JPH06142093A - Tomograph - Google Patents

Abstract

PURPOSE:To provide a tomographic image capable of obtaining a tomographic image same as the image which would be obtained when a similar motion is made accurately even if an X-ray tube and an image receiving part may device from a geometrically relative position. CONSTITUTION:A drive mechanism 3 moves an X-ray generation source 1 and an X-ray detector 2 in the opposite direction to each other keeping a geometrically similar relationship centered on one point near a subject. A position detector 4 detects moving positions of the X-ray generation source 1 and the X-ray detector 2. A storage device 5 stores image information to be outputted from the X-ray detector 2 related to an output signal of the position detector 4. A small object 6 is the one fixed unmovable relatively with respect to the subject 9 to be placed in an X-ray transmission area, for example, a small disc made of lead. An image processing means 8 extracts a projection image of the small object 6 from the image information stored in the memory 5 to determine the position thereof. A difference is determined by an arithmetic processing means 7 between a position as specified of the small object 6 and an actual position determined by the image processing means 8 and transmitted images of the images are corrected in position to be overlapped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an X-ray tomography apparatus,
In particular, the present invention relates to a reconstructed image correction unit using an X-ray tomography apparatus.

[0002]

2. Description of the Related Art Conventionally, an X-ray tomography apparatus performs X-ray imaging while relatively moving an X-ray tube and a film around a point (a tomographic center) where a portion to be inspected is centered, and includes a tomographic center and a parallel film. However, due to improvements in image processing technology in recent years, TV tomography (digital tomography) that uses an image intensifier (II) instead of film for this tomography (Also called) has been put to practical use.

In the TV tomography, instead of recording the X-ray image on the film, the TV signal of the X-ray image is sequentially stored in the memory. Then, one tomographic image is reconstructed by superimposing the stored X-ray images after the end of imaging, but the cross-sectional image to be extracted can be changed by shifting the superimposing position.

Therefore, in the conventional X-ray tomography apparatus using a film, it is necessary to perform tomography every time the cross-sectional image is changed. However, in the case of TV tomography, if one tomography is performed, other tomographic planes are subjected to image processing. It can be obtained only by operation, and there is an advantage that the X-ray exposure dose of the subject can be reduced.

[0005]

However, as a problem common to not only TV tomography but also conventional X-ray tomography apparatus using a film, in X-ray tomography, an X-ray tube and an image receiving unit (II or film) are used. It is necessary to accurately perform the similar movement of the tomographic image. If the similar movement is not accurate, the image quality of the tomographic image is significantly deteriorated. However, in reality, it is difficult to obtain an accurate similar motion due to elastic deflection, vibration, and processing error of the components forming the tomographic apparatus, and the X-ray tube and the image receiving unit are geometrically relative to each other. There is a problem in that the resolution of the tomographic image deteriorates as compared with the case where the similar movement is accurately performed because the position shifts from the position. Further, in order to improve the resolution of the tomographic image, it is necessary to strengthen the rigidity of the component parts and process the parts with high precision in order to accurately move the X-ray tube and the image receiving portion relative to each other, which causes a cost increase. It was.

The present invention was devised in view of the above problems, and is similar to the case where the similar movement is accurately performed even if the X-ray tube and the image receiving portion are displaced from the geometrical relative positions. It is an object to provide an X-ray tomographic image capable of obtaining a tomographic image.

[0007]

In order to achieve the above-mentioned object, an X-ray tomography apparatus of the present invention includes an X-ray generation source and an X-ray source, which is placed in opposition to the X-ray source with a subject interposed therebetween. Detecting means for converting the line image into an electric signal and outputting it as image information;
A drive mechanism that relatively moves the X-ray source and the detection means, a position detector that detects the moving position of the X-ray source, and image information from the detection means during relative movement are stored in association with the output of the position detector. A storage device, a small object having an X-ray absorptivity different from that of the object in the X-ray transmission region and the object in the X-ray transmission region, and a plurality of objects stored from the storage device. Of the image information, and the image processing means for obtaining the tomographic image of the subject by superimposing the image information with a predetermined positional relationship and a plurality of image information stored from the storage device. An image processing means for obtaining the transmission image position of the object and outputting it to the arithmetic processing means as transmission image position information of the small object, and when the arithmetic processing means superimposes the image information, the transmission image position information of the small object Due to the weight of each image information Wherein the position correcting the keying.

Further, in the above X-ray tomography apparatus, X
The X-ray receiving unit may be fixed, and the drive mechanism may be configured to move the X-ray generation source and the subject relatively.

