JP2015188528A - Catheter detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catheter detection device which eliminates a detection coil located in a dead zone and can reliably detect a location of a catheter end.SOLUTION: A catheter detection device comprises: a detected part located at an end of a catheter; and a detection part detecting a location of the detected part. The detected part is composed of a transmission coil generating electromagnetic waves. The detection part has: 4 first detection coils 23B, 23D, 23F, 23H which are located at symmetrical positions with respect to intersections on a coordinate axis on orthogonal coordinate axes respectively and whose respective coil axes coincide with the direction heading for the intersections; and 4 second detection coils 23A, 23C, 23E, 23G which are located at symmetrical positions with respect to intersections of the coordinate axes on the coordinate axes and whose respective coil axes coincide with directions orthogonal to directions heading for the intersections.

Description

  The present invention relates to a catheter detection device including a detected portion disposed at the distal end of a catheter and a detecting portion that detects the position of the detected portion.

  A catheter is a medical tube that is inserted and placed in a blood vessel, digestive tract, ureter, or the like for treatment or examination. For example, the most frequently used catheter (nasal feeding tube) used in the digestive tract is used for patients who have difficulty in ingestion, and is placed in the stomach from the patient's nose via the esophagus. Caloric intake is performed by administration. Nasal feeding tubes are widely used in clinical settings, but it is important that the tip of the feeding tube is properly placed in the stomach. If it is placed in the trachea by mistake, pneumothorax may occur or it may not be noticed. If liquid food is administered to the patient, death from suffocation and severe pneumonia will occur, causing serious medical errors.

  Conventionally, the confirmation method has been made by injecting about 10 ml of air from a placed tube with a syringe and listening to the sound of the bubbles. However, there are cases where it is uncertain only by listening to the bubble sound, and it is recommended by the medical safety information to make a reliable determination using a plurality of methods. Currently, another method of confirmation is to aspirate the tube and confirm that the suction contents are the contents of the stomach with a pH test paper, or take a chest X-ray to check that the tip is in the stomach. There is a way to check. However, none of the methods are sufficient, such as the indwelling site is appropriate, or the stomach contents cannot be pulled even if the tube is sucked, and there are many facilities that do not have an X-ray imaging apparatus. Even in hospitals that own X-ray imaging devices, there is a need for a simpler method that takes into account the problems of radiation exposure of patients and the trouble of moving the patient to the X-ray imaging room, taking images, interpreting them, and taking them home. ing. For example, in Patent Document 1, a transmission coil arranged in a cross shape is arranged outside the patient's body, and a rod-shaped detection coil is arranged inside the body together with the catheter. A technique for detecting the position and direction is disclosed.

JP 7-700979

  However, the technique of Patent Document 1 specifies the position of the catheter tip from the angle between the transmission coil and the detection coil, and does not specify the position of the catheter tip by plane coordinates.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a catheter detection device that can reliably detect the position of the distal end of the catheter by eliminating the detection coil located in the dead zone.

  In order to solve the above-described problem, a first technical means of the present invention is a catheter detection device including a detected portion disposed at a distal end of a catheter and a detecting portion that detects the position of the detected portion. The detected part is composed of a transmission coil that generates electromagnetic waves, and the detecting part is arranged on the orthogonal coordinate axes at symmetrical positions with respect to the intersection of the coordinate axes, and the respective coil axes coincide with the direction toward the intersection. Four first detection coils that are arranged on the coordinate axis at symmetrical positions with respect to the intersection of the coordinate axes, and each of the four second detection coils that coincides with a direction orthogonal to the direction toward the intersection. And a coil.

The second technical means further includes a substrate on which the detection unit is mounted, wherein the first detection coil is disposed on the front surface of the substrate, and the second detection coil is disposed on the back surface of the substrate. Is.
The third technical means further includes a substrate on which the detection unit is mounted, and the first detection coil and the second detection coil are respectively arranged on one side of the substrate.

  The fourth technical means further includes a display unit that displays a position of the detected unit based on a detection result of the detecting unit.

  According to the present invention, since the coil axis of the first detection coil and the coil axis of the second detection coil are arranged so as to intersect each other, even if the first detection coil is located in the dead zone, it belongs to the same set The second detection coil is not located in the dead zone. Therefore, the position of the catheter tip can be reliably detected.

It is an external appearance perspective view of the receiver of the catheter detection apparatus which concerns on this invention. (A) is a front view of the receiver of FIG. 1, (B) is a figure for demonstrating the display part of a receiver. (A) is a front view of a catheter, (B) is a figure for demonstrating the structure of a transmitter. It is a circuit block diagram applicable to the receiver of FIG. It is a figure for demonstrating generation | occurrence | production of a dead zone. It is a figure for demonstrating arrangement | positioning of the detection coil by 1st Example. It is a figure for demonstrating arrangement | positioning of the detection coil by 1st Example, and a transmission coil. It is a flowchart of position detection control by the receiver of FIG. It is a figure which shows the relationship between the calculation result of the calculating part of FIG. 4, and the position of a transmission coil. It is a figure for demonstrating the position display of the catheter front-end | tip by the display part of FIG. It is a figure for demonstrating arrangement | positioning of the detection coil by 2nd Example.

