JP4163604B2 - Magnetic fluid detection device - Google Patents

Description

  In the present invention, as a basis for identifying a sentinel lymph node (Sentinel Lymph Node), which is a lymph node to which tumor cells that have entered the lymphatic vessels from the primary tumor site first arrive, The present invention relates to a magnetic fluid detection device for measuring how it is distributed after a predetermined time.

In recent years, resection surgery for early cancer is frequently performed because the detection rate of early cancer has improved. In general, surgery for early cancer is performed for the purpose of radical cure, and therefore, in addition to a lesioned part, a plurality of lymph nodes that are suspected to metastasize around the lesioned part are often removed. In early cancer surgery, pathological examination of lymph nodes removed after surgery is performed, and the presence or absence of cancer metastasis to the lymph nodes is confirmed to determine the postoperative treatment policy.
Whether or not cancer has spread to lymph nodes at the surgical stage is unknown. For this reason, since surgery for early cancer removes a plurality of lymph nodes in the vicinity of a lesion, the burden on the patient is large.

  In recent years, there has been a demand for both patient QOL (Quality of Life) and curability in cancer resection surgery. Sentinel Node Navigation Surgery, which prevents unnecessary lymph node resection without cancer metastasis, has attracted attention as one of the techniques for that purpose. The sentinel node navigation surgery will be briefly described below.

  When cancer metastasizes to a lymph node, recent studies have revealed that it does not metastasize randomly but metastasizes from a lesion through a lymphatic vessel to a lymph node according to a certain pattern. When cancer has spread to lymph nodes, it is considered that there is always metastasis to sentinel lymph nodes. Here, the Sentinel Lymph Node (SN) is a lymph node to which cancer cells that have entered the lymphatic vessels from the primary cancer focus first arrive.

  For this reason, in early cancer surgery, it is possible to determine the presence or absence of cancer metastasis to lymph nodes by finding sentinel lymph nodes during biopsy and performing biopsy and rapid pathological examination. If cancer has not spread to the sentinel lymph nodes, early cancer surgery does not require removal of the remaining lymph nodes. On the other hand, when cancer has metastasized to the sentinel lymph node, the operation for early cancer involves excision of a plurality of lymph nodes in the vicinity of the lesion according to the metastatic state.

In early cancer surgery, by performing the sentinel node navigation surgery, in patients with no cancer metastasis to lymph nodes, unnecessary lymph node excision without cancer metastasis is not performed. The burden is reduced. The sentinel node navigation surgery is not limited to breast cancer, for example, and is also applied to open surgery such as a digestive organ or surgery using a laparoscope.
In this sentinel node navigation surgery, there is a strong demand for a detection device that can easily and accurately detect sentinel lymph nodes.

  Examples of the detection device include Japanese Patent Publication No. 2001-299676, Japanese Patent Publication No. 9-189770, Japanese Patent Publication No. 10-96782, US Pat. No. 6,205,352. Etc. are proposed.

  In recent years, SQUID magnetometers using superconducting quantum interference devices (hereinafter abbreviated as SQUIDs) have been applied in various fields. The SQUID can detect a magnetic flux of about one billionth of the geomagnetism with high sensitivity.

In recent years, as the SQUID, a high-temperature superconducting SQUID that can be used for cooling at a liquid nitrogen temperature (77.3 K: −196 ° C.) has been put into practical use.
Using this, the detection device is, for example, as described in a special issue of the Japanese Journal of Biomagnetic Science (Vol.15 No.1 2002 17th, P.31-32) An apparatus using a high-temperature superconducting SQUID has been proposed.

  In the detection method using the high-temperature superconducting SQUID, for example, as shown in FIG. 17, a magnetic fluid 102 having magnetism as a tracer is locally injected around a tumor by an injection means 101 such as a puncture needle. Then, after a predetermined time, the magnetic fluid 102 stays in the sentinel lymph node SN. In addition, FIG. 17 is explanatory drawing which shows the movement of the magnetic fluid at the time of using a magnetic fluid as a tracer.

Here, the detection device detects a sentinel lymph node by magnetizing the magnetic fluid with an electromagnet having a large magnetic force and detecting the weak residual magnetic field remaining in the magnetic fluid with the SQUID when the electromagnet is turned off. Is possible.
The magnetic fluid has a particle size as small as several hundred nm, so that the coercive force is weak and the residual magnetic field is very small. For this reason, a highly sensitive magnetic sensor such as SQUID is required.

  However, since the magnetic sensor formed by the high-temperature superconducting SQUID (hereinafter referred to as SQUID magnetic sensor) is operated at a low temperature of about −190 ° C., the sensor must be cooled using liquid nitrogen. For this reason, the detection method using the high-temperature superconducting SQUID is large in size and has poor operability. In addition, the detection method using the high-temperature superconducting SQUID needs to replace liquid nitrogen every few hours, which requires a running cost. Furthermore, the detection method using the high-temperature superconducting SQUID has problems such as danger associated with replacement of liquid nitrogen. In addition, the detection method using the high-temperature superconducting SQUID has a very small residual magnetic field of the magnetic fluid, so the influence of magnetic noise from the electrical equipment is large, and it is necessary to shield the magnetic field. Become.

On the other hand, the detection device described above is, for example, a device that detects the magnetic fluid using a plurality of magnetic sensors such as a Hall element and a magnetoresistive element as described in JP-A-2003-128590. Proposed.
The magnetic fluid detection device described in the above Japanese Patent Application Laid-Open No. 2003-128590 applies an exciting magnetic field to the magnetic fluid by exciting means such as an exciting magnet, and the magnetic field strength of the same magnetic field direction component orthogonal to the exciting magnetic field is obtained. After detecting by the plurality of magnetic sensors and taking the difference between the outputs from the plurality of magnetic sensors, signal processing is performed to detect distortion (spatial magnetic gradient) of the local magnetic field distribution due to the magnetic fluid excited by the excitation means. It is supposed to be.
JP 2001-299676 A JP-A-9-189770 JP-A-10-96782 US Pat. No. 6,205,352 JP 2003-128590 A Japanese Biomagnetic Journal Special Issue Vol. 15 No. 1; Japanese Biomagnetic Journal, 2002, 17th, p. 31-32

However, the magnetic fluid detection device described in the above-mentioned Japanese Patent Application Laid-Open No. 2003-128590 uses a magnetic sensor such as a Hall element or a magnetoresistive element that can obtain an output proportional to the strength of the magnetic field. The magnetic field change due to the magnetic fluid is very weak compared to the excitation magnetic field generated by the excitation magnetic field. For this reason, if the output from the magnetic sensor is DC amplified, the amplifier output will be saturated, and therefore it must be AC amplified.
However, when the magnetic sensor is AC-coupled with a capacitor or the like, the signal change due to the magnetic fluid is attenuated unless the magnetic field change due to the magnetic fluid is very fast.

