JP2001095789A - X-ray fluoroscopy photographing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray fluoroscopy photographing apparatus which can obtain fluoroscopy photographing image without image distortion in spite of the variation of distance between an X-ray tube and a photographing mechanism. SOLUTION: The spherical X-ray detector 11 is formed on the concave surface side of the concave shape flexible spherical substrate, which projects to the radiating direction of X-beam radiated from the X-ray tube 1. The spherical X-ray detector 11 is fixed and arranged on the concave surface side of memory alloy spherical supporting body 13. The spherical X-ray detector 11 can be moved to O-direction (up and down direction) of X-ray radiation axis. By the movement, the distance D between the X-ray focus F and the spherical X-ray detector 11 is detected by the distance detector 5. The curvature control circuit 3 calculates the curvature for center of X-ray to obtain the electric current to supply to the memory alloy spherical supporting body 13, and supplies electric current to the spherical supporting body 13. The electric current changes the curvature of the X-ray detector to have center point of X-ray focus F and curvature of radius of distance D between X-ray focus F and the spherical X-ray detector 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray fluoroscopic apparatus used for medical diagnosis, and more particularly, to an X-ray detecting device as an imaging mechanism for receiving X-rays transmitted through a subject and obtaining image data.
The present invention relates to an X-ray fluoroscopic apparatus using two-dimensional X-ray detectors arranged in a dimension (matrix).

[0002]

2. Description of the Related Art An X-ray fluoroscopy apparatus of this type includes an X-ray tube for irradiating an object with X-rays, an X-ray tube arranged opposite to the X-ray tube, receiving the transmitted X-rays from the object, and converting the image data into image data. And an image intensifier (II) for receiving an X-ray transmitted through the subject and converting the X-ray into a visible image. I. Is used in combination with a television camera that converts the output image of the above into a video signal (image data).

[0003] I. Is a large vacuum tube. Due to the shape of the convex spherical input surface protruding in the X-ray tube direction and the configuration of the electron lens system, image distortion is unavoidable, and this image distortion extends to the periphery rather than the center of the image. The distortion is large, and this peripheral distortion is corrected by image processing. However, it is not perfect, and the I.V. I. However, it does not completely eliminate the peripheral distortion, and does not correct distortion by image processing or I.T. I. The use of makes the equipment expensive. Further, flat X-ray detectors (flat panel X-ray detectors) in which the X-ray detection elements are arranged in a matrix in the vertical and horizontal directions and have no peripheral distortion have been developed and are being put to practical use.

[0004]

However, even if a flat panel X-ray detector having no peripheral distortion is used as an imaging mechanism, image distortion cannot be avoided and it cannot be a fundamental solution. That is, since the flat panel X-ray detector is a flat surface, no image distortion occurs when X-rays enter the detector perpendicularly. However, since the X-rays are irradiated in a cone shape from the focal point of the X-ray tube, this cone beam is received on the flat imaging surface of the flat panel X-ray detector,
Since the distance to the X-ray focal point differs between the center and the periphery of the flat panel X-ray detector, and the distance increases toward the periphery, image distortion that the image is enlarged toward the periphery is inevitable. There is a problem that image data without distortion cannot be obtained.

[0005] Further, in this type of X-ray fluoroscopic apparatus, contact imaging in which an imaging mechanism is brought into close contact with a subject and magnified imaging in which the imaging mechanism is separated from the subject are performed in accordance with the purpose of diagnosis, the diagnostic site, and the like. For this purpose, the distance between the X-ray tube and the imaging mechanism can be changed. Therefore, image distortion due to the difference in magnification between the central part and the peripheral part changes depending on the distance between the X-ray tube and the imaging mechanism.
Grasping the positional relationship of the site of interest and the size and shape of the object,
In addition, there is a problem that measurement on an image cannot be performed accurately.

[0006] The present invention has been made in view of such circumstances, and image distortion is remarkably reduced regardless of a change in the distance between the X-ray tube and the imaging mechanism. An object of the present invention is to provide an X-ray fluoroscopic apparatus capable of obtaining image data.