Hereinafter, the catheter detection device of the present invention will be described with reference to the drawings. FIG. 1 is an external perspective view of a receiver of a catheter detection device according to the present invention, FIG. 2 (A) is a front view of the receiver of FIG. 1, and FIG. 2 (B) is a description of a display unit of the receiver. FIG.
The catheter detection device 1 is an electromagnetic wave detection type position detection device having a receiver 20 and a transmitter to be described later. The position of the transmission coil is obtained from signals obtained by a plurality of detection coils, and the position of the catheter tip is determined. Can be detected.

As shown in FIG. 1, the receiver 20 includes a receiver body 21 having a rectangular parallelepiped shape that can be held by an operator with one hand. On the upper surface of the receiver main body 21, a display unit 40 that can display the position of the distal end of the catheter and a switch 50 that can be pushed down into the receiver main body 21 are provided.
If the switch 50 is depressed when the receiver 20 is turned off, the receiver 20 can be turned on. If the switch 50 is depressed for more than 1 second when the receiver 20 is turned on, the receiver 20 is turned off. Can be.

  As shown in FIG. 2A, in the display unit 40, for example, a resin panel is fitted into a window opened in a cross shape, and a plurality of LEDs, for example, are installed below the resin panel. Specifically, as shown in FIG. 2B, a mounting substrate 41 is provided on the lower side of the resin panel. For example, a total of 20 rectangular LEDs 42A to 42J, 43A to 43J are arranged to cross in a cross shape. The LEDs 42A to 42J are provided along the X-axis direction shown in FIG. 2B, and five LEDs 42A to 42J are arranged in each of the negative and positive directions of the X-axis with the origin LED 44 interposed therebetween. The LEDs 43A to 43J are provided along the Y-axis direction, and five LEDs 43A to 43J are arranged in each of the Y-axis negative direction and the positive direction across the origin LED 44.

  3A is a front view of the catheter, and FIG. 3B is a view for explaining the structure of the transmitter. The catheter 14 shown in FIG. 3A is formed with, for example, an outer diameter of about 2 to 4 mm and a length of about 150 cm, and is used for the digestive tract, for example. Further, for example, a through hole (not shown) is provided in the vicinity of the distal end of the catheter 14, for example, a depth scale (not shown) is attached to the side surface of the catheter 14 at intervals of 20 cm, for example, and a syringe ( An adapter 15 connected to (not shown) is provided.

  The catheter 14 can be used in combination with a guide wire (also referred to as a stylet) 16 to facilitate insertion into the patient, and the transmitter 10 utilizes the guide wire 16. Specifically, as shown in FIG. 3B, the transmitter 10 has an oscillation circuit 12 and a transmission coil 18, and the transmission coil 18 is placed at the distal end of the guide wire 16 so that it can be placed at the distal end of the catheter 14. It is installed and connected to the oscillation circuit 12 using a cord 17.

  The oscillation circuit 12 is installed in the transmitter main body 11 and can generate a square wave having a predetermined frequency (for example, 125 kHz). The oscillation circuit 12 and the transmission coil 18 are connected in series via the capacitor 13. The transmission coil 18 includes a shaft member and a conductor spirally wound around the shaft member, and the shaft member extends along a winding axis (also referred to as a coil shaft) of the conductor. The diameter of the transmission coil 18 is, for example, 1.2 mm, the length is 7 mm, and the inductance is 230 μH (1 kHz). In order to generate electromagnetic waves in the transmission coil 18, the capacitor 13 and the transmission coil 18 are set to constants that resonate at a predetermined frequency.

FIG. 4 is a circuit block diagram applicable to the receiver of FIG.
In addition to the display unit 40, the receiver 20 includes a detection circuit 22 and detection coils 23A to 23H. The detection coils 23 </ b> A to 23 </ b> H have the same performance and are connected to the detection circuit 22. The detection circuit 22 includes a multiplexer 26, an amplifier 27, an A / D converter 28, and a microcomputer 29. It is connected.

  For example, a total of eight detection coils 23A to 23H are formed. Each of the detection coils 23A to 23H includes a shaft member and a conductor wound spirally around the shaft member, and the shaft member extends along the coil axis. Each of the detection coils 23A to 23H has a diameter of, for example, 1.2 mm, a length of 7 mm, and an inductance of 230 μH (1 kHz). The detection coils 23A to 23H are connected in parallel to the capacitors 24A to 24H, respectively, so as to resonate at the drive frequency (for example, 125 kHz) of the transmission coil 18.

