JPH10276366A - X-ray equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the contrast of an X-ray image in a proper form. SOLUTION: In the process where an X-ray tube 2 and an image intensifier 3 are interlockingly moved, the X-ray image pickup device obtains pluralities of different X-ray images, detects a pixel signal strength of pixels corresponding to a lead piece 10 placed between the X-ray tube 2 and a subject M so as to use the strength for an equivalent signal strength caused by scattered Xrays. Then the equivalent signal strength is subtracted from each pixel signal of the X-ray image at a subtractor 31 for the correction and each X-ray image is superimposingly stored and integrated in a frame memory 33 to obtain a tomogram X-ray image. Since the effect of the scattered X-rays is eliminated in the tomogram X-ray image obtained as above, the contrast is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a type in which an X-ray detection signal detected by an image intensifier is digitally converted to obtain an X-ray image when the X-ray tube irradiates the subject with X-rays. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging apparatus, and more particularly to a technique for increasing the contrast of an X-ray image.

[0002]

2. Description of the Related Art A medical X-ray imaging apparatus installed in a hospital or the like includes an X-ray tube installed opposite to a subject (patient) and an image intensifier (hereinafter referred to as "I.I. Tube).
X-ray detection signals output from the imaging unit in association with X-ray exposure to the subject are converted to digital to obtain an X-ray image, and the obtained X-ray image is displayed on a screen of a TV monitor, or An X-ray image is displayed by printing on a film or the like. In the conventional X-ray imaging apparatus, usually, in addition to the simple imaging in which all tissues and organs of the imaging region are displayed in an overlapping manner, only the slice of interest in the subject is displayed in an extracted form. It is configured to perform tomography.

[0003] The principle of this tomography will be described with reference to FIG. Here, as shown in FIG. 9, the cut surface of interest Ma in the subject M is clearly displayed in a state where it is extracted. In the case of tomography, the X-ray tube 51 and the I / I tube 52 are placed in such a manner that the X-ray tube 51 and the I / I tube 52 have a symmetrical positional relationship with respect to a point on the plane of interest Ma in the subject. Are moved in conjunction with each other, and the respective X-ray images obtained during the moving process of the imaging unit are integrated.

That is, the I / I tube 52 and the I / I tube 52 are projected such that the points A and B located on the plane of interest Ma are always projected on the same points a and b on the X-ray detection surface 52a of the I / I tube 52. The X-ray tube 51 is moved in conjunction with it. As a result, the projection position on the X-ray detection surface 52a of the point C at a position deviating from the trimming plane of interest Ma changes as the imaging unit moves. When the X-ray tube 51 is at the position P1, the point C is projected on the point c1 on the X-ray detection surface 52a, and when the X-ray tube 51 moves to the position P2 where the X-ray irradiation angle is different, the point C is detected by the X-ray detection. It is projected on the point c2 of the surface 52a.

As a result, when each X-ray image is integrated, the signal at the point C is scattered (distributed) on the X-ray image.
In this manner, the point C becomes a blurred image in the integrated X-ray image. The greater the distance away from the trimming plane of interest Ma, the greater the degree of blur of the point. Therefore, by integrating a plurality of different X-ray images obtained in the process of moving the imaging unit, a tomographic X-ray image in which only the cut surface of interest Ma clearly appears can be obtained.

[0006]

However, in the case of the above X-ray imaging apparatus, there is a problem that the contrast of the finally displayed X-ray image is not sufficient. The insufficient contrast of the X-ray image is due to the scattering X
This is because a line is incident. Although a grid is provided on the front surface of the I · I tube 52 to remove scattered X-rays, the grid alone cannot sufficiently remove scattered X-rays. If the grid is densely arranged, the scattering X
Although the line rejection rate increases, the so-called straight signal X-ray (non-scattered X-ray) rejection rate, which is a true signal component, also increases, and the signal amount output from the imaging unit decreases. No improvement can be realized.

In view of the above problems, an object of the present invention is to provide an X-ray imaging apparatus capable of appropriately improving the contrast of an X-ray image.