For this reason, the magnetic fluid detection device described in Japanese Patent Application Laid-Open No. 2003-128590 cancels a signal generated by the excitation magnetic field generated by the excitation magnetic field by taking a difference between a plurality of magnetic sensors, and only changes the signal due to the magnetic fluid. Is amplified.
However, in the magnetic fluid detection device described in Japanese Patent Application Laid-Open No. 2003-128590, when the excitation magnetic field generated by the excitation magnetic field is increased in order to increase the detection sensitivity of the magnetic fluid, the output of the magnetic sensor is saturated. As a result, a change in the magnetic field due to the magnetic fluid cannot be detected. Therefore, it is difficult for the magnetic fluid detection device described in JP-A-2003-128590 to detect a small amount of magnetic fluid that stays in a lymph node or the like.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a highly sensitive magnetic fluid detection device that can detect even a small amount of magnetic fluid.

A first ferrofluid detection device according to the present invention is a ferrofluid detection device for detecting a ferrofluid staying in a subject, an excitation means for generating an excitation magnetic field for exciting the magnetic fluid, A plurality of coils for detecting distortion of the local magnetic field distribution caused by the magnetic fluid excited by the excitation magnetic field of the excitation means, oscillating the excitation means and the plurality of coils, and outputting outputs from the plurality of coils The feature is that noise such as geomagnetism is removed by taking the difference.
According to the second magnetic fluid detection device of the present invention, in the first magnetic fluid detection device, the excitation device and the vibration device that vibrates the plurality of coils, and the vibration of the vibration device are controlled. Based on the operating state of the vibration means, after removing noise such as geomagnetism by taking the difference between the outputs from the plurality of coils, the control unit detects the vibration frequency component and notifies the signal intensity according to the detection result And is characterized by providing.
The third magnetic fluid detection device according to the present invention is the second magnetic fluid detection device, wherein the vibration means is a non-magnetic vibration that can vibrate by providing the excitation means and the plurality of coils at a tip portion. A drive unit that vibrates the vibration member, and the control unit controls and drives the drive unit to vibrate the vibration member, and the plurality of coils are controlled based on an operating state of the drive unit. The vibration frequency component is detected from the difference obtained from the output.

  The magnetic fluid detection device of the present invention has an effect that the detection sensitivity of magnetic fluid is high.

  Embodiments of the present invention will be described below with reference to the drawings.

  1 to 11 relate to a first embodiment of the present invention, FIG. 1 is an explanatory view showing a magnetic fluid detection device of the first embodiment of the present invention, and FIG. 2 is a view when the probe exterior member of FIG. 1 is removed. FIG. 3 is a schematic view of the probe main body of FIG. 2, FIG. 4 is a schematic explanatory view of the magnetic fluid detection device of FIG. 1, and FIG. 4 (A) is a schematic view of the magnetic fluid detection device of FIG. 4 is a schematic explanatory diagram, FIG. 4B is a schematic explanatory diagram showing a modification of FIG. 4A, FIG. 5 is a circuit block diagram of the control unit of FIG. 1, and FIG. 6 is a circuit showing a first modification of FIG. FIG. 7 is a circuit block diagram showing a second modification of FIG. 5, FIG. 8 is an explanatory diagram showing the influence of the magnetic field generated by the motor magnet, and FIG. 8A shows the two coils for the motor unit. FIG. 8B is a schematic explanatory diagram showing the position, and FIG. FIG. 9 is a schematic diagram showing a detection unit main body formed by hardening a plurality of coils, exciting magnets, and preamplifier units with resin, and FIG. 10 is a schematic diagram showing magnetic field lines of geomagnetism perpendicular to the coils. 11 and 11 are explanatory views showing the relative orientation of the two coils with respect to the geomagnetism of FIG. 10, and FIG. 11A shows the relative orientation of the two coils with respect to the geomagnetism of FIG. FIG. 11B is an explanatory diagram when two coils change their orientation relative to the geomagnetism of FIG.

  As shown in FIG. 1, the ferrofluid detection device 1 of the first embodiment is used from outside the body, in contact with the body surface, or surgically inserted into a body cavity via a trocar, or surgically operated. The probe 2 is used by incising the body surface and contacting the inside of the body, and the control unit 4 connected to the probe 2 via the connection cable 3 and controlling the probe 2.

  The probe 2 has a grip portion on the proximal end side so as to be easily gripped and is formed in a pistol shape that is easy to operate, and detects the magnetic fluid 6 staying in the sentinel lymph node 5 inside the subject. A detection unit 7 provided with excitation means and a magnetic sensor, which will be described later, is built in the tip.

  The control unit 4 includes a display unit 8 formed of an LED (Light Emitting Diode) or an LCD (Liquid Crystal Display) for displaying a result detected by the detection unit 7, and a result detected by the detection unit 7. Is provided on the front panel to notify the operator of the detection result of the magnetic fluid 6.

  The probe 2 is covered with a probe exterior member 10 made of a nonmagnetic material. When the probe exterior member 10 is removed, the probe body 11 is exposed as shown in FIG. When the probe 2 is used for insertion into a body cavity, the probe exterior member 10 is watertight.

