Composed. Here, by using any one of the first to n-th channel interference units 14 (1) to 14 (n) as a reference, it is possible to make n−1 optical path length correction units 142. is there. Note that the optical path length may be changed using birefringence.

  Next, the basic operation of the OCT processor 400 will be described by taking the operation during radial scanning as an example.

  The OCT probe 600 inserted through the forceps channel of the endoscope 100 and led out from the forceps port 156 is arranged in close contact with or close to the measurement target S of the target measurement site along the probe longitudinal axis direction. Then, at the time of measurement, the light La emitted from the OCT light source 12 is branched into light L1 to light Ln for n channels by the optical switch 19, and the first to n-th channel interference units 14 of the interference unit 14 are respectively branched. (1) to 14 (n). Then, in each of the first to n-th channel interference units 14 (1) to 14 (n), the measurement lights L1 (1) to L1 (n) and the reference lights L2 (1) to L2 (n) are generated, The measuring lights L1 (1) to L1 (n) are given to the n-channel fibers 623 (1) to (n) of the OCT probe 600. As a result, the measurement lights L1 (1) to L1 (n) are guided to the tip of the OCT probe 600 by the n-channel fibers 623 (1) to (n), and are measured by the polyhedral mirror 621. L1 (n) is irradiated to the measuring object S positioned in the angular direction at a predetermined angular interval (360 / n degrees) around the probe longitudinal axis. Then, the return lights L3 (1) to L3 (n) from the measurement object S for the respective measurement lights L1 (1) to L1 (n) are the measurement lights L1 (1) to L1 (n) from which they are derived. Are taken in and guided by the same optical fibers 623 (1) to (n), and are taken into the first to n-th channel interference units 14 (1) to 14 (n) of the interference unit 14.

  When the return lights L3 (1) to L3 (n) are taken into the first to n-th channel interference units 14 (1) to 14 (n), the return lights L3 (1) to L3 (n) are converted to the reference light L2. Interference light L4 (1) to L4 (n) is generated by interfering with (1) to L2 (n), and balance detectors of the first to nth channel interference units 14 (1) to 14 (n), respectively. 144 is detected. Then, an interference signal generation unit 15 generates an interference signal based on the detected signal.

  The interference signal generation unit 15 performs A / D conversion of the interference signal using a wavelength sweep synchronization signal output in synchronization with the wavelength sweep period from the OCT light source 12 as a trigger. As a result, data corresponding to one wavelength sweep from each of the first to n-th channel interference units 14 (1) to 14 (n) is converted into each measurement light L (1) to L 1 (n) in the OCT probe 600. It becomes a digitized interference signal with respect to the angle in the emission direction (angle around the probe longitudinal axis).

  In addition, the interference signal generation unit 15 performs a fast Fourier transform (FFT) process on the digitized interference signals from the first to n-th channel interference units 14 (1) to 14 (n) and performs frequency processing. Data for displaying a tomographic image is generated by decomposing and using the reflection intensity data in the depth direction of the measuring object S and performing logarithmic conversion.

  The above processing is performed continuously while rotating the polyhedral mirror 621 of the OCT probe 600 by the motor 625 during radial scanning, and each of the beams emitted from the OCT probe 600 (polyhedral mirror 621) is rotated by the rotation of the polyhedral mirror 621. The angle of the measurement light L1 (1) to L1 (n) in the emission direction is changed, and interference signals at each angle are sequentially generated. Then, when the polyhedral mirror 621 rotates 360 / n degrees, an interference signal in the entire angle range of 360 degrees around the longitudinal axis of the probe is generated, and a tomographic image for one frame and a tomographic image over the entire circumference of the OCT probe 600 are displayed. 1 radial scanning line data (reflection intensity data) is generated.

  The image processing unit 17 reads the reflection intensity data, which is one radial scanning line data, from the interference signal generation unit 15, and performs luminance adjustment, contrast adjustment, gamma correction, resampling according to the display size, and coordinates according to the scanning method. Conversion and the like are performed to generate a tomographic image of one frame, and the tomographic image is displayed on the image display unit 500.

  Next, the configuration and operation of the OCT processor 400 in the present embodiment will be described.

