JP2001208504A - Electrostatic capacity type distance sensor and obstacle detection system of medical diagnostic apparatus using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the reliability and safety of a function for automatically stopping the operation of the movable part of a medical diagnostic apparatus before the movable part comes into contact with an obstacle. SOLUTION: As a distance sensor for detecting the distance between the movable part of the medical diagnostic apparatus and an obstacle, an electrostatic capacity type distance sensor for emitting electromagnetic waves from a transmission electrode to form an electromagnetic field and detecting the intensity of the electromagnetic field by a receiving electrode is used. This sensor has such a structure that the transmission electrode and the receiving electrode are arranged in opposed relationship and a hollow part is provided in the receiving electrode and the electrostatic capacity type distance sensor having this structure is attached to the movable part of the medical diagnostic apparatus to detect the obstacle before the movable part comes into contact with the obstacle to stop the operation of the movable part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a capacitance type distance sensor and an obstacle detection system for a medical diagnostic apparatus using the same, and more particularly, to an electromagnetic field emitted to the outside to form an electromagnetic field. The present invention relates to a capacitance-type distance sensor that detects an obstacle by detecting an obstacle, and an obstacle detection system that stops the operation of the medical diagnostic apparatus based on a detection signal of the sensor.

[0002]

2. Description of the Related Art Medical X-ray fluoroscopic apparatuses such as X-ray fluoroscopic tables and circulatory organ X-ray examination apparatuses have become indispensable in the field of diagnosis. Is also being used. This treatment is performed by inserting a catheter with various instruments attached to the tip under fluoroscopy into the blood vessels and organs of the subject. In recent years, it has a great advantage in that pain given to a subject can be reduced and treatment can be performed at a low cost.

[0003] Such a treatment method is called IVR (Intervention).
al Radiology). In this IVR, it is desirable to be able to three-dimensionally grasp the position and shape of the treatment target site. Therefore, a three-dimensional image is taken by an X-ray tomography apparatus (hereinafter referred to as “X-ray CT apparatus”) to grasp the position and shape of the target part, and based on the three-dimensional image, an X-ray generation system is used. Circulatory organ X-ray inspection system with an X-ray detection system supported by a C-shaped arm (Document “Medical Dental Publishing Co., Ltd .: Medical Radiation Science Course 13, Radiation Diagnostic Equipment Engineering”, page 156, FIG.
7 ”) from various angles with respect to the subject.
The radiation is emitted, and the treatment is performed with reference to the obtained fluoroscopic image.

The above-mentioned circulatory organ X-ray inspection apparatus is capable of performing various rotation and movement operations such as rotation and slide movement of a C-shaped arm so that fluoroscopy and imaging can be performed from various directions. This gives a two-dimensional X-ray image,
Diagnosis and treatment are performed in combination with the X-ray CT apparatus. That is, prior to surgery, three-dimensional X-ray CT
The position and shape of the treatment target site are confirmed based on the X-ray image, and diagnosis is performed based on the position and shape obtained by the three-dimensional X-ray image and the two-dimensional X-ray image seen through the circulatory organ X-ray inspection apparatus , Do the treatment.

As described above, since the above-mentioned circulatory organ X-ray examination apparatus has been used not only for diagnosis but also for treatment, a C-shaped arm is made to follow a contrast medium flowing in a blood vessel in accordance with this. A need has arisen for X-ray fluoroscopy and imaging by moving the X-ray imaging system over a wide area at high speed. With the increase in the moving speed of the C-shaped arm, it is absolutely necessary to avoid contact of the C-shaped arm with a patient, an operator, an accessory, or the like (hereinafter referred to as an obstacle). That is, it is important to ensure safety. For this purpose, there is a method of stopping the rotation and movement of the C-shaped arm by detecting the contact with the C-shaped arm using a mechanical contact detector and detecting the obstacle by the mechanical contact detector. . However, according to this method, if the C-shaped arm is decelerated and then stopped after coming into contact with an obstacle, a long distance is required to safely decelerate and stop because the moving speed of the C-shaped arm is high. It becomes necessary and cannot meet the above demand for high speed. Thus, when the C-shaped arm approaches an obstacle and they are at a predetermined distance, that is, before contacting the obstacle, the C-arm is decelerated by using a non-contact obstacle detector that detects the obstacle. PCT /
Published in IB97 / 00402. This detector is called an electrostatic capacitance type distance sensor, and an image intensifier (hereinafter referred to as II) as an X-ray image receiving means in which a transmitting electrode and a receiving electrode are supported at one end of a C-shaped arm. ), A constant electromagnetic field is generated from the transmitting electrode, and if an obstacle enters the electromagnetic field, the capacitance between the transmitting electrode and the receiving electrode increases, and the intensity of the electromagnetic field decreases. The obstacle can be detected in a non-contact manner by detecting this with the receiving electrode.

