JP2006267034A - Tomography device and tomography method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a tomography device and a tomography method for measuring the dynamic state function of a body to be inspected at a desired time interval. <P>SOLUTION: A processing section 10 outputs a raster trigger and a frame trigger, in synchronization with the raster trigger to a function generator 8 and a galvanomirror driver 9, when an external signal is inputted. The function generator 8 generates positive-phase and negative-phase light delay scanning voltages and applies them to optical phase modulators 4, 5. The galvanomirror driver 9 generates a galvanomirror drive voltage, in synchronization with an inputted frame trigger and applies it to a galvanomirror 7b. The optical phase modulators 4, 5 scan the optical path length of the reference light and the signal light in the direction of an optical axis (depth direction of organism). An irradiation section 7 scans the irradiation point of signal light on the surface of the organism, by making a round trip over a prescribed distance in a straight form, along the surface of the organism during a single period of the galvanomirror drive voltage. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a tomographic measuring apparatus and a tomographic measuring method for measuring a tomographic object to be examined using low coherence optical interference.

  Attempts to visualize the internal structure of a living body using light are performed in fields such as fluoroscopic imaging using X-rays and tomographic imaging of biological tissues using light waves using the principle of OCT (Optical Coherence Tomography). For example, in the field of ophthalmology, an OCT apparatus capable of displaying a tomographic image of fundus retinal detachment with a spatial resolution of about 10 μm has been put into practical use.

  The principle of OCT is that low-coherence light interference is used to identify the position of a reflection point in a living tissue along the optical axis direction (the depth direction of the living body) with a resolution of the coherence length. The OCT apparatus constitutes an optical interferometer (for example, Michelson interferometer) using a low-coherence light source, and is placed on a fine movement stage at the end of the signal light path to irradiate the surface of the living body with signal light. The reference optical path is provided with a scanning unit that scans the optical path length of the reference light by repeatedly changing the reference optical path length to a required minute dimension (for example, 1 mm), and the reference optical path end is provided with a reference A mirror that reflects light is provided. Further, as a scanning method of the optical path length of the reference light, the reference optical path length is changed by using an optical fiber phase modulator that winds an optical fiber around a PZT cylindrical actuator and is driven by a triangular wave voltage of a predetermined period.

When measuring a tomography of a living body, the reference light path length is repeatedly changed by irradiating the surface of the living body with signal light from the irradiation unit and scanning the optical path length of the reference light, until the reference optical path length and the reflection point of the deep biological layer. When the signal optical path lengths coincide with each other, a localized heterodyne beat signal due to low coherence interference is detected, and a reflected light distribution in the deep direction of the living body is acquired based on the detected signal. In order to acquire a two-dimensional tomographic image in a living tissue, every time the reference optical path length is scanned once, the fine movement stage is moved in the same direction by a fixed distance (for example, 1 to 10 μm) in synchronization with this signal. The irradiation point of light is moved along the living body surface (see Non-Patent Document 1).
Masamitsu Haruna and 1 other, “Technological development of optical coherence tomography centered on medical treatment” October 2003, Laser Research Vol.31, No.10

  However, in the apparatus of Non-Patent Document 1, when the optical path length of the reference light is scanned at a predetermined period, the irradiation point of the signal light is moved along the surface of the living body within a certain time. Although a tomographic image of a living body can be acquired, in order to measure the temporal transition of physiological phenomena occurring in living tissue, i.e., the dynamic function of the living body, the irradiation point is synchronized with an extremely fast reference optical path length scan. Therefore, it has been desired to measure the dynamic function of the living body more accurately and simply. In particular, exocrine glands that excrete secretions from glandular cells into the body or lumen play an important role in regulating body temperature, draining waste or surplus, maintaining a constant body fluid concentration and pH, It is an extremely important organ for maintaining physiological functions, and elucidation of the dynamic function of the exocrine glands is useful for the diagnosis of skin diseases and digestive system diseases. It was.

  The present invention has been made in view of such circumstances, and irradiation point scanning for scanning an irradiation point along the surface of an object to be inspected (for example, a living body) based on a predetermined optical path length scanning cycle. By setting the cycle and scanning the optical path length of the reference light in the optical path length scanning cycle, by scanning the irradiation point with the set irradiation point scanning cycle, the dynamic function of the object to be inspected can be obtained at a desired time interval. An object is to provide a tomographic measurement apparatus and a tomographic measurement method capable of measuring.

  Another object of the present invention is to start the scanning of the reference optical path length and the scanning of the irradiation point based on the signal related to the external stimulus applied to the object to be inspected. An object of the present invention is to provide a tomographic apparatus capable of measuring a dynamic function when a stimulus is applied.

  Another object of the present invention is to provide an optical path length of signal light in a direction corresponding to a scanning direction scanned by the reference optical path length scanning means in synchronization with an optical path length scanning period based on a signal related to the external stimulus. The optical path length scanning distance is doubled within the same optical path length scanning time, and the dynamic function when an external stimulus is applied to the object to be inspected is measured at higher speed. An object of the present invention is to provide a tomographic measuring apparatus capable of performing the above.

  Another object of the present invention is to provide a dynamic function at a desired time after an external stimulus is applied to the subject by outputting the signal related to the external stimulus after being delayed by a set delay time. An object of the present invention is to provide a tomographic measuring apparatus capable of measuring.

  Another object of the present invention is to provide a first signal and a second signal related to interference light between the reference light and the signal light in the first wavelength band and the second wavelength band, which have different degrees of light absorption with respect to the object to be inspected. It is an object to provide a tomographic measuring apparatus and a tomographic measuring method capable of more clearly measuring the dynamic function of the object to be inspected by calculating the difference between them.

  Another object of the present invention is to provide a linear insertion part for insertion into the lumen of a living body in a part of the signal optical path, and to transmit the signal light to the distal end of the insertion part. An object of the present invention is to provide a tomographic measuring apparatus that can measure the dynamic function of an exocrine gland below the inner wall of a lumen by providing an optical element for irradiating the inner wall and capturing reflected signal light.