  For example, when measuring a luminal region having a large tube diameter, the surface of the measurement object can be considered to be substantially flat with respect to the OCT probe 600, so that the measurement object is close to only a part of the peripheral surface of the sheath 620. To do. At this time, the tomographic images are generated by applying the measurement lights L1 (1) to L1 (n) from the OCT processor 400 to all (all channels) of the n-channel fibers 623 (1) to (n) of the OCT probe 600. If so, a tomographic image as shown in FIG. 10A is obtained. According to this, the tomographic image showing the sheath 620 is displayed in the entire 360 ° angle range around the longitudinal axis of the probe, but the tomographic image of the sheath 620 is unnecessary.

  On the other hand, the tomographic image of the measuring object S is useful, but the range in which the tomographic image of the measuring object S is obtained is smaller than the angular range of 180 degrees, for example, as shown in FIG. θ.

  Therefore, as described below, the measurement light is given only to the optical fiber related to the acquisition of the tomographic image in the angle range θ among the n-channel fibers 623 (1) to (n) of the OCT probe 600, and the other optical fibers. In this case, the number of measurement light beams applied to the OCT probe 600 is reduced by not providing the measurement light beam, so that the amount of light is increased.

  Further, if the measurement light is not supplied to a plurality of channels of the OCT probe 600 at the same time but the measurement light is supplied to only one channel of the OCT probe 600, and the channel for supplying the measurement light is switched, The light La from the OCT light source 12 does not need to be branched into a plurality of channels, and the amount of measurement light can be made sufficient.

  Here, when the measurement light is switched to be supplied to only one channel of the OCT probe 600, radial scanning is performed over the entire circumference of the OCT probe 600 (in a full angle range of 360 degrees around the probe longitudinal axis). In some cases, as shown in FIGS. 11A to 11C, any one of the light deflection surfaces 640 (1) to (6) of the rotating polyhedral mirror 621 (an example of n = 6) is used. The channels for supplying the measurement light are sequentially switched in synchronization with the rotation of the polyhedral mirror 621 so that the light deflection surface (640 (1) in the figure) becomes the light guide spot S of the measurement light. That is, when the light guide spot S on the light deflection surface 640 (1) where the measurement light is guided approaches the boundary portion with the adjacent light deflection surface 640 (6), the optical fiber that supplies the measurement light is changed to a polyhedral mirror. It switches to the optical fiber arrange | positioned at the rotation direction side of 621.

  At this time, since it is necessary to rotate the polyhedral mirror 621 once in order to perform radial scanning for one rotation (360 degrees), the scanning time becomes longer than when measuring light is simultaneously supplied to a plurality of channels. . However, when the measurement range is limited to a part of the angle range where a useful tomographic image can be obtained, the scanning speed can be increased as described later.

  First, the configuration of the OCT processor 400 suitable for supplying measurement light to only one channel among the n-channel fibers 623 (1) to (n) of the OCT probe 600 will be described. FIG. 12 is a configuration diagram showing the configuration of the OCT processor 400 in this case. Compared to the OCT processor 400 of FIG. 7, the OCT processor 400 shown in FIG. 7 includes only one k-th channel interference unit 14 (k) shown in FIG. 8, and the optical switch 19 includes the optical switch 19. It is arranged between the OCT probe 600 and the interferometer 14. In FIG. 12, the same components as those in FIG.

  The optical switch 19 switches the optical fiber optically connected to the interference unit 14 (circulator 141) to any one of the n-channel fibers 623 (1) to (n) of the OCT probe 600, The switching destination is instructed by an optical switch switching control signal from the optical switch control unit 18.

  According to the configuration of the OCT processor 400 in FIG. 12, the configuration in the OCT processor is simplified as compared with the OCT processor 400 in FIG.

  A channel of the optical fiber of the OCT probe 600 that gives measurement light from the OCT probe 600 is called an effective channel, and a channel that does not give measurement light is called an invalid channel.

  The operation of the optical switch 19 and the optical switch control unit 18 will be described with reference to the flowchart of FIG. 13 showing the procedure from setting the effective channel to starting the main scan.

