JPH09234192A - X-ray photography device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To take an X-ray image of a larger view field angle than a view field angle of an X-ray detector by setting plural X-ray radiation means at a specified interval, rotating the X-ray radiation means and an X-ray image pick-up means about a subject body, and synthesizing the obtained X-ray images to be outputted. SOLUTION: X-ray tubes 1a, 1b fixed on a movable rail 10, and an X-ray detector including a TV camera are provided on a rotary plate 6, so these are rotated about a specimen 11. The sepcimen 11 is placed on a bed top plate 7, and a center of a part of the specimen 11 to be photographed is set around a rotation center of the rotary plate 6. A radiated X-ray is transmitted through the specimen 11 to get into an X-ray grid 2 of the X-ray detector, and after it is converted into a visible light image (optical image) by an X-ray image intensifier 3, the image is formed on a photography element of the TV camera 5. At this, plural X-ray images by both X-ray tubes 1a, 1b are synthesized, and a synthesized image is displayed as a target X-ray image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray radiographing apparatus, and more particularly to accurately capturing (photographing) an X-ray image of a large field of view such as a chest of a subject in an X-ray CT (Computed Tomography) apparatus. It relates to a suitable technique.

[0002]

2. Description of the Related Art Conventionally, as a method for observing or recording a three-dimensional moving image by measuring X-ray images of a subject from a plurality of directions,
Rotation DA (Digital Angiography) or rotation DSA
The method of (Digital Subtraction Angiography) is described in Toshiba Medical Review Magazine No. 45 (1992), page 7.

According to this document, an X-ray tube is provided at one end of the C-shaped arm, and an X-ray image intensifier (X-ray II) and a television camera are provided at the other end facing the X-ray tube. It is attached, and by observing a moving image with a stereoscopic effect and obtaining a DSA image from various directions by projecting a continuous image etc. taken by a TV camera on the monitor while rotating this C-shaped arm Is.

Further, as a method of obtaining an X-ray image having a more perfect stereoscopic effect, there is a method of expressing a stereoscopic effect by connecting a plurality of tomographic images obtained by an X-ray CT apparatus by image processing. Although it is general, there is a problem that the shooting time becomes long.

In order to shorten the photographing time, an X-ray detector (X
Two-dimensional X-ray detector as X-ray detection means and X as X-ray source
A two-dimensional transmission image of the subject detected by the two-dimensional X-ray detector is obtained by using an X-ray source that irradiates the rays in a cone shape.
Cone-beam CT that reconstructs a three-dimensional CT image of the subject
Devices are known to be advantageous.

As a typical algorithm for three-dimensional image reconstruction in a cone-beam CT apparatus, "Practical Cone-Beam Algorithm; LAFeldkamp, et al.
al .; J. Optical Society of America, A / Vol. 1 (6), (1
984), pp.612-619 ", and the Feldkamp method is known.

However, in the conventional two-dimensional X-ray detector, in order to convert the X-rays transmitted through the subject into visible light, X-rays are transmitted.
Although a line image intensifier (X-ray II) is used, it is currently in practical use, that is, an X-ray image intensifier having a sufficient sensitivity has a size of about 16 inches. However, there is a problem in that it is not possible to obtain transmitted X-rays of all parts of the subject with this size.

Also, Medical Imaging Technology, Vol. 13, No. 4, (1995) 559-562.
The page shows a cone-beam CT apparatus using an X-ray image intensifier and a television camera as a two-dimensional X-ray detector.

This cone-beam CT system has a cone-shaped X-ray
When an X-ray source for irradiating X-rays and a high-resolution X-ray image intensifier installed at a position facing the X-ray source are rotated around the subject to capture an X-ray image, There is described a method of enlarging the visual field of an X-ray image in the moving direction of the bed top by imaging the bed top with the sample fixed while moving in a direction parallel to the rotational orbit plane of the X-ray source.

A typical algorithm for three-dimensional image reconstruction in a cone-beam CT system is the Feldkamp method (Practical Cone-Beam Algorithm; L.
A. Feldkamp, et al .; J. Optical Society of America,
A / Vol. 1 (6), (1984), pp.612-619) and Grangit's method (Mathematical framework of cone-beam 3D rec)
onstruction via the first derivative of the radon
transform; P.Grangeat; Mathematical Methods in Tom
ography, AKLous, F.Natterer, Eds., Lecture Notes
in mathematics, SpringerVerlag, (1990)).

As another method, Medical Electronics and Biotechnology, Vol. 33, Special Issue (1995), page 109, a large-field cone beam using a large fluorescent screen and a television camera as a two-dimensional X-ray detector. A CT device is shown.

Further, two X-ray sources provided on the same circumference and one X-ray for detecting the X-rays emitted from the X-ray sources.
By rotating the line detector around the subject,
An X-ray tube multiplex type X-ray CT apparatus for picking up an X-ray image of a subject is described in JP-A-62-249639 (see FIG. 1 of JP-A-62-249639).

This X-ray tube multiple CT apparatus has an X-ray detector whose light-receiving area can cover the irradiation areas of two X-ray tubes, and detects the X-rays emitted from each X-ray source. A part of the X-ray detector receives light and converts it into an X-ray image.

In this X-ray tube multiplex type CT apparatus, the heat generation amount of each X-ray tube is changed by selectively operating two X-ray tubes at a predetermined time interval when capturing an image. Since it is suppressed, continuous operation of the X-ray CT apparatus becomes possible.

[0015]

SUMMARY OF THE INVENTION As a result of studying the above prior art, the present inventor has found the following problems.

As a conventional X-ray imaging apparatus, particularly as a two-dimensional X-ray detector, an X-ray image intensifier, X-ray
In a rotating DA or rotating DSA apparatus using an X-ray source that irradiates X-rays in a cone shape as a radiation source, the measurement visual field is limited by the visual field size of the X-ray image intensifier.

It is technically difficult to obtain a fluorescent plate having high sensitivity and high resolution with the devices described in the above-mentioned medical electronics and biomedical engineering magazines, so that it is difficult to obtain a stereoscopic image with a large field of view and high image quality. There was a problem.

In addition, in the apparatus described in the above-mentioned Medical Imaging Technology magazine, since it is necessary to perform imaging while moving the subject, the burden on the subject is large especially in the case of imaging for the purpose of diagnosis, and the subject is not treated during surgery. However, there is a problem that it is difficult to take a picture when it requires rest.

Further, since the subject moves unintentionally due to the inertial force, it is difficult to image the subject at an accurate position.

As described above, there has been a problem that in order to expand the field of view of the object in the transverse tomographic plane direction, the imaging must be performed while moving the object, in spite of the limitation of the field of view due to the size of the detector. It was

Further, in the X-ray tube multiplex CT apparatus described in Japanese Patent Laid-Open No. 62-249639, the purpose is to prevent a decrease in the operating rate of the apparatus due to insufficient heat capacity of the X-ray tube. The detectors used when detecting the X-rays emitted from the two X-ray tubes are different only in the use area, and the X-ray images captured by the X-rays emitted from the respective X-ray tubes are different. Are the same.

Therefore, in the X-ray tube multiplex type CT apparatus described in Japanese Patent Laid-Open No. 62-249639, the X-ray imaging apparatus of the present invention has a viewing angle larger than the intended viewing angle of the X-ray detector. It is impossible to obtain an X-ray image.

As is clear from the above description, the X-ray tube multiple CT described in JP-A-62-249639.
The device also clearly differs in purpose, configuration and effect.

An object of the present invention is to provide a technique capable of capturing an X-ray image having a viewing angle larger than the viewing angle of an X-ray detector while the subject is stationary.

Another object of the present invention is to provide a technique capable of reconstructing a tomographic image having a viewing angle larger than that of the X-ray detector while the subject is kept stationary.

The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0027]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

(1) X-ray irradiating means for irradiating the subject with X-rays, X-ray imaging means for imaging the subject with X-rays, the X-ray irradiating means and the X-ray imaging means for the subject. In an X-ray imaging apparatus having a rotating means for rotating around a plurality of X-ray irradiating means, an X-ray irradiating means setting means for setting the plurality of X-ray irradiating means at predetermined intervals, and the rotating means for controlling the plurality of X-ray irradiating means. The plurality of X-ray irradiating means and the X-ray imaging means are rotated around the subject while maintaining the relative positions of the X-ray irradiating means and the X-ray imaging means, and the plurality of X-ray irradiating means are rotated. When the radiation irradiator reaches a predetermined position of rotation, the X-ray irradiator that has reached the predetermined position of rotation is operated to irradiate X-rays, and X-ray imaging control means for performing X-ray imaging of the subject. And when the plurality of X-ray irradiation means are at the predetermined position, Synthesizing a plurality of X-ray images, by combining the X-ray image of larger view angle than the viewing angle of the X-ray imaging means,
X which is the X-ray image taken at the predetermined position
And a line image synthesizing means.

(2) In the X-ray imaging apparatus of (1) described above, the X-ray imaging means is an X-ray detector for converting an X-ray image transmitted through the subject into an electric signal.

(3) In the X-ray imaging apparatus of (2) described above, the X-ray detector is a two-dimensional X-ray detector, and the X-ray irradiating means irradiates a conical X-ray. It is a device.

(4) In the X-ray imaging apparatus of (1) described above, the X-ray imaging means comprises an X-ray image intensifier and a television camera.

(5) In the X-ray radiographing apparatus according to any one of (1) to (4), the plurality of X-ray irradiating means limits the X-ray irradiating range to a predetermined range. The irradiation range limiting means is provided.

(6) In the X-ray imaging apparatus described in any one of (1) to (5) above, the X-ray irradiation means setting means is based on the size of the imaging target portion of the subject. , The intervals between the X-ray irradiation means are set.

(7) In the X-ray imaging apparatus described in any one of (1) to (6) above, the X-ray irradiating means setting means sets the intervals between the X-ray irradiating means respectively. The irradiation range including the irradiation ranges of the X-ray irradiation means is set to an interval that covers the subject.

(8) In the X-ray imaging apparatus described in any one of (1) to (7), the X-ray image synthesizing means, the X-ray irradiating means setting means, and the plurality of X-rays.
An interval between the X-ray irradiating means is set to a predetermined value on the circumference around the rotation center of the X-ray irradiating means and the X-ray imaging means.

(9) In the X-ray imaging apparatus according to any one of (1) to (8), the X-ray image synthesizing means, the X-ray irradiating means setting means, and the plurality of the plurality of X-ray irradiating means. The plurality of X-ray irradiating means are set at intervals such that two or more of the X-ray irradiating means do not reach the predetermined position of the rotation at the same time, and the X-ray irradiating means that have reached the predetermined position of the rotation are operated. Then, X-rays are emitted to image the subject.

