KR20110083848A - Tomograph - Google Patents

Abstract

PURPOSE: An X-ray-based tomography apparatus is provided to increase the resolution of an image by controlling the magnification of the apparatus. CONSTITUTION: An X-ray-based tomography apparatus is composed of a main body, an X-ray generator(20), and an X-ray detector(10). The X-ray generator and the X-ray detector are supported by a C-arm(40) which is installed in the main body and are installed at the front side of the main body. The X-ray generator faces the X-ray detector. A projected image generated from an image magnifying tube is focused to an energy sensor by a camera. The focused image is converted into an electric image signal and is digitalized.

Description

X-ray imaging equipment {Tomograph}

The present invention relates to an X-ray imaging apparatus for acquiring an image of a subject using X-rays, and more particularly, to an X-ray imaging apparatus for providing an image of a subject using an image multiplier.

Since X-Ray was invented by Roentgen in 1897, medical institutions have been using X-ray radiography as a basic tool for diagnosis. In particular, the technology is evolving, focusing on high resolution and low radiation doses for patient safety and disease prevention.

X-ray imaging equipment, the oldest type of medical diagnostic equipment, uses X-ray perspective imaging to obtain real-time video for general X-ray imaging, CT, bone density measurement, and surgery. Or fluoroscopy systems.

The most commonly used X-ray imaging apparatus has been used in hospitals for over 100 years, and it is to realize an analog image in which the distribution of X-ray dose in the two-dimensional space of the film is displayed in black and white according to the amount of photosensitivity. As a result, both the doctor and the patient have eased the treatment and treatment process, and X-rays have contributed greatly to the development of modern medicine by reducing misdiagnosis with quantitative data (film).

Nevertheless, the existing X-ray imaging system also has a number of problems such as an analog signal, the risk of radiation exposure to the body, the chemical emission due to the film phenomenon, and the development time required to read a single film.

Recently, as digitalization of information is rapidly progressing, digital radiography has emerged as a new technology to solve these disadvantages. This is because a higher resolution image can be obtained while irradiating less harmful X-rays than the conventional body.

The digital X-ray photographing apparatus is a digital next-generation product that enables an image to be displayed on a computer monitor instead of using a film in general analog X-ray. In other words, X-rays are irradiated to the X-ray detector, which is not an analog method of shooting X-rays on a film, and is converted into an electrical signal to obtain an image.

This is the biggest difference between the digital X-ray imaging apparatus and the conventional analog X-ray imaging apparatus, and it is also the most important core technology in the digital X-ray imaging apparatus.

The digital X-ray photographing apparatus includes a method using a film scanner, a computer radiography (CR) using an image plate and a reader, a method using a fluorescent plate and a CCD camera, and a flat panel type semiconductor detector according to a method of detecting X-rays. It is largely classified into a method using.

Here, the TFT flat panel type semiconductor X-ray detecting apparatus has a smaller mechanical limit than the other X-ray detecting apparatus due to its small volume and light weight, but has a low mechanical limit. It is not possible to scale without loss of resolution, and in order to obtain real-time video, pixel binning, or 4 (2 * 2 bining) or 9 (3 * 3 bining) pixels, is bundled so that it behaves like a single pixel. There is a fatal disadvantage that the number of pixels is significantly reduced and the resolution of the image is drastically reduced.

The present invention provides an X-ray imaging apparatus that is inexpensive, capable of scaling, and increasing an image resolution compared to conventional X-ray imaging apparatuses such as a TFT flat panel semiconductor X-ray detecting apparatus.

Another object of the present invention is to provide an X-ray imaging apparatus capable of providing a corrected image of a subject even when the degree of distortion of the image is changed by the influence of geomagnetism according to the location where the X-ray imaging apparatus is installed.

In one aspect, the present invention provides an X-ray generator that irradiates X-rays toward a subject; The present invention also provides an X-ray photographing apparatus including an X-ray detector having an image intensifier for converting X-rays transmitted through the subject into visible light in order to generate a projection image of the subject.

The X-ray imaging apparatus; In order to correct a distorted image of a subject distorted by a geomagnetic field acting on the image multiplier, the distorted image of the subject is corrected with preset correction data according to a plurality of places where the X-ray imaging apparatus is installed. It further comprises an image correction module for correcting.

The image correction module includes: a data providing unit for selectively providing the correction data to the distortion image of the subject to correct the distortion image of the subject; And an image correction unit configured to apply the correction data to the distortion image of the subject and reconstruct the distortion image of the subject into a correction image of the subject by the correction data.

The image correction module may correct the subject image such that the subject image has a uniform luminance distribution over the entire surface.