As described above, I.I. I. A constant electromagnetic field is formed in the vicinity of the object, and by detecting the intensity of the electromagnetic field, the presence or absence of an obstacle such as a human body and the presence of an obstacle between the human body and the body. I. You can know the positional relationship with. From the above, as the non-contact type sensor used to detect the C-shaped arm before it comes into contact with the human body and stop the C-shaped arm at a distance that does not come into contact with the human body, the above-mentioned capacitance-type distance sensor is used. The sensor is effective, especially when detecting obstacles with a large dielectric constant existing in an electromagnetic field, and has the advantage that it is not affected by vinyl or cloth with a small dielectric constant. This is suitable for detecting an obstacle and stopping the operation of the medical diagnostic apparatus to improve safety.

[0007]

As described above, the capacitance type distance sensor detects the C-shaped arm before it contacts the obstacle, and detects the C-shaped arm at a distance that does not contact the obstacle. Although effective as a non-contact distance sensor for stopping the arm, the following points to be improved remain. (1) Since the transmission electrode and the reception electrode are horizontally arranged, the detection area of the sensor can be centered between the two electrodes, so that the change in the intensity of the electromagnetic field cannot be detected uniformly on the reception electrode side. . (2) If the moving speed of the C-shaped arm and the size of the obstacle to be detected are different, the detection sensitivity of the sensor is also different, and therefore, the accuracy of detecting the distance between the C-shaped arm and the obstacle is determined by the moving speed of the C-arm. And the size of the obstacle, and cannot stop the C-shaped arm at a predetermined position.

As described above, in the above-mentioned conventional capacitance type distance sensor, an error easily occurs in the distance detection accuracy between the C-shaped arm and the obstacle in terms of detection sensitivity, and the C-shaped arm contacts the obstacle. It has been desired to improve the safety of a system for detecting this before stopping the C-shaped arm. Therefore, an object of the present invention is to improve the reliability of a function of automatically stopping the operation of a movable part of a medical diagnostic device such as a C-shaped arm before the movable part comes into contact with an obstacle, thereby improving safety. It is an object of the present invention to provide a capacitance type distance sensor capable of improving the performance and an obstacle detection system of a medical diagnostic apparatus using the same.

[0009]

The above object is achieved by the following means. (1) An electromagnetic field is formed by radiating electromagnetic waves from the transmitting electrode,
In a capacitance-type distance sensor that detects the intensity of the electromagnetic field by a receiving electrode and detects the presence of an object around the receiving electrode, the transmitting electrode and the receiving electrode are arranged to face each other, and a hollow portion is formed in the receiving electrode. Is provided. In the capacitance type distance sensor having this configuration, the transmitting electrode and the receiving electrode are arranged to face each other, and the receiving electrode is provided with a hollow portion, so that the intensity of the electromagnetic field from the transmitting electrode blocked by the hollow portion is provided. Becomes uniform in the obstacle detection area. Therefore, the detection sensitivity of the receiving electrode is increased, and a uniform and stable output is obtained in the obstacle detection area.

(2) The capacitance type distance sensor of the above (1) is provided in a movable portion of a medical diagnostic apparatus, and when the movable portion is moved by the capacitance type distance sensor, obstacles around the movable portion are removed. Upon detection, the operation of the medical diagnostic apparatus is stopped.