  The tomographic measurement apparatus according to the first aspect of the present invention separates light from a low coherence light source into reference light and signal light, and guides them to a reference light path and a signal light path, respectively. Reference optical path length scanning means for scanning the optical path length of the reference light in a long scanning period and an optical element for reflecting the reference light at the end of the reference optical path are provided, and the signal light is supplied to the surface of the object to be inspected in the signal optical path. And an irradiation point scanning means for scanning the irradiation point along the surface of the object to be inspected, scanning the optical path length of the reference light, and the surface of the object to be inspected corresponding to the optical path length of the reference light In a tomographic measuring apparatus for measuring a tomographic object based on optical interference between the signal light reflected at a deep layer position from the reference light reflected at the end of the reference optical path, based on the optical path length scanning period, Irradiation point scan cycle to set the irradiation point scan cycle The irradiation point scanning unit scans the irradiation point at a set irradiation point scanning period when the reference light path length scanning unit scans the optical path length of the reference light. And

  A tomographic measurement apparatus according to a second aspect of the present invention is the tomographic measurement apparatus according to the first aspect, wherein the reference optical path length scanning unit and the irradiation point scanning unit control the start of scanning, the external stimulation unit that applies external stimulation to the object to be examined, Acquisition means for acquiring a signal related to an external stimulus, and the control means starts scanning the reference optical path length scanning means and the irradiation point scanning means based on the signal acquired by the acquisition means. It is characterized by being.

  A tomographic measurement apparatus according to a third invention is the signal for scanning the optical path length of the signal light in the direction corresponding to the scanning direction scanned by the reference optical path length scanning means in synchronization with the optical path length scanning period in the second invention. An optical path length scanning unit is provided, and the control unit starts scanning of the signal optical path length scanning unit based on the signal acquired by the acquisition unit.

  A tomographic measurement apparatus according to a fourth invention comprises a delay time setting means for setting a delay time in the second invention or the third invention, wherein the acquisition means delays the acquired signal by a set delay time and The output is made to the control means.

  A tomographic measurement apparatus according to a fifth aspect of the present invention is the tomographic measurement apparatus according to any one of the first to fourth aspects, wherein the reference light and the signal light have a first wavelength band and a second wavelength band that have different degrees of light absorption with respect to the object to be inspected. A first detector for detecting a first signal related to optical interference between the reference light and the signal light in the first wavelength band; and an optical interference between the reference light and the signal light in the second wavelength band. A second detecting means for detecting a related second signal; and a difference calculating means for calculating a difference between the detected first signal and the second signal, and based on the calculated difference, the tomogram of the inspected object It is characterized by measuring.

  A tomographic measurement apparatus according to a sixth aspect of the present invention is the tomographic measurement apparatus according to the fifth aspect, wherein the first light source and the second light source that emit light in the first wavelength band and the second wavelength band, and the light emitted from the first light source and the second light source. A multiplexer for multiplexing, a multiplexer for distributing the light combined by the multiplexer to the reference optical path and the signal optical path, and interference light between the reference light and the signal light in the first wavelength band A demultiplexer for demultiplexing light into interference light in the second wavelength band, and the first detection means and the second detection means are based on the interference light demultiplexed by the demultiplexer, The first signal and the second signal are detected.

  A tomographic measurement apparatus according to a seventh invention is the tomographic measurement apparatus according to any one of the first to sixth inventions, wherein a part of the signal light path is provided with a linear insertion portion for insertion into a living body lumen. The insertion portion is provided with an optical element for irradiating the inner wall of the lumen with signal light and capturing the reflected signal light.

  In the tomographic measurement method according to the eighth aspect of the invention, the light from the low-coherence light source is separated into the reference light and the signal light, respectively guided to the reference light path and the signal light path, and the separated signal light is irradiated onto the surface of the object to be inspected. The optical path length of the reference light is scanned at a predetermined optical path length scanning period while scanning along the surface of the inspected object, and at a deep layer position from the inspected object surface corresponding to the optical path length of the reference light. In a tomographic measurement method for measuring a tomography of an object to be inspected based on optical interference between reflected signal light and reference light reflected by a path end of the reference optical path, an irradiation point scanning period is set based on the optical path length scanning period. When setting and scanning the optical path length of the reference light in the optical path length scanning cycle, the irradiation point on the surface of the inspection object is scanned in the set irradiation point scanning cycle.

  A tomographic measurement method according to a ninth invention is the tomographic measurement method according to the eighth invention, wherein light having a first wavelength band and a second wavelength band having different degrees of light absorption with respect to the object to be inspected is separated into reference light and signal light. The first signal and the second signal related to the optical interference between the reference light and the signal light in the wavelength band and the second wavelength band are detected, and the difference between the detected first signal and the second signal is calculated and calculated. Based on the difference, a tomogram of the object to be inspected is measured.

  In the first and eighth inventions, the reference optical path length scanning means scans the optical path length of the reference light at a predetermined optical path length scanning period. Thereby, the information that the reflected light at the boundary of the refractive index of the cell or tissue at the point where the optical path length of the scanned reference light and the optical path length of the signal light from the surface of the test object (living body) to the deep layer match, For example, based on the reflection position, amplitude, etc., information on the reflected light distribution in the depth direction of the object to be inspected, that is, information on the morphological structure of the inspected object deep layer is obtained, and the tomography of the object to be inspected is measured. The irradiation point scanning unit scans a position where the signal light is irradiated along the surface of the object to be inspected for a predetermined time when the reference optical path length scanning unit scans the optical path length of the reference light. Thereby, the two-dimensional tomography in the depth direction and the surface direction of the inspection object is measured. The irradiation point scanning unit performs irradiation point scanning at an irradiation point scanning period set based on the optical path length scanning period when the reference optical path length scanning unit scans the optical path length of the reference light. Thereby, a two-dimensional tomogram is measured at the set irradiation point scanning cycle (time interval).

  In the second invention, the acquisition means acquires a signal (eg, a pulse signal synchronized with the external stimulus) related to the external stimulus (eg, voltage, sound, etc.) applied to the subject by the external stimulus means. The control unit starts scanning the reference optical path length scanning unit and the irradiation point scanning unit based on the signal acquired by the acquisition unit. Thereby, the tomography of the test object when an external stimulus is applied to the test object is measured.