(10) In the X-ray imaging apparatus described in any one of (1) to (8) above, the X-ray image synthesizing means, the X-ray imaging control means, and the predetermined rotation. The X-ray irradiation means that have reached the position are operated one by one in a predetermined order.

(11) In the X-ray imaging apparatus described in any one of (1) to (9), the X-ray image synthesizing means, the X-ray imaging control means, and the rotating means 1 For each rotation, one X-ray irradiating means is operated from among the plurality of X-ray irradiating means.

(12) In the X-ray imaging apparatus according to any one of (1) to (11), the X-ray image synthesizing means reconstructs the X-ray image into a tomographic image of the subject. Reconfiguring means for

(13) In the X-ray imaging apparatus described in any one of the above (1) to (12), the X-ray image synthesizing means sets the predetermined position of the rotation for irradiating the X-rays. , An angle ΔΦ that equally divides 360 ° around the subject into arbitrary integers, N is the number of the plurality of X-ray irradiation means,
When the angle formed by the adjacent irradiation means among the irradiation means and the rotation center is 2θ, the angle formed by the adjacent X-ray irradiation means with respect to an arbitrary integer value M is 2θ = ΔΦ (M +
1 / N).

According to the above-mentioned means (1) to (13), a plurality of X-ray irradiating means are arranged at equal intervals on the rotating surface drawn by the X-ray irradiating means and the X-ray imaging means. An X-ray irradiation means is arranged.

At this time, the interval between the X-ray irradiating means and the X-ray irradiating direction are such that the image capturing range of the X-ray images captured by the X-rays emitted from the respective X-ray irradiating means is combined. Is set so as to cover the affected part of the subject.

Next, the X-ray irradiating means and the X-ray imaging means are rotated around the subject while the relative positions of the X-ray irradiating means and the X-ray imaging means are held by the rotating means. Let

At this time, when each X-ray irradiating means reaches a predetermined position, X-rays are radiated from the corresponding X-ray irradiating means and an X-ray image of 360 degrees around the affected part of the subject is taken. To do.

At the time of image capturing, for example, the X-ray irradiating means to be operated is determined in advance for each rotation, and only one X-ray irradiating means is operated so that an X-ray image is obtained. Is imaged.

Next, when the X-ray image has been picked up, only the X-ray image picked up when each X-ray irradiating means is present at the same position is extracted from the plurality of X-ray images. .

The X-ray image extracted at this time is an image picked up when the X-ray irradiation means reaches a predetermined position.

Therefore, the relative positional relationship between the X-ray irradiating means and the X-ray imaging means at the time of picking up each X-ray image is fixed.
The line image is the same as that when a plurality of X-ray image pickup means are provided without gaps.

Next, these X-ray images are combined into one X-ray image by the X-ray image combining means, and the X obtained by the combination is obtained.
By regarding the line image as an X-ray image captured at this position, an X-ray image having a wider viewing angle than the viewing angle that is the imaging range of the X-ray imaging means can be obtained. The viewing angle of the line image can be expanded.

Further, even if an image intensifier or the like having a larger installation area than the X-ray irradiating means is used, the X-ray photographing apparatus is not enlarged.
An X-ray image with a wide viewing angle can be obtained.

On the other hand, when the tomographic image is reconstructed by the reconstructing means, the tomographic image of the subject can be reconstructed from the X-ray image whose viewing angle is enlarged by combining them into one image. Can be expanded.

[0052]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings together with embodiments (examples) of the invention.

In all the drawings for describing the embodiments of the present invention, components having the same functions are denoted by the same reference numerals, and their repeated description will be omitted.

(Embodiment 1) FIG. 1 is a block diagram showing a schematic configuration of an X-ray imaging apparatus according to Embodiment 1 of the present invention. 1 (a) and 1 (b) are X-ray tubes (X Beam irradiation means), 2
Is an X-ray grid, 3 is an X-ray image intensifier (II), 4 is an optical lens system, 5 is a TV camera, 6 is a rotating plate, 7 is a bed top, and 10 is for moving the X-ray tube. A rail, 11 is a subject, 12 is imaging control means (X-ray imaging control means), 13 is rotary plate drive means (rotation means), 14 is X-ray tube position control means (X-ray irradiation means setting means), and 18 is Image collection processing means (X-ray image synthesizing means), 19 is image display means, 24 (a) and 24 (b) are collimators, and 25 is X.
The line irradiation range control means (irradiation range limiting means) 26 is a subject size measuring means.

Dotted lines shown in FIG. 1 indicate X-rays (X-ray beams) emitted from the X-ray tube 1 (a) in a conical shape.

Known devices and means are used as the above-mentioned devices and means.

Further, the X-ray imaging apparatus of the first embodiment reconstructs an X-ray image (X-ray transmission image) of the subject 11 imaged with X-rays and displays a tomographic image (tomographic image). The so-called X-ray CT apparatus.

In the first embodiment (including the second and third embodiments shown below), for convenience of explanation, the radius of rotation D of the X-ray tube 1 is 720 mm, the center of rotation of the rotary plate 6 and the X-ray detection. The distance d from the X-ray input surface of the detector is 380 mm, and the diameter w of the X-ray input surface of the X-ray detector is 406 mm. The above-mentioned television camera 6 shows a case where a high-resolution image pickup tube is used as an image pickup element.

In FIG. 1, X-ray tubes 1 (a), 1 (b)
Is a well-known X-ray tube, which generates an X-ray by applying a high voltage output from a high-voltage generator (not shown) and irradiates the X-ray.

The X-ray grid 2 prevents scattered X-rays and direct X-rays.
This is a well-known X-ray grid for preventing a reduction in contrast by transmitting only the lines.

The X-ray grid 2 is arranged in front of the X-ray input surface of the X-ray image intensifier 3 so that the absorber is parallel to the rotation surface of the rotary plate 6.

The X-ray image intensifier 3 has X
It is a well-known X-ray image intensifier that performs line detection on the X-ray incident surface and outputs an optical image (X-ray image) whose brightness is amplified on the output surface, and outputs a two-dimensional optical image.

The optical lens system 4 is a lens for forming an optical image of the output surface of the X-ray image intensifier 3 on the image pickup device of the television camera 5.

The television camera 5 is a well-known television camera that converts an optical image formed on an image pickup device (not shown) into an electric signal, and converts a two-dimensional optical image into an electric signal.

The rotating plate 6 is a fixing member for rotating the X-ray tubes 1 (a) and 1 (b) fixed to the X-ray tube moving rail 10 and the X-ray detector around the subject 11. The rotating means is driven by the rotating plate driving means.

The couch top 7 is a well-known couch top for fixing the subject 11 and setting the imaging region of the subject 11.

Further, the bed top plate 7 is positioned horizontally with respect to a floor surface (not shown), and moves in a direction vertical and parallel to the rotating surface of the rotating plate 6 when setting the imaged region.

The X-ray tube moving rail 10 has an arc shape along the circumference of a radius D = 720 mm around the center of rotation of the rotary plate 6, and the X-ray tubes 1 (a), 1 (b). ) Is installed so that it can move on the X-ray tube moving rail 10.

In the structure at this time, for example, first, the rotary plate 6 is provided with a projection to be the rail 10 for moving the X-ray tube, and a groove to be combined with the projection.
(A) and 1 (b).

Next, the driving force of a motor (not shown) (X-ray tube position drive means) is passed through a gear (not shown) to X
The X-ray tubes 1 (a) and 1 (b) are moved on the circumference of the radius D described above by transmitting to each of the ray tubes 1 (a) and 1 (b) and moving the irradiation position.

The subject 11 is positioned on the bed top 7, and the photographing position is standardized in the supine position, and the center of the portion of the subject 11 to be photographed is the rotation center of the rotary plate 6 (the photographing system described later). Set near the center of rotation.

The radiographing control means 12 includes the X-ray tubes 1 (a), 1
(B) operation (irradiation of X-rays), means for controlling the operation of the rotary plate drive means 13, and the television camera 5,
An imaging sequence for controlling the X-ray generation of the ray tubes 1 (a) and 1 (b) and an imaging operation of the X-ray detector, and a rotation sequence for rotating the rotary plate 6 are defined.

Therefore, the photographing control means 12 can be realized by, for example, a program executed by an information processing device (not shown).

The rotary plate driving means 13 is composed of, for example, a DC servo motor (not shown), a servo amplifier (not shown), a speed reducer (not shown), and a power transmission belt (not shown), and a DC signal is input based on a signal input to the servo amplifier. By driving the servomotor and transmitting its driving force to the rotary plate 6 via the speed reducer and the drive transmission belt,
The rotating plate 6 is rotated.

The X-ray tube position control means 14 moves the X-ray tubes 1 (a) and (b) to the X-ray tube moving rail 1 prior to the imaging operation.
0 while moving to a specified position on the rotating plate 6 during imaging.
X-ray tubes 1 (a), 1 (b) installed on the rotary plate 6 are control means for holding the position with respect to
The drive of the above-mentioned motor is controlled based on the signal from the position sensor for the vehicle.

The X-ray tube position control means 14 is realized by, for example, a program executed by an information processing device (not shown).

The image collection processing means 18 is the television camera 5
X imaged in and converted to an electrical video signal
The line image is converted into a digital signal by an A / D converter (not shown) and then stored in an internal frame memory, which is realized by a program operating by an information processing device (not shown).

The image display means 19 comprises a well-known D / A converter and a monitor device, and after converting the image data output from the image collection processing means 18 into a video signal by a D / A converter (not shown). , Display on monitor device.

The collimators 24 (a) and 24 (b) are known X-ray collimators fixed to the front surfaces of the X-ray tubes 1 (a) and 1 (b), respectively. 1 (b)
Together with this, they move on the X-ray tube moving rail 10.

The X-ray irradiation range control means 25, based on the input control signal, collimators 24 (a), 24
By controlling the collimating width of (b), the X-ray tube 1 (a),
It is means for controlling the irradiation range of X-rays irradiated from (b), and can be realized by a program executed by an information processing device (not shown).

The object size measuring means 26 is a means for measuring the size of the object 11 in the direction parallel to the rotating surface of the imaging system, and is, for example, a video camera (not shown) installed in the imaging system. This can be realized by analyzing the photographed image of the subject 11 by a known image analysis technique and measuring the size of the contour of the subject 11.

Needless to say, an operator (not shown) may perform the measurement in advance. At this time, the object size measuring means 26 causes the object 1 to be measured by the operator.
It operates as a means for storing the size of 1 and uses the stored size as the measurement value.

