JPH0799033A - Image intensifier device - Google Patents

Abstract

PURPOSE:To give a function to reduce the misregistration of images in a digital subtruction angiography(DSA) examination, to an image intensifier (I. I.) device which has a function to cut off the earth magnetism automatically. CONSTITUTION:When a normal X-ray fluorescent image is obtained, a magnetic sensor 23 detects the earth magnetism input from an input surface substrate 21, and a feed current controller 24 controls a current fed to a correction coil 22 depending on the detecting result, so as to cut off automatically the earth magnetism input from the input surface substarte 21 by the magnetism generated by the correction coil 22. When a DSA examination is carried out, an external signal GS is given to a ratch circuit 25, and thereby, a current given to the correction coil 22 immediately before the external signal GS is input is operated to be given to the correction coil 22 constantly, in the ratch circuit 25. Since a mask image and a live image are photographed in the condition that the magnetic field from the correction coil 22 is constant, the misregistration of the images is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improved invention of an image intensifier device (hereinafter, also referred to as "II device") having a function of automatically shutting off magnetism coming from an input surface substrate. .

[0002]

2. Description of the Related Art As is well known, the I device is configured by accommodating an input surface substrate, an electronic lens system, an output fluorescent screen, etc. in a tube container. Such an I.D. I-devices are generally
In order to avoid the influence of the earth's magnetism, the circumference of the tube container is magnetically shielded by a ferromagnetic metal, but if such a magnetic shield is applied to the front surface of the input side substrate that takes in incident X-rays, it will serve as a magnetic shield. X-rays are absorbed by the metal of X, the X-ray dose incident on the input surface substrate becomes small, and the X finally obtained
Since the line-transmission image becomes unclear and is not preferable, it is necessary to form a window of aluminum or the like on the front surface of the input surface substrate.

Therefore, the photoelectrons emitted from the input surface substrate are distorted by the Lorentz force due to the influence of the geomagnetism entering from the input surface substrate through the window, and the visible light image output from the output fluorescent surface is distorted. Become.

In order to avoid such an inconvenience, an I.D. equipped with a magnetostriction correction mechanism for cutting off the influence of the geomagnetism coming from the input surface substrate. There is also an I device. This magnetostriction correction mechanism is provided with a correction coil on the outer periphery of the input surface substrate, and applies a predetermined current to the correction coil to cancel the geomagnetism coming from the input surface substrate. The current applied to the correction coil has conventionally been configured to be manually adjusted by the operator.

However, there is a problem in that it is difficult to manually adjust the current applied to the correction coil so that the correction coil generates a magnetic field that cancels the geomagnetism coming from the input surface substrate. In addition, the I.D. By changing the direction of the I.I. I
Since the geomagnetism coming in from the input side substrate of the device changes, I. There was also a problem that the current applied to the correction coil had to be manually adjusted every time the direction of the I device was changed, which was troublesome.

Therefore, the inventor of the present invention made an invention in order to solve the above-mentioned problems.
We filed an application (title of invention: image intensifier device) on the 30th of March. In this device, a magnetic sensor is arranged in the vicinity of the input surface substrate, the magnetic sensor detects the geomagnetism coming from the input surface substrate, and based on the detection result, the magnetic field that cancels the geomagnetism coming from the input surface substrate. Is generated from the correction coil, the current applied to the correction coil is automatically adjusted. According to this device, the difficult operation of adjusting the current applied to the correction coil can be automatically performed, and the I.D. I
Even if the direction of the device is changed, the magnetic sensor detects the geomagnetism entering from the input side substrate in that state and automatically shuts off the geomagnetism. It is no longer necessary to manually adjust the current applied to the correction coil each time the orientation of the I-device is changed.

[0007]

This device is designed for use with a conventional X
There is no particular problem in obtaining a fluoroscopic image, but for example, D
The SA (digital subtraction angiography) inspection has the following problems. DSA
In the examination, first, a mask image of the subject is photographed, then a contrast agent is administered to the subject, and images (live images) before and after the contrast agent reaches the arterial blood vessels are photographed. Then, the mask image is subtracted from the live image (subtraction processing) to remove images of bones and the like that are common to the images, and an arterial blood vessel image (subtraction processing image) is obtained. For example, if the shooting conditions when shooting a mask image and the shooting conditions when shooting a live image are different, images such as bones that are common to each other are misaligned (misregistration has occurred. As a result of the subtraction processing, the subtraction-processed image becomes unclear. Therefore, D
In the SA inspection, it is necessary to make the shooting conditions the same when shooting the mask image and the live image.