[0008]

The X according to the first aspect of the present invention.
The X-ray imaging apparatus digitally converts an X-ray tube and an image intensifier, which are installed to face each other across a subject, and a transmitted X-ray detection signal output from the image intensifier when the subject is exposed to X-rays. An image forming means for converting to create an X-ray image, an image storing means for storing the X-ray image, and an image display means for displaying the X-ray image
In the X-ray imaging apparatus, an X-ray shielding piece located between the X-ray tube and the subject and arranged to appear as an image in the X-ray image, and an X-ray shielding piece image area in the X-ray image Signal strength detection means for detecting the signal strength of the pixel;
Image correction means for performing a correction process for subtracting the signal intensity corresponding to the signal intensity detected by the signal intensity detection means for each pixel signal of the X-ray image.

According to a second aspect of the present invention, there is provided the X-ray imaging apparatus according to the first aspect, wherein the X-ray tube and the image intensifier are positioned symmetrically with respect to a point on a plane of interest in the subject. An imaging unit moving means for moving an imaging unit composed of an X-ray tube and an image intensifier in an interlocking manner, and an X-ray shielding single image in each X-ray image obtained in the process of moving the imaging unit. X-ray shielding piece moving means for changing the position of the X-ray shielding piece with respect to the X-ray tube with the movement of the imaging unit so that the appearance position of the X-ray tube changes, and each X-ray image obtained in the moving process of the imaging unit. Image integration means for integrating to obtain a tomographic X-ray image of the section of interest of the subject.

[Operation] Next, the operation of the X-ray imaging apparatus of the present invention when performing X-ray imaging of a subject will be described. In the X-ray imaging apparatus according to the first aspect of the present invention, X-rays
When the line is irradiated, the transmitted X-ray from the subject enters the I / I tube and is detected, and is output as a transmitted X-ray signal from the imaging unit. The transmitted X-ray detection signal is digitally converted by the image forming unit, sent to the image storage unit as an X-ray image, and stored.

On the other hand, in the case of the X-ray imaging apparatus of the first aspect,
An X-ray shielding piece arranged between the X-ray tube and the subject appears as an image in the X-ray image. Then, the signal intensity of the pixel in the X-ray shielding single-image area in the X-ray image was detected by the signal intensity detecting means, and the image intensity correcting means detected each pixel signal of the X-ray image by the signal intensity detecting means. A correction process for subtracting a signal strength corresponding portion is performed. Since the X-ray shielding piece blocks the straight X-ray, the image signal of the pixel in the X-ray shielding piece image area is not based on the straight X-ray, but is actually based only on the scattered X-ray dose. Therefore, the X-ray image subjected to the subtraction correction processing by the image correction means is an image from which the influence of the scattered X-ray has been removed. As a result, it is not necessary to assign the gray scale change range of the image display to the signal component due to the scattered X-rays not related to the gray scale change in the display image, and the entire density change range can be allocated only to the signal component related to the gray scale change in the display image. , And the change in the density of the displayed X-ray image becomes more remarkable than before.

According to the X-ray imaging apparatus of the second aspect, tomographic imaging is performed to obtain a tomographic X-ray image. That is, by integrating each X-ray image obtained in the process of moving the X-ray tube and the I / I tube in conjunction with each other by the image integration means, a tomographic X-ray image of the plane of interest of the subject can be obtained. Of course, the tomographic X-ray image also has the scattering X
By the correction processing for subtracting the signal component due to the line, the change in shading becomes larger than before.

Further, since the position of the X-ray shielding piece with respect to the X-ray tube is changed by the shielding piece moving means, the appearance position of the X-ray shielding piece image in each X-ray image changes, and the X-ray image of the tomographic X-ray image is changed. It can be avoided that a part of the image is completely hidden by the image (shade) of the X-ray shielding piece and cannot be seen.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the X-ray imaging apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram illustrating a schematic configuration of the X-ray imaging apparatus according to the embodiment.