Further, the X-ray detector (X-ray imaging means) is
It is composed of a line grid 2, an X-ray image intensifier 3, an optical lens system 4 and a television camera 5, and is capable of two-dimensional X-ray detection.

The imaging system includes an X-ray detector, an X-ray tube 1 (a),
X-ray tube 1 (b), collimator 24 (a), collimator 2
4 (b), an X-ray tube moving rail 10 and a rotating plate 6.

Next, the operation of the X-ray imaging apparatus of the first embodiment shown in FIG. 1 will be described. First, the X-ray tube 1 (a) and the X-ray tube 1
The X-ray generated from the ray tube 1 (b) passes through the subject 11 and enters the X-ray grid 2.

The X-rays incident on the X-ray grid 2 are shielded from scattered rays, and then the X-ray image intensifier 3
After being converted into a visible light image (optical image) by the optical lens system 4, the optical lens system 4 forms an image on an image pickup device (not shown) of the television camera 5.

The television camera 5 converts the image into a video signal and outputs it to the image collection processing means 18.

The X-ray image intensifier 3 can be set in a photographing mode by an operator, and the X-ray detection range can be selected from 7, 9, 12, and 16 inches depending on the size of the subject 11. It can be set to any size.

The standard scanning mode in CT scanning of the television camera 5 is 60 frames per second and 525 scanning lines, but it is also possible to shoot with 30 frames per second and 1050 scanning lines.

Further, the high-definition photographing mode is set to 7.5 per second.
It is also possible to shoot with a frame and 2100 scanning lines. The image acquisition processing means 18 A / D-converts the video signal and then stores it in an internal frame memory.

Next, the geometrical distortion of the image, the shading correction of the density level of the image, and the image synthesizing process which will be described later are performed on each projected image, and then three-dimensional reconstruction is performed, and the image display means is displayed. 19 three-dimensional reconstructed X-ray CT
Display an image.

Furthermore, the image obtained by the television camera 5 in the perspective or photographing mode can be displayed by the image display means 19 as it is or after the correction is performed in real time.

FIG. 2 is a view for explaining the positional relationship between the rotation angle of the rotary plate and each X-ray tube when the X-ray image is taken in the first embodiment, and 27 is the rotation center O of the rotary plate 6. Shows a circle with radius D centered at.

In FIG. 2, X and Y are coordinate axes of an XY coordinate system fixed to the subject 11, and it goes without saying that this XY coordinate system may be set arbitrarily for the subject.

P is a coordinate axis existing on a straight line connecting the X-ray detector and the rotation center O, and φ is an angle formed by the p-axis and the X-axis.

Θ is the angle formed by the straight line connecting the X-ray tube 1 (a) and the rotation center O with the p axis, and the angle formed by the straight line connecting the X-ray tube 1 (b) and the rotation center O with the p axis. As is clear from FIG. 2, in the first embodiment, p
The X-ray tube 1 (a) and the X-ray tube 1 (b) are installed at positions symmetrical with respect to the axis.

Φ (0) to Φ (k) to Φ (L-1) indicate the positions of the X-ray generation points on the circumference 27, where L is the number of all X-ray generation points. Yes, in the first embodiment, 2
88.

Therefore, the X-ray generation points in the first embodiment are Φ (0) to Φ (287).

However, it is assumed that each X-ray generation point is fixed on the XY plane and always exists at the same position with respect to the subject 11.

Note that k is an integer value of 0 ≦ k ≦ L−1, and Φ (k) indicates the position of an arbitrary X-ray generation point.

ΔΦ is the angle of the adjacent X-ray generation points with respect to the rotation center O, and indicates a so-called imaging step angle.

At this time, ΔΦ is equidistant.

Therefore, in the first embodiment, L is 2
Since it is 88, ΔΦ is 1.25 degrees from the following equation (1).

ΔΦ = 360 / L (1) FIG. 3 shows the X-ray tube 1 (a) and the X-ray tube 1 of the first embodiment.
It is a figure which showed the detection surface position of each X-ray detector in case (b) exists in the same X-ray generation point position (PHI).
0 (a) is the position of the detection surface of the X-ray detector 20 when the X-ray tube 1 (a) makes an angle Φ with the X axis, and 20 (b) is the X-ray tube 1
(B) shows the position of the detection surface of the X-ray detector 20 when forming an angle Φ with the X axis.

At this time, the detection surfaces 20 (a), 20 (a), 20
(B) shows an X-ray input surface of the X-ray detector, that is, an X-ray input surface of the X-ray image intensifier 3 in a virtual plane, in order to explain the combining operation of the X-ray images. Is.

In FIG. 3, α is a straight line passing from the intersection of the detection surfaces 20 (a) and 20 (b) through the center of rotation O to the X-ray tubes 1 (a) and 1 (b), and the detection surface. 20
From the ends of (a) and 20 (b) on the non-intersecting side, the X-ray tube 1
An angle formed by a straight line extending from (a) and 1 (b) is shown.

Therefore, 2α is X which forms an angle Φ with the X axis.
The total viewing angle (hereinafter, referred to as imaging viewing angle) of the superimposed X-ray detectors at the line generation point is shown.

Β is an angle formed by a straight line from the end of the detection surface 20 (a) on the non-intersecting side to the rotation center O and a perpendicular line drawn from the rotation center O to the detection surface 20 (a).

L (ell) is the length of a straight line from the end of the detection surface 20 (a) on the non-intersecting side to the center of rotation O, and the center of rotation from the end of the detection surface 20 (b) on the non-intersecting side. It is the same as the length of the straight line to O.

W is the width in the direction in which the detection surface 20 (a) is parallel to the rotation surface of the rotating plate 6, and is the same as the width in the direction in which the detection surface 20 (b) is parallel to the rotation surface of the rotating plate 6. Needless to say.

D is the length of a perpendicular line drawn from the rotation center O to the detection surface 20 (a), and is the length of the detection surface 20 from the rotation center O.
It is the same as the length of the vertical line drawn in (b).

2γ is a straight line from the end of the detection surface 20 (a) on the non-intersecting side to the center of rotation O and the detection surface 20 (b).
Is an angle formed by a straight line from the end portion on the non-intersecting side to the rotation center O.

Therefore, 2γ represents the viewing angle with respect to the rotation center 0 obtained by combining the X-ray irradiation from the X-ray tube 1 (a) and the X-ray irradiation from the X-ray tube 1 (b).

Therefore, γ is represented by the following equation (2), as is apparent from FIG.

Γ = β + θ (2) where β = tan ~ ¹ (w / (2d)) (3) On the other hand, α is expressed by the following equation (4). .

[0116] ^{α = tan ~ 1 {(l} sinγ) / (D + l cosγ)} ···· (4) where

[0117]

[Equation 1]

FIG. 4 shows the inclination θ of the X-ray tube 1 (a) and the X-ray tube 1 (b) in the X-ray imaging apparatus according to the first embodiment.
The relationship with the photographing viewing angle 2α at this time is calculated by using the above-described mathematical expressions (2) to (5), and the result is shown in a graph.

As described above, the radius of gyration D of the X-ray tube 1 (a) and the X-ray tube 1 (b) is 720 mm, the distance d between the center of rotation of the rotary plate 6 and the X-ray detector is 380 mm, X
The calculation is performed on the assumption that the diameter w of the X-ray input surface of the line detector is 406 mm.

When θ is 0 degrees, it is equivalent to the conventional imaging method in which imaging is performed using one X-ray tube, and the imaging viewing angle 2α at this time is 20.9 degrees.

On the other hand, when θ is 10 degrees, the photographing viewing angle 2α becomes 28.2 degrees, which means that the photographing viewing angle is expanded by 7.3 degrees as compared with the conventional photographing method.

In this way, the X-ray tube 1 (a) and the X-ray tube 1 (b) are moved on the X-ray tube moving rail 10 and the inclination θ of the X-ray tube is changed to change the photographing field of view. It becomes possible to adjust to various values.

Therefore, the operator can adjust the optimum field of view by varying θ depending on the size of the subject.

FIG. 5 is a diagram for explaining the X-ray irradiation position of the X-ray imaging apparatus according to the first embodiment of the present invention. In the X-ray imaging apparatus according to the first embodiment, X-ray irradiation is performed as X-rays. Tube 1 (a)
And X-ray tube 1 (b) are alternately performed to capture an X-ray image.

This imaging operation will be briefly described with reference to FIG. 5. For example, first, at the time point shown in FIG. 5 (A), X-rays are irradiated from the X-ray tube 1 (a) to examine the subject. The X-ray image of 11 is imaged.

Next, at the time point when the rotary plate 6 is slightly rotated by a predetermined angle, the X-ray is irradiated with the X-ray tube 1 at the time point of FIG. 5B.
The irradiation from (b) captures an X-ray image of the subject 11.

At the time point when the rotary plate 6 is rotated by a predetermined minute angle, as shown in FIG.
The irradiation is performed from (a), and an X-ray image of the subject 11 is captured.

As described above, the rotation of the above-described predetermined angle and the irradiation of the X-rays are alternately repeated, and the X-ray image for one rotation of the imaging system is taken around the subject 11.

Therefore, since the X-ray irradiation by the X-ray tube 1 (a) and the X-ray tube 1 (b) can be performed at one time, all the X-ray images can be obtained by rotating the imaging system once. There is an effect that it is possible to perform fluoroscopy or imaging, which is imaging.

FIG. 6 is a diagram for explaining an example of the relationship between the rotation angle of the rotary plate 6 and the X-ray tubes 1 (a) and 1 (b) in the X-ray imaging apparatus according to the first embodiment. The operation of the X-ray imaging apparatus according to the first embodiment will be described below with reference to FIG.

As described above, the X-ray imaging apparatus of the first embodiment repeats the rotation of the rotary plate 6 and the irradiation of X-rays alternately, so that, for example, at the starting point (A) of FIG. 1
(B) exists at the position of the X-ray generation point Φ = 0.

This corresponds to the X-ray tube 1 shown in FIG.
This corresponds to the fact that (b) exists at the position of the X-ray generation point Φ (0).

At this time, the rotating plate 6 starts rotating in the counterclockwise direction, and at the same time, the X-ray tube 1 (b) and the X-ray tube 1 are rotated.
(A) is each X-ray generation point Φ (0), Φ (1), ..., Φ
Fluorescence or radiography is performed by alternately irradiating X-rays at any position of (L-1).

As will be described later, the X-ray tubes 1 (a) and X
When the inclination θ of the ray tube 1 (b) is set to an appropriate value, by alternately irradiating X-rays at equal time intervals, it is possible to easily capture X-ray images at all X-ray generation points. Some perspective or photography can be done.