  When the transmission coil 18 approaches the detection coils 23A to 23H and the frequency of the electromagnetic wave emitted from the transmission coil 18 is the same as its own resonance frequency, the detection coils 23A to 23H resonate by electromagnetic induction to generate electromotive force. And a sine wave of a predetermined frequency is generated. If the direction of the transmission coil 18 with respect to the detection coils 23A to 23H is constant, the amplitude of the sine wave increases as the transmission coil 18 approaches the detection coils 23A to 23H. However, a dead zone occurs according to the position of the transmission coil and the detection coil.

  FIG. 5 is a diagram for explaining the generation of the dead zone. As shown in FIG. 5A, when the coil axis of the transmission coil 18 (indicated by a one-dot chain line in the figure) is orthogonal to the coil axis of the detection coil 23 at the center, or FIG. As shown in FIG. 2, when the coil axis of the detection coil 23 (indicated by the alternate long and short dash line in the figure) is orthogonal to the coil axis of the transmission coil 18 at the center, a dead zone is generated, and both the detection coil 23 and the detection coil 23 are detected. Even if the distance from the coil 23 changes, no electromotive force is generated in the detection coil 23.

  In order to avoid this dead zone, the detection coils 23A to 23H of the present invention are arranged on the orthogonal coordinate axes at symmetrical positions with respect to the intersection of the coordinate axes, and the four coil axes coincide with the direction toward the intersection. The first detection coils 23B, 23D, 23F, and 23H, and the four second detection coils 23A, 23C, 23E, and 23G each having a coil axis that coincides with a direction orthogonal to the direction toward the intersection. .

(First embodiment)
6A and 6B are diagrams for explaining the arrangement of the detection coils according to the first embodiment. FIG. 6A shows the surface of the mounting board, and FIG. 6B shows the back surface of the mounting board.
The total of eight detection coils 23A to 23H described with reference to FIG. 4 form a set of two for the positive direction or the negative direction on the same coordinate axis for detecting the transmission coil 18, and belong to the same set. For example, a circular detection range having a diameter of about 60 mm can be formed.

  More specifically, first, the first detection coil 23F and the second detection coil 23E form one set of the X-axis positive position shown in FIG. 6, and the X-axis negative position is the first detection coil 23B. And the second detection coil 23A form one set. On the other hand, the position in the positive direction of the Y axis shown in FIG. 6 is a set of the first detection coil 23H and the second detection coil 23G, and the position in the negative direction of the Y axis is the first detection coil 23D and the second detection coil 23C. It makes one set.

  Next, as shown by a solid line in FIG. 6A, the first detection coils 23B, 23D, 23F, and 23H are mounted on the surface 25a of the mounting substrate 25, and the coil axes of the first detection coils 23B and 23F are, for example, The coil axis of each of the first detection coils 23D and 23H extends along, for example, the Y axis. For this reason, the coil axes of the first detection coils 23B, 23D, 23F, and 23H are arranged in a cross shape so as to intersect at the origin of the XY coordinates. The mounting board 25 corresponds to the board of the present invention, and is provided, for example, below the mounting board 41 described with reference to FIG. 2B. The round origin LED 44 is set to the origin of the XY coordinates of the mounting board 25. Match.

On the other hand, as shown by a solid line in FIG. 6B, the second detection coils 23A, 23C, 23E, and 23G are mounted on the back surface 25b of the mounting board 25, and each of the second detection coils 23A, 23C, and 23E is mounted. , 23G are arranged in a cross shape so as to intersect at a position different from the origin of the XY coordinates.
In the example of the first detection coil 23F and the second detection coil 23E that detect the positive position of the X axis, the coil axes of the detection coils 23E and 23F belonging to the same set cross each other with the mounting substrate 25 interposed therebetween. ing. More specifically, the second detection coil 23E is disposed perpendicular to the X axis, and the first detection coil 23F is disposed horizontally relative to the X axis. Thereby, even if one detection coil is located in the dead zone with respect to the transmission coil, the other detection coil can be prevented from being located in the dead zone.

  FIG. 7 is a diagram for explaining the arrangement of detection coils and transmission coils according to the first embodiment. When the transmission coil 18 having a coil axis along the Y axis in FIG. 6 moves along the X axis direction orthogonal to the coil axis (also referred to as a lateral direction), the first detection arranged horizontally on the X axis The coils 23B and 23F include the position of the dead band, but the second detection coils 23A and 23E arranged perpendicular to the X axis do not become the position of the dead band. Therefore, the position in the X-axis direction with respect to the transmission coil 18 along the Y-axis is detected by the second detection coils 23A and 23E as shown in FIG.