  In the third invention, the signal optical path length scanning unit scans the optical path length of the signal light in a direction corresponding to a scanning direction scanned by the reference optical path length scanning unit in synchronization with the optical path length scanning period. . For example, when the reference light path length scanning means changes the optical path length of the reference light and scans the reflection point of the signal light whose optical path length matches the optical path length of the reference light in the depth direction from the surface of the object to be inspected. The signal optical path length scanning means changes the optical path length of the signal light and scans the reflection point from the surface of the object to be inspected toward the deep portion. Similarly, the reference optical path length scanning means changes the optical path length of the reference light, and scans the reflection point of the signal light whose optical path length matches the optical path length of the reference light from the deep part of the object to be examined to the surface direction. In this case, the signal optical path length scanning unit changes the optical path length of the signal light to scan the reflection point from the deep part of the object to be inspected toward the surface.

  In the fourth invention, the acquisition means delays the acquired signal by a set delay time and outputs the delayed signal to the control means. The control unit starts scanning the reference optical path length scanning unit and the irradiation point scanning unit based on the delayed signal. As a result, the tomography of the object to be inspected after a predetermined time has elapsed after the external stimulus is applied to the object to be inspected.

  In the fifth and ninth inventions, the reference light and the signal light have a first wavelength band and a second wavelength band that have different degrees of light absorption with respect to the object to be inspected. For example, light absorption of a living body is determined by moisture contained in living tissue. Therefore, reference light and signal light having two wavelength bands (for example, the second wavelength band has a higher degree of light absorption with respect to moisture than the first wavelength band) with different degrees of light absorption with respect to moisture in the living tissue. Based on the optical interference, a first signal related to optical interference in the first wavelength band and a second signal related to optical interference in the second wavelength band are detected.

  In the case of light in the first wavelength band, since the degree of light absorption with respect to water is small, the irradiation light is reflected without being absorbed by the moisture in the exocrine glands existing in the tissue under the surface of the living body. For this reason, information (reflection position, amplitude, etc.) contained in the reflected light from the exocrine fluid in the exocrine gland is detected together with the tissue under the living body surface. On the other hand, in the case of light in the second wavelength band, since the degree of light absorption to water is large, the irradiation light is absorbed and not reflected by the exocrine liquid in the exocrine gland existing in the tissue under the surface of the living body. For this reason, only the information which the reflected light in the tissue under the living body surface has is detected. The difference between the first signal detected by the optical interference between the reference light and the signal light in the first wavelength band and the second signal detected by the optical interference between the reference light and the signal light in the second wavelength band is calculated. By doing so, the signal relating to the tissue under the living body surface is removed, and only the portion where the exocrine gland exists is measured.

  In the sixth aspect of the invention, the light of the first wavelength band and the second wavelength band emitted from the first light source and the second light source are multiplexed by a multiplexer. The light combined by the multiplexer is distributed to the reference optical path and the signal optical path by a distributor. Interference light in the first wavelength band and second interference light, which is obtained by causing the signal light reflected by the object to be inspected and the reference light reflected at the end of the reference optical path to interfere with each other by the multiplexer, are separated by the duplexer. Demultiplexes into interference light in the wavelength band. The first detection means and the second detection means are configured to generate the first signal and the second signal based on the interference light in the first wavelength band and the interference light in the second wavelength band, which are demultiplexed by the duplexer. Detect the signal.

  In the seventh invention, a part of the signal light path is provided with a linear insertion part for insertion into the lumen of a living body, and the signal light is applied to the inner wall of the lumen at the distal end of the insertion part. An optical element is provided for capturing the reflected and reflected signal light.

  In the first invention and the eighth invention, it is set when the irradiation point scanning period is set based on a predetermined optical path length scanning period and the optical path length of the reference light is scanned in the optical path length scanning period. By scanning the irradiation point with the irradiation point scanning cycle, it is possible to follow and measure the physiological function in the living tissue that changes every moment with a desired cycle, and in particular, to elucidate the dynamic function of the exocrine gland. In addition, the temporal transition of physiological phenomena that occur directly under the skin or mucous membrane can be traced two-dimensionally, which can be used greatly in clinical fields such as dermatology and digestive surgery, and throughout the medical field. It is also possible to observe the response of the exocrine glands to physiological or drug stimuli without affecting the human body.

  In the second invention, based on a signal related to an external stimulus applied to the object to be inspected, an external stimulus is applied to the object to be inspected (biological body) by starting scanning of the reference optical path length and scanning of the irradiation point. Physiological phenomena that occur directly under the skin or mucous membrane when added, particularly the exocrine gland reaction, can be traced two-dimensionally.

  In the third invention, based on the signal related to the external stimulus, the optical path length of the signal light is scanned in the direction corresponding to the scanning direction scanned by the reference optical path length scanning means in synchronization with the optical path length scanning period. , The optical path length scanning distance can be doubled with the same optical path length scanning time, and the dynamic function when an external stimulus is applied to the subject (living body) can be measured at a higher speed. .

  In the fourth invention, by outputting a signal related to the external stimulus after being delayed by a set delay time, a dynamic function after a desired time after the external stimulus is applied to the subject (living body) Can be measured.

  In the fifth invention, the sixth invention, and the ninth invention, the first signal and the first signal related to the optical interference in the first wavelength band and the second wavelength band, which have different degrees of light absorption with respect to the inspected body (living body). By calculating the difference between the two signals, the dynamic function of the test subject (living body), particularly the exocrine gland, can be measured more clearly.

  In the seventh invention, a part of the signal light path is provided with a linear insertion part for insertion into the lumen of a living body, and the signal light is applied to the inner wall of the lumen at the distal end of the insertion part. By providing an optical element to irradiate and reflect reflected signal light, the dynamic function of the exocrine gland below the inner wall of the lumen can be measured, and the temporal transition of physiological phenomena that occur directly under the mucosa is two-dimensional. Can be tracked and can be used in clinical fields such as digestive surgery.