However, in the above-mentioned apparatus, for example, when a mask image is photographed, a doctor holds an I.D. while holding a magnetic pen or the like. When the I-apparatus is approached and the pen is brought close to the magnetic sensor, the magnetic sensor detects magnetism other than the earth magnetism, and an extra magnetic field is generated from the correction coil. As a result, the mask image becomes distorted. On the other hand, when capturing a live image, misregistration occurs between the obtained live image and the mask image obtained in the above state unless magnetism other than the geomagnetism is detected by the magnetic sensor as described above. become. In this way, it is necessary to make the shooting conditions the same when shooting the mask image and the live image.
In AS inspection, when taking a mask image and a live image,
If the magnetism detected by the magnetic sensor is different, there is a problem that misregistration occurs in each obtained image.

The present invention has been made in view of the above circumstances, and when obtaining a normal X-ray fluoroscopic image, the geomagnetism is automatically cut off, and a plurality of terrestrial magnetisms are detected. An object of the present invention is to provide an image intensifier device capable of reducing misregistration of each image when the images need to be taken under the same conditions.

[0010]

The present invention has the following constitution in order to achieve such an object. That is, according to the present invention, the correction coil wound around the outer peripheral space of the input surface substrate for capturing the X-rays transmitted through the subject, the magnetic sensor arranged in the vicinity of the input surface substrate, and the detection by the magnetic sensor A magnetic field for canceling the generated magnetism, and a supply current control means for controlling a current to be generated in the correction coil so as to be supplied to the correction coil. An image intensifier device configured to cut off is provided with a supply current hold mechanism that holds a current currently applied to the correction coil based on applying a predetermined external signal.

[0011]

The operation of the present invention is as follows. Normal X
When obtaining a radiographic image, the magnetic sensor detects the geomagnetism coming in from the input surface substrate, and the supply current control means controls the current supplied to the correction coil based on the detection result, so that the correction coil The magnetic field generated from the device automatically shuts off the geomagnetism coming from the input surface substrate.

Further, for example, during the DSA inspection, the supply current hold mechanism is operated by a predetermined external signal (for example, DSA).
The current currently given to the correction coil is held by the switch signal to the inspection). The current held is I.V. Since the geomagnetism is cut off in the direction in which the I-device is facing, the mask image and the live image to be photographed are hardly affected by the geomagnetism.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a magnetostriction correction mechanism portion provided in an image intensifier device according to a first embodiment of the present invention. FIG. 1 (a) is a longitudinal sectional view thereof, and FIG. b) is a view of the input surface substrate as viewed from the X-ray incident direction. Further, FIG. 2 shows an X equipped with the first embodiment device.
It is a figure which shows schematic structure of the whole fluoroscopic apparatus. In this embodiment and each of the following embodiments, an X-ray fluoroscope having a function of performing a DSA examination will be described as an example.

As shown in FIG. 2, each end of the C-shaped arm 1 attached to the base B fixed to the floor has an I.D. I
The device 2 and the X-ray tube 3 are attached so as to face each other with the subject M interposed therebetween. The C-arm 1 is configured to be rotated by the device driving unit 4 in the body axis J direction of the subject M, around the body axis J, and around an axis orthogonal to the body axis J. The device drive unit 4 is connected to the operation panel 5, and when the operator gives an instruction from the operation panel 5, the C-shaped arm 1 is operated via the device drive unit 4, and the I.V. The directions of the I-device 2 and the X-ray tube 3 are changed so that X-ray fluoroscopy can be performed from a desired direction.

I. The visible light image output from the I device 2 is
After being converted into an electric signal by the visible light / electrical signal conversion mechanism 6, the electric signal is given to the CCU (camera control unit) 8 or the DSA image processing unit 9 via the switch 7. When a normal fluoroscopic image is obtained, the electric signal is CC
After being given directly to U8 and converted into a video signal by CCU8, an X-ray fluoroscopic image is displayed on the monitor 10. Also, D
In the case of SA inspection, the electric signal is given to the DSA image processing unit 9. The DSA image processing unit 9 converts the given electric signal (analog signal) into a digital signal, stores the data when the mask image is photographed, and when the live image is input, performs the subtraction process, The processing result is converted into an electric signal (analog signal) and given to the CCU 8 to display the subtraction processed image on the monitor 10.