Here, the image correction module corrects the brightness of the center and the periphery of the subject image equally based on the brightness of the center of the subject image.

As described above, the X-ray imaging apparatus according to the present invention has the following effects.

First, according to the present invention, there is an advantage in that the price is cheaper, the magnification can be adjusted, and the resolution of the image can be increased as compared with the TFT flat panel semiconductor X-ray detection apparatus.

Second, according to the present invention, even when the installation location is changed by moving the X-ray imaging apparatus, correction data corresponding to the installation location can be applied to quickly and conveniently correct an image distorted by the influence of geomagnetism. There is an advantage to improve the convenience and efficiency of the user.

1 is a perspective view schematically showing an embodiment of an X-ray imaging apparatus according to the present invention.
FIG. 2 is a schematic diagram illustrating a structure of an image multiplier of FIG. 1.
FIG. 3 is a diagram schematically illustrating a magnetic field distribution and an orbit of electrons in the image multiplier of FIG. 1.
4 and 5 are views schematically showing the rotational shape of the C-arm during the image acquisition process by the X-ray imaging apparatus of FIG.
6 is a reference diagram for explaining a geomagnetism.
7 is a view schematically showing the magnetic field distribution and the trajectory of the electrons by the influence of the geomagnetic.
8 is a view schematically showing the distortion of the projection image of the image multiplier due to the influence of geomagnetism.
9 is a diagram schematically illustrating a process of acquiring a corrected image by correcting an image distorted by the influence of geomagnetism in an embodiment of the X-ray imaging apparatus according to the present invention.
10 and 11 are diagrams for explaining a process of correcting an image outputted by an embodiment of the X-ray imaging apparatus according to the present invention to have a uniform luminance distribution over the entire surface.
12 to 14 are views for explaining a process of deriving correction data applied to an embodiment of the X-ray imaging apparatus according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, preferred embodiments of the present invention in which the object of the present invention can be specifically realized will be described with reference to the accompanying drawings. In describing the present embodiment, the same name and the same reference numerals are used for the same configuration and additional description thereof will be omitted below.

Referring to FIG. 1, one embodiment of an X-ray imaging apparatus according to the present invention includes a main body 30, an X-ray generator 20, and an X-ray detector 10.

The X-ray generator 20 is an apparatus for irradiating X-rays generated toward the subject P by generating X-rays. In addition, the X-ray detector 10 is located on the opposite side of the X-ray generator 20 on the basis of the subject P, and on the subject P through X-rays passing through the subject P. It is a device for acquiring a perspective image or the like.

In the present embodiment, the X-ray detector 10 and the X-ray generator 20 are supported by the C-arm (C-Arm: 40) provided in the main body 30 to face each other in a form of facing each other ( 30) is installed in front. Of course, the X-ray detector 10 and the X-ray generator 20 may be installed to have independent drive structures.

In the present invention, the X-ray detector 10 is an electrical image of the optical signal incident through the image multiplier 11 and the image multiplier 11 for generating a projection image for the subject (P). It comprises a camera 12 for converting to a signal.

The image multiplier 11 converts X-rays incident through the subject P after being irradiated from the X-ray generator 20 into visible light, and the camera 12 converts the image multiplier 11 into the visible light. Converts the information according to the projection image of the subject generated by the electrical signal.

The basic configuration of the image multiplier 11 and the light conversion process by the image multiplier are as follows.

As shown in FIG. 2 and FIG. 3, when the X-ray radiated through the subject, that is, the X-rays flows into the image multiplier 11, the image is captured on an input fluorescent screen.

At this time, the photocathode and the anode are subjected to a high voltage of approximately +25 to 35 kV to accelerate and amplify the electron.

The accelerated amplified electrons are deflected through the magnetic field distribution of the electrodes for electron optics, and form an electron trajectories to be focused on an output fluerescent screen as shown in FIGS. 2 and 3. The image multiplier 11 converts the X-rays into visible light and generates a projection image of the subject.

The camera 12 condenses the projection image generated by the image multiplier 11, that is, the light having the image of the subject P, to an image sensor through a lens, and converts the light into an electrical image signal and digitizes it.

The image sensor is a kind of optical sensor. In the present embodiment, a charge coupled device (CCD) is disclosed. In particular, the image sensor according to the present embodiment is preferably composed of an Electromagnetic Multiplying Charge Coupled Device (EMCD) having a characteristic of excluding noise light included in visible light and amplifying photo light.

4 and 5, the X-ray imaging apparatus according to the present exemplary embodiment may capture an image of a subject in various imaging modes. For example, in the tomography (CT) mode, the X-ray detector 10 And the X-ray generator 20 may be rotated with respect to the first axis or the second axis of rotation of the C-arm 40 installed opposite to each other to take a subject image at various angles.