As shown in FIGS. 2 and 3, the probe main body 11 has a slide portion 12 provided on the probe distal end side and a drive portion 13 provided on the probe proximal end side.
The slide portion 12 is made of a non-magnetic material, and a vibration member 14 that can vibrate in the longitudinal axis direction. 13 and a connecting portion 15 provided with a crank mechanism or the like for transmitting the vibration transmitted from the vibration member 14 to the vibration member 14. That is, the drive unit 13, the vibration member 14, and the connection unit 15 constitute a vibration unit. The vibrating member 14 is formed longer than the connecting portion 15 in order to separate the detecting portion 7 from the metal portion of the probe main body 11.

Further, the slide portion 12 is provided with guide members 16 for sliding and guiding the vibration member 14 in the longitudinal axis direction at two locations, the distal end side and the proximal end side.
The distal end side guide member 16 a is fixedly disposed on the distal end side of the vibration member 14. On the other hand, the proximal end side guide member 16b is fixedly disposed on the proximal end side of the vibration member 14.

  The drive unit 13 includes a motor unit 17, and converts the rotational movement of the motor unit 17 into forward and backward movements to transmit vibration to the connecting unit 15. The vibration member 14 is slid and guided by the distal end side guide member 16a and the proximal end side guide member 16b, and is vibrated in the longitudinal axis direction by vibration transmitted from the drive unit 13 via the connecting portion 15. It comes to vibrate.

Here, if a ball bearing is used between the vibration member 14 and the guide member 16, the vibration distance is short, and the ball bearing and the vibration member 14 or the drive unit 13 are fixed due to heat generation. There is fear.
In the present embodiment, as described above, the vibration member 14 is slid and vibrated with the guide member 16, so that the heat does not stick.

  The drive unit 13 may be configured to vibrate the vibration member 14 in the longitudinal axis direction using a vibrator, an ultrasonic motor, or an electrostatic actuator (not shown) instead of the motor unit 17.

The detection unit 7 is provided at the tip of the vibration member 14.
As shown in FIG. 4A, the detection unit 7 is an exciting magnet formed by a permanent magnet such as a neodymium magnet or a samarium / cobalt magnet as an exciting means for exciting the magnetic fluid 6 staying inside the subject. 21 and a coil 22 as a magnetic sensor for detecting a distortion (spatial magnetic gradient) of a local magnetic field distribution caused by the magnetic fluid 6 excited by the exciting magnet 21 is provided in the detection unit main body 23. As shown in FIG. 4B, the detection unit 7 may be configured to connect the vibration member 14 directly to the motor unit 17 of the drive unit 13.

  In this embodiment, two coils 22A and 22B are used as a plurality of magnetic sensors. The coil 22 </ b> A is provided on the distal end side of the detection unit main body 23 and is exposed at the distal end portion of the vibrating member 14. The exciting magnet 21 is disposed behind the coil 22A. Further, the coil 22 </ b> B is disposed behind the exciting magnet 21. That is, the exciting magnet 21 is disposed between the coil 22A and the coil 22B.

The detection unit 7 generates an alternating magnetic field as an excitation magnetic field depending on the vibration frequency by vibrating the excitation magnet 21 in the longitudinal direction along with the vibration of the vibration member 14 in the longitudinal direction. The magnetic fluid 6 staying inside the specimen is detected.
Here, in general, the distortion (spatial magnetic gradient) of the local magnetic field distribution by the magnetic fluid 6 increases in proportion to the intensity of the exciting magnetic field (alternating magnetic field), and the magnetic fluid is easily detected.

  However, in a magnetic sensor such as a Hall element or a magnetoresistive element, if an exciting magnet having a surface magnetic flux density of 0.1 T (Tesla) or more is arranged, the sensor output is saturated and a magnetic field change due to the magnetic fluid cannot be detected. Considering the thickness of the exterior, it is considered that the distance between the magnetic fluid and the magnetic sensor is at least 1 mm. In a magnetic sensor such as an excitation magnet having a surface magnetic flux density of 0.1 T (Tesla) and a Hall element or a magnetoresistive element, the magnetic fluid cannot be detected unless the distance between the magnetic fluid and the magnetic sensor is 1 mm or less. Then, it becomes almost impossible to detect. Therefore, although the surface magnetic flux density of the exciting magnet is desired to be 0.1 T (Tesla) or more, a Hall element or a magnetoresistive element cannot be used.

  In the present embodiment, as described above, the coil 22 is used as a magnetic sensor. The electromotive voltage v generated by the coil 22 is Faraday's law of electromagnetic induction.

Formula 1

ｎ：コイル巻き線本数
Ｈ（ｔ）：磁界
に基づき発生するようになっている。

n: number of coil windings H (t): generated based on magnetic field.

Here, since the relative positional relationship between the exciting magnet 21 and the coil 22 does not change, the coil 22 is only subjected to a static magnetic field, and the electromotive voltage v is 0 from (Equation 1).
However, if the magnetic fluid 6 is in the vicinity of the detection unit 7, the magnetic field distribution of the exciting magnetic field generated by the exciting magnet 21 by the magnetic fluid 6 is locally distorted (spatial magnetic gradient), and the magnetic field applied to the vibrating coil 22. From (Equation 1), a value proportional to the differential value of the magnetic field change is output from the coil as an electromotive voltage v.

  When viewed from the magnetic fluid 6, the exciting magnetic field generated by the exciting magnet 21 is an alternating magnetic field. As the exciting magnet 21 is made larger, the electromotive voltage v becomes larger and the detection sensitivity can be increased. The above-described permanent magnets such as neodymium magnets and samarium / cobalt magnets are small, have a large magnetic force, and are suitable for this apparatus. A neodymium magnet having a length of about 5 mm and a diameter of about 10 mm and a surface magnetic flux density of about 0.5 T (Tesla).

  Further, in this embodiment, since a plurality of coils 22 (coil 22A and coil 22B) are used, the difference between the plurality of coils 22 (coil 22A and coil 22B) is obtained as described later. Magnetic noise such as the influence of the magnetic field generated by the motor magnet of the motor unit 17 is removed.

  In this embodiment, the opening of the coil 22 (coil 22A and coil 22B) is formed to be 1 cm or less so as to be smaller than the lymph node. Thus, in this embodiment, the range in which the coil 22 (coil 22A and coil 22B) detects magnetic noise from an electric device or the like can be reduced as much as possible, and only the lines of magnetic force due to the magnetic fluid 6 can be detected. It has become.