The selection switch 1 provided on the operation panel 5 is used to switch between the normal X-ray fluoroscopic image acquisition and the DSA inspection.
1 can be performed, and depending on the selected state,
The switch 7 is switched. When the DSA inspection is selected, the state is the external signal GS,
I. The I-device 2 is configured to be applied to a latch circuit provided in a later-described magnetostriction correction mechanism.

I. The magnetostriction correction mechanism of the I. device is, as shown in FIG. The correction coil 22 wound around the outer peripheral space of the input surface substrate 21 of the I-device 2, the magnetic sensor 23 arranged in the vicinity of the correction coil 22, and the magnetism detected by the magnetic sensor 23 A magnetic field that cancels the geomagnetism coming from the substrate 21 is applied to the correction coil 2
2, a supply current control unit 24 that controls the correction coil 22 to supply a current such as that generated by the power source (not shown), and an external signal GS supplied from the operation panel 5.
The latch circuit 25 for holding the current applied from the supply current controller 24 to the correction coil 22 based on the above. The power supply and the supply current control section 24 correspond to the supply current control means in this invention. Reference numeral 26 in the drawing is an amplifier that amplifies the output signal from the magnetic sensor 23.

The amplifier 26 is configured so that the gain (sensitivity) GN of the magnetic sensor 23 and the offset OF can be set. The amplifier 26 amplifies the signal (electric signal corresponding to the detected magnetism) given from the magnetic sensor 23 according to the set gain GN, and subtracts the set offset OF from the result,
The result is supplied to the supply current controller 24.

The offset OF is for correcting an error between the magnetism detected by the magnetic sensor 23 and the geomagnetism entering from the input surface substrate 21. That is, the geomagnetism coming from the input surface substrate 21 is detected by the magnetic sensor 23.
In order to detect it most accurately, it is preferable to dispose the magnetic sensor 23 in front of the center NO of the input surface substrate 21.
When the magnetic sensor 23 is arranged on the front surface of the input surface substrate 21 in this way, a part of the X-rays incident from the input surface substrate 21 is
This is not preferable because the shadow of the magnetic sensor 23 is absorbed in the X-ray fluoroscopic image displayed on the monitor 10 after being absorbed by the magnetic sensor 23.

Therefore, in this embodiment, the magnetic sensor 23
At a position near the input surface substrate 21, that is, the input surface substrate 2
1. At any position in or near the input surface substrate region NR formed between the vertical planes sandwiching 1 and at any position in or near the gap region KR between the input surface substrate 21 and the correction coil 22. That is, the two regions NR and KR are arranged at an arbitrary position in or near the donut-shaped region WR where they overlap. Note that the incident surface substrate region NR is a region formed between two vertical planes sandwiching the input surface substrate 21 when the input surface substrate 21 is virtually provided with a vertical plane. 1 (a) is a region between a vertical plane TP1 contacting the center NO of the input surface substrate 21 and a vertical plane TP2 contacting the outer peripheral edge NG of the input surface substrate 21. Also,
The correction coil 22 is arranged at an arbitrary position in or near the input surface substrate region NR.

By arranging the magnetic sensor 23 in the above position, the geomagnetism coming from the input surface substrate 21 can be detected with a certain degree of accuracy.
In some cases, the geomagnetism entering from the input surface substrate 21 may not be accurately detected, as compared with the case where is placed in front of the center NO of the input surface substrate 21. For example, as shown in FIG. The ferromagnetic metal MM used to magnetically shield the periphery of the I-device 2 is located near the magnetic sensor 23, and therefore, due to the influence of the metal MM, the geomagnetic IB near the magnetic sensor 23. Disturbance, magnetic sensor 2
In some cases, the magnetism detected in 3 does not match the geomagnetism that enters from the input surface substrate 21.

