JP3772002B2 - In-subject tomographic imaging system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an intra-subject tomographic imaging apparatus, and more particularly to an intra-subject tomographic imaging apparatus characterized by a portion that scans an object with low interference light and ultrasound to obtain a tomographic image.
[0002]
[Prior art]
Conventionally, ultrasonic pulses are repeatedly transmitted from an ultrasonic transducer into a living tissue, and echoes of the ultrasonic pulses reflected from the living tissue are received by an ultrasonic transducer provided in the same or separate body. By gradually shifting the direction of transmitting and receiving sound pulses, echo information collected from multiple directions at the test site in the living body is displayed as an ultrasonic tomographic image of a two-dimensional visible image to diagnose diseases, etc. Various ultrasonic diagnostic apparatuses that can be used in the field have been proposed.
[0003]
As such an ultrasonic diagnostic apparatus, an external ultrasonic probe is generally used, but a thin ultrasonic probe is inserted into a treatment instrument insertion channel or the like of an endoscope through an endoscope. An internal ultrasonic probe such as a mucosal tissue that has been introduced into a body cavity and cancerized under endoscopic observation, or an ultrasonic tomographic image of a region to be examined including a lesion such as a polyp, etc. Endoscopic devices are also used.
[0004]
In recent years, various three-dimensional ultrasound probes for obtaining a three-dimensional image so that the shape of a tumor or the like formed in a subject can be grasped or the volume can be measured have been proposed.
[0005]
Japanese Patent Application Laid-Open No. 2-265536 discloses an ultrasonic probe that performs three-dimensional scanning in a spiral shape by moving the probe in the axial direction while performing radial scanning.
[0006]
Further, in JP-A-6-30939, an ultrasonic probe configured to be movable in the axial direction is improved with a probe attachment / detachment mechanism so that the ultrasonic probe and the drive unit can be attached / detached easily and reliably. There has been disclosed an ultrasonic diagnostic apparatus configured to be able to quickly move a probe to a scanning start position and perform scanning more accurately.
[0007]
Furthermore, Japanese Patent Application Laid-Open No. 8-56947 discloses a three-dimensional scanning ultrasonic probe that improves the followability of the distal end portion by a driving operation at the proximal side operation portion.
[0008]
On the other hand, recently, interference type OCT (Optical Coherence Tomography) for obtaining a tomographic image of a subject using low coherence light has been disclosed in Science Vol. 254, 1178 (1991).
[0009]
In this interference type OCT, an ultra-bright light-emitting diode (hereinafter abbreviated as SLD) as a low-coherence light source generates light having a coherence distance of about 17 μm and a wavelength of 830 nm, and this light is the first single light. The light enters from one end face of the mode optical fiber, is transmitted to the other end face (tip face) side, and is emitted from the tip face to the sample side.
[0010]
The first single mode optical fiber is optically coupled to the second single mode optical fiber by a coupler on the way. Therefore, it is branched into two at this coupler portion and transmitted. The first single-mode optical fiber (from the coupler) has a leading end that is wound around a piezoelectric element and applied with a drive signal from an oscillator to modulate the light transmitted by vibrating the first single-mode optical fiber. A vessel is formed.
[0011]
The modulated light is emitted from the tip surface of the first single-mode optical fiber to the sample side via a two-dimensional scanning unit that performs two-dimensional scanning. The light reflected on the sample side is incident on the front end face of the first single mode optical fiber, and further moved to the second single mode optical fiber by the coupler and detected by the detector.
[0012]
The detector also receives SLD light reflected by the mirror from the tip surface of the second single-mode optical fiber, that is, reference light. The mirror is moved in the direction of changing the optical path length, and light almost equal to the optical path length of the light reflected on the sample side and the optical path length reflected on the mirror interferes.
[0013]
The output of the detector is demodulated by the demodulator, and the interfering light signal is extracted, converted into a digital signal, signal processed, and image data corresponding to the tomographic image is generated and displayed on the monitor.