In this case, the X-ray photographing apparatus according to the present invention may generate a high resolution projection image by the image multiplier 11 of the X-ray detector 10, and the projection image is converted into an electrical signal by the camera 12. The display may be reconstructed into various output images such as 3D images and displayed externally.

To this end, the X-ray imaging apparatus according to the present embodiment is connected to the main body 30 and outputs various electrical signals related to various images of the subject P digitized by the camera 12 such as 3D images. The image reconstructor 50 may be configured to reconstruct an image, and the display 60 may be connected to the image reconstructor 50 to display the output image to the outside.

On the other hand, the X-ray imaging apparatus according to the present invention outputs a subject image using the image multiplier (11), as described above the image multiplier (11) by using the magnetic field distribution of the electrode for the electro-optical Since the projection image of the subject is acquired, the subject image may be distorted due to geomagnetism.

More specifically, as shown in Fig. 6, the earth has a magnet like one large magnet, which causes a magnetic field. The earth's magnetic field is called the earth's magnetic field, that is, geomagnetic or surface magnetic field, and the geomagnetism varies depending on latitude (H), vertical (Z), and inclination (I). Geomagnetism can affect electrical or electronic devices.

Referring to FIG. 7, the geomagnetism may influence the magnetic field distribution of the electro-optical electrode in the direction of the arrow as in the present embodiment, and thus is generated by the image multiplier 11 as shown in FIG. 8. Experimental results show that the S-shaped image distortion occurs in the subject image.

Accordingly, the output image finally implemented by the X-ray imaging apparatus including the image multiplier 11 is distorted, thereby degrading the quality of the output image to the subject.

In particular, in the structure of detecting the X-rays while the image multiplier 11 rotates, a large image distortion is generated due to the influence of geomagnetism. For example, when the X-ray imaging apparatus including the image multiplier 11 is operated in tomography (CT) mode, the subject is placed between the X-ray detector 10 and the X-ray generator 20 and the The C-Arm is rotated at a constant speed to obtain a plurality of subject images at predetermined intervals, and in this case, the geomagnetism distribution of the magnetic field of the image multiplier pipe 11, in particular the electro-optic electrode It affects to distort the subject image generated by the image multiplier.

Therefore, the X-ray imaging apparatus equipped with the image multiplier 11 needs to perform a correction operation for correcting the image distortion caused by the influence of geomagnetism according to the installation location. Setting up the calibration of a specimen image is very cumbersome and complex, which can be time consuming.

In particular, since the influence of the geomagnetism received by the image multiplier differs depending on the installation location moved each time the X-ray photographing apparatus equipped with the image multiplier 11 is moved, a cumbersome correction operation according to the influence of geomagnetism is performed for a long time. At the same time, geometric image correction should be performed to acquire 3D data.

However, since the geometric image correction for acquiring the 3D data corresponds to general contents that are all performed in the same general X-ray imaging apparatus, that is, obvious to those skilled in the art, a detailed description thereof will be omitted. Details on correcting distortion of an image are described.

The X-ray photographing apparatus according to the present embodiment corrects an object P distortion image generated by a geomagnetism acting on the image multiplier 11 to provide an image corrected to remove or minimize distortion. It is configured to include.

In more detail, the image correction module corrects the subject distortion image having a different degree of distortion according to a place where the X-ray imaging apparatus is installed to correspond to an installation place, thereby removing or minimizing distortion as described above. Provide a corrected image of the subject.

Here, the image correction module of the present embodiment is preset to be corrected to correspond to the degree of distortion of the image of the subject under the influence of the geomagnetism acting on the image multiplier 11 depending on the location where the X-ray imaging apparatus is installed By using the data, the distortion image of the subject can be corrected to quickly and conveniently output a correction image with the distortion removed or minimized, and eliminates the need to set a correction operation every time the X-ray imaging apparatus is moved. .

Referring to FIG. 9, in the tomography mode, the X-ray imaging apparatus of the present exemplary embodiment acquires various projection images of the subject P while rotating the C-arm 40 based on the first or second rotation axis. can do.

At this time, in order to correct the distorted image generated by the geomagnetism, the image correction module is configured to preset the subject image by using preset correction data according to a predetermined location where the X-ray imaging apparatus is to be installed. Correct.

In other words, the X-ray photographing apparatus according to the present exemplary embodiment may more quickly and quickly use a distortion image of the subject that is distorted under the influence of the geomagnetism acting on the image multiplier 11 by using correction data preset in the image correction module. It can be calibrated conveniently.