For example, an electric signal corresponding to the magnitude of the geomagnetism that actually comes in from the input surface substrate 1 (for example, the magnetic sensor 23 is arranged in front of the center NO of the input surface substrate 21 and the geomagnetism at the time of detection is detected). Electric signal for size)
However, even though it is “+ 1v”, the magnetic sensor 23
There is a case where the electric signal with respect to the magnitude of magnetism when detected by the magnetic sensor 23 when arranged as shown in FIG. 1 becomes “+ 2v”. The supply current control unit 24 is configured to control so as to supply to the correction coil 22 a current that causes the correction coil 22 to generate a magnetic field that makes the applied electric signal “0v”. In the control method, when the actual geomagnetism as described above and the magnetism detected by the magnetic sensor 23 do not match, the supply current control unit 2
When an electric signal (“+ 2v”) corresponding to the magnitude of the magnetism detected by the magnetic sensor 23 is directly applied to 4, the supply current control unit 24 causes the correction coil 22 to generate a magnetic field corresponding to “−2v”. As a result, the input surface substrate 1 has “−1v” (actual geomagnetism (magnetism corresponding to “+ 1v”) + magnetic field generated by the correction coil 22 (“−v”).
The magnetic field corresponding to the magnetic field corresponding to 2v ”)) remains, which is not preferable.

Therefore, in such a case, the error component is measured in advance, and the error component is set as the offset OF (“+ 1v” in the above case) in the amplifier 26, and the magnetic sensor 23 is used. By supplying the result of subtracting the offset OF from the electric signal corresponding to the detected magnetism to the supply current control unit 24, the error between the actual geomagnetism and the magnetism detected by the magnetic sensor 23 is corrected. That is, in the case as described above, the supply current control unit 24 displays “+
Since “1v” is given, the supply current control unit 24 controls the correction coil 22 to generate a magnetic field corresponding to “−1v”. As a result, the actual geomagnetism that comes in from the input surface substrate 21 is canceled, but the magnetic sensor 23 still reads “+ 1v” (the magnetism originally detected by the magnetic sensor 23 (magnetism corresponding to “+ 2v”) + correction). Magnetic field generated from the coil (magnetic field equivalent to "-1v")
Will be output. However, in the amplifier 26, the offset OF is subtracted from the output signal of the magnetic sensor 23, so that “0v” is given to the supply current control unit 24, and the supply current control unit 24 maintains the state. Will be controlled. If there is no error between the actual geomagnetism and the magnetism detected by the magnetic sensor 23, “0v” may be set as the offset.
In the above example, although the gain GN is not mentioned, when the gain GN is set, the result of amplifying the electric signal corresponding to the magnitude of the geomagnetism detected by the magnetic sensor 23 according to the GENI GN. From this, the result of amplifying the set offset OF according to the gain GN is subtracted.

The latch circuit 25 performs an operation of giving a current supplied from the supply current control section 24 to the correction coil 22 and an operation of holding the current supplied from the supply current control section 24 and supplying the current to the correction coil 22. External signal GS
Is configured to switch. That is,
The latch circuit 25 supplies the current supplied from the supply current control unit 24 to the correction coil 22 and holds the current when the external signal GS is not input (for example, “0v” is input). However, the current to be held is updated each time the current is supplied from the supply current control unit 24, and when the external signal GS is input (for example,
When "+ 5v" is input), instead of giving the current given from the supply current control unit 24 to the correction coil 22, the held current is given to the correction coil 22. At this time, the held current is given. Is configured not to be updated. The latch circuit 25 corresponds to the supply current hold mechanism in this invention.

Next, the operation of the apparatus having the above-described structure will be described separately for the case of obtaining a normal X-ray image and the case of the DSA inspection. First, the operation of the apparatus of the embodiment when obtaining a normal X-ray fluoroscopic image will be described. When obtaining a normal X-ray fluoroscopic image, the operator selects the selection switch 11 on the operation panel 5.
To select a normal X-ray fluoroscopic image. As a result, the external signal GS does not enter the latch circuit 25, and the output signal from the visible light image / electrical signal conversion mechanism 6 is input to the CCU 8 so that the monitor 10 displays the X-ray fluoroscopic image. The switch 7 is switched. Next, the operator An instruction is given from the operation panel 5 to set the I-device 2 and the X-ray tube 3 in desired directions.

I. When the I-device 2 and the X-ray tube 3 are oriented in a desired direction, an X-ray fluoroscopic image is taken. The effect of geomagnetism in the direction of the I-device 2 is automatically cut off.

That is, an electric signal corresponding to the magnetism detected by the magnetic sensor 23 is given to the supply current control section 24 via the amplifier 26. The supply current controller 24 outputs to the latch circuit 25 a current for causing the correction coil 22 to generate a magnetic field that makes the applied electric signal “0v”. Since the external signal GS is not input to the latch circuit 25, the current supplied from the supply current control unit 24 is directly supplied to the correction coil 22 and the current held therein is updated. Thereby, from the correction coil 22,
A magnetic field that cancels the geomagnetism coming from the input surface substrate 21 is generated.