  Similarly, when the transmission coil 18 having the coil axis along the X axis in FIG. 6 moves in the horizontal direction along the Y axis direction orthogonal to the coil axis, the first is arranged horizontally on the Y axis. Although the detection coils 23D and 23H have a dead band position, the second detection coils 23C and 23G arranged perpendicular to the Y axis do not have a dead band position. Therefore, the position in the Y-axis direction with respect to the transmission coil 18 along the X-axis is also detected by the second detection coils 23C and 23G, as shown in FIG.

  On the other hand, when the transmission coil 18 having the coil axis along the X axis in FIG. 6 moves along the X axis direction that coincides with the coil axis (also referred to as the vertical direction), the transmission coil 18 is arranged horizontally on the Y axis. Although the two detection coils 23A and 23E are located in the dead zone, the first detection coils 23B and 23F arranged perpendicular to the Y axis are not located in the dead zone. Therefore, the position in the X-axis direction with respect to the transmission coil 18 along the X-axis is detected by the first detection coils 23B and 23F, as shown in FIG. 7B.

  Similarly, when the transmission coil 18 having the coil axis along the Y axis in FIG. 6 moves along the Y axis direction that coincides with the coil axis in the vertical direction, the second coil is disposed horizontally on the X axis. Although the detection coils 23C and 23G are located in the dead zone, the first detection coils 23D and 23H arranged perpendicular to the X axis are not located in the dead zone. Therefore, the position of the Y axis with respect to the transmission coil 18 along the Y axis is also Similarly, as shown in FIG. 7B, detection is performed by the first detection coils 23D and 23H.

  As described above, since the coil axes of the first detection coils 23B, 23D, 23F, and 23H and the coil axes of the second detection coils 23A, 23C, 23E, and 23G are arranged to be orthogonal to each other, the position of the dead zone is ensured. The detection accuracy of the transmission coil can be further improved. In particular, in the structure in which the transmission coil and the detection coil extend in a rod shape, the dead zone elimination effect of the present invention is more beneficial.

  In the first embodiment, the coil axes of the first and second detection coils belonging to the same set intersect each other with the mounting board interposed therebetween. In other words, the first detection coil 23F and the second detection coil 23E that detect the position in the positive direction of the X axis will be described as an example. In the first embodiment, the first detection coil 23F is disposed on the surface 25a, for example. Since the two detection coils 23E are arranged separately on the back surface 25b, for example, the area of the mounting board can be reduced compared to the case where any of the detection coils is arranged on one side of the mounting board, and the catheter detection device can be downsized. Can do.

  Further, the first detection coil 23F and the second detection coil 23E belonging to the same set, and the first detection coil 23B and the second detection coil 23A belonging to the same set will be described as examples. In the first embodiment, the first detection coil 23F is used. And the center of the second detection coil 23E are made to coincide with each other, and the center of the first detection coil 23B and the center of the second detection coil 23A are made to coincide with each other. For this reason, the second detection coil 23E (first detection coil 23F) and the second detection coil 23A (first detection coil 23B) are arranged, for example, spaced apart from each other at symmetrical positions on the X axis. The distance between the center of the second detection coil 23E (first detection coil 23F) and the center of the second detection coil 23A (first detection coil 23B) is set to 50 mm, for example.

  In the first embodiment, the centers of the first detection coil 23H and the second detection coil 23G belonging to the same set coincide with each other, and the centers of the first detection coil 23D and the second detection coil 23C belonging to the same set are also one. In addition, the second detection coil 23G (first detection coil 23H) and the second detection coil 23C (first detection coil 23D) are, for example, arranged at a symmetrical position on the Y axis and separated from each other. The distance between the center of the second detection coil 23G (first detection coil 23H) and the center of the second detection coil 23C (first detection coil 23D) is also set to 50 mm. However, for example, the distance between the detection coils in the X axis direction and the distance between the detection coils in the Y axis direction so that the distance between the detection coils in the X axis direction is longer than the distance between the detection coils in the Y axis direction. May be set to different values.

  Here, the transmitting coil 18 moves along the direction in which the horizontal direction and the vertical direction are combined, or along the horizontal direction and the vertical direction, and for example, one of the transmitter coils 18 located on the same coordinate axis from the position of the origin. When approaching the first detection coil 23B and the second detection coil 23A (first detection coil 23D, second detection coil 23C), the first detection coil 23B and the second detection coil 23A (first detection coil 23D, second The output signal from the detection coil 23C) (the detection value is α) increases, and the output signals from the other first detection coil 23F and second detection coil 23E (first detection coil 23H, second detection coil 23G). (The detected value is β) becomes smaller.