The X-ray imaging apparatus according to the embodiment includes a top 1 that can be moved left and right and back and forth while the subject M is placed, and an X-ray tube 2 and an I. An imaging unit 4 having an I tube 3 is provided. The top 1 can be moved up and down in addition to moving left and right and back and forth. Top plate 1
Is performed by the top plate driving unit 5.

In the embodiment, the imaging unit 4
An imaging system drive unit 6 for performing an operation necessary for obtaining a tomographic X-ray image is also provided. Note that the principle of tomographic imaging by the embodiment apparatus is the same as that described above with reference to FIG.

In the case of tomographic imaging by the embodiment apparatus, as shown in FIG.
1 → position F2 → position F3 to change the X-ray irradiation angle (viewing angle), and in accordance with the change in the X-ray irradiation angle, the I / I tube 3 also moves from position f1 → position f2 → position. f3
And move. That is, a plurality of X-ray images can be obtained in the process of transferring the imaging unit while maintaining the symmetrical positional relationship between the X-ray tube 2 and the I / I tube 3 with respect to a point on the cross section of the subject. It is composed. In the case of the embodiment, the imaging system drive unit 6 has a function of changing the X-ray irradiation angle, a function of moving the position of the I / I tube, and a function of applying a high voltage to the X-ray tube 2.

In the I / I tube 3 which receives X-rays transmitted through the subject M, an X-ray fluoroscopic (light) image of the subject M is detected with the X-ray irradiation on the subject M. At the same time, the X-ray fluoroscopic image is photographed by a TV camera unit 3a attached to the back side of the I / I tube 3, and an analog signal is transmitted as a transmitted X-ray detection signal (via an amplification circuit as necessary). ) Output to the AD converter 20 of the signal processing system.

On the other hand, in the X-ray imaging apparatus according to the embodiment, a small disc-shaped lead piece (X
The X-ray shielding piece 10 is located between the X-ray tube 2 and the subject M, and is arranged in a direction (posture) that is projected as a circular shadow in the X-ray image. The lead piece 10 is connected to a rotating shaft of a motor 12 mounted on a lateral surface of the X-ray tube 2 by a support rod 11, and interlocks with the movement of the position of the X-ray tube 2 as shown in FIG. Then, the rotation axis of the motor 12 rotates by a predetermined angle, and the lead piece 10 moves as if the pendulum swings. Thereby, the position of the lead piece 10 with respect to the X-ray tube 2 changes. Of course, since the lead pieces 10 block straight X-rays, straight X-rays do not enter at positions corresponding to the lead pieces 10 on the X-ray detection surface of the I / I tube 3, and only scattered X-rays enter. It takes the form. The support rod 11 is formed of an X-ray transmitting material (for example, a plastic rod or the like).

In accordance with a control signal output from the timing signal generator 21, the transmission X
An AD converter 20 is provided for converting the line detection signal into a digital signal and outputting the digital signal as each pixel signal of an X-ray image. Each pixel signal output from the AD converter 20 is sequentially converted to X (horizontal). A frame memory (image storage means) 22a stores and addresses each pixel according to an address number continuing along the Y (vertical) direction, and stores it as an X-ray image.
22b, and a TV monitor (image display means) 23 for displaying an X-ray image on a screen is also provided. Each of the frame memories 22a and 22b can store pixel signals for one X-ray image. Therefore, in the apparatus of the embodiment, the image forming means is constituted mainly by the AD converter 20 and the timing signal generator 21.

The X-ray imaging apparatus according to the embodiment has an X-ray image X-ray image as a structural feature in the signal processing system.
Signal intensity detecting means for detecting the signal intensity of the pixels in the line shielding single image area; and image correcting means for performing a correction process for subtracting a signal intensity corresponding to the signal intensity detected by the signal intensity detecting means for each pixel signal of the X-ray image. Have. The signal intensity detecting means of the embodiment device includes a buffer memory 24, a threshold generator 25, a lead flake image area detecting unit 26, comparators 27 and 2.
8, the switch 29 and the minimum value memory 30 are mainly arranged.

