JP2010125271A - Photo tomographical image providing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photo tomographical image providing apparatus which allows to interchange the revolution velocity of an optical probe, and provide a photo tomographical image with a preferable image quality for a site observed by a user. <P>SOLUTION: The photo tomographical image providing apparatus, which rotates an optical probe to scan, obtains a reflection signal from an object to be measured, and bases on the obtained reflection signal to form the photo tomographical image of the object to be measured, includes: a measurement site specifying means for specifying the measurement site of the optical probe; and a revolution velocity interchanging means for basing on the measurement site of the specified optical probe to interchange the revolution velocity. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an optical tomographic image acquisition apparatus, and more particularly to an optical tomographic image acquisition apparatus that acquires an optical tomographic image of a biological tissue by inserting an optical probe into a body cavity in order to observe and diagnose the biological tissue.

  Conventionally, an optical tomographic imaging apparatus (optical tomographic image acquisition apparatus) using an optical coherence tomography (OCT) measurement method is known as a method for acquiring a cross-sectional image without cutting a measurement target such as a biological tissue. ing.

  This OCT measurement method is a kind of optical interferometry, in which light emitted from a light source is divided into measurement light and reference light, and the optical path length of the measurement light and reference light is within the coherence length of the light source. This is a measurement method using the fact that optical interference is detected only when the ranges match.

  Using such an optical tomographic image acquisition apparatus (OCT apparatus), an optical probe (OCT probe) is inserted into the forceps opening of the endoscope apparatus to guide the signal light and the reflected light of the signal light, and the light in the body cavity By acquiring a tomographic image, it is possible to observe and diagnose a living tissue.

For example, by rotating the optical fiber in the optical scanning probe at a constant speed and radiating in a direction perpendicular to the axis of the optical scanning probe while irradiating low interference light, tomographic image data inside the living tissue is obtained. An optical tomographic image apparatus that acquires a two-dimensional tomographic image is known (see, for example, Patent Document 1).
JP 2000-131222 A

  However, in the above-mentioned conventional one, only one rotation speed is assumed to be set as the rotation speed of the optical probe. Therefore, there is a problem that even if the resolution in the plane direction of the optical tomographic image required differs depending on the part observed by the user, for example, the part of the stomach, the large intestine, the bronchus, and the like. For example, in the case of the stomach, it is sufficient that the layer structure of the gastric mucosa can be grasped, so that the resolution is relatively coarse. Here, since improving the image resolution and improving the image processing and image display speed are trade-offs in terms of the amount of data, it is preferable that the measurement is performed with an image resolution suitable for the observation site.

  However, the conventional technique has a problem that the resolution is too rough depending on the observation site, or the resolution is finer than necessary, and it takes more time than necessary.

  The present invention has been made in view of such circumstances, and enables light to be switched with the rotation speed of the optical probe, and to provide an optical tomographic image having a suitable image quality according to the site observed by the user. An object is to provide a tomographic image acquisition apparatus.

  In order to achieve the above-mentioned object, the invention according to claim 1 rotationally scans the optical probe, acquires a reflection signal from the measurement object, and forms an optical tomographic image of the measurement object based on the acquired reflection signal. An optical tomographic image acquisition apparatus comprising: a measurement part specifying unit that specifies a measurement part of the optical probe; and a rotation speed changing unit that changes a rotation speed according to the specified measurement part of the optical probe. A characteristic optical tomographic image acquisition apparatus is provided.

  As a result, the rotation speed of the optical probe can be switched, and an optical tomographic image with suitable image quality can be obtained according to the part observed by the user.

  Further, as shown in claim 2, the rotation speed changing means rotates the rotation speed by setting a rotation speed corresponding to the specified measurement site from rotation speeds set in advance for each measurement site. It is characterized by changing the speed.

  Thereby, it can change immediately to the suitable rotational speed for every measurement region.

  According to a third aspect of the present invention, the optical probe is inserted into a body cavity from a forceps port of an endoscope.

  Thereby, also in the case of an endoscope inserted into a body cavity, the probe rotation speed can be changed according to the measurement site.

  According to a fourth aspect of the present invention, the measurement site specifying means is a measurement site input means for a user to specify a measurement site.