Embodiment 1
Hereinafter, the present invention will be described with reference to the drawings illustrating embodiments thereof. FIG. 1 is a block diagram showing the configuration of the tomographic measurement apparatus of the present invention. In the figure, reference numeral 1 denotes an SLD (Super Luminescent Diode) as a low coherence light source having a wavelength band of 1.3 μm and an oscillation spectrum width of about 50 nm.

  A single-mode optical fiber coupler 3 is connected to the SLD 1 through a single-mode optical fiber 2, and light emitted from the SLD 1 by the optical fiber coupler 3 is connected to the optical fiber coupler 3. Are separated into a reference optical path 2a and a signal optical path 2b, respectively. The light separated into the reference optical path 2a and the signal optical path 2b travels through the reference optical path 2a and the signal optical path 2b as reference light and signal light. A reference light mirror 6 is provided at the end of the reference light path 2a, and the reference light that has traveled through the reference light path 2a is reflected by the reference light mirror 6, travels in the opposite direction to the reference light path 2a, and returns to the optical fiber coupler 3. .

  In the middle of the reference optical path 2a, an optical phase modulator 4 for scanning the optical path length of the reference light (scanning the optical delay by changing the optical path length) is provided. The optical phase modulator 4 has an optical fiber 2 wound about 20 m around an actuator made of piezoelectric ceramic having a cylindrical shape (for example, an outer diameter of 50 mm and a height of 40 mm). 8, a triangular wave voltage of 500 V (for example, the maximum value is +250 V and the minimum value is −250 V) is applied.

  On the other hand, an irradiation unit 7 is provided at the end of the signal light path 2b. The irradiation unit 7 includes lenses 7a and 7c, a galvanometer mirror 7b, and the like. The signal light separated by the optical fiber coupler 3 travels along the signal optical path 2b and enters the irradiating unit 7. The irradiating unit 7 converts the signal light into parallel light by the lens 7a and enters the galvano mirror 7b, and reflects by the galvano mirror 7b. The collected signal light is collected by the lens 7c, and the collected signal light is irradiated onto the living body surface. The signal light reflected by the living body passes through the lens 7c, the galvano mirror 7b, and the lens 7a, travels in the signal light path 2b in the opposite direction, and returns to the optical fiber coupler 3.

  The galvanometer mirror 7b is a conductor and is provided with a rectangular movable plate at the center of a rod-shaped torsion bar, a mirror is formed on one surface of the movable plate, and a rectangular drive coil is formed on the other surface. In addition, both ends of the torsion bar are fixed to the metal electrodes, and the N-pole and S-pole permanent magnets are arranged along the torsion bar with the movable plate in between. The drive coil is connected to the metal electrode via a torsion bar, and the permanent magnet generates a magnetic field substantially parallel to the movable plate and substantially perpendicular to the longitudinal direction of the torsion bar. When a triangular wave voltage applied from a galvanometer mirror driver 9 to be described later is applied between the metal electrodes, an electromagnetic force generated by a current flowing through the drive coil and a magnetic field by the permanent magnet gives a torque to the movable plate, and this torque and the reaction of the torsion bar In relation to the force, the movable plate swings with the torsion bar as the swing axis. Thereby, the irradiation point of the signal light which irradiates the living body surface by swinging the mirror can be scanned linearly along the living body surface.

  In the middle of the signal optical path 2b, an optical phase modulator 5 for scanning the optical path length of the signal light is provided. The optical phase modulator 5 has the same configuration as the optical phase modulator 4. The triangular wave voltage applied to both ends of the actuator has the same period and voltage value as in the case of the optical phase modulator 4, but a reverse-phase voltage is applied. When the optical phase modulators 4 and 5 are driven by a triangular wave voltage with an applied voltage of 500 V, the scanning distance in the optical axis direction (the depth direction of the living body) is about 2.5 mm.

  The reference light reflected by the reference light mirror 6 and the signal light reflected by the living body are optically interfered by the optical fiber coupler 3, and the interference light is detected by the photodetector 11 (for example, an InGaAs PIN diode). The photodetector 11 outputs a voltage corresponding to the detected intensity of the interference light to the filter 12 as a heterodyne beat signal (hereinafter referred to as a beat signal).

  The filter 12 is a band-pass filter that transmits only a signal in a required frequency band, and outputs a beat signal from which unnecessary noise is blocked to the broadband amplifier 13. The broadband amplifier 13 amplifies the input beat signal and outputs it to the A / D converter 14. The A / D converter 14 converts, for example, a 12-bit digital signal according to the intensity of the input beat signal, and outputs the digital signal to the processing unit 10.

  The processing unit 10 can be realized by a personal computer, and includes an interface unit 10a, a RAM 10b, a display unit 10c, a storage unit 10d, an input unit 10e, and a CPU 10f. The CPU 10f can realize predetermined processing by executing a computer program read from the storage unit 10d in the RAM 10b.

  The CPU 10f includes an oscillator, a timer, and the like (both not shown), generates a desired raster trigger (for example, a rectangular pulse of 100 Hz), and based on the raster trigger, generates a frame trigger (for example, once every 10 seconds). Rectangular pulse). The raster trigger defines the period of the triangular wave voltage applied to the optical phase modulators 4 and 5 by the function generator 8, and the frame trigger scans the surface of the living body by irradiating the surface of the living body with signal light for a predetermined time. In this case, an irradiation interval (that is, a time interval for acquiring a tomographic image of one frame) is defined.

  The frame trigger interval, that is, the frame rate can be set from the input unit 10e (for example, can be set in the range of 0.1 frame / second to 4 frames / second), and the CPU 10f can be set from the input unit 10e. Based on the input frame rate, the timer is timed with reference to the raster trigger to generate a frame trigger. The set frame rate is stored in the storage unit 10d. It is also possible to set the frame rate by storing a plurality of frame rates in the storage unit 10d in advance, displaying the stored frame rates on the display unit 10c, and selecting a desired frame rate.

  The storage unit 10d stores the number of frame trigger generations. The number of generations of the frame trigger can be set by inputting from the input unit 10e in advance. Thereby, the acquisition frequency of a tomographic image can be preset.