  Furthermore, in the present embodiment, as described later, after removing the magnetic noise such as geomagnetism by taking the difference between the outputs from the plurality of coils 22 (coil 22A and coil 22B), the vibration frequency component is detected. Magnetic noise from geomagnetism and electrical equipment is removed.

  The detection unit 7 is provided with a preamplifier unit 24 including a preamplifier 24A and a preamplifier 24B for amplifying outputs from the plurality of coils 22 (coil 22A and coil 22B). That is, the detection unit 7 integrally vibrates the preamplifier unit 24 in the longitudinal axis direction along with the longitudinal vibration of the vibrating member 14 together with the exciting magnet 21 and the plurality of coils 22. Yes.

  As a result, in this embodiment, the lead wire between the coil 22 and the preamplifier section 24 does not vibrate, so there is no influence of contact resistance change or the like. Although the lead wire between the preamplifier 24 and the line driver 26 vibrates, the weak output of the coil 22 is amplified by the preamplifier 24. Therefore, even if the signal changes due to contact resistance change or the like, There is no effect because it is small compared to the signal strength.

Further, a line driver 26 for transmitting the output from the detection unit 7 to the control unit 4 is separately attached to the slide unit 12 in the vicinity of the vibration member 14 and is fixedly arranged. . That is, the line driver 26 does not vibrate. This prevents the vibration member 14 from becoming heavy by providing a relatively heavy line driver 26 on the vibration member 14.
The line driver 26 is provided with a subtractor 27 that takes a difference from the plurality of coils 22 (coil 22A and coil 22B) and an amplifier 28 that amplifies the output from the subtractor 27.

An output from the line driver 26 is transmitted to the control unit 4, and signal processing is performed by the control unit 4.
As shown in FIG. 5, the control unit 4 receives a line receiver 31 that receives the output from the line driver 26, and a low-pass filter that removes a harmonic component of the output received by the line receiver 31 and extracts an amplitude component ( LPF) 32, an amplifier 33 for amplifying the signal from the LPF 32, an A / D converter 34 for A / D converting the signal from the amplifier 33, and a digital signal converted by the A / D converter 34 And a digital signal processing circuit 35 formed by, for example, a DSP (Digital Signal Processor) for driving the display unit and the speaker by performing signal processing.

  The control unit 4 includes a motor control circuit 36 that controls and drives the motor unit 17 of the drive unit 13. The motor control circuit 36 outputs a motor drive signal to drive the motor unit 17 and receives a servo signal from the motor unit 17 to perform feedback control so as to stabilize the rotational speed of the motor. It has become. The motor control circuit 36 outputs a pulse signal synchronized with the rotation signal of the motor unit 17 to the digital signal processing circuit 35.

  The digital signal processing circuit 35 demodulates the output signal from the coil 22 (digital signal from the A / D converter 34) based on the pulse signal synchronized with the motor rotation from the motor control circuit 36, The amplitude of the vibration frequency component is detected, and the display unit 8 and the speaker 9 are driven according to the detected signal intensity.

  As a demodulation method, the pulse signal synchronized with the motor rotation and the output signal from the coil 22 (digital signal from the A / D converter 34) are digitally multiplied, or the output signal from the coil 22 (A / D) There is a method of performing a fast Fourier transform (FFT) on a digital signal from the D converter 34 and obtaining a frequency component of a vibration frequency obtained from a pulse signal synchronized with motor rotation. When the rotational speed of the motor is stable and a phase component is not required, a pulse signal synchronized with the motor rotation is not required, and the output signal from the coil 22 (A / D converter) is set with a constant vibration frequency. The digital signal from only 34).

In this case, the digital signal processing circuit 35 displays the display brightness of the LED of the display unit 8 according to the detected signal intensity, the display speed of the indicator formed by the LED or the like, or the numerical display or indicator of the LCD. The display etc. are changed.
The digital signal processing circuit 35 changes the volume, frequency or pulse train period of the speaker 9 according to the detected signal intensity.

The configuration of the control unit 4 shown in FIG. 5 is configured to perform digital signal processing, but may be configured to perform analog signal processing as shown in FIG.
As shown in FIG. 6, the control unit 4 </ b> B includes the line receiver 31, a multiplier 37 that multiplies the output from the line receiver 31 by the pulse signal from the motor control circuit 36, and the output from the multiplier 37. An LPF 32b that removes harmonic components and extracts an amplitude component, a DC amplifier 33b that amplifies an analog signal from the LPF 32b, and the digital signal processing circuit 35 according to the analog signal (voltage) intensity from the DC amplifier 33b Similarly, a voltage controlled oscillator (VCO) 38 for driving the display unit 8 and the speaker 9 is provided.

  When the magnetic fluid detection device 1 is configured in combination with an endoscope device, the control unit displays the detection result of the magnetic fluid 6 on a monitor on which an endoscopic image is displayed as shown in FIG. You may comprise.

  As shown in FIG. 7, the control unit 4C has a synthesis circuit 41 that synthesizes the detection result with the endoscope image signal output from the endoscope apparatus 40, and monitors the synthesized image signal from the synthesis circuit 41. The detection result of the magnetic fluid 6 is displayed together with the endoscopic image on the display screen of the monitor.

In this embodiment, as described above, the coils 22 </ b> A and the coils 22 </ b> B are used as the plurality of coils 22.
Here, as shown in FIGS. 8A and 8B, a magnetic field generated by a motor magnet (not shown) used in the motor unit 17 is also applied to the coil 22. The magnetic field strength varies with distance from the motor magnet. When the coil 22 is vibrated, the magnetic field strength of the motor magnet applied to the coil 22 fluctuates, so that a voltage is output from the coil 22 according to Faraday's law of electromagnetic induction. Since this voltage is not related to the presence or absence of magnetic fluid, it becomes noise for the detection of magnetic fluid.

  The magnetic field from the motor magnet attenuates exponentially in the vicinity of the motor magnet, but the gradient of the magnetic field intensity attenuation is equal over a range of several centimeters at the positions of the plurality of coils 22 that are separated to some extent. You may think.