  On the other hand, for example, when approaching the other first detection coil 23F and the second detection coil 23E (the first detection coil 23H and the second detection coil 23G) from the position of the origin, the other first detection coil 23F and the second detection coil are detected. The output signal β from the coil 23E (the first detection coil 23H and the second detection coil 23G) increases, and the first detection coil 23B and the second detection coil 23A (the first detection coil 23D and the second detection coil 23C). The output signal α from becomes smaller.

The detection signals α, β, etc. from the first and second detection coils 23A to 23H are selected by the multiplexer 26 shown in FIG. 4, amplified by the amplifier 27, and then digitally converted by the A / D converter 28, and the microcomputer. 29. The microcomputer 29 has a calculation unit 30 and an output unit 31.
The arithmetic unit 30 is configured to detect the same first and second values based on the difference signal between the two output signals obtained by the first and second detection coils, which are arranged on the same coordinate axis and whose coil axes are directed in the same direction. A sum signal of two output signals obtained by the coil is divided by a value obtained by raising the power to n (n> 1 real number). Note that n is determined by the characteristics of the transmission coil 18, the characteristics of the detection coils 23A to 23H, the ease of processing by the microcomputer 29, and the like.

More specifically, the detection signals α, β and the like from the first and second detection coils 23A to 23H are used, depending on a predetermined constant, for example, the structure and shape of the transmission coil 18 and the first and second detection coils 23A to 23H. If the constant to be set is k, the calculation unit 30 calculates as shown in Equation 1.
k (α−β) / (α + β) ⁿ Formula 1
The calculation result of the calculation unit 30 is input to the output unit 31, and the output unit 31 outputs the position of the transmission coil 18 to the display unit 40 from the value obtained by the calculation unit 30, for example.

FIG. 8 is a flowchart of position detection control by the receiver of FIG.
An operator inserts the guide wire 16 with the transmission coil 18 at the distal end into the catheter 14 and places the transmission coil 18 at the distal end of the catheter 14. Next, with the distal end of the catheter 14 as the head, the catheter 14 is inserted into the body from the patient's nasal cavity, for example, and is operated so as to go to a predetermined target position (for example, the stomach). If it is estimated that the distal end of the catheter 14 has reached a predetermined target position, the receiver 20 in the power-on state is disposed above the estimated position. When the transmission coil 18 located at the distal end of the catheter 14 approaches the first and second detection coils 23A to 23H, a sine wave having a predetermined frequency is generated in the first and second detection coils 23A to 23H.

  The microcomputer 29 outputs a setting signal for each detection coil to the multiplexer 26 (step S10). Specifically, first, the second detection coil 23A is selected in order to obtain the amplitude value of the sine wave generated in the second detection coil 23A. The signal input from the second detection coil 23A to the multiplexer 26 is amplified by the amplifier 27 and digitized by the A / D converter 28, and then input to the microcomputer 29. The amplitude value of the second detection coil 23A is A / D Calculation is performed using values sampled a plurality of times by the D converter 28 (steps S11 and S12).

At the time when the amplitude value of the second detection coil 23A is calculated, selection up to the first detection coil 23H has not been completed yet (NO in step S13). Therefore, in order to obtain the amplitude value of the sine wave generated in the first detection coil 23B, 1 is added to the counter and the process returns to step S10 (step S14).
The microcomputer 29 switches the second detection coil 23A to the first detection coil 23B and outputs it to the multiplexer 26 (step S10), and the amplitude value of the first detection coil 23B is calculated (steps S11 and S12). Thereafter, steps S10 to S14 are repeated until the amplitude value of the sine wave generated in the first detection coil 23H is calculated. The second detection coil 23A, the first detection coil 23B, the second detection coil 23C, the first detection coil 23D, the second detection coil 23E, the first detection coil 23F, the second detection coil 23G, and the first detection coil 23H. The amplitude values are A, B, C, D, E, F, G, and H, respectively.

  When the amplitude values A to H are obtained (YES in step S13), the calculation unit 30 calculates using the amplitude values B, D, F, and H related to the front surface 25a of the mounting board 25 and the amplitude value related to the back surface 25b. Calculations using A, C, E, and G are executed (step S15). Specifically, for example, in order to obtain the position of the transmission coil 18 on the X axis, the arithmetic unit 30 first calculates a sum signal (A + E) of two output signals obtained by the second detection coils 23A and 23E, and The sum signal (B + F) of the two output signals obtained by the first detection coils 23B and 23F is calculated.

  The microcomputer 29 determines whether the calculated sum signal (A + E) or sum signal (B + F) is below a predetermined threshold value, and if neither exceeds the predetermined threshold value (YES in step S16), the X axis is It is determined that there is no detection. On the other hand, when the predetermined threshold value is exceeded (NO in step S16), it is determined whether or not the sum signal (A + E) related to the back surface 25b is equal to or greater than the sum signal (B + F) related to the front surface 25a (step S17).