[0014]
[Problems to be solved by the invention]
However, the resolution of the tomographic image by ultrasonic waves is several hundred μm and the depth of arrival is about 10 mm, and the resolution of the tomographic image by low interference light is several tens of μm and the depth of arrival is about 2 mm. On the other hand, there is a problem that an appropriate and effective tomographic image cannot be obtained at the resolution and the reaching depth.
[0015]
The present invention has been made in view of the above circumstances, and by obtaining a tomographic image having a high resolution at a depth near the surface of the subject and a depth at the reaching depth, an appropriate and effective subject tomographic observation It is an object of the present invention to provide an intra-subject tomographic imaging apparatus capable of performing the above.
[0016]
[Means for Solving the Problems]
An intra-subject tomographic imaging apparatus of the present invention includes a light source that generates low-interference light, and a single mode for emitting the low-interference light to the subject and detecting reflected light reflected from the subject. A light guide means comprising a fiber; a scanning emission means for scanning and emitting the low interference light emitted from the single mode fiber; a reference generated from the reflected light from the object detected by the single mode fiber and the light source; Interference light extracting means for causing interference with light and extracting an interference signal corresponding to the interfered interference light; and emitting ultrasonic waves in the same direction as the low interference light emitted from the scanning emitting means and reflecting from the subject An ultrasonic transducer for detecting the ultrasonic echo, pulse generation means for generating a drive pulse for driving the ultrasonic transducer, and the ultrasonic transducer Said receiving means for receiving ultrasonic echoes out, the performs signal processing on the interference signal and the ultrasonic echo, and a signal processing means for constructing a tomographic image of at least said subject deep direction, the The signal processing means synthesizes the optical tomographic image obtained by the interference signal and the ultrasonic tomographic image deeper than the optical tomographic image obtained by the ultrasonic echo to construct the tomographic image. Features.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0018]
1 to 8 relate to an embodiment of the present invention, FIG. 1 is a configuration diagram showing a configuration of an intra-subject tomographic imaging apparatus, and FIG. 2 is a configuration diagram showing a configuration in the distal end portion of the insertion probe of FIG. 3 is a first explanatory view for explaining the operation of the intra-subject tomographic imaging apparatus of FIG. 1, FIG. 4 is a second explanatory view for explaining the action of the intra-subject tomographic imaging apparatus of FIG. 1, and FIG. FIG. 6 is a configuration diagram showing the configuration in the distal end portion of the second modification of the insertion probe of FIG. 1, and FIG. 7 is a configuration diagram showing the configuration in the distal end portion of the second modification of the insertion probe in FIG. FIG. 8 is a block diagram showing a configuration of a modification of the intra-subject tomographic imaging apparatus of FIG. 1.
[0019]
As shown in FIG. 1, the intra-subject tomographic imaging apparatus 1 of the present embodiment is covered with an outer sheath 2 inserted into a slender and flexible body cavity, and a three-dimensional image is obtained by low interference light and ultrasonic waves. An insertion probe 3 for obtaining a signal, and an optical tomography for detecting light that generates low-coherence light, guides it to the insertion probe 3 side, and reflects reflected light from the affected part in the body cavity as measurement light with reference light The image signal detection device 4 and the signal processing for the interference signal detected by the optical tomographic image signal detection device 4 are performed, and the ultrasonic transducer 5 disposed at the distal end of the insertion probe 3 is driven to output an ultrasonic echo signal. The signal processing device 6 for signal processing and a monitor 7 for displaying the video signal output from the signal processing device 6, and this monitor 7 includes an optical tomographic image by low coherent light and an ultrasonic echo signal. An acoustic tomogram is displayed. It has become to so that.
[0020]
In the optical tomogram signal detection device 4, a low coherence light source 11 including an ultra-high luminance light emitting diode (hereinafter abbreviated as SLD) as a light source that generates low coherence light is disposed. The SLD of the low coherence light source 11 generates low coherence light having a wavelength of, for example, 830 nm and a coherence distance of about several tens of μm. Note that the wavelength of the SLD may be 1300 nm in addition to 830 nm.