The buffer memory 24 is a lead image area detecting section 26
The pixel signal is held by the output signal. The lead flake image area detecting unit 26 outputs an output signal based on the control signal of the timing signal generator 21 when the image signal from the AD converter 20 is for a pixel in a certain area including the lead flake image. The threshold generator 25 outputs a reference signal that is a reference for the comparison operation of the comparator 27. The comparator 27 compares the signal intensities of the pixel signal and the reference signal. The comparator 28
A comparison is made between the signal intensities of the pixel signals held in the buffer memory 24 and the pixel signals stored in the minimum value memory 30. The switch 29 is a switch that performs an on / off operation (open / close operation) according to an output signal from the comparator 28. When the switch 29 is closed, the signal stored in the minimum value memory 30 is updated to the pixel signal held in the buffer memory 24.

Further, the image correcting means of the embodiment device is constituted mainly by a subtractor 31, and the subtracter 31 detects a minimum value from each pixel signal read from the frame memory 22a or 22b. The pixel signal stored in the memory 30 is subjected to subtraction processing and then output to the adder 32.

Further, in the X-ray imaging apparatus of the embodiment, the adder 3 is used as an image integrating means for integrating a plurality of different X-ray images obtained in the process of moving the imaging section to obtain a tomographic X-ray image.
2 and a frame memory (image storage means) 33 for storing and storing pixel signals with the same pixel addresses as those of the frame memories 22a and 22b. To one terminal of the adder 32, a pixel signal (for example, address I) sent from the subtractor 31 is input, and to the other terminal of the adder 32, a pixel of address I of the frame memory 33 is input. The signal is read and input. The two pixel signals are added by the adder 33, sent to the frame memory 33, and updated and stored as a new pixel signal at the address I. The same processing is performed on the pixel signals at all addresses of the X-ray image, the X-ray image is integrated, and a tomographic X-ray image is created.

The X-ray images or tomographic X-ray images stored in the frame memories 22 a and 22 b and the frame memory 33 are appropriately transmitted to the TV monitor 23 via a DA converter 34.
To be displayed on a screen or printed on a sheet by a printer (not shown). In addition, the apparatus of the embodiment is also provided with an operation unit 35 for inputting commands, data, and the like necessary for executing shooting. The operation unit 35 is configured by input devices such as a keyboard and a so-called mouse.

Next, the operation when tomographic imaging is performed by the embodiment apparatus having the above-described configuration will be specifically described with reference to the drawings.

First, the X-ray tube 2 irradiates the subject M placed on the top 1 with X-rays at the position F1, and the I / I tube 3 moves to the position f1.
Receives transmitted X-rays, and a transmitted X-ray detection signal is output from the TV camera unit 3a to the AD converter 20. The AD converter 20 converts the transmitted X-ray detection signal into a digital signal, stores the converted signal in the frame memory 22a, and stores the X-ray image. At this time, the pixel signal is also output to the buffer memory 24, and the pixel signal is constantly stored and updated. Frame memory 22
The X-ray image G1 stored in “a” has a circular effective screen as shown in FIG. In the case of the X-ray image G1, the pixel signal is
According to the control signal of the timing signal generator 21, from the left address to the right address (X
Direction), and when it reaches the right end, it is stored again sequentially from the left address to the right address (X direction) in the horizontal line one position below the top row (a position advanced by one address in the Y direction). This is repeated, and when the storage at the right end address of the lowermost horizontal line is completed, the X-ray image G1 has been stored.

Simultaneously with the formation and storage of the X-ray image G1, the lead flake image area detecting section 26 displays the pixel signal output to the buffer memory 24 based on the control signal of the timing signal generator 21 by a dashed line in FIG. It is monitored whether or not the pixel belongs to the area E shown in FIG. The area E has a lead piece 10 inside.
Is determined in advance according to the installation position of the lead piece 10 so as to include the image (shade). The lead flake image area detection unit 26 determines whether or not the pixel signal output to the buffer memory 24 belongs to the area E by counting the timing signal from the timing signal generator 21.