  The storage unit 10d stores a plurality of tomographic image acquisition times (for example, 0.1 second to 4 seconds), which are scanning times for the irradiation unit 7 to scan the irradiation points on the living body surface. The tomographic image acquisition time is set by displaying the stored tomographic image acquisition time on the display unit 10c and selecting a desired tomographic image acquisition time. The tomographic image acquisition time can be set within the range of the frame rate. The CPU 10f transmits the set tomographic image acquisition time to the galvanometer mirror driver 9 via the interface unit in advance.

  The CPU 10f outputs the generated raster trigger and frame trigger to the function generator 8 and the galvanometer mirror driver 9 via the interface unit 10a, respectively. The CPU 10f counts the number of output times of the output frame trigger, and repeatedly outputs the frame trigger until it matches the number of times of generating the frame trigger stored in the storage unit 10d. When the frame trigger output count matches the generation count, the CPU 10f stops the frame trigger output and also stops the raster trigger output.

  The CPU 10f generates a raster trigger and a frame trigger when an external signal input from the delay unit 16 described later is acquired via the interface unit 10a. Note that, even when an external signal is not input from the delay unit 16, the CPU 10f receives the start command input from the input unit 10e, the raster trigger and the frame trigger, the function generator 8 and the galvanometer mirror driver, respectively. 9 can also be output.

  The CPU 10f samples the digital signal input from the A / D converter 14 via the interface unit 10a in synchronization with the raster trigger, and detects beat data (obtained by detecting the optical interference signal) as a result of sampling. Data obtained by A / D converting the beat signal) is stored in the storage unit 10d.

  The CPU 10f reads out the beat data stored in the storage unit 10d in units of one frame, assigns brightness according to the magnitude of the read beat data to each pixel, generates a two-dimensional tomographic image, and stores the generated tomographic image. Store in unit 10d. Further, the CPU 10f can also display the generated two-dimensional tomographic image on the display unit 10c every time it is generated. In this case, the horizontal axis (X axis) of the two-dimensional tomographic image corresponds to half of the cycle of the raster trigger, and the vertical axis (Y axis) corresponds to the captured image acquisition time. It is also possible to display a tomographic image by performing pseudo color display according to the size of the read beat data.

  The function generator 8 applies an optical delay scanning voltage, which is a 500 V triangular wave voltage of normal phase and reverse phase, to the optical phase modulators 4 and 5 in synchronization with the raster trigger output from the processing unit 10.

  The galvanometer mirror driver 9 stores the tomographic image acquisition time transmitted from the processing unit 10 in advance, and the rising time and the falling time are set as the tomographic image acquisition time in synchronization with the frame trigger output from the processing unit 10. A galvano mirror driving voltage having an equal triangular wave voltage is generated and applied to the galvano mirror 7b. Thereby, the irradiation part 7 scans an irradiation point by reciprocating on a straight line along the living body surface with the rise time and the fall time of the galvano mirror drive voltage.

  The external stimulation unit 15 includes a voltage generator for causing a minute current to flow through the living body, and outputs an external signal to the delay unit 16 in synchronization with the generation of a voltage that is an external stimulation to the living body. The delay unit 16 includes a timer, delays the external signal input from the external stimulation unit 15 by a time set by the timer, and outputs the delayed signal to the processing unit 10. The timer can be set, and a desired delay time can be set (for example, 0 to several seconds).

  Next, the operation of the CPU 10f will be described. FIG. 2 is a flowchart showing the processing procedure of the CPU 10f. The CPU 10f determines whether or not an external signal is input (S10). If no external signal is input (NO in S10), the process of step S10 is continued.

  On the other hand, when an external signal is input (YES in S10), the CPU 10f acquires the external signal (S11) and outputs a raster trigger (S12). The CPU 10f outputs a frame trigger in synchronization with the raster trigger (S13), and counts the number of frame trigger outputs (S14).

  The CPU 10f determines whether or not beat data has been input (S15). If no beat data has been input (NO in S15), the process of step S15 is continued. On the other hand, when beat data is input (YES in S15), the CPU 10f acquires beat data (S16), and generates a tomographic image based on the acquired beat data (S17). The CPU 10f can also display the generated tomographic image on the display unit 10c each time it is generated.

  The CPU 10f determines whether or not the number of frame trigger outputs is equal to a preset setting value (S18). If the number of output is not equal to the set value (NO in S18), the processing from step S13 is continued. On the other hand, when the number of outputs is equal to the set value (YES in S18), the CPU 10f ends the process.

  Next, the operation of the tomographic measurement apparatus according to the present invention will be described. FIG. 3 is a time chart showing the operation of the tomographic measurement apparatus of the present invention. When an external signal from the external stimulation unit 15 is input to the processing unit 10 via the delay unit 16, the CPU 10f outputs a raster trigger and a frame trigger to the function generator 8 and the galvanometer mirror driver 9, respectively.

  The function generator 8 generates normal-phase and negative-phase optical delay scanning voltages in synchronization with the input raster trigger, and outputs the generated normal-phase and negative-phase optical delay scanning voltages to the optical phase modulators 4 and 5, respectively. Apply. The galvano mirror driver 9 generates a galvano mirror driving voltage in synchronization with the input frame trigger, and applies the generated galvano mirror driving voltage to the galvano mirror 7b.

  The optical phase modulators 4 and 5 expand and contract the optical fiber 2 wound according to the magnitude of the applied optical delay scanning voltage, so that the reference light and signal light in the optical axis direction (biological depth direction) Scan the optical path length. Since the optical delay scanning voltage applied to the optical phase modulators 4 and 5 is 180 degrees out of phase, when the optical fiber 2 of the optical phase modulator 4 is extended, the optical fiber 2 of the optical phase modulator 5 is extended. When the optical fiber 2 of the optical phase modulator 4 contracts, the optical fiber 2 of the optical phase modulator 5 extends. By using two optical phase modulators, the optical path length can be changed twice during one period of the optical delay scanning voltage compared to a configuration using one optical phase modulator, and the scanning speed is increased. can do.