The calculation unit 30 employs the better condition for position detection, out of the sum signal (A + E) related to the back surface 25b or the sum signal (B + F) related to the front surface 25a. Specifically, when the sum signal (A + E) is equal to or greater than the sum signal (B + F) (YES in step S17), the process proceeds to step S18 and the values A and E on the back surface 25b are adopted. In this case, k = 900 and n = 1.5, and calculation is performed as shown in Equation 2.
900 × (A−E) / (A + E) ^1.5 (Formula 2)

On the other hand, when the sum signal (A + E) is not equal to or greater than the sum signal (B + F) (NO in step S17), the process proceeds to step S19 to adopt the values B and F of the surface 25a. In this case, k = 6000, n = 2, and calculation is performed as shown in Equation 3.
6000 × (B−F) / (B + F) ² Formula 3
The calculation result (position on the X axis) of the calculation unit 30 is held until it is displayed on the display unit 40, for example (step S20).

  Subsequently, since the calculation of the position of the transmission coil 18 on the Y axis has not been completed yet (NO in step S21), the process returns to step S15. The calculation unit 30 uses the sum signal (C + G) of the two output signals obtained by the second detection coils 23C and 23G and the sum signal (D + H) of the two output signals obtained by the first detection coils 23D and 23H. Calculate. If none of the predetermined threshold values is exceeded (YES in step S16), it is determined that the Y axis is not detected.

On the other hand, when the sum signal (C + G) related to the back surface 25b and the sum signal (D + H) related to the front surface 25a exceed a predetermined threshold (NO in step S16), whether the sum signal (C + G) is equal to or greater than the sum signal (D + H). Is determined (step S17).
When the sum signal (C + G) is equal to or greater than the sum signal (D + H) (YES in step S17), the arithmetic unit 30 proceeds to step S18 and adopts the values C and G of the back surface 25b. In this case, k = 900 and n = 1.5, and calculation is performed as shown in Equation 4.
900 × (CG) / (C + G) ^1.5 (Formula 4)

On the other hand, when the sum signal (C + G) is not equal to or greater than the sum signal (D + H) (NO in step S17), the process proceeds to step S19 to adopt the values D and H of the surface 25a. In this case, k = 6000, n = 2, and calculation is performed as shown in Equation 5.
6000 × (D−H) / (D + H) ² Formula 5
The calculation result (position on the Y axis) of the calculation unit 30 is held until it is displayed on the display unit 40, for example (step S20). Since the calculation in the two directions has been completed (YES in step S21), the display on the display unit 40 is updated (step S22).

FIG. 9 is a diagram showing the relationship between the calculation result of the calculation unit of FIG. 4 and the position of the transmission coil.
FIG. 9A shows the case where the transmission coil 18 is moved along the direction orthogonal to the coil axis (k = 900, n = 1.5). The position is obtained in increments of 1 mm. In FIG. 7A, CL = 90 mm is indicated by a circle, CL = 100 mm by a circle, CL = 110 mm by a square, CL = 120 mm by a square, CL = 130 mm by a circle, and CL = 130 mm by a circle. As for the calculation result, it was recognized that a straight line was drawn slightly in the range from −30 mm to +30 mm in the range from −30 mm to +30 mm, although it was slightly curved at +30 mm or more and −30 mm or less in any CL. Further, in the range from −10 mm to +10 mm, it was recognized that there was almost no difference between the CLs.

  FIG. 9B shows a case where the transmission coil is moved along a direction coinciding with the coil axis (k = 6000, n = 2), and the calculation result of the calculation unit 30 is incremented by 1 mm at the position of the transmission coil 18. Seeking in. When CL = 90 mm shown in FIG. 7B is indicated by a circle, CL = 100 mm by a circle, CL = 110 mm by a square, CL = 120 mm by a square, and CL = 130 mm by a circle, As for the calculation results, it was recognized that a curve was slightly drawn at +25 mm or more or −25 mm or less in any CL, but an almost straight line was recognized in the range from −25 mm to +25 mm. Further, in the range from −20 mm to +20 mm, it was recognized that there was almost no difference between the CLs.

Thus, since the calculation result of the calculation unit 30 changes linearly with respect to the position of the transmission coil 18, the position of the transmission coil 18 can be determined from the calculation result of the calculation unit 30. And the calculation result of this calculating part 30 can be utilized for the lighting position of LED42A-42J demonstrated by FIG. 2 (B), 43A-43J.
Specifically, when the calculation result of the calculation unit 30 is +5 or more, the LED 42J is lit in the X-axis direction and the LED 43J is lit in the Y-axis direction. When the calculation result is less than +5 but +4 or more, the LED 42I is lit in the X-axis direction and the LED 43I is lit in the Y-axis direction. When the calculation result is less than +4 but +3 or more, the LED 42H is lit in the X-axis direction and the LED 43H is lit in the Y-axis direction. When the calculation result is less than +3 but +2 or more, the LED 42G is lit in the X-axis direction and the LED 43G is lit in the Y-axis direction. When the calculation result is less than +2 but +1 or more, the LED 42F is lit in the X-axis direction and the LED 43F is lit in the Y-axis direction.

