JP5663241B2 - 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 probe characterized by radial scanning of measurement light onto a measurement target of the measuring light, an optical tomographic imaging apparatus using the same, 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 the deterioration of the S / N ratio 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.

  At that time, since the number of effective measurement lights also changes depending on the positional relationship between the optical fiber and the measurement target, the positional relationship between the optical fiber and the measurement target is considered in order to reduce the number of measurement lights as much as possible. It is desirable.

The present invention has been made in view of such circumstances, and provides measurement light to an optical probe including one or more optical fibers (light guide means) for a polyhedral mirror having a plurality of light deflection surfaces. In an optical tomographic imaging apparatus for acquiring a tomographic image, an optical tomographic imaging apparatus for improving the quality of a tomographic image by suppressing the reduction of the amount of measurement light capable of effectively acquiring a tomographic image as much as possible and an operating method thereof are provided. The purpose is to do.

In order to achieve the object, an optical tomographic imaging apparatus according to claim 1 divides light emitted from a light source into measurement light and reference light, and irradiates the measurement object with the measurement light. The reflected light from the light and the reference light are combined, the interference light when the reflected light and the reference light are combined is detected as an interference signal, and the tomographic image of the measurement object is acquired using the interference signal an optical tomographic imaging apparatus, toward the Do tubular sheath elongated, and multiple light guiding means disposed within the sheath, the measurement light emitted from the light guide means to the side of the sheath and a polyhedral mirror having a plurality of light deflection faces for deflecting Te, an optical probe the light guide means is arranged to be rotatable about the longitudinal axis of the sheath within the sheath, before Kifuku number of light Measuring light from the light source is given to all of the means, and along the circumferential direction of the sheath. A pre-scanning unit that acquires at least an interference signal in the region, and a region to be measured is determined as a measurement region among the regions along the circumferential direction of the sheath based on the interference signal or tomographic image acquired by the pre-scanning unit A measurement area determining means for adjusting the position of the light guide means around the longitudinal axis in the sheath according to the measurement area determined by the measurement area determining means, and the measurement And a main scanning unit that provides the measurement light from the light source only to the light guide unit related to the acquisition of the tomographic image of the measurement region determined by the region determination unit, and acquires the tomographic image of only the measurement region. It is characterized by.

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 light guiding unit and the polyhedral mirror are rotated. the is moved in the longitudinal axis direction of the optical probe is characterized by generating a three-dimensional volume data that is constructed from a plurality of tomographic images.

  An optical tomographic imaging apparatus according to a third aspect of the present invention is the optical tomography apparatus according to the first or second aspect, wherein the measurement region determination unit is configured to perform the measurement based on an intensity or integral value of an interference signal acquired by the prescan unit. It is characterized by determining the area.

  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, wherein the light emitted from the light source is divided into measurement light and reference light, irradiated to the measurement object with the measurement light, and reflected light from the measurement object Optical tomographic imaging that combines the reference light, detects the interference light when the reflected light and the reference light are combined as an interference signal, and acquires the tomographic image of the measurement object using the interference signal An apparatus, an elongated cylindrical sheath, a plurality of light guides disposed in the sheath, and a plurality of lights for deflecting measurement light emitted from the light guides toward the side surface of the sheath A polyhedral mirror having a deflection surface, wherein the light guide means includes an optical probe disposed so as to be rotatable around the longitudinal axis of the sheath in the sheath , and further includes a pre-scan means, a measurement region determining means, , Light guide means position adjusting means and main scan A method of operating a optical tomographic imaging apparatus that includes a stage, the prescanning means, along the circumferential direction of the sheath gives the measurement light from the light source to all of the plurality of light guide means area A pre-scanning step for acquiring at least an interference signal, and a region in which the measurement region determination unit performs measurement among regions along the circumferential direction of the sheath based on the interference signal or tomographic image acquired by the pre-scan unit A measurement region determination step for determining the measurement region as a measurement region, and the light guide unit position adjustment unit is arranged around the longitudinal axis of the light guide unit in the sheath according to the measurement region determined by the measurement region determination unit . a light guide unit position adjustment step of adjusting the position, the is the scanning means, only guiding means related to acquiring a tomographic image of a determined measurement region by the measuring region determining means It is characterized by comprising, a main scan step of acquiring a tomographic image of only the measurement area by applying the measurement light from the light source.