If the obstacle detection system of the medical diagnostic apparatus is applied to a C-shaped arm of a circulatory organ X-ray inspection apparatus,
I. supported on the arm. I. The X-ray tube and the X-ray tube can be prevented from coming into contact with a patient, an operator or the like, and safety can be improved.

[0012]

FIG. 1 shows the configuration of a capacitance type distance sensor according to the present invention. In FIG. 1, reference numeral 1 denotes a transmitting electrode for generating an electromagnetic field in an area for detecting an obstacle, and 2 denotes a receiving electrode for detecting the intensity of the electromagnetic field when an obstacle exists in the electromagnetic field. Transmitting electrode 1 and receiving electrode 2 are circulatory organs X
I. as an X-ray image receiving means supported on a C-shaped arm of the X-ray inspection apparatus I. And the like, and is supported by a supporting means (not shown). An oscillating circuit 3 generates an AC voltage having a frequency of F and a voltage of V, amplifies the voltage to a predetermined voltage by an amplifier circuit 4, and applies the amplified voltage to the transmission electrode 1. A constant electromagnetic field is generated around 8. On the other hand, the receiving electrode 2 detects the intensity of the electromagnetic field formed by the transmitting electrode 1, that is, the electromagnetic wave having the frequency F by the resonance circuit 5, amplifies the detected voltage by the amplifier circuit 6, and outputs the amplified voltage 10 The output voltage 9 of the oscillating circuit 3 is compared with the output voltage of the comparing and amplifying circuit 7 to detect and amplify the difference between the amplitudes of the two signals. The receiving electrode 2 is provided with a hollow portion to increase the detection sensitivity (the reason why the detection sensitivity can be increased by providing the hollow portion will be described later).

In the obstacle detecting device having such a configuration, I.I. I. When there is no obstacle such as a human body around the uniform moving body, the output signal 9 of the oscillation circuit 3 and the reception electrode 2
Since the value of the signal 10 detected in the step (a) is equal,
The output of the detection signal 11 becomes 0, and no obstacle is detected. However, when a human body such as a patient or an operator approaches the moving body 8, when the human body is considered to be a dielectric and grounded, an electromagnetic field formed around the moving body is
Transmission electrode 1 and reception electrode 2 depending on the capacitance of the human body
And the electromagnetic field changes, causing a change in the electromagnetic field. The intensity of the electromagnetic field near the receiving electrode 1 decreases as the human body approaches the moving object, and the amplitude of the signal 10 detected by the receiving electrode 2 increases as the human body approaches the moving object 8. Become smaller. Since the output signal 9 of the oscillation circuit 3 is always constant, the detection signal 11 of the comparison amplifier circuit 7 increases as the signal 10 detected by the reception electrode 2 decreases. Therefore, it can be determined that the larger the detection signal 11 of the comparison amplification circuit 7 is, the closer the human body is to the moving body 8, and conversely, the smaller the detection signal 11 is,
It can be considered that there is a human body at a distance from the moving body. When the detection signal 11 is 0, it indicates that there is no obstacle such as a human body around the moving body 8. As described above, by forming a constant electromagnetic field around the moving body and detecting the intensity of the electromagnetic field, the presence or absence of an obstacle such as a human body and the positional relationship between the human body and the moving body 8 can be determined in a non-contact manner. Can be detected.

Next, it is more effective to arrange the transmitting electrode 1 and the receiving electrode 2 of the obstacle detecting system using the capacitance type distance sensor according to the above principle, as shown in FIG. A method of further increasing the detection sensitivity by using this arrangement method will be described with reference to FIGS.

In FIG. 2, (a) shows a case where a transmitting electrode Tx and a receiving electrode Rx are arranged horizontally, and (b) shows a transmitting electrode Tx.
This shows a case where x and the receiving electrode Rx are arranged to face each other. The transmission electrode has a vertical width of X cm and a horizontal width of Y cm.
And a copper plate having an area S ₀ (= X × Y) and a thickness of about several mm, and a receiving electrode having the same vertical width, horizontal width, area and thickness as the transmitting electrode.

An AC voltage V having a frequency F is applied to the transmission electrode, and a parallel resonance circuit including a coil having an inductance L and a capacitor having a capacitance C which resonates at the frequency F is connected to the reception electrode. One of the resonance circuits is grounded.