[0021]
Although not shown, the low coherence light is converted into linearly polarized light having a predetermined polarization plane through a lens, a polarizer, and the like in the low coherence light source 11, and further at 5 to 20 KHz via an optical modulator. After the frequency modulation, the light enters from one end face (hereinafter referred to as a base end face) of the first single mode optical fiber 12a and is transmitted to the other end face (hereinafter referred to as a front end face).
[0022]
The optical fiber 12a is optically coupled to the second single mode optical fiber 12b by a PANDA coupler 13 in the middle. Therefore, the low coherence light generated by the SLD of the low coherence light source 11 is branched into two at the PANDA coupler 13 and transmitted.
[0023]
The distal end surface of the optical fiber 12a is optically coupled to the proximal end surface of the third single-mode optical fiber 12c inserted through the optical scanning probe 3, and is inserted into the distal end portion of the insertion probe 3 as will be described later. The affected area is irradiated with low coherent light from the distal end surface of the optical fiber 12c. Further, the low coherence light branched from the PANDA coupler 13 is transmitted through the optical fiber 12b, and is irradiated and reflected on the mirror 15 through the lens 14 from the front end surface of the optical fiber 12b in the optical tomographic image signal detection device 4. The
[0024]
The return light of the low coherence light from the affected part is transmitted again through the optical fiber 12c and the optical fiber 12a, is transmitted to the base end face side of the optical fiber 12b by the PANDA coupler 13, and is output to the photodetector 16. At this time, the low-coherence light reflected by the mirror 15 and transmitted through the optical fiber 12b through the lens 14 is also output to the photodetector 16 as reference light.
[0025]
Here, the mirror 15 can be moved back and forth in the optical axis direction by the actuator 17. When an optical tomographic image of the affected part is obtained, the mirror 15 is reflected by the mirror 15 and driven by the back and forth driving of the mirror 15 of the actuator 17. The optical path length of the reference light until it is incident on the optical fiber 16 is set to be almost equal to the optical path length of the low-coherence light that has returned from the affected area 20 through the optical fiber 12a.
[0026]
That is, by changing the position of the mirror 15 to change the optical path length on the reference light side, the optical path length on the measurement light side that is equal to the optical path length on the reference light side changes in the depth direction of the affected part 20 . These two low-coherence lights having almost the same optical path length interfere with each other and are detected by the photodetector 16.
[0027]
A wound compensation ring 18 is provided between the distal end surface of the optical fiber 12b and the PANDA coupler 13 so as to substantially compensate the optical path length to the affected part 20 side by the optical fiber 12a.
[0028]
The signal photoelectrically converted by the photodetector 16 is amplified by the amplifier 21, and then the light of the low-coherence light source 11 as a reference signal is sent to a lock-in amplifier (not shown) of the demodulator 22 in the signal processing device 6. It is input together with a drive signal of a modulator (not shown) or a signal having the same phase as this. Then, a signal component having the same frequency as the reference signal in the signal from the photodetector 16 is extracted, and further detected and amplified.
[0029]
The detection signal from the demodulator 22 is converted into a digital signal by the A / D converter 23, and is input to the computer unit 24 that performs various signal processing and displays an optical tomographic image with low coherence light on the monitor 7.
[0030]
The computer unit 24 controls the control unit 25 that controls driving of the actuator 17 and a scanning unit (to be described later) of the optical scanning probe 3 to perform two-dimensional scanning with low coherent light on the affected part with low coherent light. It is like that.
[0031]
The signal processing device 6 also includes a pulse generator 26 that generates a drive pulse for driving the ultrasonic transducer 5 controlled by the control device 25, and the drive pulse generated from the pulse generator 26 is transmitted by a transmission amplifier 27. And then transmitted to the ultrasonic transducer 5 through the switch 28 and the slip ring 36. The ultrasonic transducer 5 irradiates the affected part with ultrasonic waves by this drive pulse, obtains an ultrasonic echo, and sends it as an ultrasonic echo signal to the reception amplifier 29 of the signal processing device 6 via the slip ring 36 and the switch 28. After being amplified by the reception amplifier 29, it is converted into a digital signal by the A / D converter 30 and input to the computer unit 24.