Further, in order to obtain an X-ray fluoroscopic image from another direction, the operator gives an instruction from the operation panel 5, and the I.D. I device 2, X
Even when the wire tube 3 is oriented in another direction, the I.D. The influence of the geomagnetism in the direction of the I. device 2 is automatically cut off in the same manner as described above, and the current held in the latch circuit 25 is I.V. The current for canceling the geomagnetism is held in the direction in which the I-device 2 is facing.

That is, the I.D. I device 2
In the direction in which the current is directed, the geomagnetism entering from the input surface substrate 21 is always automatically shut off, and the current held in the latch circuit 25 is the current I.V. I device 2
The current for canceling the earth's magnetism is always held in the direction in which

Next, the operation of the embodiment apparatus in the case of the DSA inspection will be described. The DSA test is based on I.S. I device 2, X-ray tube 3
A fixed image to capture a mask image and a live image;
There is a method of taking a mask image and a live image while rotating the I-device 2 and the X-ray tube 3.

First, I. A method of capturing the mask image and the live image with the I apparatus 2 and the X-ray tube 3 fixed will be described.
In this case, the operator must perform the I.D. operation before switching the selection switch 11 of the operation panel 5 to the DSA inspection. I device 2, X-ray tube 3
Is instructed from the operation panel 5 to set the direction for DSA inspection. I. When the I apparatus 2 and the X-ray tube 3 are oriented in the direction of the DSA inspection, the I.I. In the direction of the I device 2, the geomagnetism entering from the input surface substrate 21 is automatically cut off, and the current applied to the correction coil 22 at that time is held. This is because the changeover switch 11 has not been switched to the DSA inspection yet, so that the external signal GS is not input to the latch circuit 25.

Next, the operator switches the selection switch 11 to the DSA.
Switch to inspection. As a result, the latch circuit 25 supplies the current held therein to the correction coil 22. In the direction in which the I-device 2 is currently facing, the correction coil 22 generates a magnetic field that cancels the geomagnetism coming from the input surface substrate 21. Further, the output signal from the visible light image / electrical signal conversion mechanism 6 is input to the DSA image processing unit 9, and the monitor 1
The switch 7 is switched so that the subtraction processing image is displayed at 0.

In this state, the operator first photographs the mask image and then the live image. When the mask image and the live image are photographed, the geomagnetism coming from the input surface substrate 21 is blocked, so that the mask image and the live image that are not affected by the geomagnetism can be obtained. The current supplied from the latch circuit 25 to the correction coil 22 is always irrespective of the current supplied from the supply current control unit 24, in other words, regardless of the change in magnetism detected by the magnetic sensor 23. Since it is constant, when the magnetism other than the earth magnetism is detected by the magnetic sensor 23 when capturing either the mask image or the live image, for example, a magnetic pen held by the doctor is brought close to the magnetic sensor 23. In this case, the magnetic field generated by the correction coil 22 is always constant, and one image is not distorted.

It should be noted that the I.D. I
When a DSA inspection is performed using the apparatus, both the mask image and the live image are affected by the geomagnetism, and the I.V. equipped with a magnetostriction correction mechanism that manually adjusts the current applied to the correction coil. If the DSA inspection is performed by the I apparatus, there remains a problem that a troublesome adjustment must be performed to eliminate the influence of the earth magnetism. On the other hand, in this embodiment, it is possible to automatically block the influence of the geomagnetism and obtain a mask image and a live image without distortion due to the geomagnetism.

Furthermore, in the conventional apparatus which automatically cuts off the earth's magnetism, in other words, changes the magnetic field from the correction coil in response to the detection data of the magnetic sensor in real time, when capturing either a mask image or a live image. In addition, when the magnetic sensor 23 detects a slight magnetism other than the earth magnetism,
As a result of the magnetic sensor 23 reacting to generate an extra magnetic field from the correction coil 22, the mask image and the live image have different imaging conditions, and misregistration occurs in each obtained image. On the other hand, in this embodiment, even if magnetism other than the geomagnetism is detected by the magnetic sensor 23, the mask image and the live image are photographed under almost the same conditions (the same magnetic field is generated from the correction coil 22). can do. It should be noted that, for example, since a magnetic pen held by the doctor is brought close to the magnetic sensor 23, a slight amount of magnetism enters from the input surface substrate 21, which causes image distortion. Absent. On the other hand, image distortion caused by an extra magnetic field generated from the correction coil 22 due to a slight amount of magnetism being brought close to the magnetic sensor 23 can be ignored in reducing misregistration of each image. Not a thing.