  As a result, the user can change the probe rotation speed suitable for the part only by specifying the part, and a tomographic image having an image quality suitable for the part can be obtained.

  According to a fifth aspect of the present invention, the measurement site specifying means specifies the measurement site based on a captured image of an endoscope inserted into a body cavity.

  According to a sixth aspect of the present invention, the measurement part specifying means specifies a measurement part from an insertion position of an endoscope to be inserted into a body cavity and a length of the inserted endoscope. .

  Furthermore, as shown in claim 7, the measurement site specifying means includes a linear scale attached to the endoscope and a length of the endoscope inserted by the encoder detector attached to the endoscope insertion portion. It is characterized by detecting the thickness.

  As a result, since the apparatus automatically specifies the measurement site and changes the probe rotation speed, the user concentrates on observation and obtains a tomographic image at a rotation speed suitable for each site without worrying about the rotation speed. be able to.

  As described above, according to the present invention, the rotation speed of the optical probe can be switched, and an optical tomographic image having a suitable image quality can be obtained according to the part observed by the user.

  Hereinafter, an optical tomographic image acquisition apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a schematic configuration of an optical tomographic image acquisition apparatus according to the first embodiment of the present invention.

  An optical tomographic image acquisition apparatus 10 of the present embodiment shown in FIG. 1 acquires an optical tomographic image of a measurement object by an optical coherence tomography (OCT) measurement method, particularly TD-OCT (Time Domain OCT). is there. The optical tomographic image acquisition apparatus 10 of the present embodiment branches a light source unit (light source unit) 12 that emits light La for measurement, and the light La emitted from the light source unit 12 into measurement light L1 and reference light L2. At the same time, the return light L3 and the reference light L2 from the measurement target S, which is the subject, are combined and an optical fiber coupler (branching / combining unit) 14 that generates interference light L4 and L5 and the optical fiber coupler 14 are branched. The optical probe (optical probe device) 16 including the rotation-side optical fiber FB1 that guides the measured light L1 to the measurement target and guides the return light L3 from the measurement target, and the measurement light L1 to the rotation-side optical fiber FB1. The fixed-side optical fiber FB2 that guides the return light L3 guided along with the rotation-side optical fiber FB1, and the rotation-side optical fiber FB1 can rotate with respect to the fixed-side optical fiber FB2. The optical rotary adapter 18 that transmits the measurement light L1 and the return light L3, the interference light detection unit 20 that detects the interference lights L4 and L5 generated by the optical fiber coupler 14 as interference signals, and this interference light detection The processing unit 22 that processes the interference signal detected by the unit 20 to acquire an optical tomographic image (hereinafter also simply referred to as “tomographic image” or “OCT image”) and the tomographic image acquired by the processing unit 22 are displayed. Display unit 24.

  In addition, the optical tomographic image acquisition apparatus 10 is combined with the optical path length adjustment unit 26 that adjusts the optical path length of the reference light L2, the optical fiber coupler 28 that splits the light La emitted from the light source unit 12, and the optical fiber coupler 14. Detectors 30a and 30b that detect the waved interference lights L4 and L5, respectively, and a control operation unit 32 that inputs various conditions to the processing unit 22 and the display unit 24, changes settings, and the like.

  As will be described later, in the optical tomographic image acquisition apparatus 10 shown in FIG. 1, various light including the above-described emission light La, measurement light L1, reference light L2, return light L3, and the like is transmitted between components such as optical devices. Various optical fibers FB (FB3, FB4, FB5, FB6, FB7, etc.) including the rotation-side optical fiber FB1 and the fixed-side optical fiber FB2 are used as light paths for guiding and transmitting in FIG.

  The light source unit 12 emits OCT signal light (for example, laser light having a wavelength of 1.3 μm). For example, the light source unit 12 emits low-coherence light La such as SLD (Super Luminescent Diode) or ASE (Amplified Spontaneous Emmision). The light source 12a which injects | emits and the lens (optical system) 12b for condensing the low coherent light La inject | emitted from the light source 12a and injecting into optical fiber FB4 are provided. The light La emitted from the light source unit 12 is input to the optical fiber coupler 14 through the optical fibers FB4 and FB3.