[0032]
Then, by the processing of the computer unit 24, an ultrasonic tomographic image is displayed together with the optical tomographic image on the monitor 7 described above, as shown in FIG. As shown in FIG. 4, it is also possible to display on the monitor 7 a composite image in which a tomographic image near the affected surface is an optical tomographic image and a further deeper tomographic image is an ultrasonic tomographic image.
[0033]
In the insertion probe 3, as shown in FIG. 2, the optical fiber 12 c is disposed on the insertion center axis, and the low interference light emitted from the distal end surface of the optical fiber 12 c passes through the GRIN (gradient index) lens 31 to the prism 32. As a result, the optical axis is bent in a direction perpendicular to the insertion center axis, and the affected part is irradiated.
[0034]
Further, the ultrasonic wave from the ultrasonic transducer 5 provided at the distal end of the insertion probe 3 is irradiated to the proximal end side of the insertion probe 3 in the direction of the central axis of insertion, and by an acoustic mirror 33 formed on the back surface of the prism 32. The affected area is irradiated through a substantially cylindrical ultrasonic transmitting member 34 from a right angle direction opposite to the low interference light with respect to the insertion center axis. The outer sheath 2 contains an ultrasonic transmission medium 3a such as water, liquid paraffin, or aqueous carboxymethyl cellulose solution.
[0035]
The ultrasonic transducer 5 is bonded and fixed to the distal end opening side of the ultrasonic transmission member 34, and the prism 32 is bonded and fixed to the proximal end opening side of the ultrasonic transmission member 34. A window portion 34a is provided on the side portion so that low interference light emitted from the distal end surface of the optical fiber 12c and passing through the prism 32 can be applied to the affected area. Furthermore, the proximal end opening side of the ultrasonic transmission member 34 is connected to a cylindrical coil shaft 35 through which the insertion probe 3 is inserted.
[0036]
Returning to FIG. 1, the proximal end opening side of the coil shaft 35 is connected to a drive device 37 that rotates around the insertion center axis. The driving device 37 includes a motor 38 that supplies a rotational driving force and a gear unit 39 that transmits the driving force of the motor to the coil shaft 35. The motor 38 is controlled by the control device 25.
[0037]
In this embodiment configured as described above, it is possible to observe a tomographic image of a shallow and deeply affected area with an optical tomographic image using low interference light, and simultaneously observe a deeper tomographic image of the affected area with an ultrasonic tomographic image. Therefore, appropriate and effective tomographic observation of the affected area can be performed.
[0038]
In the present embodiment, the ultrasonic transducer 5 is provided by being bonded and fixed to the distal end opening side of the ultrasonic transmitting member 34. However, as shown in FIG. A prism 32 that bends light in a direction perpendicular to the optical axis of the insertion center axis is provided, and an annular ultrasonic transducer 5a having an opening for transmitting the light at the center is provided on the side of the ultrasonic transmission member 34. It may be configured. As shown in FIG. 6, the same effect as described above can be obtained even if the annular ultrasonic transducer 5a is disposed on the side surface opposite to the reflection direction of the prism 32.
[0039]
In the present embodiment, the ultrasonic transducer 5 is provided on the distal opening side of the ultrasonic transmission member 34. However, as shown in FIG. 7, a fixing member 51 is provided on the inner side of the distal end of the outer sheath 2. By treating the affected part confirmed by the optical tomographic image by the low interference light by providing the ultrasonic probe 52 for treatment to treat the affected part in the same direction as the low interference light on the fixing member 51 and configuring the insertion probe. Is also possible.