By the way, as shown in FIG. 4, a drive control section 12 is provided in the X-ray fluoroscope provided with this embodiment,
The operation procedure described above may be automatically performed by the drive control unit 12. In addition, in FIG. 4, the C-arm and the X-ray tube are not shown.

That is, the operator selects the changeover switch 1
1 is switched to the DSA inspection and the DSA inspection is performed. By instructing the directions of the I-device 2 and the X-ray tube 3 from the operation panel 5, the information is given to the drive control unit 12. In the drive controller 12, first, the I.D. The device drive unit 4 is controlled to adjust the directions of the I-device 2 and the X-ray tube 3.
And I. I device 2 and X-ray tube 3 are set in the set direction (D
The drive control unit 1 is turned toward the SA inspection direction).
The external signal GS is applied from 2 to the latch circuit 25. In addition,
I. When the I-device 2 and the X-ray tube 3 are oriented in the set direction, the geomagnetism coming in from the input surface substrate 21 is automatically cut off in that direction, at which time the correction coil 2
The current given to 2 is held by the latch circuit 25. Then, the mask image and the live image are captured in order.

Next, I. A method of photographing the mask image and the live image while rotating the I-device 2 and the X-ray tube 3 will be described. Also in this case, the operator should perform the I.D. operation before switching the selection switch 11 of the operation panel 5 to the DSA inspection. I device 2, X
An instruction is given from the operation panel 5 to set the wire tube 3 in a predetermined direction.

I. The predetermined direction in which the I-device 2 and the X-ray tube 3 are directed is, for example, I.I. It is an intermediate position between the start point and the end point for rotating the I-device 2 and the X-ray tube 3. For example, as shown in FIG. I device 2 from the point a (start point) of 0 ° to the X axis to the point b (end point) of 90 ° to the X axis,
In the case where the mask image and the live image are photographed by rotating 90 °, 4 with respect to the X axis which is an intermediate position between the points a and b.
I.I. The I-device 2 is moved.

Then, I. When the I-device 2 is set to the point c, the geomagnetism coming in from the input surface substrate 21 is automatically cut off, and the current given to the correction coil 22 at that time is held in the latch circuit 25.

Next, the operator sets the selection switch 11 to DS
Switch to A inspection. As a result, the latch circuit 25 supplies the current held therein to the correction coil 22. Further, the switch 7 is switched so that the subtraction processing image is displayed on the monitor 10.

Then, the operator The operation panel 5 is instructed to move the I device 2 to the point a, and the I.I. When the I device 2 is moved to the point a, the I.I. The mask image is photographed while rotating the I device 2 to the point b. Next, I.
The I-device 2 is moved to the point a again, and the I.I. A live image is taken while rotating the I-device 2 from point a to point b.

At this time, I.D. The I-device 2 is affected by the geomagnetism except when it is located at the point c, but the effect is suppressed to be small. That is, in FIG. The electric signal corresponding to the geomagnetism coming from the input surface substrate 21, that is, the magnetism detected by the magnetic sensor 23 when the I device 2 is positioned is “−1.5 v”, and the I.V. If the electric signal corresponding to the magnetism detected by the magnetic sensor 23 is “−0.5 v” when the I device 2 is located, the I.V.
The electric signal corresponding to the magnetism detected by the magnetic sensor 23 when the I-device 2 is located is “−1.0 v” because it is between the points a and b. At the point c, in order to block the geomagnetism, the correction coil 22 outputs “+1”.
A magnetic field corresponding to "v" is generated, and the state is maintained during DSA imaging.

Therefore, the I.D. When the I device 2 is at the point a, the magnetic field (“+1
corresponding to “v”), the geomagnetism coming from the input side substrate 21 is “−0.5v” (−1.5 + (+ 1.
0)). Device I is from point a to c
As approaching the point, the geomagnetism entering from the input side substrate 21 decreases. In addition, I. When the I device 2 is at the point b, the magnetic field generated from the correction coil 22 causes the geomagnetism coming from the input surface substrate 21 to correspond to “+0.5 v”. I device is b
As the point approaches the point c, the geomagnetism entering from the input surface substrate 21 decreases.