  First, a pre-scan is performed before the main scan (step S10). In the pre-scan, in synchronization with the rotation of the polyhedral mirror 621, the measurement light is sequentially switched and supplied to the n-channel fibers 623 (1) to (n), and the tomographic image of the entire angular range of 360 degrees around the longitudinal axis of the probe. That is, it is a process of acquiring a tomographic image over the entire circumference of the OCT probe 600. At this time, the optical switch control unit 18 instructs 600 optical fibers (channels) of the OCT probe that supplies the measurement light from the interference unit 14 by a control signal supplied to the optical switch 19. The optical switch 19 supplies the measurement light from the interference unit 14 to the optical fiber of the OCT probe 600 designated in accordance therewith.

  As a result, the channel through which the measurement light is applied is switched so that the measurement light is guided to the specific light deflection surface of the polyhedral mirror 621 as described above, and when the polyhedral mirror 621 rotates 360 degrees, A tomographic image in the entire angle range of 360 degrees is generated and displayed on the image display unit 500.

  Next, the measurement range is determined. That is, the angle range in the direction in which the measurement light is emitted is determined (step S12). The measurement range can be determined either manually or automatically.

  When performing manually, an operator confirms the pre-scan tomographic image displayed on the image display part 500, determines a measurement range with a predetermined input means, and determines. For example, in the case of FIG. 10A, it is determined by specifying to include the angle range θ.

  In the case of performing automatically, for example, the measurement range is determined by detecting the range in which the measurement target S exists based on the tomographic image obtained by the pre-scan and the interference signal generated by the interference signal generation unit 15. . Specifically, the pixel values (excluding the sheath 620) of each part of the tomographic image obtained by the pre-scan are compared with a predetermined threshold value, and an angle range where a pixel value larger than the threshold value exists is set as the measurement range. decide. Alternatively, at the time of pre-scanning, the intensity (absolute value) of the interference signal or its integrated value is obtained for each angle in the emission direction of the measurement light. Then, an angle range in which the intensity or integrated value is larger than a predetermined threshold is determined as a measurement range. In the example of FIG. 10A, the angle ranges P1, P2, and P6 are measurement ranges.

  Next, an effective channel is determined (step S14). This process is a process of determining, as an effective channel, a channel that includes the measurement range (angle range) determined in step S12 as the angle range in the measurement light emission direction. That is, an optical fiber necessary for measuring the measurement range determined in step S12 is determined among the n-channel fibers 623 (1) to (n) of the OCT probe 600.

  Then, the main scan is started (step S16). At this time, the polyhedral mirror 621 rotates, and the optical switch controller 18 controls the optical switch 19 to sequentially switch and apply the light La from the OCT light source 12 only to the optical fiber of the effective channel. For example, during pre-scanning, measurement light is sequentially switched and applied to all of the n-channel fibers 623 (1) to (n) of the OCT probe 600, and FIG. 14 (A) (shows the case of n = 6). In this way, the measurement light is sequentially guided to all the light deflection surfaces 640 (1) to 640 (6) of the polyhedral mirror 621 (the black circle S indicates the waveguide location). On the other hand, in this scan, measurement light is sequentially switched and applied to only some of the n-channel fibers 623 (1) to (n) of the OCT probe 600, and a polyhedral mirror as shown in FIG. The measurement light is guided only on a part of the light deflection surfaces of 621 (black circles S indicate waveguide locations and are reduced to 3 locations).

  Here, in this scan, the polyhedral mirror 621 is rotated, and the optical switch control unit 18 controls the optical switch 19 in synchronization with the rotation, and the measurement light is sequentially switched and applied only to the optical fiber of the effective channel. An example of a polyhedral mirror 621 with n = 6 will be described with reference to FIG. First, it is assumed that the effective channels are determined as three optical fibers 623 (a), 623 (b), and 623 (c) among the six-channel fibers 623 (1) to 623 (6). In the figure, a, b, and c are light guides on the light deflection surface of the measurement light when the measurement light is emitted from each of the optical fibers 623 (a), 623 (b), and 623 (c). The black circles indicate the light guide locations where the measurement light is actually guided. From FIG. 13A to FIG. 13C, the same radial scanning operation as that described with reference to FIG. 13 is performed. First, the measurement light is applied to the optical fiber 623 (a) as shown in FIG. Then, it is assumed that the measurement light is guided to the light guide location a on the light deflection surface 640 (1).