According to the present invention, it is possible to like quality of the tomographic image is suppressed only Ru can effectively reduce the power of the measuring beam can obtain 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. Flow chart showing the procedure from setting the valid channel to starting the main scan Explanatory diagram used to explain effective channel setting

  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 rotating body 663 at the tip portion. And is arranged annularly at equiangular intervals (60 degrees) around the longitudinal axis of the flexible shaft 622, ie, 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 rotating body 663 is rotatably supported by the holding frame 660, and the holding frame 660 is in contact with the inner surface of the sheath 620 as described above, and the tip portions of the 6-channel fibers 623 (1) to 623 (6). The positions of the polyhedral mirror 621 and the 6-channel fibers 623 (1) to 623 (6) are held in a prescribed positional relationship.

  Further, the 6-channel fibers 623 (1) to 623 (6) are entirely covered with a thin and substantially cylindrical endothelium 661 having flexibility like the sheath 620, and the tip of the endothelium 661 is a rotating body. It is fixed to 663. Therefore, the polyhedral mirror 621, the 6-channel fibers 623 (1) to 623 (6), the flexible shaft 622, the holding frame 660, the rotating body 663, and the endothelium 661 included in the sheath 620 are sheath inclusion members. Advancing / retreating means that moves integrally in the longitudinal direction of the probe, and at least one of the 6-channel fibers 623 (1) to 623 (6), the flexible shaft 622, and the endothelium 661 is advanced / retreated in the longitudinal direction. Are connected to the forward / backward drive mechanism 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. In addition, if the endothelium 661 connected to the rotator 663 is rotated, the rotator 663 rotates, and the position of the 6-channel fibers 623 (1) to 623 (6) around the longitudinal axis of the probe is rotated in the sheath 620. It can be made to. The rotation of the 6-channel fibers 623 (1) to 623 (6) may be configured to rotate the advance / retreat driving mechanism 631 or the inner skin 661 by a motor, or a clutch that is primarily connected to the flexible shaft 622. A connecting mechanism such as the above may be provided so that the connection and disconnection can be switched manually or electrically, and the polyhedral mirror 621 rotates. The endothelium 661 may be simply rotated manually.

  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 configuration of the OCT processor of FIG. 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. The OCT light source 12 as means and the light La emitted from the OCT light source 12 are branched into light L1 to light Ln for a maximum of n channels, and the number of branches and the channel to which the branched light is supplied are switched (light An optical switch 13 for switching a supply destination channel for branching and supplying La), and first to n-th channels for detecting interference waves by demultiplexing n-channel light L1 to light Ln into measurement light and reference light. The interference signal is generated by the interference unit 14 including the interference units 14 (1) to 14 (n) and the interference waves from the first to n-th channel interference units 14 (1) to 14 (n) of the interference unit 14. An interference signal generation unit 15 for generating a signal, and an image for generating a tomographic image and three-dimensional volume data of the measurement target S based on the interference signal generated by the interference signal generation unit 15 and displaying these images on the image display unit 500 A processing unit 17; and an optical switch control unit 18 that gives an optical switch switching control signal to the optical switch 13 and instructs switching of a supply destination channel that supplies the light La from the optical OCT light source 12. Is done.

  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 optical switch 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 operation of the optical switch 13 and the optical switch control unit 18 will be described later, and the optical switch 13 uses the first to nth channels of the interference unit 14 in the same manner as when a branch coupler is provided instead of the optical switch 13. In the following description, it is assumed that n channels of light L1 to light Ln are supplied to all of the interference units 14 (1) to 14 (n).

  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 13, 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, supply of measurement light to the OCT probe 600 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. The optical fiber channel of the OCT probe 600 that gives measurement light from the OCT probe 600 and the corresponding channel such as the interference unit 14 in the OCT probe 600 are called effective channels, and the channel that does not give measurement light is called an invalid channel. Shall.

  The optical switch 13 shown in FIG. 7 divides and supplies the light La from the OCT light source 12 only to the effective channel, and the light from the OCT light source 12 according to the control signal from the optical switch control unit 18. The channel which branches and gives La is switched. As a result, compared to the case where the light La from the OCT light source 12 is branched into all channels, the amount of measurement light of the effective channel can be increased, and a tomographic image with good image quality can be generated.