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

  The optical fiber coupler 14 splits the light La incident from the light source unit 12 through the optical fiber FB4, the optical fiber couplers 28, and FB3 into the measurement light L1 and the reference light L2. The measurement light L1 is input to the optical rotary adapter 18 via the optical fiber FB2, and the reference light L2 is input to the optical path length adjustment unit 26 via the optical fiber FB5.

  Furthermore, the optical fiber coupler 14 is reflected by the measurement target S and the reference light L2 that has been subjected to frequency shift and change of the optical path length by the optical path length adjustment unit 26 and returned to the optical fiber FB5, as will be described later. The acquired return light L3 guided from the optical fiber FB1 and the optical fiber FB2 is multiplexed and emitted to the optical fiber FB3 and the optical fiber FB6.

  The optical probe 16 is connected to the optical fiber FB2 via the optical rotary adapter 18. The measurement light L1 is input from the optical fiber FB2 to the optical fiber FB1 in the optical probe 16 through the optical rotary adapter 18. The input measurement light L1 is transmitted through the optical fiber FB1 and irradiated onto the measurement object S. Then, the optical probe 16 acquires the return light L3 reflected by the measuring object S, transmits the acquired return light L3 through the optical fiber FB1, and emits it to the optical fiber FB2 through the optical rotary adapter 18. It has become.

  The optical rotary adapter 18 optically connects the fixed optical fiber FB2 and the optical fiber FB1 rotating in the optical probe 16.

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

  Here, the optical tomographic image acquisition apparatus 10 is provided on the optical path of the optical fiber FB6 branched from the optical fiber coupler 28 and detects the light intensity of the interference light L4, and the interference provided on the optical fiber FB7. And a detector 30b for detecting the light intensity of the light L5.

  The interference light detection unit 20 adjusts the balance of the intensity of the interference light L4 detected from the optical fiber FB6 and the intensity of the interference light L5 detected from the optical fiber FB7 based on the detection results of the detectors 30a and 30b.

  The interference light detection unit 20 detects the light intensity of the interference light L4 by, for example, heterodyne detection. Specifically, when the sum of the total optical path length of the measurement light L1 and the total optical path length of the return light L3 is equal to the total optical path length of the reference light L2, it is strong or weak at the difference frequency between the reference light L2 and the return light L3. A beat signal that repeats is generated. As the optical path length is changed by the optical path length adjustment unit 26, the measurement position in the depth direction of the measurement target S changes, and the interference light detection unit 20 detects a plurality of beat signals at each measurement position. ing.

  Information on the measurement position is output from the optical path length adjustment unit 26 to the interference light detection unit 20 and the processing unit 22. An optical tomographic image is generated in the processing unit 22 based on the beat signal detected by the interference light detection unit 20 and information on the measurement position in the mirror drive mechanism 42.

  The processing unit 22 acquires a tomographic image from the interference signal detected by the interference light detection unit 20 in this way. Specifically, the region where the optical probe 16 and the measurement target S are in contact at the measurement position, more precisely, the surface of the probe outer tube (sheath) of the optical probe 16 and the surface of the measurement target S are in contact. A region that can be regarded as being present is detected by a signal from the optical rotary adapter 18, and a tomographic image is acquired from the interference signal detected by the interference light detector 20.

  The display unit 24 includes a CRT or a liquid crystal display device, and displays the tomographic image transmitted from the processing unit 22.

  The optical path length adjustment unit 26 has a function of changing the optical path length of the reference light L2 in order to change the measurement position in the measurement target S in the depth direction, and the reference light L2 emission side (that is, the optical fiber FB5). The optical fiber FB5 is disposed at the end opposite to the optical fiber coupler 14). A phase modulator 34 is disposed in the middle of the optical fiber FB5 that is the optical path of the reference light L2. The phase modulator 34 has a function of giving a slight frequency shift to the reference light L2.

  The optical path length adjustment unit 26 changes the optical path length of the reference light L2, and includes an optical system 36 and a reflection mirror 38. The optical system 36 has a function of converting the reference light L2 emitted from the optical fiber FB5 into parallel light and condensing the reference light L2 reflected from the reflection mirror 38 onto the optical fiber FB5. The reflection mirror 38 is disposed on the movable stage 40, and the movable stage 40 is provided so as to be movable in the arrow A direction by a mirror driving mechanism 42. When the movable stage 40 moves in the direction of the arrow A, the optical path length of the reference light L2 is changed. In this way, the optical path length of the reference light L2 is adjusted.