Time point (B) shows the time when the rotary plate 6 rotates 180 degrees with respect to the time point (A), and time point (C) shows that the rotary plate 6 rotates 360 degrees with respect to the time point (A). Indicates the time point.

At the time point (C), the X-ray tube 1 (b) is again located at the position of the X-ray generation point Φ (0), and the photographing is completed.

Next, FIG. 7 shows a diagram for explaining a method of determining the inclination θ of the X-ray tube 1 (a) and the X-ray tube 1 (b) of the X-ray imaging apparatus according to the first embodiment. A method of determining the tilt θ of the X-ray imaging apparatus according to the first embodiment will be described with reference to FIG.

First, the X-ray tube 1 (a) and the X-ray tube 1
The slope θ of (b) is determined as shown in the following equation (6) for an arbitrary integer M.

2θ = ΔΦ (M + 1/2) (6) However, ΔΦ is a photographing step angle given by the above-mentioned equation (1), and FIG. 7 shows the case of M = 3. is there.

When 2θ is determined in this way, the X-ray tube 1 (a) and the X-ray tube 1 (() are rotated every time the rotary plate 6 is rotated at a constant speed and the rotary plate 6 is rotated by the angle ΔΦ / 2. By alternately irradiating X-rays according to b) and capturing an X-ray image transmitted through the subject 11, all X-ray generation points Φ (0),
With Φ (1), ..., Φ (L-1), it is possible to easily perform fluoroscopy or photographing.

Next, the operation in this case will be described in detail with reference to FIG.

First, at the time point shown in FIG.
The X-ray tube 1 (a) exists at the position of the X-ray generation point Φ (k), and at this time, X-rays are emitted from the X-ray tube 1 (a) to perform fluoroscopy or radiography.

As described above, k is an arbitrary value 0 ≦ k
It is an integer value of ≦ L−1, and Φ (k) indicates the position of an arbitrary X-ray generation point.

Next, at the time point shown in FIG. 7B when the rotary plate 6 is rotated by the angle ΔΦ / 2 with respect to the time point shown in FIG. 7A, the X-ray tube 1 (b) generates X-rays. Point Φ (k + 4)
X-ray tube 1 at this point
From (b), X-ray is irradiated to perform fluoroscopy or radiography.

At the time point shown in FIG. 7C where the rotary plate 6 is rotated by the angle ΔΦ / 2 with respect to the time point shown in FIG. 7B, the X-ray tube 1 (a) has an X-ray generation point Φ ( k + 1), and at this time, the X-ray tubes 1 (a) to X
Irradiate a line for fluoroscopy or photography.

The above-described series of operations are repeated until the rotary plate 6 makes one revolution, that is, the X-ray tube 1 (a) returns to the position of the X-ray generation point Φ (k), and at the time of returning. Stop shooting.

By performing the above-mentioned photographing operation, all X-ray generation points Φ (0), Φ (1), ..., Φ (L-
In 1), fluoroscopy or radiography can be performed on each of the X-ray tube 1 (a) and the X-ray tube 1 (b).

At this time, with respect to the L X-ray generation points, X is generated for each of the X-ray tube 1 (a) and the X-ray tube 1 (b).
Since line irradiation is performed, the total number of shots is 2L.

Further, by rotating the rotary plate 6 at a constant speed, the time intervals of X-ray irradiation can be made equal, so that the capturing intervals of the TV camera 5, that is, the X-ray image capturing intervals are made equal. be able to.

For example, the scanning mode in CT scanning of the television camera 5 is set to 60 frames per second and the number of scanning is 525.
If the number of all X-ray generation points L is set to 288, the time required for all imaging is 9.6 seconds.

In order to determine the value of M, an approximate value of 2θ is first calculated by the size of the subject 11 and then the following expression (7) is satisfied for 2θ. After obtaining the minimum M, the accurate 2θ is calculated by the above equation (6).
Should be obtained.

2θ ≦ ΔΦ (M + 1/2) (7) FIG. 8 shows the same X in the X-ray imaging apparatus according to the first embodiment.
FIG. 9 is a diagram for explaining a method of synthesizing two X-ray transmission images of two objects, which are fluoroscopically or photographed by X-rays irradiated at the line generation point, into one image, and FIG. It is a figure for demonstrating the synthetic image obtained by.

In the X-ray imaging apparatus according to the first embodiment, as shown in FIG.
As shown in FIG. 5, an X-ray fluoroscopic image or a radiographed image of the subject 11 can be obtained at the positions of the two X-ray detectors that are tilted rightward or leftward by θ with respect to the same X-ray generation point. .

Therefore, as described above with reference to FIG. 3, it is possible to synthesize the images collected at the respective positions to create one image with a large field of view, and display it.
For example, first, consider the virtual detection plane 90 shown in FIG. 8 for the image information stored in the memory (not shown).

At this time, the virtual detection surface 90 includes the rotation center O of the rotary plate 6 and is arranged perpendicular to the straight line connecting the X-ray tubes 1 (a), 1 (b) and the rotation center O. To do.

Next, the image information collected from the X-ray detector when the X-ray tubes 1 (a) and 1 (b) reach the same X-ray generation point is displayed on the virtual detection surface 90 described above. Project to create one composite image.

Here, the projection of the image information is irradiated from the X-ray generation point to the detection point 92 which constitutes the virtual detection surface 90, and the X-ray beam 93 which passes through the detection point 92.
It can be realized by projecting the projected image 94 of the subject on the virtual detection surface 90.

FIG. 9 is a diagram showing a display example of an X-ray image of the subject 11 synthesized on the virtual detection surface 90 described above.
The central position 91 on the virtual detection surface 90 is the X-ray of the subject.
The display is performed so as to coincide with the central position 95 on the display screen 97 for displaying the fluoroscopic or photographed image.

At this time, by using a horizontally long display screen 97, the subject 1 in the display screen 97 is
It is possible to display the entire display portion 96 of the X-ray fluoroscopic image or the photographed image 1 without causing the defect.

Next, a method of reconstructing an X-ray CT image in the imaging method of the X-ray imaging apparatus of the first embodiment will be described.

As described above, the composite image of the subject 11 projected on the virtual detection plane 90 shown in FIG. 9 is detected by the virtual detector having a wider field of view than that of the actual X-ray detector. It can be considered as an X-ray transmission image of the subject.

Therefore, all X-ray generation points Φ (0),
A three-dimensional X-ray CT image of the subject 11 having a wider field of view than before can be reconstructed by creating the composite image for Φ (1), ..., Φ (L-1) and performing signal processing. .

FIG. 10 is a diagram for explaining a method of synthesizing overlapping portions when synthesizing X-ray images at the same X-ray generation point in the X-ray imaging apparatus according to the first embodiment. When the X-ray transmission images of the two fluoroscopic or radiographic images of the subject are combined into one, the projection data that overlaps is shown by the diagonal lines.

In particular, FIG. 10 (A) shows a case where an X-ray tube before limiting the X-rays is used, and FIG. 10 (B) shows a region in which the projected images are doubly present in the composite image. Figure, Figure 1
0 (C) is a diagram for explaining a case where the irradiation range of the X-ray tube 1 (a) is limited, and FIG. 14 (D) shows an overlapping part when the irradiation range of the X-ray tube 1 (b) is limited. Diagram to explain,
FIG. 14 (E) is a diagram for explaining an overlapping portion when the irradiation range is limited, and FIG. 14 (F) is a diagram showing a combined image combined by FIG. 14 (E).

In FIG. 10A, the overlapping area 100, which is the portion where the visual field ranges overlap with respect to the respective positions of the detection surfaces 20 (a) and 20 (b) of the X-ray detector, is shown by hatching.

As shown in FIG. 10A, when the detection point 92 on the virtual detector surface exists in the overlapping area 100, the X-ray emitted from the X-ray generation point and passing through the detection point 92.
The projection image of the subject 11 by the line beam 93 is the detection surface 20.
Projected images 94 (a) and (a) on (a) and (b), respectively.
Obtained as (b).

Therefore, X passing through the overlap area 100
For line beams, there will be duplicate projection data.

As described above, with respect to the projection data which is doubly present, by projecting the average value of these on the virtual detection plane 90 when the composite image is created, the S /
N can be improved.

As described above, FIG. 10B is a diagram showing a region in which the projected images are doubly present in the composite image, and the subject 1 obtained by the detection surfaces 20 (a) and 20 (b).
The X-ray transmission image of No. 1 corresponds to the elliptical display portions 96 (a) and (b) on the display screen 97, respectively.

Therefore, the display portions 96 (a) and (b) are displayed.
In the common part 101 of, the projected images are doubly present, and their average value is displayed.

As described above, the object 11 is doubly exposed to the X-ray beam passing through the overlapping region 100.

However, since the X-ray beam passing through the overlapping region 100 passes through the portion of the subject 11 near the center where the subject thickness is large, the X-ray absorption is generally large, and
The S / N of the projection data collected is low.

Therefore, although the exposure dose of the subject 11 increases, the S / N of the X-ray image can be improved by averaging the projection data as described above.

Needless to say, a collimator may be used to limit the X-ray irradiation range in order to reduce the X-ray exposure dose of the subject 11.

FIGS. 10B and 10C show the X-ray source 1
(A), (b) and their corresponding detection surfaces 20 (a),
It is a figure explaining the method of limiting the irradiation range of X-rays by the collimators 24 (a) and (b) respectively with respect to (b).

In FIGS. 10B and 10C, the X-ray irradiation range 102 is set by the collimators 24 (a) and (b).
By limiting (a) and (b) to an area narrower than the actual detection area, the overlap area 100 is reduced.

FIG. 10E shows the overlapping area 100 at this time. Compared with FIG. 10A, the overlapping area 100 is reduced and the X-ray exposure dose of the subject 11 is decreased. Is clear.

Therefore, as described above, the subject 11
The effect is to reduce the amount of X-ray exposure.

Further, FIG. 10 (F) is a diagram showing a region in which a projected image is doubly present in the composite image obtained with respect to FIG. 10 (E). Compared with FIG. 10 (B), Since the common part 101 is reduced, it can be seen that the X-ray exposure dose of the subject 11 is reduced, and the above-described effect is obtained.

Next, FIG. 11 shows a view for explaining the visual field size of the composite image shown in FIG. 7, and the visual field size of the composite image will be described below with reference to this figure.

In FIG. 11, 96 is a display portion, 97 is a display screen, H is the horizontal visual field size of the composite image, and V is the vertical visual field size of the composite image.

However, the visual field size in this case does not represent the size of the display portion 96 on the display screen 97, but the size on the virtual detector plane 90 corresponding thereto.