When it is determined that the pixel is in the area E,
The lead flake image area detector 26 outputs an output signal, and causes the comparator 27 to start an operation of comparing (intensity) the pixel signal stored in the buffer memory 24 with the reference signal from the threshold generator 25. . If the intensity of the pixel signal is greater than the intensity of the reference signal, nothing happens and the process proceeds to the next process.

However, for example, as shown in FIG. 2, in the line HL that horizontally crosses the image GA of the lead piece 10,
When the intensity of the pixel signal changes from left to right along the horizontal line HL, as shown in FIG. 3, the intensity of the pixel signal becomes lower than the intensity of the reference signal. If the intensity of the pixel signal is smaller than the intensity of the reference signal as shown by a symbol R1 in FIG. 3, the comparator 27 outputs an output signal and holds the pixel signal in the buffer memory 24, and the comparator 28
Starts a comparison between the intensity of the held pixel signal and the intensity of the minimum value signal stored in the minimum value memory 30 (for example, a reference signal is initially stored).

If the intensity of the held pixel signal is greater than the intensity of the minimum value signal, the hold of the buffer memory 24 is released, and the process proceeds to the next step without any occurrence. However, if the intensity of the held pixel signal is smaller than the intensity of the minimum value signal, the comparator 28 outputs an output signal and closes (turns on) the switch 29 for a certain period. When the switch 29 is closed, the minimum signal previously stored in the minimum memory 30 is transferred to the buffer memory 2.
4 is changed and stored (updated) to the pixel signal held at 4. Hereinafter, similar processing is performed on the pixel signals of the respective pixels of the horizontal line between the upper side and the lower side in the region E, and as a result, for example, the pixel signal min1 having the minimum intensity value shown in FIG. It is stored in the value memory 30.

The pixel signal min1 stored in the minimum value memory 30 is determined to be a signal based on only scattered X-rays. This is because the lead flake image is a signal generated by scattered X-rays where straight X-rays are blocked. Usually, among the pixel signals of the pixels in the lead flake image, the signal having the minimum intensity is
It can be seen that it exactly corresponds to the signal component due to only scattered X-rays. At the time of an image signal for a pixel outside the area E, the comparators 27 and 28 do not operate at all, and the processing proceeds to the next processing. Thus, the storage of the X-ray image G1 and the detection and storage of the pixel signal min1 corresponding to the influence of the scattered X-rays are completed.

Subsequent to the end of the storage of the X-ray image G1 and the detection and storage of the pixel signal min1, a correction process by the subtractor 31 is performed. That is, the pixel signal of each pixel of the X-ray image G1 is sequentially read out, and the subtracter 31 subtracts the pixel signal min1 from the pixel signal.
3 is stored. By the subtraction processing by the subtracter 31, the image stored in the frame memory 33 is one in which the influence of the scattered X-ray has been removed.

On the other hand, in parallel with the execution of the correction processing on the X-ray image G1, the X-ray tube 2 is moved to the position F2, and the I / I tube 3 is moved to the position f2, and photographing is performed. Similarly, the storage of the X-ray image G2 shown in FIG. 4 and the detection and storage of the pixel signal min2 having the minimum intensity among the pixel signals of the pixels in the area E indicated by the dashed line in FIG. 4 are executed. The X-ray image G2 is stored in the frame memory 22b. Note that the minimum value memory 30 stores the pixel signal min1 previously detected and stored during the process of detecting the pixel signal min2.
For a necessary period. Also, X
When the wire tube 2 moves to the position F2, the lead pieces 10 move in conjunction with each other, and therefore, as shown in FIG.
Move to the center of the line image G2.

Subsequent to the end of the storage of the X-ray image G2 and the detection and storage of the pixel signal min2, a subtracter 31 is applied to the X-ray image G2.
Is performed. Also in this case, in parallel with the execution of the correction processing on the X-ray image G2, the X-ray tube 2 is moved to the position F3, and the I / I tube 3 is moved to the position f.
3 and the photographing is performed. Similarly, the storage of the X-ray image G3 shown in FIG. 5 and the pixel having the minimum intensity among the pixel signals of the pixels in the area E shown by the dashed line in FIG. Signal mi
The detection and storage of n3 is executed. The X-ray image G3 is stored in the frame memory 22a. When the X-ray tube 2 moves to the position F3, the lead piece 10 also moves in conjunction therewith, so that the image GA
Moves further downward as shown in FIG.