  The optical phase modulators 4 and 5 scan back and forth between the surface of the living body and a predetermined depth in the deep part of the living body during one period of the optical delayed scanning voltage. In addition, the scanning depth of the living body deep part can be adjusted by changing the maximum voltage and the minimum voltage of the optical delay scanning voltage.

  The galvanometer mirror 7b rotates the mirror in accordance with the magnitude of the applied galvanometer mirror driving voltage, whereby the irradiating section 7 irradiates the signal light on the living body surface during one cycle of the galvanometer mirror driving voltage. A point is scanned by reciprocating a predetermined distance linearly along the surface of the living body. Note that the scanning distance can be adjusted by changing the maximum voltage of the galvano mirror drive voltage.

  In synchronism with the frame trigger, the CPU 10f processes the beat data input during the time from when the galvano mirror drive voltage reaches 0V to the maximum value, that is, during the tomographic image acquisition time, as one frame unit. Generate and display an image.

  Thus, the tomographic measurement apparatus of the present invention repeatedly scans from the surface of the living body to a predetermined depth in synchronization with the raster trigger, and synchronizes with the frame trigger generated based on the raster trigger. A predetermined distance is scanned along the living body surface during the tomographic imaging time. Since the period of the frame trigger and the tomographic imaging time can be set to desired values, the tomographic measurement apparatus of the present invention can acquire a two-dimensional tomographic image in time series at a desired frame interval and A tomographic image can be acquired at a desired time.

  4 and 5 are explanatory views showing tomographic images of the two-dimensional dynamic function of sweat glands at a human fingertip. FIG. 4 shows a case where ultrasonic jelly is applied to the fingertip surface, and FIG. 5 shows a case where nothing is applied to the fingertip surface. In the figure, the horizontal axis is the direction of the cross-sectional depth of the fingertip, the vertical axis is the direction along the surface of the fingertip, 1 mm wide, 2 mm long, and the pixel size is 2.5 μm × 5 μm. The scanning cycle of the optical path length is 100 Hz, the captured image acquisition time is 4 seconds, and the frame trigger cycle is 10 seconds.

  Sweat glands are present at the arrows in the figure. The sweat gland is a spiral tube having a diameter of about 40 μm, and the cross section of the sweat gland when the sweat passes appears to be a dotted line. A certain amount of sweat is sucked up from the glandular cells in the dermis, and the sucked sweat is released to the body surface through the sweat glands. When ultrasonic jelly is applied to the fingertip surface, sweat is absorbed by the ultrasonic jelly on the body surface, but when nothing is applied to the fingertip surface, sweat particles released on the body surface ( Small water droplets) can be measured vividly. A series of processes in which sweat is sucked from glandular cells in the dermis and released to the body surface through the sweat gland is one cycle. The cycle when ultrasonic jelly is applied is about 190 seconds, and the cycle when nothing is applied Is about 100 seconds. Thus, the two-dimensional tomographic image of the present invention was acquired in time series, and the two-dimensional dynamic function of sweat glands was clarified.

  As described above, in the present invention, the body tissue is repeatedly scanned in the depth direction in synchronization with the raster trigger, and the predetermined trigger is synchronized with the frame trigger generated based on the raster trigger. During the tomographic imaging time, the irradiation point of the signal light is scanned linearly between a predetermined distance along the living body surface. Since the frame trigger period and tomographic imaging time can be set to desired values, in the present invention, two-dimensional tomographic images can be acquired in time series at desired frame intervals, and for each frame. A tomographic image can be acquired at a desired time. Thereby, the physiological function in the living tissue that changes every moment can be tracked and measured in a desired cycle.

  In the present invention, an external signal is generated in synchronization with an external stimulus applied to the living body, and scanning of the reference optical path length and scanning of the irradiation point are started in synchronization with the generated external signal. When an external stimulus is applied to the physiology, physiological phenomena that occur directly under the skin or mucous membrane, particularly the reaction of the exocrine glands, can be traced two-dimensionally. In addition, by outputting an external signal with a desired time delay, the physiological function occurring in the living tissue can be measured after a desired time has elapsed after the external stimulus is applied, and the response of the living tissue to the external stimulus can be measured. It can be observed more accurately.

Embodiment 2
In the first embodiment, the light source having a wavelength band of 1.3 μm is used, but in the second embodiment, two light sources having different wavelength bands are used. FIG. 6 is a block diagram showing the configuration of the tomographic measurement apparatus of the second embodiment. Hereinafter, differences from the first embodiment will be described.

In the figure, 31 is a fiber ASE (Amplified Spontaneous Emission) as a low coherence light source having a wavelength band of 1.9 μm (λ ₂ ) and an oscillation spectrum width of about 95 nm. A multiplexer 32 is connected to the SLD ₁ having a wavelength band of 1.3 μm (λ ₁ ) and the fiber ASE 31 having a wavelength band of 1.9 μm (λ ₂ ) through a single-mode optical fiber 2. The multiplexer 32 multiplexes light in the wavelength bands of λ ₁ and λ ₂ , and distributes or combines the combined light in the very wide wavelength band from 1.3 μm to 1.9 μm. To a possible optical fiber coupler).

  The light combined by the multiplexer 32 is separated into a reference optical path 2a and a signal optical path 2b that are respectively constituted by the optical fibers 2 connected to the multiplexer 33. The light separated into the reference optical path 2a and the signal optical path 2b travels through the reference optical path 2a and the signal optical path 2b as reference light and signal light. A reference light mirror 6 is provided at the end of the reference light path 2a. The reference light that has traveled through the reference light path 2a is reflected by the reference light mirror 6, travels in the opposite direction to the reference light path 2a, and returns to the multiplexer 33. An irradiating unit 7 is provided at the end of the signal light path 2b. The signal light separated by the coupler 33 travels along the signal light path 2b and enters the irradiating unit 7, and the signal light reflected by the living body is signal light path 2b. Proceed in the opposite direction and return to the combiner 33.

The multiplexer 33 causes the signal light and the reference light having the wavelength bands of λ ₁ and λ ₂ to interfere with each other, and guides the interference light to the duplexer 34. The demultiplexer 34 demultiplexes into interference light having a wavelength band of λ ₁ and interference light having a wavelength band of λ ₂ . The photodetectors 11 and 11 detect interference light having wavelength bands of λ ₁ and λ ₂ , respectively. The photodetectors 11 and 11 output a voltage corresponding to the detected intensity of the interference light to the filters 12 and 35 as a beat signal.