Here, the same vertical width as the transmitting electrode and the receiving electrode,
Copper plate with width, area and thickness to be detected (obstacle)
Regarding the detection characteristics with respect to the distance and arrangement between the detection target and the transmission electrode and the reception electrode, the resonance voltage (resonance at the frequency F) of the resonance circuit connected to the reception electrode is determined. 2A), and the measured values are measured in the case of a horizontal arrangement in which the transmission electrode and the reception electrode are arranged side by side as shown in FIG. 2A, and in the case where the transmission electrode and the reception electrode are vertically arranged as shown in FIG. Were compared with the case of the opposed arrangement arranged in FIG. Here, assuming that the distance between the transmitting electrode and the receiving electrode is d, the distance between the transmitting electrode and the copper plate to be detected is h, and the distance from the center of the transmitting electrode to the center of the copper plate to be detected is a, these d and h ,
Using a as a parameter, the resonance voltage V generated in the resonance circuit connected to the receiving electrode was measured. The detected resonance voltage is Vx, the resonance voltage in the horizontal arrangement is Vx, the resonance voltage in the opposed arrangement is Vy, and the resonance voltage when there is no detection object around the electrodes is Vox, Voy was used in the arrangement.

FIGS. 3A and 3B show, for each parameter, the detection characteristics in the case of horizontal arrangement and the case of opposite arrangement. However, FIGS. 3A and 3B show that the receiving electrode is provided with a hollow portion (the area of the hollow portion is ／ of the total area of the receiving electrode. This is hereinafter referred to as the standard area of the hollow portion). It is a characteristic of the case.

(A) Detection characteristics for distance a between transmission electrode and copper plate to be detected The distance d between the transmission electrode and the reception electrode is 10 mm, the distance h between the transmission electrode and the copper plate to be detected is 50 mm, and the transmission electrode is fixed. FIG. 3A shows the relationship between the distance a from the center of FIG. 1 to the center of the copper plate to be detected and the detection voltages (resonant voltages) Vx and Vy. In the case of the horizontal arrangement, the detection voltage Vx changes in inverse proportion to the square of the distance a, and the detection voltage Vx approaches Vox as the distance a increases. On the other hand, in the case of the opposed arrangement, the detection target is between the electrodes (0 <
When h <d), the detection voltage Vy changes depending on the distance a, and decreases as the distance from the receiving electrode decreases. When the detection target is above the receiving electrode (h> d), the detection voltage Vy does not change much depending on the distance a and takes a value close to Voy. Note that the detection voltage Vy is larger than the detection voltage Vx at the time of horizontal arrangement for the same detection target distance a, and Voy> Vox.

From these facts, comparing the horizontal arrangement and the opposed arrangement, when the object to be detected is between the opposed electrodes, the detected voltage is high, the rate of change of the detected voltage per unit distance is large, and the detection sensitivity is the highest. It turns out that it is high.

(B) Detection characteristics for distance L from the center of the receiving electrode to the center of the copper plate to be detected The distance d between the transmitting electrode and the receiving electrode is 10 mm, and the distance h between the transmitting electrode and the copper plate to be detected is 50 mm. FIG. 3B shows the relationship between the distance L from the center of the receiving electrode to the center of the copper plate to be detected and the detection voltages (resonant voltages) Vx and Vy. In the case of the horizontal arrangement, the detection voltage Vx decreases as the distance L increases, and the detection voltage Vx approaches Vox as the distance L increases. The detection voltage Vx is high when the detection target is between the transmission electrode and the reception electrode, and decreases as the detection target approaches the reception electrode. For this reason, the detection area in the case of the horizontal arrangement is formed around the center between the transmission electrode and the reception electrode. On the other hand, also in the case of the opposed arrangement, the detection voltage Vy decreases as the distance L increases, and the detection voltage Vy approaches Voy as the distance L increases. Also, comparing the case where the detection target is between the electrodes and the case where the detection target is outside the electrodes, the rate of change of the detection voltage Vy is larger when the detection target is outside the electrodes, and the slope of the detection characteristic is flat. There is a part and a part with inclination. Note that the detection region at the time of the opposed arrangement is formed symmetrically with respect to the transmission electrode. From the above, the detection area in the case of the horizontal arrangement is created centering between the transmission electrode and the reception electrode, and the detection area in the case of the opposed arrangement is created centering on the transmission electrode. It can be seen that the detection area is formed around the reception electrode, and uniform detection accuracy is obtained.