As described above, since the virtual detector plane 90 is defined to exist at the position of the rotation center O of the rotary plate 6, the size of the visual field on the virtual detector plane is the center position of the subject 11. Express the size of the field of view.

Therefore, the values of the visual field sizes H and V defined here can be directly utilized in determining the visual field size with respect to the size of the subject 11, and in particular, V
The value of is defined as the minimum field size that is vertically restricted due to the circular field of view of the X-ray detector.

Therefore, the value of the visual field size V in the horizontal direction is given by the following equation (8) when the major axis and the minor axis of the ellipse are defined as b and a, respectively, as shown in FIG.

[0186]

[Equation 2]

However, the values of a, b, and c are each expressed by the following equation (9).

[0188]

(Equation 3)

On the other hand, the value of the visual field size H in the horizontal direction is given by the following expression (10).

[0190]

(Equation 4)

From the above, the horizontal and vertical directions of the composite image when the X-ray imaging apparatus according to the first embodiment is used by using the above-mentioned equation (2) and equations (8) to (10). The field-of-view sizes H and V can be obtained using θ as a parameter.

FIG. 12 is a diagram showing the spatial resolution of an X-ray transmission image in the X-ray imaging apparatus of the first embodiment, and the representative value of the visual field size of the composite image with respect to the X-ray tube and its inclination θ.

In FIG. 12, as described above, the radius of gyration D of the X-ray tube is 720 mm, the center of rotation of the rotary plate 6 and the X axis.
The distance d to the line detector is 380 mm.

Also, the television camera 5 has 525 scanning lines,
An image is captured at 60 frames per second, and the number L of X-ray generation points is 288.

In FIG. 12, FIG. 12A shows the spatial resolutions of the X-ray image intensifier 3 for the imaging modes of 7, 9, 12, and 16 inches.

Here, the spatial resolution is such that the inclination θ of the X-ray tube is 0.
It is defined by the spatial resolution at the position of the rotation center O of the rotary plate 6 when it is set to (zero).

When the inclination θ of the X-ray tube is increased, the spatial resolution changes, but this does not depend on the position on the detection surface of the X-ray detector, the position of the X-ray detector with respect to the X-ray tube, or the like. Needless to say.

The values shown in FIG. 12A are typical spatial resolution values.

FIG. 12 (B) shows the vertical field size V of the composite image with respect to the photographing mode of each X-ray image intensifier 3 with the inclination θ of the X-ray source being 5 degrees, 10 degrees,
It is calculated for the case of 15 degrees.

FIG. 12C shows the field size H in the horizontal direction of the composite image when the inclination θ of the X-ray source is 5 degrees and 10 degrees with respect to the photographing mode of each X-ray image intensifier 3.
It is calculated for the case of 15 degrees.

In the X-ray imaging apparatus according to the first embodiment, the values shown in FIGS. 12A to 12C are stored in the read-only memory as a reference table, and the X-ray image in It is used to determine the photographing mode of the tensioner 3 and the inclination θ of the X-ray tube.

In FIGS. 12B and 12C, the inclination θ of the X-ray tube is set to 5, 1 for simplicity.
Although only three types of 0 and 15 degrees are shown, it is needless to say that the setting of θ at the time of photographing can be more appropriately performed by preparing a reference table for a finer step of θ. .

Next, FIG. 13 is a diagram for explaining the procedure up to the start of imaging, and FIG. 14 is a block diagram for explaining the operation of the X-ray imaging apparatus according to the first embodiment.
The operation will be described with reference to FIGS. 13 and 14.

The procedure up to the start of imaging will be described with reference to FIG.
1 based on the size of the subject 11 measured by the operator or the size of the subject 11 set by the operator.
1 measurement area is determined and recorded in the memory (step 1
60).

Next, with respect to the size of the measurement area of the subject 11 recorded in the memory in step 160, a set of horizontal and vertical visual field sizes H and V including all or most of them. Are all selected and set as candidates (step 161).

When the set of H and V is obtained, it is performed by referring to the above-mentioned table shown in FIG. 12, which is stored in the read-only memory in advance.

Next, with respect to the set of H and V selected in step 161, all combinations of the photographing mode of the X-ray image intensifier 3 and the inclination θ of the X-ray tube that realize these are stored in the memory as candidate values. Record (Step 1
62).

From all the candidate values recorded in step 162, the horizontal and vertical field of view sizes H,
The optimum candidate value is determined according to V and spatial resolution (step 163).

The optimum candidate value may be determined automatically in the X-ray imaging apparatus of this embodiment, manually by an operator, or by combining both. It may be semi-automatic.

When obtaining the optimum candidate, the above-mentioned FIG. 12A stored in advance in the read-only memory is used.
This is done by referring to the table corresponding to (D).

As a method of automatically determining the optimum candidate value, for example, the following method is available.

First, from among all the candidate values,
A set of H and V that is extremely large with respect to the size of the measurement region of the subject 11 is excluded from the candidate values.

Next, as the second option, some of the remaining candidate values having a high spatial resolution are selected in order from the top, and the remaining candidate values are excluded.

Next, thirdly, from among the remaining candidate values, the one having the shortest shooting time is selected as the optimum candidate value.

Needless to say, the order of the first to third procedures may be freely changed according to the will of the operator.

Further, any one of the above-mentioned first to third procedures or all the procedures are manually performed based on the intention of the operator, and the remaining procedures are automatically performed by the information processing device, for example. It goes without saying that the optimum candidate value can be determined by a semi-automatic or manual method in which the optimum candidate value is determined.

Next, the optimum candidate value obtained in step 163 is recorded in the memory (step 164).

Next, with respect to the optimum candidate value obtained in step 164, first, the minimum M that satisfies the equation (7) is obtained, and then the accurate X-ray tube 1 for this minimum M is obtained.
The inclination θ of (a) and 1 (b) is obtained (step 16
5).

Next, of the candidate values stored in the memory in step 164 described above, the inclination θ of the X-ray tube is calculated in step 1
It is replaced with the accurate inclination θ of the X-ray tube obtained in step 65 to obtain the final set value (step 166).

The photographing mode of the X-ray image intensifier 3 is set to the final set value recorded in step 166, and the X-ray tube is moved so that the inclination θ of the X-ray tube becomes the set value. The X-ray tube is moved on the rail 10 (step 167).

Further, the operator may change the X-ray irradiation range for each of the X-ray tubes 1 (a) and 1 (b) by the method shown in FIG. 10, if necessary.

Finally, in step 168, photographing is started.

Next, the procedure for creating a composite image and the procedure for reconstructing an X-ray tomographic image (X-ray CT image) will be described with reference to FIG. 14. First, as shown in FIG. The video signal of the object collected by the A.D.
After being converted into a digital signal by the converter 110, it is stored in the image memory 111.

In the image memory 111, Φ
(0), Φ (1), ..., Φ (L-1) indicate memory banks that store image information (image data) that are X-ray images collected at the respective X-ray generation points.

Further, (a) and (b) of the image memory at each X-ray generation point are the photographing tubes 1 (a) and (a), respectively.
3B shows a memory bank storing image data collected for (b).

When shooting is performed in accordance with the procedure shown in FIG. 7 described above, the A / D converted image data is first
Φ (0) (b), and then Φ (LM)
(A), Φ (1) (b), Φ (L-M + 1) (a),
, .PHI. (L-1) (b), .PHI. (L-M-1) (a) are stored in this order, and the storage of the image data ends.

After the image data is completely stored in the image memory 111 by the procedure described above, the geometric distortion correction means 112 reads the image data of (1) and (2) at each X-ray generation point, The geometric distortion of the image caused by the X-ray detector is corrected for each image.

As a method of correcting geometric distortion, the method described in Medical Electronics and Bio-Optics, page 222 of the 33rd Annual Meeting of the ME Society of Japan (1994) can be mentioned.

The image data for which the geometric distortion has been corrected is subjected to image composition by the image composition means 113.

However, the image composition is performed according to the above-described embodiment shown in FIGS.

At this time, the combined images obtained by image combining are overwritten in the memory banks in which the images before combining are stored, and are again stored in the image memory 111.

FIG. 14B is a diagram showing a state in which image composition has been performed for all memory banks Φ in FIG. 14A and storage of synthesized images has all been completed. , A composite image of the subject 11 obtained at the corresponding X-ray generation point is stored.

Therefore, when observing an X-ray image, the image data stored in each memory bank is
It may be displayed directly by the image display means 19.

Further, by subjecting the composite image described above to image reconstruction using the reconstruction processing means 114, the subject 11
It is needless to say that the X-ray three-dimensional CT image can be obtained.

As the reconstruction processing, the Feldkamp method, the Grandiet method, or the like described above can be used as they are.

In the middle of the image reconstruction, the intermediate result of the reconstructed image is stored in the image memory 11 for sequentially storing the reconstructed images.
Stored in 5.

The reconstructed image of the subject 11 stored in the image memory 115 is displayed on the image display means 19 during the reconstruction process or after the reconstruction process is completed.

As described above, X of the first embodiment
According to the X-ray imaging apparatus, in an X-ray apparatus that obtains X-ray fluoroscopic images or X-ray imaging images or X-ray CT measurement values of the subject 11 from two directions, a plurality of X-ray sources and a single X-ray source facing each other are provided. Rotating plate 6 with fixed imaging system consisting of X-ray detector
By rotating around the subject, it is possible to obtain an X-ray transmission image of a region wider than the field of view of the X-ray detector in the direction parallel to the rotating surface of the rotating plate 6.

Therefore, the field of view of the cross-sectional plane of the X-ray fluoroscopic image, the X-ray radiographic image, or the X-ray CT image can be enlarged.

Further, since the field of view for imaging can be expanded, it is possible to improve the diagnostic ability of lung cancer or the like, which conventionally had to be imaged multiple times.

As described above, X in the first embodiment
According to the X-ray imaging apparatus, the rotation control means 12 is attached to the X-ray tube moving rail 10 provided on the rotation surface of the rotary plate 6, and the X-ray tube 1 (a) and the X-ray tube 1 (b) are attached. The angle is 2
Arrange so that it becomes θ.

At this time, the angle 2θ and the X-ray irradiation direction are X-rays emitted from the X-ray tubes 1 (a) and 1 (b).
The imaging range in which the X-ray images captured by the X-ray are combined is set so as to cover the affected part of the subject 11 that is the imaging target.

Next, the X-ray tubes 1 (a), 1 (b) and the X-ray detector are held at the relative positions, that is, the X-ray tubes 1 (a), 1 (b) are moved to the X-ray tube. While being fixed to the rail 10 for moving the X-ray tube, the X-ray tube 1 (a), 1
(B) and the X-ray detector are rotated around the subject 11.