[0040]
Further, as shown in FIG. 8, a treatment tool for an ultrasonic endoscope 75 having a CCD 72 controlled by a camera control unit (CCU) 71 and an ultrasonic transducer 74 driven by an ultrasonic processor 73 in the distal end portion. An optical tomogram obtained from the insertion probe 3, the ultrasonic transducer 74, and the CCD 72 by the signal processing device 6 is inserted into the channel, and the optical probe to obtain an optical tomogram controlled by the optical tomogram signal detection device is inserted. An ultrasonic tomographic image and an endoscopic image may be superimposed on the monitor 7.
[0041]
[Appendix]
(Additional Item 1) a light source that generates low interference light;
A light guide means comprising a single mode fiber for emitting the low interference light to the subject and detecting the reflected light reflected from the subject;
Scanning emitting means for scanning and emitting the low interference light emitted from the single mode fiber;
Interference light extraction means for causing the reflected light from the subject detected by the single mode fiber to interfere with the reference light generated from the light source, and extracting an interference signal corresponding to the interfered light;
An ultrasonic transducer that emits ultrasonic waves in the same direction as the low interference light emitted from the scanning emitting means and detects ultrasonic echoes reflected from the subject;
Pulse generating means for generating a driving pulse for driving the ultrasonic transducer;
Receiving means for receiving the ultrasonic echo detected by the ultrasonic transducer;
An intra-subject tomographic imaging apparatus comprising signal processing means for performing signal processing on the interference signal and the ultrasonic echo and constructing at least a tomographic image of the subject in the depth direction.
[0042]
(Additional Item 2) The scanning emitting means and the ultrasonic transducer are disposed at a distal end of an elongated insertion portion that can be inserted into the subject, and the low interference light and the ultrasonic wave are transmitted from the insertion portion. The intra-subject tomographic imaging apparatus according to Additional Item 1, wherein irradiation is performed in a circumferential direction of a longitudinal axis.
[0043]
(Additional Item 3) The intra-subject tomogram according to Additional Item 2, wherein the scanning emitting means is a light reflecting member that is rotatable around the longitudinal axis disposed at a distal end portion of the insertion portion. Imaging device.
[0044]
(Additional Item 4) The signal processing unit simultaneously constructs an optical tomographic image obtained by the interference signal and an ultrasonic tomographic image obtained by the ultrasonic echo, respectively. The intra-subject tomographic imaging apparatus according to any one of 2 and 3.
[0045]
(Additional Item 5) The signal processing unit synthesizes an optical tomographic image obtained by the interference signal and an ultrasonic tomographic image deeper than the optical tomographic image obtained by the ultrasonic echo to generate the tomographic image. The intra-subject tomographic imaging apparatus according to any one of Additional Items 1, 2, or 3, wherein the tomographic imaging apparatus is constructed into an image.
[0046]
(Additional Item 6) The ultrasonic transducer is disposed at a distal end of the distal end portion of the insertion portion, emits the ultrasonic wave in the longitudinal axis direction, and is provided by an acoustic mirror disposed on the side opposite to the light reflecting member. The intra-subject tomographic imaging apparatus according to claim 3, wherein the ultrasonic wave is scanned on the same plane as the low interference light.
[0047]
(Additional Item 7) The inside of the subject according to Additional Item 3, wherein the ultrasonic transducer is fixed to the light reflecting member, and the ultrasonic wave is scanned on the same plane as the low interference light. Tomographic imaging device.
[0048]
(Additional Item 8) The intra-subject tomographic imaging apparatus according to Additional Item 7, wherein the ultrasonic transducer has a hole through which the low-interference light is transmitted at a central portion.
[0049]
(Additional Item 9) The intra-subject tomographic imaging apparatus according to Additional Item 7 or 8, wherein the ultrasonic transducer is an annular ultrasonic transducer.