  The operation of the optical switch 13 and the optical switch control unit 18 will be described with reference to the flowchart of FIG. 11 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). The pre-scan provides measurement light using all of the n-channel fibers 623 (1) to (n) of the OCT probe 600 as effective channels and rotates the polyhedral mirror 621 so that the entire angular range of 360 degrees around the longitudinal axis of the probe is obtained. Tomographic image, that is, a tomographic image over the entire circumference of the OCT probe 600 is acquired. At this time, the optical switch 13 branches the light La from the OCT light source 12 into all the n channels by the control signal from the optical switch control unit 18 and causes the light L1 to light Ln to be in the first to nth channel interference. To parts 14 (1) to 14 (n).

  Accordingly, the measurement lights L1 (1) to L (n) are transmitted from the first to n-th channel interference units 14 (1) to 14 (n) to all the n-channel fibers 623 (1) to (n) of the OCT probe 600. , And the measurement lights L1 (1) to L (n) are emitted from the OCT probe 600. Then, when the polyhedral mirror 621 rotates 360 / n degrees, a tomographic image of the entire angle range of 360 degrees around the probe longitudinal axis 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 interference signal generated in the interference signal generation unit 15 during the prescan. Specifically, the intensity (absolute value) of the interference signal or its integral 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. You may make it perform the same determination with the pixel value of a tomographic image. In the example of FIG. 10A, the angle ranges P1, P2, and P6 are ranges including the measurement range.

  Next, the n-channel fibers 623 (1) to 623 (n) of the OCT probe 600 are rotated in the sheath 620 (step S14). As a result, the positional relationship between the measurement range and the n-channel fibers 623 (1) to 623 (n) is optimized. For example, if only one channel is used as the effective channel when the measurement range is narrow, the two channels are effective because the positional relationship between the optical fiber and the measurement range is poor even when the measurement range can be measured. There is a case where it has to be a channel. Therefore, the rotating body 663 (endothelium 661) of FIG. 2 is automatically rotated using a motor or manually rotated, and the positional relationship between the n-channel fibers 623 (1) to 623 (n) and the measurement range is determined. Reduce the number of measurement beams as much as possible.

  Here, in step S12, the central value (center of gravity) of the interference signal intensity or integral value obtained for each angle is obtained, and the optimum angular position (where the effective channel can be reduced most) is set to the angular position n. Channel fibers 623 (1) to 623 (n) may be arranged.

  Next, an effective channel is determined (step S16). 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 optical switch control unit 18 controls the optical switch 13 to branch and supply the light La from the OCT light source 12 only to the effective channel, and rotates the polyhedral mirror 621. For example, during pre-scanning, measurement light is applied to all of the n-channel fibers 623 (1) to (n) of the OCT probe 600, as shown in FIG. 12A (showing the case of n = 6). The measurement light is 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 given to only some of the n-channel fibers 623 (1) to (n) of the OCT probe 600, and one of the polyhedral mirrors 621 as shown in FIG. The measurement light is guided only on the light deflection surface of the portion (the black circle S indicates the waveguide location and is reduced to 3 locations).

  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.

  As a result, the measurement light is supplied only to the effective channels, and the amount of the measurement light is increased as compared with the case where the measurement light is supplied to all the channels, and a tomographic image with good image quality is generated.

  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 three-dimensional volume data is acquired.

  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. In particular, the position of the optical fiber around the probe length in the sheath 620 can be adjusted to adjust the positional relationship between the optical fiber and the measurement range (measuring object), so there is only one optical fiber. Even it is effective.

  In addition, it is not always necessary to set the entire measurement range where the measurement target S exists as a measurement range. For example, a predetermined number (one or a predetermined number) of channels (optical fibers) are used as effective channels, and measurement is performed using the effective channels. The possible range may be the measurement range. At this time, a part of the range where the measurement target S exists may be outside the measurement range, but the center of the range where the measurement target S exists as much as possible (for example, the integrated value of the interference signal at each angle has a predetermined threshold value). If the rotational position of the optical fiber around the longitudinal axis of the probe is adjusted in the OCT probe 600 so that the center (centroid) of the exceeding range becomes the center of the effective channel measurement range, the main scan is performed. Is preferred. Further, when only one channel is set as an effective channel, the configuration of the OCT processor 400 can be simplified. That is, in the configuration of the OCT processor 400 of FIG. 7, the first to n-th channel interference units 14 (1) to 14 (n) for n channels are unnecessary, and the interference unit 14 for 1 channel shown in FIG. And the light from the OCT light source 12 may be incident on the interference unit 14 without passing through the optical switch 13. Then, the optical switch 13 is disposed between the interference unit 14 (circulator 141 in FIG. 8) and the OCT probe 600, and the optical switch 13 causes the optical fiber of any one channel of the OCT probe 600 to interfere with the interference unit 14. And the channel to be connected may be switched. Switching of the connection destination by the optical switch 13 may be performed by the optical switch control unit 18 as in the above embodiment.