[0007]

In order to achieve the above-mentioned object, an X-ray fluoroscopic apparatus according to the present invention comprises an imaging mechanism in which a large number of X-ray detecting elements are provided on a concave surface whose imaging surface protrudes in the X-ray radiation direction.
A spherical two-dimensional X-ray detector arranged in two dimensions,
The curvature of the spherical two-dimensional X-ray detector is defined as the X-ray tube and the 2
It is characterized in that it is changed according to the distance between the dimensional X-ray detectors.

Therefore, according to the X-ray fluoroscopy table of the present invention having such a configuration, the curvature of the spherical two-dimensional X-ray detector is limited between the X-ray tube and the spherical two-dimensional X-ray detector. The radius of curvature changes with the radius between the X-ray tube (more precisely, the X-ray focal point) and the spherical two-dimensional X-ray detector. Irrespective of the distance between the line detectors, the distance from the center to the periphery of the two-dimensional X-ray detector to the X-ray focal point is the same at any position on the imaging surface, and no image distortion occurs.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the X-ray fluoroscopic table according to the present invention will be described with reference to the drawings. As shown in FIG. 1, a subject (patient) M is placed on a table B, and an X-ray tube 1 is disposed below the subject M, and an imaging mechanism 11 is disposed above the X-ray tube 1 so as to face the X-ray tube 1. . The imaging mechanism 10 has a spherical two-dimensional X-ray in which X-ray detection elements are two-dimensionally (vertically and horizontally) arranged.
In this embodiment, in the X-ray detector 10, an X-ray detecting element is formed on the concave side of a concave flexible spherical base 12 protruding in the radiation direction of the X-ray beam emitted from the X-ray tube 1. It is a spherical two-dimensional X-ray detector.

The spherical two-dimensional X-ray detector (hereinafter referred to as a spherical X-ray detector) 11 is, for example, a concave surface of a spherical support 13 made of a copper-based shape memory alloy and formed in a spherical shape. The spherical support 13 made of a shape memory alloy (hereinafter referred to as a memory alloy spherical support) 13 has a radius of curvature of a spherical surface which changes in accordance with a current supplied to the support.

The memory alloy spherical support 13 is held by a case 15 via a tubular support arm 14.
The lead wire 2 connected to the memory alloy spherical support 13 and the signal line 4 ′ from the X-ray detecting element of the spherical X-ray detector 11 pass through the inside of the arm 14 and are led out of the case 15. The other end of the lead wire 2 whose one end is connected to the memory alloy spherical support 13 is connected to the curvature control circuit 3, and the signal line 3 of the spherical X-ray detector 11 is connected to the image processing circuit 4.

Further, an imaging mechanism 10 composed of the X-ray tube 1 and the spherical X-ray detector 11 is mounted on a frame (not shown). In the drawing, at least a direction perpendicular to the paper surface can be moved, and the imaging mechanism 10 can move in a direction (up-down direction) of the X-ray emission axis O with respect to a frame (not shown) as shown by an arrow in the figure. In addition, the X-ray tube 1 when the imaging mechanism 10 moves up and down is provided in the frame or the case 15 of the imaging mechanism 10.
A distance detector 5 for detecting a distance D between the focal point F of the lens and the spherical X-ray detector 11 is provided. An output signal of the distance detector 5 is supplied to the curvature control circuit 3. In the figure,
Reference numeral 6 denotes a monitor, and 7 denotes an image memory.

Next, the spherical X-ray detector will be described. The spherical X-ray detector 11 in FIG.
The function is the same as that of the flat panel X-ray detector, and this type of solid operation type flat panel X-ray detector is known from JP-A-4-212456 and JP-A-4-212458. In addition, an X-ray or a semiconductor layer that senses light converted from the X-ray and converts it into a charge and a switching element matrix composed of switching elements such as thin film transistors and field effect transistors are integrated, and the switching elements are integrated into two. An image signal is obtained by dimensional scanning, and the configuration is shown in FIGS. 2 and 3.

In FIG. 2, reference numeral 20 denotes a semiconductor layer, and a bias electrode 22 connected to a bias power source 21 is provided on one surface.
However, a matrix-like signal electrode 23 in which detection elements (pixels) are arranged two-dimensionally (vertically and horizontally) is formed on the other surface. Reference numeral 24 denotes a switching element matrix composed of switching elements 25 such as thin film transistors (TFTs).
The semiconductor layer 20 and the switching element matrix 24, which are connected to the respective signal electrodes 23, are manufactured on a base (not shown) by a thin film technique. In the drawing, reference numeral 26 denotes a capacitor for storing electric charges, which is manufactured by a thin-film technology similarly to the semiconductor layer 20 and the switching element matrix 25.