Therefore, according to the present embodiment, even if the installation location of the X-ray imaging apparatus is moved and the installation location is changed, when the change of the installation location of the X-ray imaging apparatus is input to the X-ray imaging apparatus, the preset correction data is used to correspond to the corresponding installation location. The corrected image of the subject can be generated quickly and conveniently, thereby improving user convenience and efficiency.

In order to perform such a convenient and efficient image correction, the image correction module according to the present embodiment, the data providing unit for selectively providing the correction data to the distortion image of the subject to correct the distortion image of the subject And an image correction unit configured to apply the correction data to the distortion image of the subject to reconstruct the distortion image of the subject into a correction image of the subject by the correction data. Of course, the image correction module is provided with a data storage unit for storing the preset correction data.

In more detail, an optical signal distorted by the geomagnetism from the image multiplier is picked up by the camera, in particular the image sensor, and the image sensor converts it into an electric image signal, thereby distorting the subject image (image sensor). And a projection image of a subject as an image signal output from the subject, and the image correction module generates the corrected image of the subject by applying the correction data to the distortion image of the subject. And the corrected image of the subject generated as described above is provided to the image reconstructor.

On the other hand, the camera 12 focuses the optical signal passing through the image multiplier 11 to the image sensor by using a lens, the amount of light focused on the image sensor is reduced from the center to the outside due to the characteristics of the lens Tends to be.

In addition, since the geomagnetism acting on the image multiplier 11 also affects the distribution of brightness collected by the image sensor, the subject image output through the X-ray imaging apparatus has non-uniform brightness.

In order to solve this problem, the X-ray imaging apparatus according to the present embodiment, as shown in Figures 10 and 11, the final output image of the subject implemented through the image sensor has a uniform brightness distribution across the entire surface It may include a configuration to correct to have.

In more detail, as shown in FIG. 10, the X-ray imaging apparatus according to the present exemplary embodiment performs a flat field correction (FFC) correction operation, which uniformly corrects the brightness of the subject image by the image correction module in advance, The final output image output through the monitor may have a uniform brightness, that is, a uniform luminance distribution over the entire surface.

In the present embodiment, the FFC correction operation refers to an operation of equally correcting the brightness of the center and the periphery of the subject image based on the center brightness of the subject image generated by the image multiplier 11. .

For example, the FFC correction operation may be performed by the X-ray generator 20 radiating X-rays to a circular test object with power and current within a range in which the image sensor is not saturated, that is, within a range in which the image sensor can operate normally. Acquiring the subject image (FIG. 10A, which is referred to as a primary subject image), and then, based on the central brightness of the primary subject image, the peripheral brightness of the subject image, that is, The brightness of the outer portion may be performed by correcting the same as the center brightness.

In more detail, the brightness gradient (tilt) of the primary subject image is obtained based on the central brightness of the primary subject image. At this time, the brightness gradient of the primary subject image along the horizontal line (X axis) passing through the center of the primary subject image, more specifically, the pixel value (Pixel Value, brightness) of the image sensor corresponding to the horizontal line Value).

The center brightness of the primary subject image is set to a coefficient 1, and a correction coefficient is calculated so that the brightness (peripheral brightness) of other portions except for the center of the primary subject image is equal to the center brightness. Therefore, the correction coefficient corresponding to each pixel on the horizontal line is a value obtained by dividing the center pixel value corresponding to the center of the horizontal line by the pixel value of each pixel on the horizontal line.

The right half of the first subject image is corrected according to the pixel value along the right line (+ line) at the center of the horizontal line, and the pixels located at the same radius from the center of the subject image have the same pixel value. It is also possible to perform the overall luminance correction of the right half in an assumed manner. The left half of the primary subject image may also perform overall luminance correction in the same manner as above using the pixel value of the left line (-line) at the center of the horizontal line.

As a result, the correction coefficient is gradually increased from the center of the subject image toward the periphery, and the image calculated based on the correction coefficient (FIG. 10 (b)) becomes brighter from the center to the periphery.

Next, when the luminance of the subject image is corrected by multiplying the correction coefficient by each pixel value of the image sensor in the primary subject image, the output image of the subject having uniform brightness as a whole may be completed.

Therefore, the final output image of the subject implemented by the X-ray imaging apparatus according to the present invention may have an even luminance distribution over the entire surface, thereby improving image quality.

Meanwhile, a process of setting correction data for correcting the distorted image of the subject that is distorted by the geomagnetism will be described in detail as follows.

As shown in FIGS. 12 to 14, the X-ray imaging apparatus according to the present embodiment is a task of correcting a distortion image of the subject at various places where the X-ray imaging apparatus is to be used to derive the correction data. Perform DC (Distortion Correction) work.