That is, at the start point and the end point, the geomagnetism entering from the input surface substrate 21 has the original width of each magnetic field entering from the input surface substrate 21 at the start point and the end point (in the above case, , ("1.5
"1 / 2v" which is an absolute value of "v"-"0.5v": this is BH), that is, "+ 1 / 2BH"
And “−1 / 2BH” (in the above case, “+ 1/2 × 1”
v = + 0.5v ”and“ −1 / 2 × 1v = −0.5v ”)
It is possible to suppress the influence of the geomagnetism at the start point and the end where the influence of the geomagnetism is maximized.

Further, since the influence of the geomagnetism as described above is the same when the mask image and the live image are taken, the misregistration of each image can be reduced.

It should be noted that the I.D. I
If a DSA inspection is performed by the apparatus, both the mask image and the live image will be greatly affected by the geomagnetism, and the I.V. equipped with a magnetostriction correction mechanism that manually adjusts the current applied to the correction coil. If the DSA inspection is performed by the I-device, it is necessary to make a troublesome adjustment to eliminate the influence of the geomagnetism. On the other hand, in this embodiment, it is possible to obtain a mask image and a live image in which distortion due to geomagnetism is suppressed to be small.

Further, in the conventional apparatus for automatically blocking the geomagnetism, a mask image and a live image without distortion of the geomagnetism can be obtained. The problem of misregistration of each image that occurs when detecting a strong magnetic field remains. On the other hand, in this embodiment, although the mask image and the live image are distorted by the geomagnetism, the influence thereof can be suppressed to a small level, and the mis-raretion of each image can be reduced.

By the way, also in the X-ray fluoroscopic apparatus provided with this embodiment, the above-mentioned I.S. As in the case of the DSA inspection performed by fixing the I-device 2 and the X-ray tube 3, the drive control unit 12 as shown in FIG. I device 2, X-ray tube 3
The drive control unit 12 may be configured to automatically perform the above-described operation procedure in the DSA inspection performed while rotating the.

That is, the operator selects the changeover switch 1
1 is switched to the DSA inspection and the DSA inspection is performed. By instructing the start point and the end point of the I-apparatus 2 and the X-ray tube 3 from the operation panel 5, the information is obtained.
Given to 2. In the drive controller 12, first, the I.D. The device drive unit 4 is controlled so as to move the I device 2 and the X-ray tube 3 to an intermediate position between the start point and the end point. And I. When the I-device 2 and the X-ray tube 3 are set at the intermediate position between the start point and the end point, the drive control section 12 gives the external signal GS to the latch circuit 25. And I. The I-device 2 and the X-ray tube 3 are moved to the starting point, and the mask image is photographed while rotating from that position to the ending point. The I apparatus 2 and the X-ray tube 3 are moved to the starting point again, and the live image is controlled while rotating from that position to the ending point.

Next, the configuration of the second embodiment device of the present invention will be described with reference to FIG. This second embodiment device uses the latch circuit 25 of the first embodiment as a supply current hold mechanism.
Instead of, the latch circuit 30 is provided between the amplifier 26 and the supply current controller 24.

The latch circuit 30 switches between the operation of directly supplying the signal supplied from the amplifier 26 to the supply current control section 24 and the operation of simply supplying "0v" to the supply current control section 24 by the input of the external signal GS. Is configured. That is, in the state where the external signal GS is not input, the signal given from the amplifier 26 is given directly to the supply current control section 24. As a result, the device operates so as to cancel the geomagnetism detected by the magnetic sensor 23 in real time. On the other hand, when the external signal GS is input, “0v” is given to the supply current controller 24. As a result, in the supply current control unit 24, even if the geomagnetism detected by the magnetic sensor 23 changes, the current that is currently applied to the correction coil 22 (immediately before the external signal GS is applied is applied to the correction coil 22). Current) is always applied to the correction coil 22.

Even if the apparatus is constructed as described above, the same operation and effect as those of the first embodiment described above can be obtained.

By constructing the supply current holding mechanism as in the above-described first and second embodiments, it is only necessary to attach the predetermined latch circuits 25 and 30 to the conventional device. The device can be manufactured inexpensively and easily.