Here, the imaging is performed by the X-ray tubes 1 (a) and 1 (b).
Are operated alternately. At this time, the X-ray tube 1 (a),
The interval of 1 (b), that is, the angle formed by the straight line connecting the X-ray tube 1 (a) and the rotation center and the straight line connecting the X-ray tube 1 (b) and the rotation center satisfies the above-mentioned expression (6). By setting the angle and rotating the rotating plate 6 at a constant speed, the X-ray tube 1 (a) and the X-ray tube 1 (b) are alternately turned to the X-ray generation point Φ ( Since k) is reached, the time intervals of X-ray irradiation can be equalized.

Further, the intervals of capturing (imaging) X-ray images by the television camera 5 can be made equal.

Next, when the image pickup of the X-ray image is completed, (a) and (b) of the image memory 111 for the image data.
The X-ray images stored in the respective banks are combined into one as shown in FIG. 8 described above, stored again in the original position, and the combined X-ray image is used to generate the X-ray images shown in FIG. As shown in FIG. 5, an X-ray image having a wider viewing angle than the viewing angle of the image intensifier 3 can be obtained, so that the viewing angle of the X-ray image can be expanded while the subject 11 is stationary.

On the other hand, in the case of reconstructing a tomographic image by a reconstructing means (not shown), the tomographic image of the subject can be reconstructed from the X-ray image whose viewing angle is enlarged by combining them into one image. The corner can be enlarged.

Furthermore, since the S / N ratio of the X-ray image can be improved, the diagnostic ability of lung cancer and the like can be improved.

(Second Embodiment) FIG. 15 shows a second embodiment.
Of the X-ray imaging apparatus, the rotation of the rotary plate 6 and the X-ray tube 1
(A), It is a front schematic diagram for demonstrating an example of the relationship of X-ray irradiation by the X-ray tube 1 (b).

In FIG. 15, the rotary plate 6 is rotated twice, and the direction of rotation is reversed between the first rotation and the second rotation.

The relationship between the rotation of the rotary plate 6 and the X-ray image capturing by the X-ray tube 1 (a) and the X-ray tube 1 (b) will be described below with reference to FIG.

First, at the starting point (A), the X-ray tube 1 (b) is X
It exists at the position of the line generation point Φ = 0. This corresponds to the fact that the X-ray tube 1 (b) exists at the position of the X-ray generation point Φ (0) in FIG.

At the same time when the rotary plate 6 starts to rotate in the counterclockwise direction, the X-ray tube 1 (b) causes the X-ray generation points Φ (0), Φ.
(1), ..., Φ (L-1) is irradiated with X-rays,
Fluorograph or photograph.

Time point (B) shows the time when the rotary plate 6 rotates 180 degrees with respect to the time point (A), and time point (C) shows that the rotary plate 6 rotates 360 degrees with respect to the time point (A). Indicates the time point.

From time (A) to time (C), X-ray irradiation is performed only by the X-ray tube 1 (b), and the X-ray tube 1 (a) is operated by X-ray irradiation.
Do not irradiate the line.

At time (C), when the X-ray tube 1 (b) returns to the position of the X-ray generation point Φ (0) again, the X-ray tube 1 (b) stops irradiation of X-rays.

At time point (D), the rotary plate 6 continues to rotate counterclockwise after time point (C), and the X-ray tube 1 (a) is at the position of the X-ray generation point Φ (0). is there.

From the time point (C) to the time point (D), the rotational speed of the rotary plate 6 is gradually decreased so that the rotational speed becomes 0 at the time point (D).

From time (C) to time (D),
Both the X-ray tube 1 (a) and the X-ray tube 1 (b) stop irradiation of X-rays.

At the time point (D), the rotating direction of the rotary plate 6 is reversed to clockwise.

At the same time when the rotary plate 6 starts rotating in the clockwise direction, the X-ray tube 1 (a) moves to the X-ray generation points Φ (0), Φ.
X-rays are irradiated at (L-1), Φ (L-2), ..., Φ (1) to perform imaging.

Time point (E) shows the time when the rotary plate 6 rotates 180 degrees with respect to the time point (D), and time point (F) has the rotary plate 6 rotate 360 degrees with respect to the time point (D). Indicates the time point.

From time point (D) to time point (F), X-ray irradiation is performed only by the X-ray tube 1 (a), and X-ray tube 1 (b) is operated by X-ray irradiation.
Do not irradiate the line.

At time (F), when the X-ray tube 1 (a) returns to the position of the X-ray generation point Φ (0) again, the X-ray tube 1 (a) stops irradiation of X-rays, End fluoroscopy or filming.

For the sake of supplement, FIG. 15 shows the time change of the rotation angle Φ of the photographing system.

Further, T is a rotation cycle required for the rotary plate 6 to make one rotation around the subject, and τ is a transition time required to transit from the time point (C) to the time point (D).

For example, when the scanning mode is set to 60 frames per second and the television camera 5 having the scanning number of 525 is used and the number L of all X-ray generation points is 288, the rotation cycle T is 4.
8 seconds, and the typical transition time τ is 0.4
Seconds.

Therefore, the time required for all photographing is 2T.
Since it is calculated as + τ, it takes 10 seconds.

When the image is taken by the X-ray imaging apparatus of the second embodiment, the image information (image data) after A / D conversion is the Φ of FIG.
(0) (b), followed by Φ (1) (b),
..., Φ (L-1) (b), Φ (L-1) (a), ..., Φ
(0) The data is stored in the order of (a), and the storage in the memory is completed.

The schematic configuration of the X-ray imaging apparatus according to the second embodiment is the same as the schematic configuration of the X-ray imaging apparatus according to the first embodiment shown in FIG. 1, and the control program of the imaging control means 12 will be described above. It can be realized by changing to a program that realizes the procedure.

As described above, X of the second embodiment
According to the X-ray imaging apparatus, the X-ray tube 1
By operating only (a) to capture an X-ray image, and in the next rotation of the second rotation, only the X-ray tube 1 (b) is activated to capture an X-ray image. Similarly to the X-ray imaging apparatus of No. 1, the X-ray image intensifier 3 of the X-ray image intensifier 3 is generated by generating a composite image from the X-ray images taken when the X-ray tubes 1 (a) and 1 (b) are at the same position. An X-ray image with a viewing angle larger than the viewing angle can be obtained.

Therefore, the field of view of the cross-sectional tomographic plane of the X-ray fluoroscopic image, the X-ray radiographic image, or the X-ray CT image can be enlarged.

Furthermore, since the S / N ratio of the X-ray image can be improved, the diagnostic ability of lung cancer and the like can be improved.

(Embodiment 3) FIG. 16 is a view for explaining the arrangement of X-ray tubes of an X-ray imaging apparatus according to Embodiment 3 of the present invention, and the X-rays of Embodiments 1 and 2 described above. This is a case where the number of X-ray tubes of the imaging apparatus is set to one or three instead of two.

In FIG. 16, 1 (c) is the X-ray tube 1.
It is an X-ray tube as in (a) and 1 (b).

FIG. 16 (A) shows that two X-ray tubes are mounted as shown in the first and second embodiments, or
FIG. 2 is a diagram showing a case where imaging is performed using only one X-ray tube in an X-ray imaging apparatus equipped with a plurality of X-ray tubes, and the X-ray tube 1 (a) is placed on a rail 10 for moving the X-ray tube. Move with, X
It is located in front of the line detector and takes pictures.

The front face in this case is an extension of a straight line connecting the X-ray detector and the center of rotation of the rotary plate 6.

In this case, only the X-ray tube 1 (a) is used for photographing, and the X-ray tube 1 (b) is not used.

Imaging at this time is equivalent to that of the conventional rotary DSA apparatus or cone beam CT apparatus.

Although the case where the X-ray tube 1 (a) is used for imaging is shown here, the selection of the X-ray tube to be used is not limited to that of the X-ray tube 1 (a) and the X-ray tube 1 (b). It goes without saying that one of them can be selected according to the frequency of use and the like.

FIG. 16B is a diagram showing a case where the number of X-ray tubes is three, and the X-ray tube 1 (b) is arranged in front of the X-ray detector, and the X-ray tube 1 ( a) and the X-ray tube 1 (c) are symmetrically arranged at positions inclined by 2θ to the left and right with respect to the X-ray tube 1 (b).

Even when the number of X-ray tubes is four or more, similarly, by arranging the X-ray tubes at symmetrical positions with respect to the X-ray detector, the field of view can be further expanded. Needless to say.

Next, FIG. 17 shows a diagram for explaining the relationship between the inclination θ of the X-ray tube and the number of X-ray tubes.
7, the relationship between the inclination θ of the X-ray tube and the number of X-ray tubes will be described.

In FIG. 17, as described above, when three X-ray tubes are arranged as shown in FIG. 16B, each X-ray tube exists at the same X-ray generation point position Φ. In this case, the positions of the detection surfaces of the respective X-ray detectors are shown in an overlapping manner.

When the total viewing angle of the superposed X-ray detectors with respect to the rotation center O is 2γ, γ is as shown in FIG.
As is clear from, it can be expressed by the following equation (11).

Γ = β + 2θ (11) Here, β is the angle given by the above-mentioned equation (3).

On the other hand, in general, N X-ray tubes (where N ≧
Γ when used (natural number of 1) is given by the following equation (12).

Γ = β + (N−1) θ (12) Further, with respect to γ obtained in this way, the photographing viewing angle 2
α can be obtained by using the above-described equation 4.

Further, even when there are N X-ray tubes, the imaging procedure described in the first and second embodiments can be applied.

When the imaging procedure described in the first embodiment is applied, all the X-ray tubes for all two adjacent X-ray tubes are set so that the angle 2θ between them becomes the following expression (13). To place.

2θ = ΔΦ (M + 1 / N) (13) At this time, for each rotation of the rotation plate 6 by the angle ΔΦ / N, N X
Since any one of the X-ray tubes is sequentially located on each X-ray detection point, by rotating the rotary plate 6 once at a constant speed,
All X-ray generation points Φ (0), Φ (1), ..., Φ (L-
In 1), fluoroscopy or photographing can be easily performed.

FIG. 18 is a diagram showing the visual field size of a composite image in the horizontal and vertical directions in the case where radiography is generally performed using N X-ray tubes in the X-ray radiographing apparatus according to the third embodiment. Is.

In FIG. 18, H represents the horizontal visual field size of the composite image, while V represents the vertical visual field size of the composite image.