  The filter 12 is a band-pass filter that transmits only a signal in a required frequency band, and outputs a beat signal from which unnecessary noise is blocked to the broadband amplifier 13. The broadband amplifier 13 amplifies the input beat signal and outputs it to the A / D converter 14.

  Similarly, the filter 35 is a band-pass filter that transmits only a signal in a required frequency band, and outputs a beat signal from which unnecessary noise is blocked to the broadband amplifier 36. The broadband amplifier 36 amplifies the input beat signal and outputs it to the A / D converter 37.

  The A / D converters 14 and 37 convert, for example, a digital signal composed of 12 bits according to the intensity of the input beat signal, and output the digital signal to the processing unit 10. The CPU 10f of the processing unit 10 samples the digital signals input from the A / D converters 14 and 37 via the interface unit 10a in synchronization with the raster trigger, and stores beat data obtained as a result of the sampling in the storage unit 10d. To remember.

  The CPU 10f reads out the beat data stored in the storage unit 10d in units of one frame, performs a difference calculation of the read beat data, and assigns brightness corresponding to the magnitude of the beat data after the difference calculation to each pixel, thereby displaying the display unit A two-dimensional tomographic image is displayed in 10c. In addition, about the part similar to Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  Next, the operation of the tomographic measurement apparatus according to the second embodiment will be described. Note that the description of the same parts as those in Embodiment 1 is omitted. FIG. 7 is an explanatory diagram showing the wavelength dependence of light absorption by water. FIG. 7A shows an oscillation spectrum of the SLD 1 having a wavelength band of 1.3 μm and the fiber ASE 31 having a wavelength band of 1.9 μm as low-coherence light sources. As shown in the figure, SLD1 has a spectral width of about 50 nm, and fiber ASE31 has a spectral width of about 95 nm.

  For tomographic measurement of a living tissue, light needs to be transmitted well in the living tissue, and generally near infrared light having a wavelength of 0.7 to 2 μm is used. Especially, in the range whose wavelength is 1-2 micrometers, the light absorption in a biological body is determined with water. FIG. 7B shows the absorption coefficient in the vicinity of light having a wavelength of 1.3 μm and light having a wavelength of 1.9 μm. The light in the vicinity of 1.9 μm has a larger amount of light absorption than the light in the vicinity of 1.3 μm. For example, when the propagation distance of light in the living tissue is 1 mm, the wavelength is 1.9 μm. Light absorption is greater than 40 dB compared to 1.3 μm light.

  In the beat signal detected by the interference light from the SLD 1 in the wavelength band of 1.3 μm, the absorption of light due to moisture in the living tissue is small, so that the exocrine fluid in the exocrine gland is reflected together with the signal light reflected by the structure of the living tissue. The information (reflection position, amplitude, etc.) of the signal light reflected by is included. On the other hand, in the beat signal detected by the interference light by the fiber ASE 31 in the wavelength band of 1.9 μm, the light absorption by the moisture in the living tissue is large, so that the signal light is not reflected by the exocrine fluid and the structure of the living tissue. Only information of the reflected signal light (reflection position, amplitude, etc.) is included.

  The difference between the beat data obtained by digitally converting the beat signal obtained by optical interference in the wavelength band of 1.3 μm and the beat data obtained by digitally converting the beat signal obtained by optical interference in the wavelength band of 1.9 μm by the CPU 10f Since the beat signal in the living tissue is equivalent in each wavelength band, only the beat signal in the portion where the exocrine fluid exists in the living tissue can be detected.

  As described above, in the present invention, a beat signal is detected by optical interference in two wavelength bands having different degrees of light absorption with respect to a living body, and by calculating a difference between beat signals in the respective wavelength bands, It is possible to more clearly measure the dynamic functions of living tissues, particularly exocrine glands.

  In the above-described embodiment, the irradiation unit 7 irradiates the signal surface under the living body surface of a fingertip or the like. However, the present invention is not limited to this, and it is below the inner wall of a lumen such as the esophagus or stomach. A configuration using an endoscope to irradiate signal light may be used.

  FIG. 8 is a schematic diagram illustrating a configuration of an irradiation unit using an endoscope. In the figure, 51 is an endoscope operation unit. The endoscope operation unit 51 is provided with an angle knob for controlling the bending of the endoscope up and down, left and right, and the endoscope operation unit 51 is inserted by inserting a signal light path 2b composed of the optical fiber 2 The unit 53 is connected. At the distal end portion 54 of the insertion portion 53, light guides 57 and 57 for irradiating the inside of the lumen, an objective lens 56 for capturing an image inside the lumen, and an opening 58 for entering and exiting a 45-degree prism 55 described later. It has. In addition, a driving unit 52 for driving the 45 degree prism 55 is connected to the endoscope operation unit 51.

  A movable part (not shown) movable through a general-purpose channel of the endoscope is provided in the insertion part 53 of the endoscope, and an optical fiber 2, a green lens (not shown), and a 45 degree prism are provided in the movable part. 55 or the like is attached, and the entire movable part can be moved in the optical axis direction by a wire (not shown). The drive unit 52 is connected to the wire so as to scan a predetermined distance in the tomographic image acquisition time in synchronization with the frame trigger. Thereby, the signal light can be irradiated in the direction perpendicular to the optical axis through the 45 degree prism 55. The signal light reflected in the tissue under the lumen inner wall travels in the opposite direction through the signal light path 2b via the 45 degree prism. The 45-degree prism 55 may be rotated. Further, a mirror may be used in place of the 45 degree prism 55.

  In the above-described embodiment, the light source has a wavelength band of 1.3 μm and 1.9 μm. However, the wavelength band is a wavelength band of light in a desired wavelength band depending on a living tissue to be measured. Can be used. Further, the light source is not limited, and a femtosecond laser, a halogen lamp, or the like can be used.