  When the polyhedral mirror 621 rotates 30 degrees and the light deflection surface 640 (1) rotates to the position including the light guiding portion b with respect to the state of FIG. 5A, the optical fiber to which the measurement light is applied is the optical fiber 623. The optical fiber 623 (b) is switched from (a), and the measurement light is guided to the light guide location b. FIG. 4B shows a state where the lens is further rotated by 30 degrees.

  Subsequently, when the polyhedral mirror 621 rotates 30 degrees with respect to the state shown in FIG. 5B and the light deflection surface 640 (1) rotates to the position including the light guide portion c, the optical fiber to which the measurement light is applied is light. The fiber 623 (b) is switched to the optical fiber 623 (c), and the measurement light is guided to the light guide point c. FIG. 4C shows a state where the lens is further rotated by 30 degrees.

  As described above, the measurement light is switched to the optical fibers adjacent in the rotation direction from FIG. 10A to FIG. 10C when all the optical fibers of the OCT probe 600 are effective fibers (the measurement range is limited). The optical fiber to which the measurement light is applied is switched so that the measurement light is always guided to the specific light deflection surface.

  On the other hand, when the polyhedral mirror 621 rotates 30 degrees with respect to the state of FIG. 10C, the optical fiber to which the measurement light is applied is switched from the optical fiber 623 (c) to the optical fiber 623 (a). FIG. 4D shows a state where it is further rotated by 30 degrees. FIG. 4D is equivalent to the state of FIG. 1A, and the operations from FIG. 1A to FIG. 1D are repeated.

  By switching the optical fiber that supplies measurement light in this way, a tomographic image in the measurement range can be acquired faster than the polyhedral mirror 621 rotates once, and the scanning speed can be increased. In this scan, components such as an internal polyhedral mirror 621 and n-channel fibers 623 (1) to 623 (n) are moved in the probe longitudinal axis direction by the advance / retreat drive mechanism 631 with respect to the sheath 620 of the OCT probe 600. Then, linear scanning is performed simultaneously or alternately with radial scanning by rotation of the polyhedral mirror 621, and at this time, three-dimensional volume data is acquired. At this time, when the scanning speed is increased by switching as described above, the time required for the entire scanning is greatly reduced.

  In this manner, the measurement light is emitted from the OCT probe 600 only by the effective channel and the return light is taken in, and the tomographic image is generated by the radial scanning and displayed on the image display unit 500. For example, when a tomographic image as shown in FIG. 10A is obtained in the pre-scan, if the angular ranges P1, P2, and P6 are determined as measurement ranges in step S12, a tomographic image as shown in FIG. 10B is displayed. Will be. Further, since the measurement light is supplied by sequentially switching to the optical fiber of the effective channel of the OCT probe 600 without branching the measurement light, there is no reduction in the amount of measurement light compared to the case where the measurement light is supplied to all channels simultaneously. A tomographic image with good image quality is generated.

  In the above embodiment, the aspect in which the number of light deflecting surfaces of the polyhedral mirror in the OCT probe 600 and the number of optical fibers match is shown, but the present invention does not match the number. Even applicable. Further, the configuration of the OCT probe 600 to which the present invention can be effectively applied is not limited to that shown in the above embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Diagnostic imaging apparatus, 12 ... OCT light source, 14 ... Interference part, 15 ... Interference signal generation part, 17 ... Image processing part, 18 ... Optical switch control part, 19 ... Optical switch, 100 ... Endoscope, 114 ... Equipment Insertion part, 156 ... Forceps opening, 200 ... Endoscopic processor, 400 ... OCT processor, 500 ... Image display part, 600 ... OCT probe, 620 ... Sheath, 621 ... Polyhedral mirror, 622 ... Flexible shaft, 623 ... Optical fiber, 624 ... GRIN lens, 625, 626 ... motor, 640 ... light deflection surface

Claims (7)