  The control operation unit 32 includes input means such as a keyboard and a mouse, and control means for managing various conditions based on the input information, and is connected to the processing unit 22 and the display unit 24. The control operation unit 32 inputs, sets, and changes various processing conditions in the processing unit 22 and changes the display setting of the display unit 24 based on an operator instruction input from the input unit.

  Note that the control operation unit 32 may display an operation screen on the display unit 24, or may provide a separate display unit to display the operation screen.

  At the time of measurement, the optical fiber FB1 in the optical probe 16 rotates as indicated by an arrow in the figure, and the measurement light L1 is irradiated while rotating with respect to the measuring object S from the light emitting unit 44 installed at the tip thereof. Is done. In this way, the optical probe 16 rotates (to be precise, the light emitting portion 44 in the optical probe 16 rotates, but this is also simply referred to as the optical probe 16 rotating), thereby providing a two-dimensional fault. An image can be obtained.

  An example of the OCT image (optical tomographic image) of the measuring object S at this time is schematically shown in FIG.

  The processing unit 22 acquires the interference signal (tomographic information) IS for one cycle (for one line) acquired by the interference light detection unit 20 in the radial direction of the optical probe 16 (the direction indicated by the arrow R in the figure). One tomographic image B as shown in FIG. 2 is generated. A black portion indicated by reference numeral 50 in the drawing represents an observation site where the optical probe 16 contacts the measuring object S.

  Further, each point arranged on the circumference in FIG. 2 represents each scan (scan), α is each scan interval of the interferometer, and this is the image resolution (resolution) in the radial direction. Therefore, when the probe rotation speed is low, the radial scan interval becomes narrow and high resolution is obtained. Conversely, when the probe rotation speed is high, the radial scan interval becomes wide and low resolution is obtained.

  At this time, it is preferable that the measurement is performed with an image resolution suitable for the part observed by the user. Since the image resolution of the optical tomographic image acquisition apparatus using OCT is determined by the rotation speed of the probe, it is necessary to set a probe rotation speed suitable for the part according to the measurement part.

  Therefore, the optical tomographic image acquisition apparatus 10 of the present invention is capable of switching the probe rotation speed (the rotation speed of the light emitting unit 44 in the optical probe 16) corresponding to the part observed by the user.

  First, the first embodiment allows the user himself to switch the probe rotation speed.

  Therefore, the optical tomographic image acquisition apparatus 10 of the first embodiment includes a measurement site rotation speed storage unit 46 and a user site setting unit 48, as shown in FIG.

  The measurement site rotation speed storage unit 46 has a plurality of types set in advance for each site, for example, the probe rotation speed for the stomach is ○ rpm, the probe rotation speed for the bronchi is Δ rpm, and the probe rotation speed for the large intestine is □ rpm. The probe rotation speed is stored.

  The user part setting unit 48 sets the probe rotation speed corresponding to the part by designating the part through the user. When the user changes the probe rotation speed in accordance with the part, the user designates the part via the user part setting unit 48, so that the probe rotation speed stored in the measurement part rotation speed storage unit 46 can be selected. Specify the probe rotation speed corresponding to the specified part. Then, the designated probe rotation speed is sent to the control operation unit 32. The control operation unit 32 sends a signal to the optical rotary adapter 18 and controls the optical probe 16 to rotate at a designated probe rotation speed.

  Thus, in the present embodiment, when the user designates a measurement site such as the stomach, the large intestine, and the bronchus via the user site setting unit 48, the rotational speed set in advance for each designated measurement site. The optical probe 16 is controlled to rotate.

  Further, if the OCT image displayed on the display screen of the display unit 24 is displayed and recorded as the resolution of the image, such as “fine mode” or “normal mode”, the probe rotation speed at that time is recorded later. When the image is observed, it is preferable that the image is measured at what probe rotation speed. In addition, the display method may be displayed with the words indicating the mode as described above, or of course, the probe rotation speed itself may be displayed.