However, the visual field size in this case does not represent the size of the display portion 96 on the display screen 97, but the size on the virtual detector plane 90 corresponding thereto.

The virtual detector plane 90 is the rotation center O of the rotary plate 6.
The field size on the virtual detector surface expresses the field size at the center position of the subject 11 because it is defined to exist at the position of.

Therefore, as described above, the values of the visual field sizes H and V defined in this embodiment are the same as those of the subject 1.
For a size of 1, it can be used directly in determining the field size.

In FIG. 18, the value of V is defined as the minimum visual field size restricted in the vertical direction because the visual field of the X-ray detector is circular.

Generally, these values change depending on the number N of X-ray tubes, but the change amount of such a value is small.

Therefore, it is practically acceptable to represent these by the value of V when the number N of X-ray tubes as shown in FIG. 14 is 2, and therefore, as described above, equation (8) , (9).

On the other hand, the value of the visual field size H in the horizontal direction is given by the above equations (10) and (11).

From the above, the horizontal and vertical directions of the composite image are calculated using the equations (8) to (10) and the equation (11) with the number N of X-ray tubes and the inclination θ of the X-ray tubes as parameters. The visual field sizes H and V can be obtained.

FIG. 19 is a perspective view of the X-ray imaging apparatus according to the third embodiment, and a composite of the X-ray transmission image of the subject 11 to be imaged, with respect to the spatial resolution, the imaging time, and the inclination θ of the X-ray tube. It is a figure which shows the representative value of the visual field size of an image about the case where the number N of X-ray tubes is 1-4.

In FIG. 19, as described above, the radius of rotation D of the X-ray tube is 720 mm, the center of rotation of the rotary plate 6 and the X axis.
The distance d to the line detector is 380 mm.

Also, the television camera 5 has 525 scanning lines,
An image is captured at 60 frames per second, and the number L of X-ray generation points is 288.

FIG. 19A shows the spatial resolution of the X-ray image intensifier 3 for the imaging modes of 7, 9, 12, and 16 inches.

Here, the spatial resolution is 0 for the inclination θ of the X-ray tube.
In this case, the spatial resolution at the position of the rotation center O of the rotary plate 6 is defined.

When the inclination θ of the X-ray tube is increased, the spatial resolution changes, but this does not depend on the position on the detection surface of the X-ray detector, the position of the X-ray detector with respect to the X-ray tube, or the like. Needless to say.

The values shown in FIG. 19A are typical spatial resolution values.

FIG. 19B shows the relationship between the number N of X-ray tubes and the imaging time.

However, the photographing time here indicates the time required for performing fluoroscopy or photographing in accordance with the image pickup procedure described in the first embodiment.

When fluoroscopy or radiography is performed according to this procedure, the radiography time required when the number N of X-ray tubes is 1 is T, and the radiography time required when the number of X-ray tubes is N. Becomes NT.

In FIG. 19C, the vertical view size V of the composite image is shown with respect to the X-ray image intensifier 3 photographing modes in which the inclination θ of the X-ray source is 5 degrees and 10 degrees.
It is calculated for the case of 15 degrees.

The vertical view size V of the composite image is
For details, see FIG.

In the X-ray radiographing apparatus of this embodiment, as shown in FIG.
The values shown in 9 (A) to (C) and FIG. 12 (B) are
Each of them is stored in a read-only memory as a reference table, and is used to determine the imaging mode of the X-ray image intensifier 3 and the inclination θ of the X-ray tube during imaging.

Note that in FIG. 19C and FIG. 12B, the inclination θ of the X-ray tube is set to 5, 1 for simplicity.
Although only three types of 0 and 15 degrees are shown, it is needless to say that the setting of θ at the time of photographing can be more appropriately performed by preparing a reference table for a finer step of θ. .

FIG. 20 shows the X-ray imaging apparatus according to the third embodiment in which the X-ray is determined based on the size of the measurement region of the subject 11.
FIG. 6 is a block diagram showing a procedure for determining the number N of the X-ray tubes, the imaging mode of the X-ray image intensifier 3, the inclination θ of the X-ray tube, and starting imaging.

However, the number N of X-ray tubes is determined within the range of 1 to N with respect to the number N of X-ray tubes actually mounted.

First, the measurement area of the subject 11 is determined based on the size of the subject 11 measured by the subject size measuring means 26 or the size of the subject 11 set by the operator, and the measured region is stored in the memory. Record (step 600).

Next, with respect to the size of the measurement region of the subject 11 recorded in the memory in step 600, a set of horizontal and vertical visual field sizes H and V including all or most of them. Are all selected and set as candidates (step 601).

When obtaining the set of H and V, the above-mentioned FIG. 19 stored in the read-only memory in advance is used.
And a table corresponding to FIG. 12B is referred to.

Next, for the set of H and V selected in step 601, the number N of X-ray tubes that realizes these, the shooting mode of the X-ray image intensifier 3,
All combinations of inclinations θ of the X-ray tube are recorded in the memory as candidate values (step 602).

Of all the candidate values recorded in step 602, the horizontal and vertical visual field sizes H and V are obtained.
Alternatively, the optimum candidate value is determined according to the spatial resolution and the photographing time (step 603).

The optimum candidate value may be determined automatically or manually by an operator,
It goes without saying that a combination of both may be performed semi-automatically.

The optimum candidate is obtained by referring to the tables stored in the read-only memory in advance and corresponding to FIGS. 19 and 12B.

As a method of automatically determining the optimum candidate value, for example, the following method is available.

First, from among all candidate values,
A set of H and V that is extremely large with respect to the size of the measurement region of the subject 11 is excluded from the candidate values.

Next, as the second, some of the remaining candidate values having a high spatial resolution are selected in order from the top, and the remaining candidate values are excluded.

Thirdly, from the remaining candidate values,
The one with the shortest shooting time is selected as the optimum candidate value.

Needless to say, the order of the above-mentioned first to third procedures may be freely changed according to the will of the operator.

In addition, any one of the above-mentioned procedures 1 to 3 or all the procedures are manually performed based on the intention of the operator, and the remaining procedures are automatically performed by the information processing apparatus, for example. It is needless to say that the optimum candidate value can be determined by a semi-automatic or manual method that is performed by.

Next, the optimum candidate value obtained in step 603 is recorded in a memory (not shown) (step 60).
4).

For the optimum candidate value obtained in step 604, first, the minimum M that satisfies the following equation (14) is obtained.

Next, the accurate inclination θ of the X-ray tube 1 with respect to this minimum M is obtained by the above-mentioned equation (13) (step 605).

2θ ≦ ΔΦ (M + 1 / N) (14) Of the candidate values stored in the memory (not shown) in step 604, the inclination θ of the X-ray tube is calculated as the exact X obtained in step 605. The inclination θ of the wire tube is replaced with the final setting value (step 606).

Next, the number N of X-ray tubes and the photographing mode of the X-ray image intensifier 3 are set with respect to the final set values recorded in step 606.

Further, the X-ray tube is moved on the X-ray tube moving rail 10 so that the inclination θ of the X-ray tube becomes a set value. Further, the operator changes the X-ray irradiation range for each X-ray tube according to the method described above (step 607).

Finally, in step 608, photographing is started.

In this case, the image memory 11
The size of 1 is, for example, Φ for three X-ray tubes.
Needless to say, the number of banks is increased as in (0) (a), Φ (0) (b), and Φ (0) (c).

As described above, X in the third embodiment
According to the radiographic apparatus, in order to obtain an X-ray fluoroscopic image, an X-ray radiographic image, or an X-ray CT measurement value of the subject 11 from a plurality of directions, a plurality of X-ray tubes 1 (a), 1 (b) are used. ) And an X-ray image intensifier 3 facing them, and a rotating plate 6 having a fixed imaging system is rotated about the subject 11 so as to move in a direction parallel to the rotating surface of the rotating plate 6. It is possible to obtain an X-ray transmission image of a region wider than the visual field of the X-ray image intensifier 3 which is a line detector.

Therefore, the field of view of the cross-sectional plane of the X-ray fluoroscopic image, X-ray radiographic image, or X-ray CT image can be enlarged.

Furthermore, since the S / N ratio of the X-ray image can be improved, the diagnostic ability of lung cancer and the like can be improved.

Although the present invention has been specifically described based on the first to third embodiments, the present invention is not limited to the embodiments of the present invention, and various modifications can be made without departing from the scope of the invention. Of course,

For example, as the X-ray detector, an X-ray image intensifier 3, an optical lens system 4, and a television camera 5 having a high-resolution image pickup tube as a photographing element was used. It goes without saying that the present invention can also be applied to vessels.

As the other X-ray detector described above,
For example, an X-ray detector composed of an X-ray image intensifier, an optical lens system and a CCD camera,
Fluorescent plate, optical lens system and high resolution image pickup tube or CC
An X-ray detector, a two-dimensional semiconductor sensor, or the like, which includes a television camera having D as an imaging element, can be used.

Needless to say, the present invention can be applied to a general X-ray fluoroscopic apparatus, X-ray imaging apparatus, stereoscopic X-ray imaging apparatus and the like.

Further, as shown in FIGS. 12 and 19, the viewing angle of the X-ray image obtained by the synthesis increases as the number of X-ray tubes 1 increases, but as the number of X-ray tubes 1 increases, the imaging is performed. Time and the memory capacity of the image memory 111 required to store the X-ray image increase, and the configuration of the X-ray imaging apparatus becomes complicated.

On the other hand, by increasing the interval θ between the adjacent X-ray tubes, the size of the X-ray images obtained by the synthesis can be increased in the H direction, but the size in the V direction becomes smaller.

Therefore, in the X-ray imaging apparatus of the present invention, the number of X-ray tubes 1 is about 2 to 3, and the interval θ is
Is about 0 to 15 degrees.

When the interval θ is 0 degree, it can be realized by using one of a plurality of X-ray tubes as shown in FIG. 16, for example.

[0350]

The effects obtained by the representative ones of the inventions disclosed in the present application will be briefly described as follows.

(1) An X-ray image having a viewing angle larger than that of the X-ray detector can be taken with the subject stationary.

(2) X-ray image Since the X-ray image amplified by the intensifier is directly converted into an electric signal by the television camera, it is possible to take an image in a bright room.

(3) Since the amount of X-rays irradiated to the subject can be limited by setting the X-ray irradiation range that is unnecessary for synthesizing the X-ray images, the amount of X-ray exposure of the subject can be minimized. You can keep it to the limit.

(4) Since the size of the subject and the resolution of the X-ray detecting means required for imaging can be changed by adjusting the interval between the X-ray irradiating means, the X-ray image can be obtained under conditions suitable for the subject. Can be imaged.