Therefore, when the coil 22 is oscillating, the magnetic field intensity changes from the motor magnets applied to the coil 22A and the coil 22B are equal, and the output voltages are considered to be equal.
From the above, if the difference between the outputs of the coils 22A and 22B is taken, the influence from the motor magnet can be removed.

  Further, as shown in FIG. 9, the detection unit 7 is configured by hardening the plurality of coils 22 (coil 22 </ b> A and coil 22 </ b> B), the excitation magnet 21, and the preamplifier unit 24 with a resin 50 in the detection unit main body 23. ing. That is, since the coil 22A and the coil 22B are hardened with the resin 50 in a state of being arranged in parallel, even if the detection unit 7 vibrates due to the vibration of the vibration member 14, the direction and position of each other are not changed. It is designed not to change.

  Here, in this embodiment, by vibrating the vibrating member 14 in the longitudinal axis direction, the detection unit 7 is vibrated, for example, about 1 to 2 mm in the longitudinal axis direction. For this reason, between the said detection part 7 and the said probe exterior member 10, there exists a space of about 1-2 mm for the said detection part 7 to vibrate.

In general, the strength of the magnetic field becomes weaker in inverse proportion to the square of the distance. For this reason, the position of the coil 22A is preferably as close to the tip side as possible.
Therefore, in this embodiment, the coil 22A is disposed within a range of 1 mm or less from the distal end surface of the detection unit main body 23.

Here, as shown in FIG. 10, it is assumed that the magnetic field lines of geomagnetism traverse perpendicular to the coil 22.
If the coil 22A and the coil 22B move relative to each other and the relative orientation and position thereof change as shown in FIG. On the other hand, a change in the magnetic field lines of the geomagnetism that crosses occurs. Then, even if the difference between these coils 22A and 22B is taken, it becomes impossible to remove the magnetic noise caused by the combined magnetic field obtained by combining the geomagnetism with the magnetic field generated by the motor magnet as described above.

  However, in this embodiment, as described above, even if the detection unit 7 vibrates due to the vibration of the vibration member 14, the direction and position of the coil 22A and the coil 22B do not change. For this reason, as shown to FIG. 11 (A), these coil 22A and coil 22B have the same change of the magnetic field line of the geomagnetism which crosses.

  Therefore, in this embodiment, when the difference between the coils 22A and 22B is taken, magnetic noise caused by the combined magnetic field obtained by combining the geomagnetism with the magnetic field generated by the motor magnet as described above can be removed.

The magnetic fluid detection device 1 configured as described above is used to identify the sentinel lymph node 5 by detecting the magnetic fluid 6 staying in the sentinel lymph node 5 in the subject.
First, the operator inserts a puncture needle (not shown) into the lower layer of the lesioned part of the subject and locally injects the magnetic fluid 6 near the lesioned part. Then, the magnetic fluid 6 injected into the lesioned part moves from the injection site to the lymphatic vessel, reaches the sentinel lymph node 5 after 5 to 15 minutes, and stays in the sentinel lymph node 5.

  Then, the surgeon uses the probe 2 of the magnetic fluid detection device 1 by being surgically inserted into a body cavity through a trocar (not shown), or used from the outside of the body surface. The surgeon detects the magnetic fluid 6 staying in the sentinel lymph node 5 while moving the tip of the probe 2 relative to the vicinity of the lesioned part of the patient.

  At this time, in the probe 2, the motor unit 17 of the driving unit 13 is controlled and driven by the control of the motor control circuit 36 of the control unit 4. Vibration is transmitted to the connecting portion 15.

  The probe 2 is slid-guided by the guide members 16a and 16b and vibrated in the longitudinal axis direction by the vibration transmitted from the driving unit 13 through the connecting portion 15, The detection unit 7 is vibrated in the longitudinal axis direction. Then, the probe 2 generates an alternating magnetic field depending on the vibration frequency when the exciting magnet 21 of the detection unit 7 is vibrated in the longitudinal axis direction.

  Here, when the magnetic fluid 6 exists in the vicinity of the lesioned part of the patient, the alternating magnetic field generated by the exciting magnet 21 excites the magnetic fluid 6 through the space near the probe. Then, the alternating magnetic field is sucked or bounced in the vicinity of the magnetic fluid 6 to cause local distortion in the magnetic field distribution, thereby changing the spatial gradient (magnetic flux density) of the magnetic field distribution. The distortion of the local magnetic field distribution (change in magnetic flux density) due to the magnetic fluid 6 is detected by the plurality of coils 22 (coil 22A and coil 22B).

Here, the coil 22A and the coil 22B can detect the distortion (spatial magnetic gradient) of the local magnetic field distribution caused by the magnetic fluid 6 without being affected by the excitation magnetic field (alternating magnetic field) as described above. The outputs from the coils 22A and 22B are amplified by the preamplifier 24A and the preamplifier 24B, respectively, and output to the line driver 26.
In the line driver 26, the subtractor 27 takes a difference between outputs from the coils 22 </ b> A and 22 </ b> B, and the difference is amplified by the amplifier 28 and transmitted to the control unit 4.

  Here, the detection unit 7 includes the excitation magnet 21 and the plurality of coils 22 (coil 22 </ b> A and coil 22 </ b> B), and the preamplifier unit 24 moves in the longitudinal direction along with the vibration in the longitudinal direction of the vibration member 14. By vibrating, the lead wires between the plurality of coils 22 (coil 22A and coil 22B) and the preamplifier section 24 do not vibrate as described above, so there is no influence of contact resistance change or the like.

  Although the lead wire between the preamplifier unit 24 and the line driver 26 vibrates, the weak output of the coil 22 is amplified by the preamplifier unit 24. Therefore, even if the signal changes due to a contact resistance change or the like, it is amplified. There is no effect because it is small compared to the signal strength later. Therefore, noise due to vibration of the coil 22 (coil 22A and coil 22B) and the exciting magnet 21 can be prevented.