  In addition, the probe rotation speed is set in advance for each part, but a user who has viewed the displayed image may further adjust (finely adjust) the probe rotation speed.

  Next, a second embodiment of the present invention will be described.

  In the second embodiment, image determination is performed on a normal endoscopic image to specify a measurement site, and the optical probe is rotated at a probe rotation speed set in advance for the specified site.

  FIG. 3 shows a schematic configuration of the optical tomographic image acquisition apparatus according to the second embodiment.

  As shown in FIG. 3, the optical tomographic image acquisition apparatus 100 of this embodiment has substantially the same configuration as the optical tomographic image acquisition apparatus 10 of the first embodiment shown in FIG. Instead of the user site setting unit 48 of the optical tomographic image acquisition apparatus 10, an endoscopic image is obtained from the endoscope imaging unit 50 and the measurement site is specified with reference to the data of the site image database (part image DB) 52. The endoscope image processing unit 54 is provided.

  Therefore, constituent elements other than those related to the endoscope image processing unit 54 are denoted by the same reference numerals as those of the optical tomographic image acquisition apparatus 10 in FIG.

  The endoscope imaging unit 50 captures a normal endoscopic image, and detects illumination light reflected by the measurement site with an imaging element such as a CCD. The electric signal of the reflected light detected by the endoscope imaging unit 50 is sent to the endoscope image processing unit 54.

  The endoscopic image database 52 is a database in which a large number of part images obtained by previous observations are accumulated.

  The endoscopic image processing unit 54 performs signal processing on the transmitted signal to generate an endoscopic image. Then, the endoscopic image processing unit 54 collates this image with the part image stored in the part image database 52 and specifies which part the measurement part imaged by the endoscope imaging part 50 is. It is specified by performing image processing such as pattern extraction or color extraction.

  The measurement site specified by the endoscope image processing unit 54 is sent to the control operation unit 32. When the control operation unit 32 receives the measurement site, the control operation unit 32 calls the probe rotation speed corresponding to the measurement site from the rotation speeds set in the measurement site rotation speed storage unit 46 in advance, and the optical probe 16 moves at this rotation speed. Control to rotate.

  As described above, in this embodiment, the user does not specify a part, but the apparatus automatically specifies the measurement part and changes the probe rotation speed corresponding to the specified part. The user can concentrate on the observation without worrying about the probe rotation speed.

  Next, a third embodiment of the present invention will be described.

  In the third embodiment, a measurement site is specified from a place where an endoscope is inserted into a body cavity and the length of the inserted endoscope.

  FIG. 4 shows a schematic configuration of the optical tomographic image acquisition apparatus according to the third embodiment.

  As shown in FIG. 4, the optical tomographic image acquisition apparatus 200 of this embodiment has substantially the same configuration as the optical tomographic image acquisition apparatus 10 of the first embodiment shown in FIG. An endoscope length reading unit 56 and a site determination unit 60 are provided instead of the user site setting unit 48 of the optical tomographic image acquisition apparatus 10 of FIG.

  The endoscope length reading unit 56 detects the length of the portion inserted into the body cavity of the endoscope.

  FIG. 5 shows an example of the endoscope length reading unit 56. The example shown in FIG. 5 is a case where the endoscope 64 is inserted into the body cavity from the mouth. A scale (linear scale) 64 a is attached to the endoscope 64. In addition, when the endoscope 64 is inserted from the mouth, an encoder detector 66 that reads the scale 64a of the endoscope 64 is installed as an endoscope length reading unit 56 in a mouthpiece that is attached to the mouth of the subject. .

  The insertion length of the endoscope 64 is detected from the scale 64a read by the encoder detector 66. The endoscope insertion length data 58 may be sent directly from the encoder detector 66 to the site determination unit 60, or the user reads the endoscope insertion length detected by the encoder detector 66, and the user May be input to the part determination unit 60.

  On the other hand, the data of the place where the endoscope 64 is inserted is input to the part determination unit 60. As a place where the endoscope 64 is inserted into the body cavity, a mouth, a nose, an anus, and the like are conceivable. The endoscope insertion location data 62 may be automatically determined by the apparatus and sent to the site determination unit 60, or may be input by the user.