[0009]

With the above construction, the X-ray tomography apparatus of the present invention is
The detection means converts the transmitted X-ray image into an electric signal and outputs it as image information, the drive mechanism relatively moves the X-ray source and the detection means, and the position detector detects the moving position of the X-ray source and stores it. The device stores the image information from the detecting means during relative motion in association with the output of the position detector, the arithmetic processing means retrieves the plurality of stored image information from the storage device, and stores each image information in a predetermined positional relationship. To obtain a tomographic image of the subject. On the other hand, the image processing means extracts a plurality of image information stored from the storage device, obtains the transmission image position of the small object from each image information, and outputs it as the transmission image position information of the small object to the arithmetic processing means. The arithmetic processing unit corrects the superposition position of each image information according to the transmission image position information of the small object when superposing the image information.

[0010]

1 is a block diagram showing the construction of an embodiment of an X-ray diagnostic apparatus according to the present invention.

In FIG. 1, 1 is an X-ray generation source, 2 is an X-ray detector as detection means, 2a is II (image intensifier), 2b is an A / D converter, 3 is a drive mechanism, and 4 is position detection. 5 is a storage device, 6 is a small object having a high X-ray absorption rate, 7 is an arithmetic processing means, 8 is an image processing means, 9 is a subject, 10 is a high voltage generator, 11 is an X-ray controller, and 12 is An operation console, 13 is a display device, and 14 is a top plate on which a subject is placed.

In the present embodiment, the X-ray generation source 1 is an X-ray tube and is connected to a high voltage generator 10 and an X-ray controller 11 to generate X-rays. The X-ray detector 2 is II2a, an intensifying tube and A /
The D-converter 2b irradiates the subject 9 with X-rays from the X-ray generation source 1, converts the transmitted X-rays that have passed through the subject 9 into electric signals, and outputs them as image information.

The drive mechanism 3 is a drive means for moving the X-ray generation source 1 and the X-ray detector 2 in opposite directions while maintaining a geometrically similar relationship around a certain point near the subject.

The position detector 4 detects the moving positions of the X-ray generator 1 and the X-ray detector 2. However, the positional relationship between the X-ray generation source 1 and the X-ray detector 2 is geometrically similar to each other maintained by the driving mechanism 3, and therefore the position of the X-ray generation source 1 may be detected.

The storage device 5 is composed of a memory for storing a plurality of pieces of image information output from the X-ray detector 2 during tomography in association with the output signal of the position detector 4.

The small object 6 is a small object which is fixed so as not to move relative to the subject 9 and is placed in the X-ray transmissive region and has a different X-ray absorption rate from the surroundings. In this embodiment, a small disc made of lead is used as the small object 6, and is placed on the top plate 14 as shown in FIG.

The arithmetic processing means 7 sequentially takes out the respective pieces of image information stored in the storage device 5 and superimposes them to create a tomographic image. At this time, by simply superposing the image information, a tomographic image of the plane X0 including the point O of the relative movement of the X-ray generation source 1 and the detector 2 and parallel to the X-ray detection plane is obtained. Further, by superimposing the pieces of image information while shifting them appropriately, a tomographic image of an arbitrary plane parallel to the plane X0 can be obtained.

The image processing means 8 sequentially extracts a plurality of image information stored in the storage device 5 and extracts a projected image of the small object 6 from each of the image information to determine the position of the small object image in each image information. It is output to the arithmetic processing means as transmission image position information of the obtained small object.

When the image information is overlaid, the arithmetic processing means 7 further corrects the overlay position of each image information by the transmission image position information of the small object input from the image processing means 8.

The display device 13 visually displays the image information position-corrected by the arithmetic processing means 7 as a tomographic image of the subject.

The principle of position determination by the small object 6 in the position correction of the image information by the arithmetic processing means 7 is as follows.

In the image information stored in the storage device 5, a transmission image of the subject 9 and a transmission image of the small object 6 are shown. FIG. 2 shows the tomographic image F1 by omitting the transmission image of the subject 9 from the tomographic images obtained at each time point of the relative movement of the X-ray generation source 1 and the detector 2. , F
2, ..., Fn and small objects 6 imprinted on them are shown. In FIG. 2, the projection positions of the small objects in each image are sequentially changed. This is because the positions of the X-ray generation source 1 and the X-ray detector 2 are relative to the small object 6 during tomography. This is to change the position.

FIG. 3 shows the tomographic images F1, F2, ...
.. is a tomographic image obtained by superimposing Fn by the arithmetic processing means 7, and a point P indicated by a white circle in FIG.
This is the position where the small object 6 should be when the radiation source 1 and the X-ray detector 2 move in opposite directions while maintaining a geometrically similar relationship, and the locus of the point P is linearly copied on the tomographic image. It should be embedded. However, the locus of the small object 6 that is actually imprinted is the point P like the point Pi indicated by the black circle in FIG.
Deviates from the linear trajectory of. This deviation is caused by the vibrations and processing errors of the components forming the X-ray tomography apparatus as described above, and this deviation causes the resolution of the finally obtained tomographic image to deteriorate.