Then, the control unit 4 removes the harmonic component from the output received by the line receiver 31 by the LPF 32 and extracts the amplitude component, amplifies the extracted amplitude component by the amplifier 33, and A / D by the A / D converter 34. Convert.
Then, the control unit 4 causes the digital signal processing circuit 35 to output from the plurality of coils 22 (coil 22A and coil 22B) based on the pulse signal from the motor control circuit 36 (digital from the A / D converter 34). The signal) is subjected to digital signal processing such as fast Fourier transform to detect the amplitude of the vibration frequency component, and the display unit 8 and the speaker 9 are driven according to the detected signal intensity.

  The display unit 8 displays the distortion (spatial magnetic gradient) of the local magnetic field distribution with an indicator or a number. In this case, when the probe tip approaches the magnetic fluid 6, the indicator 8 gradually increases the indicator swing or number, and when the probe tip moves away from the magnetic fluid 6, the indicator swing or number gradually decreases. is doing.

  The speaker 9 generates a sound corresponding to the distortion of the local magnetic field distribution (spatial magnetic gradient). In this case, the speaker 9 generates a sound so that the sound gradually increases when the probe tip approaches the magnetic fluid 6, and the sound gradually decreases when the probe tip moves away from the magnetic fluid 6. Alternatively, the speaker 9 generates sound such that the sound frequency changes in proportion to the distance between the probe 2 and the magnetic fluid 6.

  Thus, the magnetic fluid detection device 1 of the first embodiment can accurately detect the position of the magnetic fluid 6 staying in the sentinel lymph node 5 without picking up magnetic noise such as geomagnetism. The location can be identified.

  FIGS. 12 to 16 relate to a second embodiment of the present invention, FIG. 12 is an explanatory view showing a magnetic fluid detecting device of the second embodiment, FIG. 13 is an explanatory view of the drive unit of FIG. 12A is a schematic explanatory view of the drive unit of FIG. 12, FIG. 13B is an external view showing the eccentric cam of FIG. 13A, and FIG. FIG. 15 is an explanatory diagram showing a circuit configuration when an exciting electromagnet is used instead of the exciting magnet, and FIG. 16 is a frequency according to the circuit configuration of FIG. 16A is a graph showing the signal strength of the output from one coil with respect to the frequency according to the circuit configuration of FIG. 15, and FIG. 16B is a graph showing the signal strength with respect to the frequency according to the circuit configuration of FIG. Indicates the signal strength of the output from the other coil Rough, 16 (C) is a graph showing the signal intensity of the difference signal corresponding to a difference between the output from the coil of the output and 16 from the coil of FIG. 16 (A) (B).

  In the first embodiment, the probe 2 and the control unit 4 are configured separately, but the second embodiment is configured by incorporating a control unit in the probe. Since the other configuration is the same as that of the first embodiment, the description thereof will be omitted, and the same components will be described with the same reference numerals.

That is, as shown in FIG. 12, the magnetic fluid detection device 1 </ b> B of the second embodiment is configured by providing a probe 2 </ b> B incorporating a control unit 4.
The probe 2B is configured by providing a control board 71 on which a control circuit is mounted as a control unit behind the drive unit 13B, and a battery 72 for supplying power to the rear of the control board 71. The control board 71 is provided with an LED 73 as a display unit connected to the control board 71. The battery 72 may be configured to be charged by an electromotive force from the charging coil 72A.

Further, the probe 2B is formed such that the probe exterior member 10B is transparent, and the light emission state of the LED 73 can be seen through the probe exterior member 10B. The drive unit 13B is configured by providing a motor unit 17.
More specifically, as shown in FIGS. 21A and 21B, the drive unit 13B includes a motor unit 17 and an eccentric cam 74 provided on the output shaft 17a of the motor unit 17. Configured.

  The eccentric cam 74 is connected to a connecting portion 15, and the vibration member 14 is connected to the distal end side of the connecting portion 15 by a spring 75. When the spring 75 is pressed toward the distal end side of the connecting portion 15, the spring 75 receives a biasing force by the spring stopper member 75a.

The probe 2B is controlled by the control circuit of the control board 71 so that the motor portion 17 of the driving portion 13 rotates against the urging force of the spring 75, and this rotational motion is converted into the eccentric cam. It is converted into forward and backward movement by 74 and transmitted to the connecting portion 15 to vibrate the vibration member 14 in the longitudinal axis direction.
Therefore, in addition to obtaining the same effect as the first embodiment, the magnetic fluid detection device 1B according to the second embodiment is composed of only the probe 2B, so that it can be downsized and has good operability.

The probe may be configured to vibrate in the left-right direction by swinging (shaking) the tip portion in the left-right direction as shown in FIG.
As shown in FIG. 14, the probe 2D is configured such that the distal end portion 81 can swing in the left-right direction around the fulcrum 81a. For this reason, since the amount of movement of the probe 2D in the left-right direction is increased, the moving speed of the probe 2D can be increased.

Here, since the coil 22 (coil 22A and coil 22B) detects a change in magnetic flux across the opening (change in magnetic flux density), the faster the time change is, the faster the output changes according to the Faraday's law of electromagnetic induction. The (electromotive voltage) signal increases.
As a result, the probe 2D has a fast moving speed of the detection unit 7, so that the moving speed of the coil 22A and the coil 22B is also fast, and a very large output (electromotive voltage) signal can be obtained.

In the first and second embodiments, the excitation magnet 21 using a permanent magnet is used as the excitation means, and the excitation magnetic field generated by the excitation magnet 21 by vibration is configured as an AC magnetic field. As an exciting means, an exciting electromagnet 90 may be used as shown in FIG.
As shown in FIG. 15, the exciting electromagnet 90 is configured by winding a coil 92 around an iron core 91, and an alternating current is supplied to the coil 92 from an alternating current power supply 94 via an electromagnet driver 93.

Then, the magnetic fluid 6 staying inside the subject is excited by the alternating magnetic field generated by the exciting electromagnet 90. Then, the distortion (spatial magnetic gradient) of the local magnetic field distribution caused by the magnetic fluid 6 is detected by the coil 22 (coil 22A and coil 22B).
Here, the outputs from the coils 22A and 22B are as shown in FIGS. 16A and 16B, respectively, for example. Then, when the output difference is taken by the subtractor 27, the difference signal becomes as shown in FIG.