In this configuration, when the X-ray transmitted through the subject passes through the bias electrode 22 and enters the semiconductor layer 20, the X-ray is absorbed by the semiconductor layer 20 to generate an electron-hole pair (charge). The generated charge is supplied to a bias power supply 21.
The electric charge shift occurs due to the voltage applied to the bias electrode 22, and the electric charge is accumulated in the capacitor 26. The amount of the electric charge accumulated in the capacitor 26 depends on the semiconductor layer 2.
Depends on the X-ray dose incident on zero.

The switching lines 27 of the switching elements 25 constituting the switching element matrix 24
Is connected to the switching element driving circuit 28 as shown in the equivalent circuit of FIG. 3, and the readout line 29 is connected to the multiplexer 31 via the amplifier 30. When the switching element 25 is driven by the switching element driving circuit 28, The charge accumulated in the capacitor 26 of each detection element (pixel) of one line in which the switching element 25 is turned on is simultaneously output to the readout line 29, and the switching element drive circuit 28 sequentially drives the switching element 25, so that the pixel Are two-dimensionally scanned, and the signal output to the readout line 29 is converted into an image signal for each pixel by the multiplexer 31 and input to the A / D converter 32, where A
A digital image signal for each pixel is obtained from the / D converter 32, and a two-dimensional X-ray image is obtained by processing the digital image signal.

FIGS. 2 and 3 show incident X
It is a direct conversion type flat panel X-ray detector that directly converts a line into an electric charge (electric signal) in the semiconductor layer.
A scintillator layer for converting light into light, a photodiode array formed in a matrix on the surface of the scintillator layer as a photodetector, and a TFT connected to each photodiode array. Each T
An indirect conversion type flat panel X-ray detector that obtains an image signal by reading signal charges accumulated in each pixel by sequentially turning on the FT switch may be used. In the flat panel X-ray detector, the semiconductor layer 20, the switching element matrix 24, the capacitor 26, and the like are manufactured by a thin film technology on a flat base. The spherical two-dimensional X-ray detector 11 used in the present invention has a spherical surface. Fabricated on the concave side of a flexible substrate by thin film technology.

Subsequently, in order to perform X-ray fluoroscopy with the embodiment apparatus having the above-described configuration, first, the X-rays generated by the X-ray tube 1 are directed toward the subject M placed on the bed B. Irradiate. The transmitted X-rays transmitted through the subject M are transmitted to the spherical X-ray detector 1
The first semiconductor layer 20 converts the charges into electric charges, the switching elements 25 convert the electric signals into electric signals, and output the digital signals as image data (image data). A fluoroscopic image is projected on the screen.

The operator, while observing the fluoroscopic image projected on the monitor 6, moves the frame for holding the X-ray tube 1 and the imaging mechanism 10 facing each other and / or moves the bed B, or
The imaging mechanism 10 is moved up and down (in the case of close contact imaging, the imaging mechanism is brought into close contact with the body surface of the subject, and in the case of enlarged imaging, the imaging mechanism is moved away from the surface of the subject body) so that the target image can be observed. Then, the radiographing is performed at an appropriate timing, and the radiographed part is recorded in the image memory 7 as a still image or a moving image. The image recorded in the image memory 7 at the time of shooting can be confirmed on the monitor 6.

The distance D between the X-ray focal point F and the spherical X-ray detector 11 due to the vertical movement of the imaging mechanism 10 during positioning is detected by the distance detector 5, and the detection signal is supplied to the curvature control circuit 3. . The curvature control circuit 3 calculates a curvature corresponding to the distance D between the focal point F of the X-ray tube detected by the distance detector 5 and the spherical X-ray detector 11, and calculates the spherical X-ray detector 1.
A current to be supplied to the memory alloy spherical support 13 for converting the curvature of the first curve into the calculated curvature is obtained, and the current is supplied to the memory alloy spherical support 13 to change the curvature of the spherical X-ray detector 11 to X. The curvature is changed to a radius having a distance D between the line focus F and the spherical X-ray detector 11 as a radius.