(5) Correction of the X-ray image picked up by the X-rays emitted from each X-ray irradiating means by setting each X-ray irradiating means on the circumference centered on the rotation center at predetermined intervals. Since the same procedure can be performed, each X-ray image can be easily corrected.

(6) By arranging the X-ray irradiating means so that two or more X-ray irradiating means are not simultaneously positioned at a predetermined position of rotation, which is a position for irradiating X-rays and capturing an X-ray image. While the rotating means makes one revolution, each X-ray irradiating means sequentially reaches the position where the X-ray image is picked up.
X-ray imaging can be performed simply by rotating.

Since only one X-ray irradiating device operates, the rotating device can be rotated at a constant speed.

(7) The X-ray image is picked up by operating the X-ray irradiation means which has reached a predetermined position of rotation, which is a position for irradiating X-rays and picking up an X-ray image, in a predetermined order. Since it can be determined, it becomes easy to store the X-ray image.

(8) Since the switching operation of the X-ray irradiating means can be simplified by specifying the X-ray irradiating means to be operated for each rotation of the rotating means, the X-ray irradiating means, the rotating means and the X-ray irradiating means The line imaging means can be easily controlled.

(9) By providing the reconstructing means,
Since a tomographic image can be reconstructed based on an X-ray image having a viewing angle larger than that of the X-ray imaging means, the viewing angle is larger than that of the X-ray detector while the subject is stationary. A tomographic image can be reconstructed.

(10) The rotation means is set by setting the angle formed by the adjacent X-ray irradiation means with respect to the rotation center and the predetermined rotation position ΔΦ so that 2θ = ΔΦ (M + 1 / N) is satisfied. Since each X-ray irradiator sequentially reaches the position for capturing an X-ray image during one rotation of X, X-ray imaging can be performed only by rotating the rotating unit once.

Further, since the predetermined positions of rotation are arranged at equal intervals, the operation intervals of the X-ray irradiating means can be made constant.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an X-ray imaging apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram for explaining a positional relationship between a rotation angle of a rotating plate and each X-ray tube when capturing an X-ray image in the first embodiment.

FIG. 3 is an X-ray tube 1 (a) and an X-ray tube 1 according to the first embodiment.
It is the figure which showed the detection surface position of each X-ray detector in case (b) exists in the same X-ray generation point position (PHI).

FIG. 4 is an X-ray tube 1 in the X-ray imaging apparatus according to the first embodiment.
Inclination θ of (a) and the X-ray tube 1 (b) with respect to the rotating plate
3 is a graph showing the relationship between the image pickup viewing angle 2α and

FIG. 5 is a diagram for explaining an X-ray irradiation position of the X-ray imaging apparatus according to the first embodiment.

FIG. 6 is a diagram for explaining an example of a relationship between a rotation angle of a rotating plate and X-ray tubes 1 (a) and 1 (b) in the X-ray imaging apparatus according to the first embodiment.

FIG. 7 is an X-ray tube 1 (a) of the X-ray imaging apparatus according to the first embodiment.
FIG. 6 is a diagram for explaining a method of determining the inclination θ of the X-ray tube 1 (b).

FIG. 8 is the same X in the X-ray imaging apparatus according to the first embodiment.
It is a figure for demonstrating the method of synthesize | combining the X-ray transmission image of the two to-be-examined objects fluoroscopically or imaged by the X-ray irradiated at the line generation point into one sheet.

FIG. 9 is a diagram for explaining a composite image obtained by the image composition shown in FIG. 8.

FIG. 10 is a diagram for explaining a method of synthesizing overlapping portions when synthesizing X-ray images at the same X-ray generation point in the X-ray imaging apparatus according to the first embodiment.

FIG. 11 is a diagram for explaining the visual field size of the composite image shown in FIG. 7.

FIG. 12 is a diagram showing a spatial resolution of an X-ray transmission image in the X-ray imaging apparatus according to the first embodiment and a representative value of a visual field size of a combined image with respect to an X-ray tube and its inclination θ.

FIG. 13 is a diagram for explaining a procedure until the X-ray imaging apparatus according to the first embodiment starts imaging.

FIG. 14 is a block diagram for explaining the operation of the X-ray imaging apparatus according to the first embodiment.

FIG. 15 is a schematic front view for explaining an example of the relationship between the rotation of the rotating plate and the X-ray irradiation by the X-ray tube 1 (a) and the X-ray tube 1 (b) in the X-ray imaging apparatus according to the second embodiment. It is a figure.

FIG. 16 is a diagram for explaining the arrangement of X-ray tubes in the X-ray imaging apparatus according to the third embodiment of the present invention.

FIG. 17 is a diagram for explaining the relationship between the inclination θ of the X-ray tube and the number of X-ray tubes.

FIG. 18 is a diagram showing the field-of-view size of a combined image in the horizontal and vertical directions when imaging is performed using N X-ray tubes in the X-ray imaging apparatus according to the third embodiment.

FIG. 19 is a perspective view of the X-ray imaging apparatus according to the third embodiment,
FIG. 3 is a diagram showing a representative value of a visual field size of a composite image with respect to a spatial resolution, an imaging time, and an inclination θ of an X-ray tube of an X-ray transmission image of a subject to be imaged.

FIG. 20 shows the number of X-ray tubes, X, based on the size of the measurement region of the object in the X-ray imaging apparatus according to the third embodiment.
It is the block diagram which showed the procedure until the imaging mode of a line image intensifier, the inclination of an X-ray tube are determined, and imaging is started.

[Explanation of symbols]

1 (a), 1 (b), 1 (C) ... X-ray tube, 2 ... X-ray grid, 3 ... X-ray image intensifier, 4 ... Optical lens system, 5 ... Television camera, 6 ... Rotating plate, Reference numeral 7 ... Bed top, 8 ... Weight, 9 ... Rail for moving weight, 10 ... Rail for moving X-ray tube, 11 ... Subject, 12 ... Imaging control means, 13 ... Rotating plate driving means, 14 ... X-ray tube position Control means, 15 ... Weight position control means, 16 ... X-ray tube position measurement means, 17 ... Rotating plate angle measurement means, 18 ... Image collection processing means, 19 ... Image display means, 20 ... Detection surface of X-ray detector, 21 ... Rail for moving line detector, 22 ... X-ray detector position control means, 23 ... X
Line detector position measuring means, 24 (a), 24 (b) ... Collimator, 25 ... X-ray irradiation range control means, 26 ... Subject size measuring means, 110 ... A / D converter, 111 ... Image memory, 112 ... Geometric distortion correcting means, 113 ... Image combining means, 114 ... Reconstructing means, 115 ... Image memory for reconstruction.

Claims (13)

[Claims] 1. An X-ray irradiating means for irradiating a subject with X-rays, an X-ray imaging means for imaging the subject with X-rays, and the X-ray irradiating means and the X-ray imaging means for the subject. An X-ray imaging apparatus having rotating means for rotating the X-ray irradiating means, wherein the X-ray irradiating means setting means for setting the plurality of X-ray irradiating means at predetermined intervals, and the rotating means for controlling the plurality of X-ray irradiating means. The plurality of X-ray irradiating means and the X-ray imaging means are rotated around the subject while maintaining the relative positions of the X-ray irradiating means and the X-ray imaging means, and the plurality of X-ray irradiating means are rotated.
When the X-ray irradiating unit reaches a predetermined position of rotation, the X-ray irradiating unit that has reached the predetermined position of rotation is operated to irradiate X-rays, and X-ray imaging control unit for performing X-ray imaging of the subject. And synthesizing a plurality of X-ray images captured by the plurality of X-ray irradiating means at the predetermined position, and synthesizing X-ray images having a viewing angle larger than the viewing angle of the X-ray imaging means, An X-ray image synthesizing device, comprising: an X-ray image synthesizing unit that converts the X-ray image into an X-ray image captured at the predetermined position. 2. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging unit is an X-ray detector that converts an X-ray image transmitted through the subject into an electric signal. 3. The X-ray detector is a two-dimensional X-ray detector, and the X-ray irradiator is an X-ray irradiator that irradiates a conical X-ray. X-ray equipment. 4. The X-ray imaging unit is an X-ray detection device including an X-ray image intensifier and a television camera, and the X-ray irradiation unit is an X-ray irradiation device that irradiates a conical X-ray. The X-ray imaging apparatus according to claim 1, wherein: 5. The X-ray irradiating means comprises an irradiation range limiting means for restricting an X-ray irradiation range to a predetermined range, according to any one of claims 1 to 4. The described X-ray imaging apparatus. 6. The X-ray irradiating means setting means sets an interval between the X-ray irradiating means based on a size of an imaging target portion of a subject.
The X-ray imaging apparatus according to claim 1. 7. The X-ray irradiating means setting means is provided for each X-ray irradiation means.
7. The X according to claim 1, wherein an interval between the X-ray irradiators is set to an interval in which an irradiation range including the irradiation ranges of the respective X-ray irradiators covers the subject. X-ray equipment. 8. The X-ray irradiating means setting means sets an interval between each of the X-ray irradiating means on a circumference around a rotation center of the plurality of X-ray irradiating means and the X-ray imaging means. The X-ray imaging apparatus according to claim 1, wherein the X-ray imaging apparatus is set to a predetermined value. 9. The X-ray irradiation means setting means sets the plurality of X-ray irradiation means at intervals such that two or more of the plurality of X-ray irradiation means do not simultaneously reach a predetermined position of the rotation. 9. Then, the X-ray irradiating means that has reached a predetermined position of the rotation is operated to irradiate X-rays, and the X-ray image of the subject is picked up. X-ray equipment. 10. The X-ray imaging control means operates the X-ray irradiation means which have reached a predetermined position of the rotation one by one in a predetermined order.
The X-ray imaging apparatus according to claim 1. 11. The X-ray imaging control means operates one X-ray irradiation means from the plurality of X-ray irradiation means for each rotation of the rotation means. The X-ray imaging apparatus according to any one of 1 to 9. 12. The X-ray imaging apparatus according to claim 1, further comprising reconstruction means for reconstructing the X-ray image into a tomographic image of a subject. 13. The predetermined position of the rotation for irradiating the X-rays is an angle ΔΦ that equally divides 360 ° around the subject into arbitrary integers, and the number of the plurality of X-ray irradiating means is N. , An arbitrary integer value M when the angle formed by the adjacent X-ray irradiating means in the X-ray irradiating means and the rotation center is 2θ.
, The angle formed by the adjacent X-ray irradiation means is 2θ.
2. The method according to claim 1, wherein: ΔΦ (M + 1 / N)
13. The X-ray imaging apparatus according to any one of 1 to 12.