  Here, when the calculation result is less than +1 but is -1 or more, when only the X-axis direction falls within this range, for example, LEDs 42F and 42E positioned on both sides of the round origin LED 44 are turned on, When only the Y-axis direction falls within this range, the LEDs 43F and 43E located on both sides of the round origin LED 44 light up, and when both the X-axis direction and the Y-axis direction fall within this range, The origin LED 44 is lit.

  When the calculation result is less than −1 but is −2 or more, the LED 42E is lit in the X-axis direction and the LED 43E is lit in the Y-axis direction. When the calculation result is less than −2 but is −3 or more, the LED 42D is lit in the X-axis direction and the LED 43D is lit in the Y-axis direction. When the calculation result is less than −3 but is −4 or more, the LED 42C is lit in the X-axis direction and the LED 43C is lit in the Y-axis direction. When the calculation result is less than −4 but is −5 or more, the LED 42B is lit in the X-axis direction and the LED 43B is lit in the Y-axis direction. When the calculation result is less than −5, the LED 42A is lit in the X-axis direction and the LED 43A is lit in the Y-axis direction.

FIG. 10 is a view for explaining the display of the position of the catheter tip by the display unit of FIG.
When the receiver 20 is placed above the estimated position, the calculation unit 30 obtains the position of the transmission coil 18 from the amplitude values of the first and second detection coils 23A to 23H as described above, and the output unit 31 The position is output to the display unit 40.
For example, in the X-axis direction, the calculation result of the calculation unit 30 is less than +5 but +4 or more. In the Y-axis direction, the calculation result is less than +4 but +3 or more. As shown, the LED 42I is lit in the X-axis direction, and the LED 43H is lit in the Y-axis direction. Therefore, it can be easily understood that the tip of the current catheter 14 is near the intersection of the lit LED 42I and the LED 43H.

  Subsequently, when the receiver 20 is moved toward the intersection of the lit LED 42I and the LED 43H, in other words, obliquely upward to the right in FIG. 10A, each LED for the X coordinate and the Y coordinate. Are sequentially turned on so as to approach the intersection of the display unit 40. When the calculation results in both the X-axis direction and the Y-axis direction are less than +1 but exceed -1, the round origin LED 44 is turned on as shown in FIG.

In addition, even if it arrange | positions the receiver 20 above the estimated position, when it does not light on the display part 40, this receiver 20 is moved so that a circle may be drawn, for example. Thereafter, when the LED for the X coordinate and the LED for the Y coordinate are turned on, it is understood that the intersection is the current position of the distal end of the catheter.
After confirming that the distal end of the catheter 14 has reached a predetermined target position, the operator gently pulls out the transmission coil from the catheter 14 together with the guide wire 16.

  In the first embodiment, the first detection coils 23B, 23D, 23F, and 23H are disposed on the front surface 25a of the mounting board 25, and the second detection coils A, 23C, 23E, and 23G are disposed on the back surface 25b. . However, the first detection coils 23B, 23D, 23F, and 23H are arranged on the front surface 25a and the back surface 25b, for example, in two pieces, and the second detection coils 23A, 23C, 23E, and 23G are disposed on the front surface 25a and the back surface 25b. For example, it can be divided into two pieces.

(Second embodiment)
FIG. 11 is a diagram for explaining the arrangement of the detection coils according to the second embodiment.
In the first embodiment, a total of eight first and second detection coils 23A to 23H are mounted on the front surface 25a and the back surface 25b of the mounting board 25, respectively, but only mounted on the front surface 25a or the back surface 25b of the mounting board 25. You can also. Specifically, the X-axis positive position shown in FIG. 11 is a set of the first detection coil 23F and the second detection coil 23E, and the negative X-axis position is the first detection coil 23B and the second detection coil 23E. The detection coil 23A forms one set, the Y-axis positive direction position forms the first detection coil 23H, the second detection coil 23G forms one set, and the Y-axis negative direction position forms the first detection coil 23D, the second detection coil 23G. The detection coil 23C forms one set.

  The coil axes of the first detection coils 23B and 23F extend, for example, along the X axis, and the coil axes of the first detection coils 23D, 23H extend, for example, along the Y axis, and the first detection coils 23B, 23D. , 23F, and 23H are arranged in a cross shape so as to intersect at the origin of the XY coordinates. The coil axes of the second detection coils 23A, 23C, 23E, and 23G are arranged in a cross shape so as to intersect at a position different from the origin of the XY coordinates.