FIG. 4 schematically shows this state. In the figure, the curvature of the spherical X-ray detector 11 when the distance between the X-ray focal point F and the spherical X-ray detector 11 is D1 is:
Although the spherical surface KI has a curvature having a radius of a distance D1 about the focal point F of the X-ray tube, the spherical X-ray detector 11 moves upward to move between the X-ray focal point F and the spherical X-ray detector 11. Distance is D
When the distance changes to 2, the distance D2 is detected by the distance detector 5 and supplied to the curvature control circuit 3. The curvature control circuit 3
Based on the detected distance D2, a curvature having a radius of the distance D2 about the X-ray focal point F is calculated, and the spherical X-ray detector 11 is provided with a memory alloy spherical support 13 for bending to the calculated curvature. The current to be supplied is obtained, and the obtained current is supplied to the memory alloy spherical support 13, and the curvature of the spherical X-ray detector 11 is determined by the distance D2 between the X-ray focal point F and the spherical X-ray detector 11.
Is changed to a spherical surface K2 having a radius of curvature.

As described above, the spherical X-ray detector 1 is changed according to the distance D between the X-ray focal point F due to the movement and the spherical X-ray detector 11.
1 is a sphere having a radius centered on the X-ray focal point F and having a radius equal to the distance D between the X-ray focal point F and the spherical X-ray detector 11, so that the center of the spherical X-ray detector 11 At any position on the imaging surface of the spherical X-ray detector 11 reaching the periphery thereof, the distance to the X-ray focal point F is equal at any position on the imaging surface, and the distance between the X-ray focal point F and the spherical X-ray detector 11 is The distance becomes D, and X and the imaging planes at the center and the periphery of the spherical X-ray detector 11
Image distortion due to a difference in magnification ratio due to a difference in distance from the line focal point F does not occur, and a fluoroscopic image without image distortion is obtained.

FIG. 5 shows a case in which the curvature of the spherical X-ray detector 11 is adjusted by a plurality of telescopic arms (actuators) 40 comprising a fixed part 41 and a movable part 42 fixed to a case (not shown). In this embodiment, the curvature control circuit determines the length of each telescopic arm based on the distance between the X-ray focal point F and the spherical X-ray detector 11 detected by the distance detector. By adjusting the length (the amount of expansion or contraction) of the forty, the curvature of the spherical X-ray detector 11 is changed to a curvature having a radius equal to the distance D between the X-ray focal point F and the spherical X-ray detector 11. In FIG. 1, FIG.
The same reference numerals are given to the same components as those described above, and the connection between each movable part 42 of each telescopic arm 40 and the spherical base 12 of the spherical X-ray detector 11 is performed by a free (pivot) joint (not shown). Made through.

In the above-described embodiment, the spherical substrate is
The two-dimensional spherical X-ray detector is formed by forming the line detecting element by the thin film technology. However, a large number of flat panel X-ray detectors on a small plane are used, and a combination of many planes of each flat panel X-ray detector is used. Thus, a pseudo-spherical spherical X-ray detector (hereinafter, referred to as pseudo-spherical X-ray detector) may be formed, and the curvature may be changed by adjusting the inclination angle of each adjacent flat panel X-ray detector. .

FIG. 6 is a schematic diagram for explaining the pseudo-spherical X-ray detector thus configured and its curvature adjustment. A plurality of small flat panel X-ray detectors 11 ′ are attached to the elastic support 43. The flat panel X-ray detector 11 ′ is fixed to a large-area two-dimensional detector, and each flat panel X-ray detector 11 ′ is attached to a telescopic arm including a fixed part and a movable part 42 fixed to a case as shown in FIG. The linked X-ray detector is a pseudo-spherical X-ray detector whose spherical surface is approximated by a plane. In such a configuration, when the distance detector detects the distance D between the pseudo spherical X-ray detector and the X-ray focal point F, the curvature control circuit sets the distance D detected by the distance detector as a radius. The curvatures are calculated, and the inclination angles θ1, θ2, θ3 with the adjacent detectors for forming a pseudo spherical surface circumscribed or inscribed on the spherical surface of the curvature calculated by each flat panel X-ray detector 11 '. ... and by adjusting the length of each telescopic arm so that it is at that angle,
The curvature of the pseudo spherical X-ray detector is changed.