[0050]
(Additional Item 10) An elongated insertion portion that can be inserted into the subject;
A light source that generates low interference light;
The single-mode fiber is inserted through the insertion portion, emits the low interference light to the subject from the end surface on the distal end side of the insertion portion, and detects reflected light reflected from the subject. A light guiding means;
Scanning emitting means for scanning and emitting the low interference light emitted from the single mode fiber;
Interference light extraction means for causing the reflected light from the subject detected by the single mode fiber to interfere with the reference light generated from the light source, and extracting an interference signal corresponding to the interfered light;
Signal processing means for performing signal processing on the interference signal and constructing at least a tomographic image in the depth direction of the subject;
In the distal end portion of the insertion portion, a therapeutic ultrasonic transducer for irradiating a powerful ultrasonic wave to a part of a scanning surface scanned by the scanning emitting means,
Driving means for driving the therapeutic ultrasonic transducer;
An intra-subject tomographic imaging apparatus comprising:
[0051]
【The invention's effect】
As described above, according to the intra-subject tomographic imaging apparatus of the present invention, it is possible to obtain a tomographic image having a high resolution at the depth near the surface of the subject by the interference signal and a deep tomographic image by ultrasonic echoes at the reaching depth. There is an effect that an appropriate and effective subject tomographic observation can be performed.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a configuration of an intra-subject tomographic imaging apparatus according to an embodiment of the present invention. FIG. 2 is a configuration diagram showing a configuration in a distal end portion of an insertion probe in FIG. FIG. 4 is a first explanatory diagram for explaining the operation of the intra-subject tomographic imaging apparatus. FIG. 4 is a second explanatory diagram for explaining the action of the intra-subject tomographic imaging apparatus. FIG. 6 is a configuration diagram showing a configuration in the distal end portion of the second modification of the insertion probe of FIG. 1. FIG. 7 is a configuration diagram showing a configuration in the distal end portion of the insertion probe of FIG. FIG. 8 is a configuration diagram showing a configuration in the distal end portion of a modification. FIG. 8 is a configuration diagram showing a configuration of a modification of the tomographic imaging apparatus in a subject in FIG.
DESCRIPTION OF SYMBOLS 1 ... In-subject tomographic imaging apparatus 2 ... Outer sheath 3 ... Insertion probe 4 ... Optical tomographic image signal detection apparatus 5 ... Ultrasonic transducer 6 ... Signal processing apparatus 7 ... Monitor 11 ... Low coherence light source 12a ... (1st (Single mode) optical fiber 12b (second single mode) optical fiber 13 ... PANDA coupler 14 ... lens 15 ... mirror 16 ... photodetector 17 ... actuator 18 ... compensation ring 21 ... amplifier 22 ... demodulator 23 ... A / D Converter 24 ... Computer unit 25 ... Control device 26 ... Pulse generator 27 ... Transmitting amplifier 28 ... Switch 29 ... Receiving amplifier 30 ... A / D converter 31 ... GRIN lens 32 ... Prism 33 ... Acoustic mirror 34 ... Ultrasonic transmission Member 35 ... Coil shaft 36 ... Slip ring 37 ... Drive device 38 ... Motor 39 ... Gear part

Claims (1)

A light source that generates low interference light;
A light guide means including a single mode fiber for emitting the low interference light to the subject and detecting the reflected light reflected from the subject;
Scanning emitting means for scanning and emitting the low interference light emitted from the single mode fiber;
Interference light extraction means for causing the reflected light from the subject detected by the single mode fiber to interfere with the reference light generated by the light source, and extracting an interference signal corresponding to the interfered light;
An ultrasonic transducer that emits ultrasonic waves in the same direction as the low interference light emitted from the scanning emitting means and detects ultrasonic echoes reflected from the subject;
Pulse generating means for generating a driving pulse for driving the ultrasonic transducer;
Receiving means for receiving the ultrasonic echo detected by the ultrasonic transducer;
Signal processing means for performing signal processing on the interference signal and the ultrasonic echo, and constructing at least a tomographic image in the depth direction of the subject,
The signal processing unit synthesizes an optical tomographic image obtained by the interference signal and an ultrasonic tomographic image deeper than the optical tomographic image obtained by the ultrasonic echo to construct the tomographic image. A tomographic imaging apparatus in a subject characterized by the above .

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