First, as shown in FIG. 12, a distortion correction plate (hereinafter referred to as a phantom plate 70) having a plurality of bead holes 71 is installed on the X-ray incident surface side of the image multiplier 11. do. In the present embodiment, the bead holes 71 are regularly arranged at regular intervals, for example, in the up / down / left and right directions of the phantom plate 70.

13 and 14, in the tomography (CT) mode, the C-arm 40 is rotated on the first rotation shaft or in the state where the phantom plate 70 is installed in the image multiplier 11. The object image is acquired for each corresponding angle by rotating about the second rotation axis.

The plurality of bead points corresponding to the plurality of bead holes 71 are generated in the obtained subject image, and the subject images generated through the image multiplier are distorted due to the influence of the geomagnetism. Bead points also appear in distorted positions.

In order to obtain the corrected image of the subject by correcting the subject image, more specifically, the distortion image of the subject, the positions of the bead points generated in the subject image corresponding to the bead hole 71 are obtained.

In more detail, the horizontal and vertical lines are drawn in accordance with the vertical width and the horizontal width between several bead points located adjacent to a region where distortion is not severe in the subject image, that is, a central region of the subject image. A virtual line for dividing the image up, down, left and right in a grid form, and a line connecting the bead points, that is, a bead line distorted by a geomagnetism, to form intersections of the virtual lines and the bead points. Find the location. Here, when the intersections of the virtual lines are not affected by the geomagnetism, they are treated as positions of bead points formed in the subject image corresponding to the bead holes.

The reason for forming the virtual line based on the bead points positioned in the center of the subject image is that the center of the subject image is minimally affected by geomagnetism.

Then, vectors (hereinafter, referred to as correction vectors) between the intersection points for moving the bead points located in the subject image to the intersection points corresponding thereto are obtained.

The correction vectors may be calculated based on a partial region of the subject image, and the correction vectors of remaining bead points positioned outside the region where the correction vector is calculated may be obtained using interpolation.

A correction vector map (UV map) including correction vectors for all the bead points calculated as described above is used as correction data and stored in the data storage unit of the image correction module, particularly the image correction module.

In this case, the correction vector map, that is, the correction data is set for all of the plurality of subject images obtained at all angles, and a plurality of places (multiple Xs) where the X-ray imaging apparatus according to the present embodiment is to be installed. In advance, and store in the image correction module, that is, the data storage unit.

Therefore, according to the X-ray imaging apparatus according to the present embodiment, the image correction module uses the correction data preset by the image correction module to quickly distort the subject image that is distorted due to the influence of the geomagnetism acting on the image multiplier 11. It can be conveniently corrected to generate an X-ray image of which distortion is eliminated or minimized, and when the installation position of the X-ray imaging apparatus is changed, when the installation position is input, the image of the subject is corrected by the corresponding correction data. The user's convenience and efficiency can be improved.

Having looked at the preferred embodiment according to the present invention as described above, in addition to the embodiment described above, the fact that the present invention can be embodied in other specific forms without departing from the spirit or scope of the present invention It is obvious to them.

Therefore, the above-described embodiments are to be considered as illustrative rather than restrictive, and the present invention is not limited to the above description, but may be modified within the scope of the appended claims and equivalents thereof.

10: X-ray detector 11: Image multiplier
12: camera 20: X-ray generator
30: main body 40: C-arm (C-Arm)
50: output image reconstructor 60: display unit
70: phantom plate

Claims (5)

An X-ray generator for irradiating X-rays toward the subject; And
And an X-ray detector having an image intensifier for converting the X-rays transmitted through the subject into visible light to generate a projection image of the subject. The method of claim 1,
In order to correct a distorted image of a subject distorted by a geomagnetic field acting on the image multiplier, the distorted image of the subject is corrected with preset correction data according to a plurality of places where the X-ray imaging apparatus is installed. X-ray imaging apparatus further comprises an image correction module to correct. The method of claim 2,
The image correction module is:
A data providing unit selectively providing the correction data to the distortion image of the subject to correct the distortion image of the subject; And
And an image correction unit configured to apply the correction data to the distortion image of the subject and reconstruct the distortion image of the subject into a correction image of the subject by the correction data. The method of claim 1,
And the image correction module corrects a subject image generated through the image multiplier so that the final output image of the subject has a uniform luminance distribution over the entire surface. The method of claim 4, wherein
The image correction module, the X-ray imaging apparatus for correcting the same brightness of the center and the surrounding of the subject image based on the brightness of the center of the subject image generated through the image multiplier.

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