In the embodiment shown in FIG. 6, a spherical surface having a radius of curvature equal to the distance between the X-ray focal point and the imaging mechanism (pseudo spherical X-ray detector) is approximated by a plane. Although image distortion cannot be completely eliminated as described above, peripheral distortion can be remarkably improved as compared with imaging with a large-area flat panel X-ray detector. In particular, if the size of each flat panel X-ray detector is reduced, As the distance increases, the curvature can be made closer to a spherical surface having a curvature whose radius is the distance between the X-ray focal point and the imaging mechanism, and a fluoroscopic image with less image distortion can be obtained.

In the current technology, the production of a large-area flat panel X-ray detector, particularly, a spherical two-dimensional X-ray detector has a low yield and is expensive. If a spherical surface is formed by a combination of flat panel X-ray detectors, a two-dimensional detector can be configured at low cost. FIG. 1 shows an embodiment in which the present invention is applied to an under-tube type X-ray fluoroscopic apparatus. However, the present invention relates to an over-tube type X-ray fluoroscopic apparatus in which an X-ray tube is arranged above and an imaging mechanism is arranged below. The present invention can also be applied to a device, a C-arm type X-ray fluoroscopic apparatus that holds an X-ray tube and an imaging mechanism at opposite ends, and the like.

[0028]

According to the X-ray fluoroscopic apparatus of the present invention, since the curvature of the spherical two-dimensional X-ray detector can be changed, the image distortion can be reduced regardless of the change in the distance between the X-ray tube and the imaging mechanism. A significantly reduced fluoroscopic image or a fluoroscopic image without image distortion is obtained. As a result, it is possible to accurately grasp and measure the positional relationship of an organ, a site of interest, and the like on an image, and the size and shape of an object, and to perform accurate diagnosis and treatment.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of an X-ray fluoroscopic apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of a flat panel X-ray detector.

FIG. 3 is an equivalent circuit diagram of FIG.

FIG. 4 is a schematic diagram for explaining a change in curvature of the spherical two-dimensional X-ray detector used in FIG. 1;

FIG. 5 is a view showing another embodiment of a curvature adjusting mechanism of the spherical two-dimensional X-ray detector.

FIG. 6 is a schematic diagram for explaining the configuration of another spherical two-dimensional X-ray detector and curvature adjustment.

[Explanation of symbols]

1: X-ray tube 3: Curvature control circuit 4: Image processing circuit 5: Distance detection circuit 6: Monitor 7: Image memory 10: Imaging mechanism 11: Spherical two-dimensional X-ray detector (spherical X-ray detector) 11 ' ... Flat panel X-ray detector 12 ... Spherical base 13 ... Spherical support made of shape memory alloy (memory alloy spherical support) 14 ... Support arm 15 ... Case 40: Telescopic arm 41 ... Fixed part 42 ... Movable part F: X-ray focus O: X-ray emission axis

Claims (2)

[Claims] 1. An X-ray tube for irradiating an X-ray to a subject with the subject interposed therebetween, and an imaging mechanism for receiving transmitted X-rays transmitted through the subject are arranged to face each other. An X-ray fluoroscopic apparatus capable of changing a distance between mechanisms, wherein said imaging mechanism has a plurality of X-ray detection elements arranged two-dimensionally on a concave surface protruding in an X-ray radiation direction. An X-ray fluoroscopic apparatus, wherein the curvature of the two-dimensional X-ray detector changes according to the distance between the X-ray tube and the two-dimensional X-ray detector. 2. An X-ray tube for irradiating an object with X-rays, and an imaging surface for receiving transmitted X-rays transmitted through the object, a concave surface protruding in the X-ray radiation direction, and a large number of X-ray detecting elements are two-dimensionally arranged. A two-dimensional spherical X-ray detector, a distance detecting means for detecting a distance between the X-ray tube and the spherical two-dimensional X-ray detector, and a detecting signal from the distance detecting means. The two-dimensional X
An X-ray fluoroscopic apparatus, comprising: control means for changing a curvature of a line detector.