On the other hand, the correction processing for the X-ray image G2 is as follows.
This is the same as the case of the X-ray image G1, but the operation of storing the data in the frame memory 33 after the subtraction processing is slightly different from that of the X-ray image G1. The subtracted X-ray image G2 (for example, J
As the pixel signal of the pixel (at the address), the pixel signal at the address J in the frame memory 33 is read out, the two pixel signals are added, and the sum is stored at the address J in the frame memory 33 (update storage).
Is done. When the processing of adding and storing the pixel signals has been completed for all the pixels, the X-ray images G1 and G2 have been integrated. Of course, the X-ray image G3 is similarly subjected to image component processing, and as a result, as shown in FIG. 6, a tomographic X-ray image G4 obtained by integrating the X-ray images G1 to G3 is stored in the frame memory 33. Will be remembered. Note that a series of flows of the tomographic operation performed by the above-described embodiment apparatus are summarized on the flowchart shown in FIG. Also, in the above explanation,
Three X-ray images with different X-ray irradiation angles are obtained and integrated,
Although one tomographic X-ray image has been obtained, of course, in the actual case,
The number of X-ray images obtained in the process of moving the imaging unit is not limited to three, but it is common to obtain and integrate a larger number of X-ray images.

It should be noted that the lead piece image GA in each of the X-ray images G1 to G3 is substantially zero in each X-ray image by the correction processing.
In the tomographic X-ray image G4 integrated and stored in the frame memory 33, as shown in FIG.
The trace of A appears as a band-shaped image Ga that continues vertically,
The image on the section of interest is not hidden by the band image Ga.

The contrast of the tomographic X-ray image G4 is improved as compared with the conventional one. FIG. 7 is a graph showing a signal waveform of the tomographic X-ray image G4. In the conventional case, as shown by a dashed line in FIG. 7, a signal component Sa related to a change in shading in the display image and a shading in the display image. The entire density change range (for example, of 256 gradations) is assigned to a signal range in which the offset Ba due to the scattered X-ray irrelevant to the change is combined. On the other hand, in the case of the present invention, as shown by the solid line in FIG. 7, the offset Ba due to the scattered X-ray is removed, and the entire density change range is allocated only to the signal Sb related to the change in density in the display image. . As a result, in the displayed tomographic X-ray image, the change in density becomes more remarkable than before, the contrast is improved, and the minute change in the affected part can be easily understood.

The present invention is not limited to the above embodiment, but can be modified as follows. (1) In the above embodiment, the influence of scattered X-rays is removed in tomography, but the influence of scattered X-rays is removed in normal X-ray fluoroscopy in which integration of X-ray images is not performed. The thing can also be mentioned as a modification.

(2) In the above embodiment, the lead piece is moved in conjunction with the movement of the X-ray tube. However, a modification in which the positional relationship between the X-ray tube and the lead piece is fixed is also a modification. As However, in this case, the lead fragment image appears densely in the tomographic X-ray image. However, if the lead piece is installed at a position where the lead piece image does not hinder diagnosis, such as a peripheral part of the tomographic X-ray image, there is no particular problem in practical use.

(3) In the above embodiment, X is used for tomography.
The configuration in which the X-ray tube and the I / I tube take other well-known movement modes, such as an arc movement, a spiral movement, and an elliptical movement, during tomography, although the X-ray tube and the I / I tube move in parallel. It is needless to say that the above is also a modified example.

(4) In the above embodiment, the X-ray shielding piece disposed between the X-ray tube and the subject is a small disk-shaped lead piece. Needless to say, the material is not limited to lead.

(5) In the above embodiment, the correction processing for removing (subtracting) the influence of scattered X-rays is performed before integrating each X-ray image. However, each X-ray image is integrated before correction. With
There is also a configuration in which an addition value of the minimum intensity pixel signals min1 to min3 in each X-ray image is obtained, and the integrated X-ray image is collectively subjected to (subtraction) correction processing for eliminating the influence of scattered X-rays. A modification is given.