  In the above-described embodiment, the external stimulation unit generates a voltage in order to pass a minute current through the living body. However, the present invention is not limited to this. For example, an impact sound, a sound having a different frequency is used. Any device that can stimulate a living body, such as a device that generates the above, etc.

It is a block diagram which shows the structure of the tomographic measurement apparatus of this invention. It is a flowchart which shows the process sequence of CPU. It is a time chart which shows operation | movement of the tomography measuring apparatus of this invention. It is explanatory drawing which shows the tomographic image of the two-dimensional dynamic function of the sweat gland in a human fingertip. It is explanatory drawing which shows the tomographic image of the two-dimensional dynamic function of the sweat gland in a human fingertip. 6 is a block diagram illustrating a configuration of a tomographic measurement apparatus according to Embodiment 2. FIG. It is explanatory drawing which shows the wavelength dependence of the light absorption by water. It is a schematic diagram which shows the structure of the irradiation part using an endoscope.

Explanation of symbols

1 SLD
DESCRIPTION OF SYMBOLS 2 Optical fiber 2a Reference optical path 2b Signal optical path 3 Optical fiber coupler 4, 5 Optical phase modulator 6 Reference light mirror 7 Irradiation part 7a, 7c Lens 7b Galvano mirror 8 Function generator 9 Galvano mirror driver 10 Processing part 10a Interface part 10b RAM
10c Display unit 10d Storage unit 10e Input unit 10f CPU
11 Photodetector 12, 35 Filter 13, 36 Broadband amplifier 14, 37 A / D converter 15 External stimulator 16 Delay unit 31 Fiber ASE
32 multiplexer 33 multiplexer 34 demultiplexer

Claims (9)

The light from the low-coherence light source is separated into the reference light and the signal light and guided to the reference optical path and the signal optical path, respectively, and the optical path length of the reference light is set to the reference optical path at a predetermined optical path length scanning period. A reference optical path length scanning means for scanning and an optical element for reflecting the reference light at a path end of the reference optical path are provided, and the signal light path is irradiated with the signal light on the surface of the object to be inspected, and the irradiation point is the inspection target An irradiation point scanning means for scanning along the body surface, scanning the optical path length of the reference light, and reflecting the signal light reflected at a deep layer position from the surface of the object to be inspected corresponding to the optical path length of the reference light; In a tomography measuring apparatus for measuring a tomography of an object to be inspected based on optical interference with reference light reflected by a path end of the reference light path,
An irradiation point scanning cycle setting means for setting an irradiation point scanning cycle based on the optical path length scanning cycle;
The irradiation point scanning means includes
A tomographic measurement apparatus characterized in that, when the optical path length of the reference light is scanned by the reference optical path length scanning means, the irradiation point is scanned at a set irradiation point scanning period. Control means for controlling the scanning start of the reference optical path length scanning means and the irradiation point scanning means;
An external stimulus means for applying an external stimulus to the subject;
Obtaining means for obtaining a signal related to the external stimulus,
The control means includes
2. The tomographic measurement apparatus according to claim 1, wherein scanning of the reference optical path length scanning unit and the irradiation point scanning unit is started based on a signal acquired by the acquisition unit. In synchronization with the optical path length scanning period, the optical path length scanning means for scanning the optical path length of the signal light in a direction corresponding to the scanning direction scanned by the reference optical path length scanning means,
The control means includes
The tomographic measurement apparatus according to claim 2, wherein the signal optical path length scanning unit starts scanning based on the signal acquired by the acquisition unit. A delay time setting means for setting the delay time;
The acquisition means includes
The tomographic measurement apparatus according to claim 2 or 3, wherein the acquired signal is delayed by a set delay time and output to the control means. Reference light and signal light are
Having a first wavelength band and a second wavelength band having different degrees of light absorption with respect to the object to be inspected;
First detection means for detecting a first signal related to optical interference between the reference light and the signal light in the first wavelength band;
Second detection means for detecting a second signal related to optical interference between the reference light and the signal light in the second wavelength band;
Difference calculating means for calculating a difference between the detected first signal and second signal,
The tomographic measurement apparatus according to any one of claims 1 to 4, wherein a tomography of the object to be examined is measured based on the calculated difference. A first light source and a second light source that emit light in the first wavelength band and the second wavelength band;
A multiplexer that combines the light emitted by the first light source and the second light source;
A multiplexer that distributes the light combined by the multiplexer to the reference optical path and the signal optical path;
A demultiplexer for demultiplexing the interference light between the reference light and the signal light into the interference light in the first wavelength band and the interference light in the second wavelength band;
The first detection means and the second detection means are:
6. The tomographic measurement apparatus according to claim 5, wherein the first signal and the second signal are detected based on interference light demultiplexed by the demultiplexer. A part of the signal optical path is provided with a linear insertion portion for insertion into the lumen of a living body,
7. The optical element for irradiating the inner wall of the lumen with signal light and capturing the reflected signal light is provided at the distal end of the insertion portion. The tomographic measurement apparatus described. The light from the low-coherence light source is separated into reference light and signal light, guided to the reference light path and signal light path, respectively, the separated signal light is irradiated onto the surface of the object to be inspected, and the irradiation point is scanned along the surface of the object to be inspected However, the optical path length of the reference light is scanned at a predetermined optical path length scanning period, and the signal light reflected at the deep layer position from the surface of the object corresponding to the optical path length of the reference light and the path of the reference optical path In a tomography measurement method for measuring a tomography of an object to be inspected based on optical interference with reference light reflected at an end,
Set an irradiation point scanning cycle based on the optical path length scanning cycle,
A tomographic measurement method, comprising: scanning an irradiation point on the surface of an object to be inspected with a set irradiation point scanning cycle when scanning the optical path length of the reference light with the optical path length scanning cycle. Separating light having a first wavelength band and a second wavelength band having different degrees of light absorption with respect to the object to be inspected into reference light and signal light;
Detecting a first signal and a second signal related to optical interference between the reference light and the signal light in the first wavelength band and the second wavelength band;
Calculating the difference between the detected first and second signals;
The tomographic measurement method according to claim 8, wherein the tomographic measurement of a test object is performed based on the calculated difference.

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