CN108324294A - X-ray filming apparatus - Google Patents

Abstract

The present invention provides an X-ray imaging device. Among the four sides of the X-ray irradiated area, the side on the cathode side is also accurately detected, and the X-ray irradiated area is accurately detected. An X-ray imaging device is provided, comprising: an X-ray source having an X-ray tube for irradiating an object with X-rays; an X-ray aperture for limiting an X-ray irradiation area irradiated from the X-ray source to the object; An X-ray detector that irradiates and transmits X-rays of the subject through the X-ray aperture; an image processing unit that generates an X-ray image based on an electrical signal output from the X-ray detector; a cathode detection unit that detects cathode position information of a side located on the cathode side of the X-ray tube among four sides of the X-ray irradiation area in the generated X-ray image; and based on the cathode position obtained by the cathode detection unit An irradiation area detection unit that detects an X-ray irradiation area in the X-ray image based on the information.

Description

X-ray camera

technical field

The present invention relates to an X-ray imaging device, which uses an X-ray aperture to set an irradiation area of X-rays irradiated from an X-ray source, and uses a detector to detect X-rays passing through an area corresponding to the set irradiation area, thereby obtaining to visualize.

Background technique

In the past, an X-ray imaging device is known, which reduces the scattered rays of X-rays in addition to reducing the radiation of the unnecessary imaging area, thereby improving the image quality. The X-ray aperture that narrows the irradiation range of the irradiated X-rays. In such an X-ray imaging device, position information of the X-ray aperture is obtained using a position detector or the like, and an area corresponding to the opening of the X-ray aperture is imaged.

For example, Patent Document 1 discloses an X-ray image diagnostic apparatus in which an X-ray aperture position detector specifies an X-ray aperture area in an image based on position information or X-ray tube angle information.

prior art literature

patent documents

Patent Document 1: JP Unexamined Publication No. 2008-200075

However, in the X-ray image diagnostic apparatus of Patent Document 1, since the therapeutic effect is not considered, it is not mentioned that there is a difference in the sharpness of the aperture side on the anode side of the X-ray tube and the aperture side on the cathode side. Detection accuracy in the X-ray aperture area will decrease.

The X-ray tube generates X-rays by applying a high voltage of tens of kV to one hundred and tens of kV between the cathode (filament) and the anode (target), so that the thermal electrons emitted from the cathode accelerate to the anode and collide with the anode. At this time, in the cathode-anode direction, since the X-rays irradiated on the anode side advance in the anode and are released, the low-energy X-rays are more absorbed by the metal in the anode, and the high-energy X-rays are more absorbed by the metal in the anode. release. On the other hand, the X-rays irradiated to the cathode side are less affected by being absorbed by the metal in the anode. Therefore, among the X-rays irradiated from the X-ray tube, the energy distribution of the X-rays irradiated to the anode side in the cathode-anode is shifted to a side higher than the energy distribution of the X-rays irradiated to the cathode side (refer to FIG. 11 ).

Therefore, in the X-ray image after passing through the aperture, the sharpness of the image near the side of the cathode side becomes lower than that of the image near the side of the anode side among the four sides of the rectangular X-ray irradiation area. ease.

For this reason, unless the side of the X-ray irradiated area is accurately determined whether it is located on the anode side or the cathode side, the X-ray irradiated area may not be detected with high accuracy.

Contents of the invention

The present invention is made in view of the above circumstances, and an object of the present invention is to accurately detect the side on the cathode side among the four sides of the X-ray irradiation area after the X-rays pass through the aperture, thereby accurately detecting the X-ray irradiation area.

In order to solve the above-mentioned problems, the present invention provides the following means.

One aspect of the present invention provides an X-ray imaging apparatus including: an X-ray source having an X-ray tube for irradiating an object with X-rays; an X-ray aperture for limiting a radiation irradiation area; an X-ray detector for detecting X-rays irradiated through the X-ray aperture and transmitted through the subject; and generating an X-ray image based on an electrical signal output from the X-ray detector an image processing unit; a cathode detection unit that detects cathode position information representing a side on the cathode side of the X-ray tube among four sides of the X-ray irradiation area in the X-ray image generated by the image processing unit; and an irradiation area detection section that detects an X-ray irradiation area in the X-ray image based on the cathode position information obtained by the cathode detection section.