  The part determination unit 60 determines the measurement part at that time from the data of the endoscope insertion location and the endoscope length inserted into the body cavity from the location. For example, when 20 cm is inserted from the mouth, it is determined whether it is a bronchi or esophagus, and when it is inserted 40 cm, it is determined that it is a stomach. Since individual differences are also conceivable, it is preferable to collect various samples in advance and accumulate a large number of data on the relationship between the insertion location and the insertion length and site. Then, for example, it may be determined which data is used from the height of the person.

  The measurement site specified by the site determination unit 60 in this way is sent to the control operation unit 32. The control operation unit 32 calls and sets the probe rotation speed corresponding to the sent measurement site from the measurement site rotation speed storage unit 46, and the optical probe 16 is rotationally controlled at this rotation speed.

  In addition, about the component other than the part which concerns on the endoscope length reading part 56 and the site | part determination part 60, the same code | symbol as the optical tomographic image acquisition apparatus 10 of FIG. 1 is attached | subjected and detailed description is abbreviate | omitted.

  Thus, in this embodiment, the measurement site is identified from the length of the inserted portion of the endoscope, and an optical tomographic image is obtained at the probe rotation speed corresponding to the measurement site, Since the rotation speed is changed to an appropriate rotation speed according to each measurement site without any particular awareness of the user, a tomographic image having a suitable image quality according to the measurement site can be obtained.

  The optical tomographic image acquisition apparatus of the present invention has been described in detail above, but the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the scope of the present invention. Of course.

1 is a block diagram illustrating a schematic configuration of an optical tomographic image acquisition apparatus according to a first embodiment of the present invention. It is explanatory drawing which shows typically an example of the OCT image (optical tomographic image) of a measuring object. It is a block diagram which shows schematic structure of the optical tomographic image acquisition apparatus which concerns on 2nd Embodiment of this invention. It is a block diagram which shows schematic structure of the optical tomographic image acquisition apparatus which concerns on 3rd Embodiment of this invention. It is explanatory drawing which shows an example of an endoscope length reading part.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Optical tomographic image acquisition apparatus (1st Embodiment), 12 ... Light source part, 14 ... Optical fiber coupler, 16 ... Optical probe, 18 ... Optical rotary adapter, 20 ... Interference light detection part, 22 ... Processing part, 24 Display unit 26 Optical path length adjusting unit 32 Control operation unit 46 Measurement site rotation speed storage unit 48 User part setting unit 50 Endoscope imaging unit 52 Site image database 54 Internal Endoscopic image processing unit, 56 ... endoscope length reading unit, 60 ... site determination unit, 100 ... optical tomographic image acquisition device (in the second embodiment), 200 ... optical tomographic image acquisition (in the third embodiment) apparatus

Claims (7)

An optical tomographic image acquisition apparatus that rotationally scans an optical probe, acquires a reflection signal from a measurement target, and forms an optical tomographic image of the measurement target based on the acquired reflection signal,
Measurement site specifying means for specifying the measurement site of the optical probe;
An optical tomographic image acquisition apparatus comprising: a rotation speed changing means for changing a rotation speed according to the specified measurement site of the optical probe.   The rotation speed changing means changes the rotation speed by setting a rotation speed corresponding to the specified measurement part from rotation speeds set in advance for each measurement part. Item 4. The optical tomographic image acquisition apparatus according to Item 1.   The optical tomographic image acquisition apparatus according to claim 1, wherein the optical probe is inserted into a body cavity from a forceps opening of an endoscope.   The optical tomographic image acquisition apparatus according to claim 1, wherein the measurement site specifying unit is a measurement site input unit that allows a user to specify a measurement site.   The optical tomographic image acquisition apparatus according to claim 3, wherein the measurement site specifying unit specifies the measurement site based on a captured image of an endoscope inserted into a body cavity.   4. The optical tomographic image acquisition according to claim 3, wherein the measurement part specifying unit specifies a measurement part from an insertion position of an endoscope to be inserted into a body cavity and a length of the inserted endoscope. apparatus.   The measuring part specifying means detects the length of the inserted endoscope by a linear scale attached to the endoscope and an encoder detector attached to the endoscope insertion portion. Item 7. The optical tomographic image acquisition apparatus according to Item 6.

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