  However, the second detection coils 23A, 23C, 23E, and 23G are arranged, for example, outside the first detection coils 23B, 23D, 23F, and 23H, and detect the position of the X axis in the positive direction. In the example of the second detection coil 23E, the coil axes of the first detection coil 23F and the second detection coil 23E belonging to the same set intersect each other on, for example, the surface 25a of the mounting substrate 25. Thereby, even if one detection coil is located in the dead zone with respect to the transmission coil, the other detection coil can be prevented from being located in the dead zone. In this case, the length required in the thickness direction of the mounting substrate can be reduced as compared with the case where the mounting substrate 25 is divided into the front surface 25a and the back surface 25b, and the catheter detection device can be made thinner. .

  In each of the above embodiments, the transmitter and the receiver are separated from each other. However, the transmitter circuit of the transmitter is built in the receiver, and the transmitter coil is connected to the receiver via a cord. Good. In each embodiment, the example of the LED has been described, but the display unit may be formed of a liquid crystal panel.

DESCRIPTION OF SYMBOLS 1 ... Catheter detection apparatus, 10 ... Transmitter, 11 ... Transmitter main body, 12 ... Oscillator circuit, 13 ... Condenser, 14 ... Catheter, 15 ... Adapter, 16 ... Guide wire, 17 ... Cord, 18 ... Transmitting coil, 20 ... Receiver, 21 ... Receiver body, 22 ... Detection circuit, 23B, 23D, 23F, 23H ... First detection coil, 23A, 23C, 23E, 23G ... Second detection coil, 24A-24H ... Capacitor, 25 ... Mounting board 25a ... front surface, 25b ... back surface, 26 ... multiplexer, 27 ... amplifier, 28 ... A / D converter, 29 ... microcomputer, 30 ... arithmetic unit, 31 ... output unit, 40 ... display unit, 41 ... mounting board, 42A- 42J: LED in the X-axis direction, 43A to 43J ... LED in the Y-axis direction, 44 ... LED for origin, 50 ... switch.

In order to solve the above-described problem, a first technical means of the present invention is a catheter detection device including a detected portion disposed at a distal end of a catheter and a detecting portion that detects the position of the detected portion. The detected part is composed of a transmission coil that generates electromagnetic waves, and the detecting part is arranged on the orthogonal coordinate axes at symmetrical positions with respect to the intersection of the coordinate axes, and the respective coil axes coincide with the direction toward the intersection. Four first detection coils that are arranged on the coordinate axis at symmetrical positions with respect to the intersection of the coordinate axes, and each of the four second detection coils that coincides with a direction orthogonal to the direction toward the intersection. It has a coil, further comprising a cross-shaped display unit based on the detection result indicating the position of the detected portion of the detector, together with the match direction of the cross-shaped display unit to the coordinate axis In a state that the intersection point of the cross-shaped display unit fitted to the intersection of the axes is obtained by, characterized in that the display unit is arranged on the upper side of the first detection coil and the second detection coil.

According to a fourth technical means, a value based on a difference signal between two output signals obtained by two of the first detection coils arranged on the same coordinate axis among the four first detection coils, Divide the sum signal of the two output signals by the value raised to the nth power (where n> 1 is a real number) to obtain the position of the detected part, or arrange on the same coordinate axis among the four second detection coils The value based on the difference signal between the two output signals obtained by the two second detection coils is divided by the value obtained by multiplying the sum signal of the two output signals to the nth power (where n> 1 is a real number). Then, the position of the detected part is obtained.

Claims (4)

A catheter detection device comprising a detected part arranged at the tip of a catheter and a detecting part for detecting the position of the detected part,
The detected part consists of a transmission coil that generates electromagnetic waves,
The detectors are arranged on the orthogonal coordinate axes at symmetrical positions with respect to the intersection of the coordinate axes, each of the first detection coils having a coil axis that coincides with the direction toward the intersection, and the coordinate axis on the coordinate axis. A catheter detection device comprising four second detection coils that are arranged at symmetrical positions with respect to the intersection of coordinate axes, and each coil axis coincides with a direction orthogonal to a direction toward the intersection. A board on which the detection unit is mounted;
The catheter detection apparatus according to claim 1, wherein the first detection coil is disposed on a front surface of the substrate and the second detection coil is disposed on a rear surface of the substrate. A board on which the detection unit is mounted;
The catheter detection apparatus according to claim 1, wherein the first detection coil and the second detection coil are respectively disposed on one side of the substrate.   The catheter detection apparatus according to claim 1, further comprising a display unit that displays a position of the detected unit based on a detection result of the detection unit.

Images