A longitudinal optical probe having a plurality of light guiding means;
Switch means for switching the light guide means for providing light emitted from the light source to any one of the plurality of light guide means;
Pre-scanning means for sequentially obtaining a tomographic image over the entire region along the circumferential direction of the optical probe by sequentially switching light guiding means for providing light from the light source by the switch means among the plurality of light guiding means;
A determining unit that determines a light guiding unit that gives light from the light source among the plurality of light guiding units based on the tomographic image acquired by the pre-scanning unit;
Of the plurality of light guiding means, the light guiding means for applying light from the light source by the switch means is sequentially switched to only the light guiding means determined by the determining means, and one of the regions along the circumferential direction of the optical probe. A main scanning means for acquiring a three-dimensional volume data by acquiring a tomographic image of only a region of a part and moving a region for acquiring a tomographic image in the longitudinal axis direction of the optical probe;
Equipped with a,
The optical probe has a plurality of light guides in a slender cylindrical sheath and a plurality of light deflecting each light emitted from the plurality of light guides in different directions in the circumferential direction. A polyhedral mirror having a light deflection surface of
When acquiring a tomographic image, by rotating the polyhedral mirror, a plurality of regions in which the deflection direction of each light emitted from the plurality of light guides is divided into all regions along the circumferential direction An optical tomographic imaging apparatus, wherein the optical tomographic imaging apparatus changes within a range that falls within each of the regions . The main scanning unit moves the plurality of light guide units and the polyhedral mirror in the longitudinal axis direction of the optical probe while rotating the polyhedral mirror around the longitudinal axis of the optical probe, thereby obtaining a plurality of tomographic images. The optical tomographic imaging apparatus according to claim 1 , wherein the three-dimensional volume data to be constructed is generated. The determining means determines whether or not the pixel value at each position of the tomographic image acquired by the pre-scanning means is equal to or greater than a predetermined threshold, and the light guiding means related to acquisition of a tomographic image in an area larger than the predetermined threshold claim 1, wherein the determining a light guide means for providing light from said light source, or, 2 of the optical tomographic imaging apparatus. The polyhedral mirror includes an n-sided pyramid having a planar n-gonal shape (where n is a natural number of 3 or more) as a bottom surface, the top vertex side being cut at a predetermined height, and n light deflection surfaces from the n-sided pyramid surface. a generally n pyramid shape formed of claim 1, 2 wherein the n light deflecting surface as a rotation about the longitudinal axis of the sheath, characterized in that it is configured to be rotated, or, in the 3 The optical tomographic imaging apparatus described. Longitudinal shape comprising a plurality of light guide means and a polyhedral mirror having a plurality of light deflecting surfaces for deflecting each light emitted from the plurality of light guide means in different directions in a region along the circumferential direction An optical probe; a switch unit that switches a light guide unit that gives light emitted from a light source among the plurality of light guide units to any one; a prescan unit; a determination unit; and a main scan unit. by rotating the pre-Symbol polyhedral mirror together given a light emitted from the light source to the light guiding means of the optical probe, the polarization direction of light of each emitted from the plurality of light guide means, said circumferential An operation method of an optical tomographic imaging apparatus for obtaining a tomographic image by changing in a range that is within each of a plurality of regions that divide all regions of a region along a direction,
The pre-scanning means sequentially switches light guiding means for providing light from the light source by the switch means among the plurality of light guiding means, and obtains tomographic images over the entire region along the circumferential direction of the optical probe. A pre-scanning process,
The determining unit determines a light guiding unit that gives light from the light source among the plurality of light guiding units based on the tomographic image acquired by the pre-scanning unit ;
The main scanning means sequentially switches the light guiding means for applying light from the light source by the switch means to the light guiding means determined by the determining means among the plurality of light guiding means, and the circumferential direction of the optical probe. A main scan step of acquiring a tomographic image of only a part of the region along the line and moving the region for acquiring the tomographic image in the longitudinal axis direction of the optical probe to acquire three-dimensional volume data;
A method for operating an optical tomographic imaging apparatus comprising: The determination step includes guiding means for a pixel value at each position of the tomographic image acquired by the pre-scanning means determines whether more than a predetermined threshold value, related to the acquisition of the tomographic image of the region larger than a predetermined threshold value 6. The method of operating an optical tomographic imaging apparatus according to claim 5, wherein: is determined as light guiding means for providing light from the light source. Said determining step, a tomographic image acquired by the pre-scanning means is displayed on the image display means, when the displayed area of the scanning based on the tomographic image which is designated by the input means, to the designated area 7. The method of operating an optical tomographic imaging apparatus according to claim 6, wherein light guiding means for providing light from the light source is determined based on the light guiding means.

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