Next, the structure of the apparatus of the third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the supply current control unit 24 is composed of a microcomputer including a CPU 41, a ROM (read-only memory) 42, an internal memory 43, etc., and a supply current holding mechanism is incorporated in the supply current control unit 24. It is a structure.

That is, the signal output from the amplifier 26 is converted into a digital signal by an A / D (analog to digital) converter (not shown), and is supplied to the supply current control section 24. In the supply current control unit 24, when the external signal GS is not input, a current that causes the correction coil 22 to generate a magnetic field that cancels the earth magnetism that enters from the input surface substrate 21 based on the supplied signal is supplied. The calculated current data (digital value) is output and stored in the internal memory 43. Supply current control unit 2
The current data output from 4 is converted into an analog signal by a D / A (digital to analog) converter (not shown) and then applied to the correction coil 22. Amplifier 26 to A
Every time there is an input through the / D converter, the above operation is repeated, and the latest current data is updated in the internal memory 43.

On the other hand, when the external signal GS is input, the current data stored in the internal memory 43 is output, and the current data is supplied to the correction coil 22 via the D / A converter. At this time, even if there is an input from the amplifier 26 or the A / D converter, the current data is not calculated and the internal memory 43 is not updated.

Each procedure (program) as described above
Are stored in the ROM 42, and the CPU 41 executes each process according to the program.

By constructing the apparatus as described above, the same operation and effect as those of the above-described first embodiment can be obtained.

It should be noted that the correction coil 2 is controlled by the external signal GS.
The configuration of the supply current hold mechanism that holds the current currently given to the second embodiment is not limited to the above-described embodiments, and various modifications can be implemented.

[0061]

As is apparent from the above description, according to the present invention, the correction coil is currently provided to the image intensifier device having the function of automatically blocking the geomagnetism coming from the input surface substrate. Since a supply current hold mechanism for holding the current being held based on the fact that an external signal is applied is provided, when obtaining a normal X-ray fluoroscopic image, it is possible to always obtain an X-ray fluoroscopic image without the influence of geomagnetism. As well as multiple Xs, such as DSA inspection
When it is necessary to capture the fluoroscopic image under the same imaging conditions, the current applied to the correction coil is held so that the magnetic sensor detects magnetism other than the earth's magnetism only when capturing a predetermined image. Can also reduce the misregistration of each resulting image.

Further, since the supply current hold mechanism is constructed so as to be operated by an external signal, there are a mode in which the geomagnetism which comes in from the input surface substrate is automatically cut off and a mode in which the current given to the correction coil is held. Can be switched by an external signal.

Further, in the mode in which the current supplied to the correction coil is held, since the current in the correction coil immediately before the external signal is applied is held, the input is performed in the direction of the image intensifier device immediately before the external signal is applied. The geomagnetism that comes in from the surface substrate is blocked, and in that state, for example, a mask image and a live image in a DSA inspection can be obtained, so that a mask image and a live image that are less influenced by the geomagnetism can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a magnetostriction correction mechanism portion provided in an image intensifier device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an entire X-ray fluoroscopic apparatus including the apparatus of the first embodiment.

FIG. 3 is a diagram showing a state of geomagnetism in the vicinity of a magnetic sensor.

FIG. 4 is a diagram showing a schematic configuration of a modified example of the entire X-ray fluoroscopic apparatus.

5: I. DSA while rotating the I device and X-ray tube
When performing an inspection, I. It is a figure for demonstrating the initial setting position of I device.

FIG. 6 is a diagram showing a configuration of a second embodiment device of the present invention.

FIG. 7 is a diagram showing the configuration of a third embodiment device of the present invention.

[Explanation of symbols]

 2 ... Image intensifier device 21 ... Input surface substrate 22 ... Correction coil 23 ... Magnetic sensor 24 ... Supply current control unit 25, 26 ... Latch circuit (supply current hold mechanism) GS ... External signal M ... Subject

Claims (1)

[Claims] 1. A correction coil wound around an outer peripheral space of an input face substrate for taking in X-rays transmitted through a subject, a magnetic sensor arranged in the vicinity of the input face substrate, and detected by the magnetic sensor. And a supply current control means for controlling a magnetic field for canceling the magnetism so as to supply the correction coil with a current that is generated by the correction coil, and automatically shuts off the magnetism coming from the input surface substrate. An image intensifier device configured to hold the current supplied to the correction coil based on the application of a predetermined external signal. Tensifier device.