  At this time, if the magnetic fluid 6 does not exist, the outputs from the coils 22A and 22B are the same intensity signal output, and if the difference between them is taken, the signal intensity shown in FIG. When the fluid 6 is present, the output from the coil 22A closer to the magnetic fluid 6 is a stronger signal output than the coil 22B. Taking these differences, the signal intensity shown in FIG. Appears depending on the frequency.

Therefore, the magnetic fluid detection device using the exciting electromagnet 90 instead of the exciting magnet 21 can detect the magnetic fluid 6.
As a result, the magnetic fluid detection device does not require a vibration mechanism, so the structure is simplified, the size can be reduced, and the operability is good.

  The present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention.

[Appendix]
(Additional item 1)
A magnetic fluid detection device for detecting magnetic fluid staying inside a subject,
Exciting means for generating an exciting magnetic field for exciting the magnetic fluid;
A plurality of coils for detecting distortion of a local magnetic field distribution due to the magnetic fluid excited by an excitation magnetic field of the excitation means;
The magnetic fluid detection apparatus is characterized in that the excitation means and the plurality of coils are vibrated, and noise such as geomagnetism is removed by taking a difference between outputs from the plurality of coils.

(Appendix 2)
The excitation means and the vibration means for vibrating the plurality of coils, and the vibration of the vibration means are controlled, and based on the operating state of the vibration means, the difference between outputs from the plurality of coils is taken to obtain noise such as geomagnetism. The magnetic fluid detection device according to claim 1, further comprising: a control unit that detects a vibration frequency component and notifies a signal intensity corresponding to the detection result after removing the vibration frequency component.

(Appendix 3)
The magnetic fluid detection device according to appendix 1, wherein openings of the plurality of coils are formed smaller than a lymph node of the subject.

(Appendix 4)
The vibration means includes a non-magnetic vibration member that can vibrate by providing the excitation means and the plurality of coils at a tip portion, and a drive unit that vibrates the vibration member,
The control unit controls and drives the drive unit to vibrate the vibration member, and detects a vibration frequency component from a difference obtained from outputs of the plurality of coils based on an operation state of the drive unit. The magnetic fluid detection device according to appendix 2, wherein:

(Appendix 5)
The magnetic fluid detection device according to item 2 or 3, wherein the excitation means is a permanent magnet having a surface magnetic flux density of 0.1 T (Tesla) or more.

(Appendix 6)
4. The magnetic fluid detection device according to item 2 or 3, wherein the exciting means is a neodymium magnet or a samarium / cobalt magnet.

(Appendix 7)
The magnetic fluid detection device according to claim 4, wherein the drive unit includes a motor unit, and the rotational movement of the motor unit is converted into forward and backward movement to vibrate the vibration member.

(Appendix 8)
5. The magnetic fluid detection device according to appendix 4, wherein the drive unit is an ultrasonic motor or an electrostatic actuator.

(Appendix 9)
The vibrating member is biased by a spring;
The magnetic fluid detection device according to claim 4, wherein the driving unit includes a cam that presses the vibration member against an urging force of the spring.

(Appendix 10)
The magnetic fluid detection device according to claim 4, wherein the plurality of coils are solidified with resin so that the directions and positions of the coils are not changed by vibration of the vibration member.

(Appendix 11)
A magnetic fluid detection device for detecting magnetic fluid staying inside a subject,
Excitation means for generating an excitation magnetic field for exciting the magnetic fluid; a plurality of coils for detecting distortion of a local magnetic field distribution caused by the magnetic fluid excited by the excitation magnetic field of the excitation means; the excitation means and the plurality of A probe having vibration means for vibrating the coil integrally;
While controlling the vibration of the vibration means of the probe, and based on the operating state of the vibration means, taking the difference of outputs from the plurality of coils and removing noise such as geomagnetism, and then detecting the vibration frequency component A control unit for notifying the signal strength according to the detection result;
A magnetic fluid detection device comprising:

(Appendix 12)
The magnetic fluid detection device according to claim 11, wherein the probe is formed in a pistol shape with a grip portion.

(Appendix 13)
A magnetic fluid detection device for detecting magnetic fluid staying inside a subject,
Exciting means for generating an exciting magnetic field for exciting the magnetic fluid;
A plurality of coils for detecting distortion of a local magnetic field distribution due to the magnetic fluid excited by an excitation magnetic field of the excitation means;
Vibration means for integrally vibrating the excitation means and the plurality of coils;
The vibration of the vibration means is controlled and, based on the operating state of the vibration means, the difference between outputs from the plurality of coils is taken to remove noise such as geomagnetism, and then the vibration frequency component is detected and detected. A control unit for notifying the signal strength according to the result;
A magnetic fluid detection device comprising: a probe comprising:

(Appendix 14)
The probe is configured such that a tip portion thereof is swingable in a left-right direction around a fulcrum, and a moving speed is increased by increasing a moving amount in the left-right direction of the excitation means and the plurality of coils. Item 14. The magnetic fluid detection device according to additional item 13.

(Appendix 15)
A magnetic fluid detection device for detecting magnetic fluid staying inside a subject,
Exciting means for generating an exciting magnetic field for exciting the magnetic fluid;
A plurality of coils for detecting distortion of a local magnetic field distribution due to the magnetic fluid excited by an excitation magnetic field of the excitation means;
A preamplifier for amplifying outputs from the plurality of coils;
The magnetic fluid detection apparatus is characterized in that the excitation means, the plurality of coils, and the preamplifier are vibrated, and a difference in output from the plurality of coils is taken to remove noise such as geomagnetism.

(Appendix 16)
The excitation means, the vibration means for vibrating the plurality of coils and the preamplifier, and the vibration of the vibration means are controlled and the difference between the plurality of coils amplified by the preamplifier is taken to remove noise such as geomagnetism. The magnetic fluid according to claim 15, further comprising a control unit that detects a vibration frequency component based on an operating state of the vibration unit and notifies a signal intensity according to the detection result. Detection device.

(Appendix 17)
Item 16. The magnetic fluid detection device according to item 15, wherein openings of the plurality of coils are formed smaller than lymph nodes of the subject.