(C) Characteristics with respect to the area of the hollow portion of the receiving electrode From the characteristics shown in FIGS. 3 (a) and 3 (b), it can be said that the opposing arrangement is more advantageous. When the target is outside or between the electrodes, the detection sensitivity is low. The reason is that the receiving electrode is grounded through the resonance circuit, and the electromagnetic field formed by the transmitting electrode is blocked by the receiving electrode. Therefore, in order to improve this, as shown in FIG. 2 (c), by providing a hollow in the receiving electrode, the detection sensitivity can be increased even when there is a detection target outside between the electrodes. By doing so, the electromagnetic field formed by the transmission electrodes can be distributed outside the electrodes without being blocked by the reception electrodes, and the detection sensitivity can be improved outside the electrodes. Therefore, the distance (interval) between the transmission electrode and the reception electrode is fixed, and the distance L from the reception electrode to the detection target and the detection voltage Vy are set using the area S of the hollow portion provided in the reception electrode as a parameter.
FIG. 3 (c) shows the result of the measurement of the relationship. FIG.
From (c), by providing a hollow portion in the receiving electrode, the detection voltage Vy is higher than when no hollow portion is provided,
That is, it can be seen that the detection sensitivity can be greatly improved. In this case, it has been found that the detection sensitivity is highest when the area S of the hollow portion provided in the receiving electrode is set to around three-fourths of the area So without the hollow portion. When the distance d between the transmitting electrode and the receiving electrode is about 6 mm to about 20 mm,
Highest detection sensitivity.

From the above, by arranging the transmitting electrode and the receiving electrode to face each other and providing a hollow portion in the receiving electrode, the detection sensitivity is greatly improved as compared with the conventional case where the transmitting electrode and the receiving electrode are horizontally arranged. It can be seen that it improves.

The capacitance type distance sensor having the above structure is used as an I.D. I. The case where it is attached to the side surface of the device will be described. FIG. 4A is a mounting view in which electrodes are horizontally arranged (in the case of using a conventional capacitance type distance sensor), and FIG. 4B is a mounting view in which electrodes are opposed to each other (capacitance according to the present invention). (When a mold distance sensor is used).

In FIG. 4, in order to enable detection from any direction, I.D. I. , A plurality of receiving electrodes are arranged. Considering the mounting area, when the electrodes are arranged horizontally, the sum of the area of the transmitting electrode Sxa, the area of the receiving electrode Sxb, and the area between the electrodes Sxc is required. On the other hand, when the electrodes are arranged to face each other, the receiving electrodes are arranged above the transmitting electrodes. I. The area required for attachment to the side surface is only the area Sya of the transmission electrode. In addition, I. I. Is determined by the voltage V applied to the transmitting electrode and the area S thereof.

From these facts, if the transmission area is the same so that the same electromagnetic field range is generated between the horizontal arrangement and the opposite arrangement, the mounting area of the transmission electrode and the reception electrode is larger in the case of the opposite arrangement. There is an advantage that only a small number is required. This means that the capacitance type distance sensor according to the present invention can be attached to a small object to be detected. For example, even if the X-ray image receiving means is a small flat panel, the sensor according to the present invention can be used. Applicable.

As described above, by arranging the electrodes facing each other, not only the detection sensitivity can be improved, but also the mounting area can be reduced.

The above-mentioned I.V. with the capacitance type distance sensor shown in FIG. I. FIG. 5 shows an example of using a circulatory organ X-ray inspection apparatus in which is supported by a C-arm.