Therefore, the arithmetic processing means 7 finds the difference between the original position of the small object 6 and the actual position of the small object 6 obtained by the image processing means 8, and the small object of each image is calculated by the difference. Since the images including the projected image of the small object 6 are superimposed on the original position as shown in FIG. 4 by correcting and superimposing the position of 6, the clear tomographic image without deterioration of resolution can be obtained. Can be done. The original position of the small object 6 is uniquely determined by the geometrical positional relationship among the X-ray generation source 1, the X-ray detector 2 and the small object 6, and when each image information is captured. It can be easily calculated and obtained from the signal (position information) of the position detector 4 of.

Further, in the tomographic image obtained by superimposing each image, the projected image of the small object 6 becomes an intermittent projected image as shown in FIG. 4, but the image shown in FIG. 4 is emphasized for explanation. In reality, it is represented as a so-called out-of-focus image on a tomographic image, and is thinner than the transmission image of the tomographic plane of the subject to be drawn, so that it does not interfere with the diagnosis. In addition, considering that it may not be a sufficiently blurred image and interferes with diagnosis,
It is also possible to perform a process of reducing (or increasing) the density of the projected image of the small object 6 to the density level in the vicinity thereof by the image processing means 8.

In the above description, the subject 9 is fixed and the X-ray generation source 1 and the X-ray detector 2 are moved in opposite directions, but the X-ray detector 2 is fixed and the subject 9 and X-rays are fixed. The same result can be obtained by taking an image while moving the line source 1 relatively in the same direction. In this case, a mechanism for moving the top 14 is required to move the subject 9, but this type of apparatus is usually equipped with the mechanism. It is also relatively easy to fix the X-ray detector 2 and drive only the X-ray generation source 1. Therefore, it is possible to perform X-ray tomography without resolution deterioration with a simple mechanism.

Although one embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to the above embodiment and various modifications can be made.

[0028]

As described above, according to the present invention, when the X-ray transmission images stored in the storage device are superposed, even if the X-ray tube and the image receiving portion are deviated from the exact similar position, the deviation ( Error) and superimposing them, there is a shift in the relative position between the X-ray tube and the image receiving unit due to vibration of parts constituting the X-ray tomography apparatus and a processing error, and a shift due to other causes. In the same way, a tomographic image without deterioration of resolution can be obtained as in the case where the X-ray tube and the image receiving part make a similar motion accurately, and the resolution of the tomographic image is improved. Can be provided to the diagnostician.

Further, in the apparatus of the present invention, in order to accurately move the X-ray tube and the image receiving unit relative to each other, it is not necessary to particularly strengthen the rigidity of the constituent parts, and it is not necessary to process the parts with high precision. Moreover, since the configuration of the apparatus can be simplified, it is possible to supply a low-cost X-ray diagnostic apparatus.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a transmission image of a small object in a tomographic image obtained at each time point of relative movement between an X-ray generation source and an X-ray detector.

FIG. 3 is a diagram showing a position of a small object in a tomographic image obtained by superimposing the tomographic images of FIG.

FIG. 4 is a diagram showing a position of a small object in a tomographic image obtained by superimposing each tomographic image of FIG. 2 after correction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray generation source 2 X-ray detector (detection means) 3 Driving mechanism 4 Position detector 5 Storage device 6 Small object 7 Arithmetic processing means 8 Image processing means 9 Subject

Claims (2)

[Claims] 1. An X-ray generation source and a subject are sandwiched between the X-ray generation source and the subject.
A detection unit that is arranged opposite to the radiation source, converts the transmitted X-ray image into an electric signal and outputs it as image information, a drive mechanism that relatively moves the X-ray source and the detection unit, and a movement position of the X-ray source. A position detector for detecting, a storage device for storing image information from the detecting means during the relative motion in association with the output of the position detector, and a device fixed in the X-ray transmission region relative to the subject. , The object and a small object having an X-ray absorptance different from that of the object in the X-ray transmission region, and the plurality of stored image information are taken out from the storage device, and the respective image information are superposed in a predetermined positional relationship. An arithmetic processing unit for obtaining a tomographic image of the subject together, and a plurality of the stored image information are taken out from the storage device, the transmission image position of the small object is obtained from each of the image information, and the transmission of the small object is obtained. The performance as image position information Image processing means for outputting to the processing means, and when the arithmetic processing means superimposes the image information, the superimposing position of each image information is corrected by the transmission image position information of the small object. X-ray tomography apparatus. 2. The X-ray tomography apparatus according to claim 1, wherein the X-ray image receiving unit is fixed, and the drive mechanism relatively moves the X-ray generation source and the subject. Imaging device.