(6) In the above embodiment, the pixel signal having the minimum intensity among the pixel signals of the pixels in the lead piece image area in the area E is determined to be a signal intensity corresponding to the scattered X-ray. The signal intensity corresponding component is not limited to the pixel signal having the minimum intensity. For example, a modification in which the average value of the pixel signals of some pixels in the lead piece image area in the X-ray image is set to a signal intensity corresponding portion is given as a modified example.

[0045]

As is clear from the above description, according to the X-ray imaging apparatus of the first aspect of the present invention, the offset due to the influence of scattered X-rays is removed from the X-ray image. The change in shading can be increased, and the contrast is improved.

According to the X-ray imaging apparatus of the second aspect,
Since it has a configuration for integrating a plurality of different X-ray images obtained in the process of moving the X-ray and the image intensifier in conjunction with each other, a tomographic X-ray image can be obtained, and
Since the position of the ray shielding piece changes, on the tomographic X-ray image,
The X-ray shielding piece image (moving trajectory) only appears faintly.
The image is not hidden by the image of the line shielding piece.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an X-ray imaging apparatus according to an embodiment.

FIG. 2 is a diagram schematically illustrating an X-ray image obtained by an example apparatus.

FIG. 3 is a graph showing a change in pixel signal intensity in the horizontal direction of the X-ray image of FIG. 2;

FIG. 4 is a diagram schematically illustrating another X-ray image obtained by the example apparatus.

FIG. 5 is a view schematically showing another X-ray image obtained by the example apparatus.

FIG. 6 is a diagram schematically showing a tomographic X-ray image obtained by the apparatus according to the embodiment.

FIG. 7 is a graph showing a change in pixel signal intensity in the tomographic X-ray image of FIG. 7;

FIG. 8 is a flowchart illustrating a flow of a tomographic imaging operation performed by the apparatus according to the embodiment.

FIG. 9 is an explanatory diagram showing the principle of tomographic imaging by the X-ray imaging apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 2 ... X-ray tube 3 ... Image intensifier 4 ... Photographing image part 10 ... Small disk-shaped lead piece 20 ... AD converter 23 ... TV monitor 22a, 22b ... Frame memory 27, 28 ... Comparator 30 ... Minimum value Memory 31 ... Subtractor 32 ... Adder 33 ... Frame memory

Claims (2)

[Claims] An X-ray tube and an image intensifier installed opposite to each other with a subject interposed therebetween, and a transmitted X-ray detection signal output from the image intensifier when X-rays are irradiated onto the subject. An image forming means for converting to create an X-ray image, an image storing means for storing the X-ray image, and an image display means for displaying the X-ray image
In the X-ray imaging apparatus, an X-ray shielding piece located between the X-ray tube and the subject and arranged to appear as an image in the X-ray image, and an X-ray shielding piece image area in the X-ray image Signal strength detection means for detecting the signal strength of the pixel;
An X-ray imaging apparatus, comprising: image correction means for performing a correction process for subtracting a signal intensity corresponding to a signal intensity detected by the signal intensity detection means for each pixel signal of an X-ray image. 2. The X-ray imaging apparatus according to claim 1, wherein the X-ray tube and the image intensifier are positioned so that the X-ray tube and the image intensifier have a symmetrical positional relationship with respect to a point on a plane of interest of the subject. An imaging unit moving means for moving an imaging unit consisting of a ray tube and an image intensifier in conjunction with each other, and in each X-ray image obtained in the process of moving the imaging unit, the appearance position of the X-ray shielding piece image changes. X-ray shielding piece moving means for changing the position of the X-ray shielding piece with respect to the X-ray tube in accordance with the movement of the imaging unit, and integrating the respective X-ray images obtained in the moving process of the imaging unit to interest the subject. An X-ray imaging apparatus comprising: image integration means for obtaining a tomographic X-ray image of a cut plane.