In FIG. 5, one end of a C-shaped arm 20 is provided with an electrostatic capacitance type distance sensor shown in FIG. I. 22 (including optics and television camera)
An X-ray tube 21 is attached to the other end of the C-shaped arm 20. The C-shaped arm 20 is supported by a support 25 via a holder 23 and a support post 24. The C-shaped arm 20 is configured to be rotatable and slidable by a known mechanism by a holder 23, and is configured to be able to change the height of the C-shaped arm 20 by a known mechanism by a column 24. The C-shaped arm 20 having such a configuration is rotated, the slide amount and the height are changed, and the patient is positioned at the fluoroscopy and imaging positions of the patient. The X-ray tube 21 irradiates X-rays, and the X-ray amount transmitted through the patient To I. I. 22 and this I.I.
I. The output X-ray image 22 is picked up by a television camera via an optical system, image-processed by an image processing device (not shown), and a fluoroscopic or photographed image is displayed on a monitor for inspection and diagnosis.
The capacitance type distance sensor according to the present invention includes the I.D.
I. 22, a transmitting electrode 1 and a receiving electrode 2 having a hollow portion are arranged to face each other as shown in FIG. I. (Details of the attachment are omitted). I. Detects this before the patient or the surgeon comes in contact with it, and sends this detection signal to a control device (not shown), and the control device allows the C-arm to rotate, slide, move up and down, etc. Is stopped to prevent a patient or an operator from coming into contact with the C-shaped arm. By using this capacitance type distance sensor for the C-shaped arm of the circulatory organ X-ray inspection apparatus, the sensitivity of detecting an obstacle is improved compared to the obstacle detection system using the conventional capacitance type distance sensor, In addition, since the detection area is widened, it is possible to detect obstacles with high sensitivity and high stability. Therefore, the safety of the circulatory organ X-ray inspection apparatus is improved.

It should be noted that the present invention can be applied to an X-ray diagnostic apparatus for use to prevent contact with a patient or an operator by rotating or moving in addition to the C-shaped arm of the circulatory organ X-ray inspection apparatus. Needless to say, the present invention can be applied to medical diagnostic devices other than the X-ray diagnostic device.

[0031]

As described above, according to the present invention,
In the obstacle detection system in which the movable part of the medical diagnostic apparatus detects the contact with the patient or the operator without contact when the movable part of the medical diagnostic apparatus is moved, and stops the operation of the movable part, the detection sensitivity of the obstacle is increased. In addition, since the obstacle detection area is widened, it is possible to stably detect the obstacle, thereby improving the safety of the medical diagnostic apparatus.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a capacitance type distance sensor of the present invention.

FIG. 2 is a diagram showing the arrangement and structure of a transmission electrode and a reception electrode.

FIG. 3 is a detection characteristic diagram of the capacitance type distance sensor based on the arrangement and structure of FIG. 2;

FIG. 4 is a diagram in which a capacitance type distance sensor according to the present invention is attached to an image intensifier.

FIG. 5 shows a capacitance type distance sensor according to the present invention,
The figure which shows the example used for the C-shaped arm of the line inspection apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 transmission electrode 2 reception electrode 3 oscillation circuit 4 amplification circuit 5 resonance circuit 6 amplification circuit 7 comparison amplification circuit 8 moving object 11 obstacle detection signal 20 C-shaped arm 21 X-ray tube 22 image intensifier (II)

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2F063 AA02 AA03 AA49 BA29 CA40 DA01 DB04 DB07 DD06 HA01 HA04 HA05 HA11 LA02 LA05 LA23 ZA01 4C093 AA05 CA33 CA35 DA02 EC16 EC57 FA45 FA59 FA60

Claims (2)

[Claims] 1. An electrostatic capacitance type distance sensor that emits an electromagnetic wave from a transmission electrode to form an electromagnetic field, detects the intensity of the electromagnetic field by a reception electrode, and detects the presence of an object around the reception electrode. A capacitance-type distance sensor, wherein the transmission electrode and the reception electrode are arranged to face each other, and a hollow portion is provided in the reception electrode. 2. The capacitance type distance sensor according to claim 1, which is provided on a movable part of a medical diagnostic apparatus, wherein an obstacle around the movable part is removed when the movable part is moved by the capacitance type distance sensor. An obstacle detection system for a medical diagnostic device, wherein the obstacle detection system stops the operation of the medical diagnostic device upon detection.