  DESCRIPTION OF SYMBOLS 10 ... Diagnostic imaging apparatus, 12 ... OCT light source, 13 ... Optical switch, 14 ... Interference part, 15 ... Interference signal generation part, 17 ... Image processing part, 18 ... Optical switch control part, 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, 663 ... rotating body

Claims (5)

The light emitted from the light source is divided into measurement light and reference light, and the measurement object is irradiated with the measurement light, the reflected light from the measurement object and the reference light are combined, and the reflected light and the reference An optical tomographic imaging apparatus that detects interference light when light is combined as an interference signal, and acquires a tomographic image of the measurement object using the interference signal,
Has a Do tubular sheath elongated, and multiple light guiding means disposed within the sheath, a plurality of light deflection faces for deflecting towards the measurement light emitted from the light guide means to the side of the sheath An optical probe provided with a polyhedral mirror, wherein the light guide means is arranged to be rotatable around the longitudinal axis of the sheath in the sheath;
A prescanning means for obtaining at least an interference signal region along the circumferential direction of the sheath gives the measurement light from the light source to all of the light guide means of the front Kifuku number,
A measurement area determination means for determining a measurement area as a measurement area among areas along the circumferential direction of the sheath based on an interference signal or a tomographic image acquired by the prescan means;
Light guide means position adjusting means for adjusting the position of the light guide means around the longitudinal axis in the sheath according to the measurement area determined by the measurement area determining means;
A main scanning unit that applies the measurement light from the light source only to the light guide unit related to the acquisition of the tomographic image of the measurement region determined by the measurement region determination unit, and acquires the tomographic image of the measurement region only;
An optical tomographic imaging apparatus comprising:   The main scanning unit is constructed from a plurality of tomographic images by moving the light guiding unit and the polyhedral mirror in the longitudinal axis direction of the optical probe while rotating the polyhedral mirror about the longitudinal axis of the optical probe. The optical tomographic imaging apparatus according to claim 1, wherein the three-dimensional volume data is generated.   The optical tomographic imaging apparatus according to claim 1, wherein the measurement region determining unit determines the measurement region based on an intensity or an integral value of an interference signal acquired by the prescan unit.   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. 4. The n-shaped pyramid shape formed with the n-shaped light deflecting surface being rotatable about the longitudinal axis of the sheath as a rotation center. Optical tomographic imaging device. The light emitted from the light source is divided into measurement light and reference light, and the measurement object is irradiated with the measurement light, the reflected light from the measurement object and the reference light are combined, and the reflected light and the reference An optical tomographic imaging apparatus that detects interference light when light is combined as an interference signal, and acquires a tomographic image of the measurement object using the interference signal,
A polyhedron having an elongated cylindrical sheath, a plurality of light guides disposed in the sheath, and a plurality of light deflection surfaces for deflecting measurement light emitted from the light guides toward the side surface of the sheath And a light probe disposed in the sheath so as to be rotatable around the longitudinal axis of the sheath , and further includes a pre-scanning means, a measurement region determining means, and a light guiding means position. An operation method of an optical tomographic imaging apparatus including an adjusting unit and a main scanning unit ,
It said prescanning means includes a prescan step of obtaining at least an interference signal region along the circumferential direction of the sheath gives the measurement light from the light source to all of the plurality of light guide means,
The measurement region determining means, in the region along the circumferential direction of the sheath, based on the obtained interference signal or the tomographic image by the prescanning means, and the measurement area determining step of determining a region to be measured as a measurement region,
A light guide means position adjustment step in which the light guide means position adjustment means adjusts the position of the light guide means around the longitudinal axis in the sheath according to the measurement region determined by the measurement region determination means ;
A book in which the main scanning unit applies the measurement light from the light source only to the light guide unit related to the acquisition of the tomographic image of the measurement region determined by the measurement region determination unit and acquires the tomographic image of only the measurement region. Scanning process;
A method for operating an optical tomographic imaging apparatus comprising:

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