(Appendix 18)
The vibration means includes a non-magnetic vibration member that can vibrate by providing the excitation means, the plurality of coils, and the preamplifier at a tip portion, and a drive unit that vibrates the vibration member,
The control unit controls and drives the drive unit to vibrate the vibration member, and detects a vibration frequency component from a difference obtained from outputs of the plurality of coils based on an operation state of the drive unit. Item 18. The magnetic fluid detection device according to Item 16.

(Appendix 19)
The magnetic fluid detection device according to claim 18, wherein the driving unit includes a motor unit, and the rotational movement of the motor unit is converted into forward and backward movement to vibrate the vibration member.

(Appendix 20)
Item 20. The magnetic fluid detection device according to Item 18, wherein the driving unit is an ultrasonic motor or an electrostatic actuator.

(Appendix 21)
The vibrating member is biased by a spring;
The magnetic fluid detection device according to appendix 18, wherein the drive unit includes a cam that presses the vibration member against an urging force of the spring.

(Appendix 22)
Item 19. The magnetic fluid detection device according to Item 18, wherein the plurality of coils are solidified with resin so that the directions and positions of the coils are not changed by vibration of the vibration member.

(Appendix 23)
A magnetic fluid detection device for detecting magnetic fluid staying inside a subject,
Excitation means for generating an excitation magnetic field for exciting the magnetic fluid, a plurality of coils for detecting distortion of the local magnetic field distribution due to the magnetic fluid excited by the excitation magnetic field of the excitation means, and outputs from the plurality of coils A probe having a preamplifier, and a vibrating means for integrally vibrating the excitation means, the plurality of coils and the preamplifier,
After controlling the vibration of the vibration means of the probe and removing noises such as geomagnetism by taking the difference between the plurality of coils amplified by the preamplifier, the vibration frequency component is calculated based on the operating state of the vibration means. A control unit for detecting and notifying the signal intensity according to the detection result;
A magnetic fluid detection device comprising:

(Appendix 24)
24. The magnetic fluid detection device according to appendix 23, wherein the probe is formed in a pistol shape with a grip portion.

(Appendix 25)
A magnetic fluid detection device for detecting magnetic fluid staying inside a subject,
Exciting means for generating an exciting magnetic field for exciting the magnetic fluid;
A plurality of coils for detecting distortion of a local magnetic field distribution due to the magnetic fluid excited by an excitation magnetic field of the excitation means;
Vibration means for integrally vibrating the excitation means, the plurality of coils and the preamplifier;
While controlling the vibration of the vibration means and taking the difference between the plurality of coils amplified by the preamplifier to remove noise such as geomagnetism, the vibration frequency component is detected based on the operating state of the vibration means A control unit for notifying the signal strength according to the detection result;
A magnetic fluid detection device comprising: a probe comprising:

(Appendix 26)
The probe is configured such that a tip portion thereof is swingable in a left-right direction around a fulcrum, and a moving speed is increased by increasing a moving amount in the left-right direction of the excitation means and the plurality of coils. The magnetic fluid detection device according to appendix 25.

It is explanatory drawing which shows the magnetic fluid detection apparatus of 1st Example of this invention. It is an external view which shows the probe main body at the time of removing the probe exterior member of FIG. It is the schematic of the probe main body of FIG. It is a schematic explanatory drawing of the magnetic fluid detection apparatus of FIG. It is a circuit block diagram of the control part of FIG. FIG. 6 is a circuit block diagram illustrating a first modification of FIG. 5. FIG. 6 is a circuit block diagram illustrating a second modification of FIG. 5. It is explanatory drawing which shows the influence by the magnetic field which a motor magnet produces | generates. It is a schematic diagram which shows the detection part main body comprised by hardening a some coil, the exciting magnet, and the preamplifier part with resin. It is a schematic diagram which shows the magnetic field line of the geomagnetism which traverses perpendicularly with respect to a coil. It is explanatory drawing which shows the relative direction of two coils with respect to the geomagnetism of FIG. It is explanatory drawing which shows the magnetic fluid detection apparatus of 2nd Example. It is explanatory drawing of the drive part of FIG. It is a schematic explanatory drawing which shows the probe front end side comprised so that it may vibrate in the left-right direction by rocking | fluctuating (shaking) a front-end | tip part in the left-right direction. It is explanatory drawing which shows the circuit structure at the time of using an exciting electromagnet instead of an exciting magnet. It is a graph which shows the signal strength with respect to the frequency by the circuit structure of FIG. It is explanatory drawing which shows the movement of the magnetic fluid at the time of using a magnetic fluid as a tracer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetic fluid detection apparatus 2 Probe 4 Control part 5 Sentinel lymph node 6 Magnetic fluid 7 Detection part 8 Display part 9 Speaker 10 Probe exterior member 11 Probe main body 14 Vibration member 15 Connection part 17 Motor part 21 Excitation magnet 22A, 22B Coil 23 Detection Main body 24 Preamplifier part 24A, 24B Preamplifier 26 Line driver 27 Subtractor 50 Resin agent Patent attorney Susumu Ito

Claims (3)

A magnetic fluid detection device for detecting magnetic fluid staying inside a subject,
Exciting means for generating an exciting magnetic field for exciting the magnetic fluid;
A plurality of coils for detecting distortion of a local magnetic field distribution due to the magnetic fluid excited by an excitation magnetic field of the excitation means;
The magnetic fluid detection apparatus is characterized in that the excitation means and the plurality of coils are vibrated, and noise such as geomagnetism is removed by taking a difference between outputs from the plurality of coils.   The excitation means and the vibration means for vibrating the plurality of coils, and the vibration of the vibration means are controlled, and based on the operating state of the vibration means, the difference between outputs from the plurality of coils is taken to obtain noise such as geomagnetism. The magnetic fluid detection device according to claim 1, further comprising: a control unit that detects a vibration frequency component after removing the signal and notifies a signal intensity corresponding to the detection result. The vibration means includes a non-magnetic vibration member that can vibrate by providing the excitation means and the plurality of coils at a tip portion, and a drive unit that vibrates the vibration member,
The control unit controls and drives the drive unit to vibrate the vibration member, and detects a vibration frequency component from a difference obtained from outputs of the plurality of coils based on an operation state of the drive unit. The magnetic fluid detection device according to claim 2.

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