Invention effect

According to the present invention, the side located on the cathode side among the four sides of the X-ray irradiated area can be accurately detected, and the X-ray irradiated area can be accurately detected.

Description of drawings

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

2 is a flowchart showing the flow of processing for storing setting information in the X-ray imaging device according to the first embodiment of the present invention.

FIG. 3(A) is a diagram illustrating a readout area for mapping the distribution of captured images in the X-ray imaging device according to the first embodiment of the present invention, and FIG. A graph showing the results of distribution mapping in the X-ray imaging device according to the first embodiment.

4 is a flowchart showing the flow of X-ray irradiation area detection processing in the X-ray imaging device according to the first embodiment of the present invention.

5 is a flowchart showing the flow of cathode position information generation processing in the X-ray imaging device according to the first embodiment of the present invention.

FIG. 6(A) is a graph obtained by plotting pixel values in the readout region, and FIG. 6(B) is a graph for comparison with a graph obtained by thinning processing.

7 is a flowchart showing the flow of cathode position information generation processing in the X-ray imaging device according to the second embodiment of the present invention.

8 is a graph showing the relationship between the number of thinning and pixel positions during thinning processing in the X-ray imaging devices according to the first embodiment and the modified example of the second embodiment of the present invention.

9 is a graph showing the relationship between the number of thinning and the tube voltage during thinning processing in the X-ray imaging apparatuses according to the first embodiment and the modified example of the second embodiment of the present invention.

10 is a graph showing the relationship between differential filter coefficients and pixel positions when generating a frequency image in the X-ray imaging apparatus according to the first embodiment and the modified example of the second embodiment of the present invention.

FIG. 11(A) is a diagram illustrating the state of X-rays generated from an X-ray tube, and FIG. 11(B) is a graph comparing energy distributions of X-rays irradiated on the anode side and the cathode side.

Label description

1 Image processing unit

2 System control unit

3 monitors

10 X-ray tube rotation mechanism

11 X-ray source

12 X-ray apertures

13 X-ray detector

14 Detector Rotation Mechanism

20 Image Processing Department

21 Image storage unit

22 Cathode detection part

23 Irradiation area detection unit

28 System information storage unit

30 X-ray images

31 X-ray irradiation area

32 readout area

P subject

Detailed ways

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The X-ray imaging device according to the embodiment of the present invention includes: an X-ray source 11 having an X-ray tube for irradiating the subject P with X-rays; A limited X-ray aperture 12; an X-ray detector 13 that detects X-rays irradiated through the X-ray aperture 3 and passes through the subject P; a rotating mechanism 14 that rotates the X-ray detector 13; The image processing part 20 that generates the X-ray image from the electrical signal that is output; the image storage part 21 that temporarily stores the X-ray image generated in the image processing part 20; A cathode detection unit 22 that detects cathode position information of a side located on the cathode side of the X-ray tube among the sides; and an irradiation area detection unit that detects an X-ray irradiation area in an image based on the cathode position information obtained by the cathode detection unit 22 twenty three.

<First Embodiment>

Specifically, as shown in FIG. 1 , the X-ray imaging device according to the first embodiment of the present invention includes: an X-ray source 11, an X-ray diaphragm 12, an X-ray detector 13, a rotating mechanism 14, an image processing unit 1, System control unit 2, and display 3. The X-ray imaging device can capture both X-ray fluoroscopic images and X-ray imaging images (still images).

The X-ray source 11 includes an X-ray tube that generates X-rays, and irradiates the subject with the X-rays generated in the X-ray tube. The X-ray tube is rotationally driven by the X-ray tube rotating mechanism 10 as required. The X-ray aperture 12 limits the X-ray irradiation area irradiated to the subject P from the X-ray source 11 . The X-ray detector 13 detects the X-rays irradiated through the X-ray aperture 3 and transmitted through the subject P, and outputs an electric signal corresponding to the amount of the transmitted X-rays to the image processing unit 1 . The X-ray detector 13 is rotationally driven by a detector rotation mechanism 14 .

The image processing unit 1 includes an image processing unit 20 , an image storage unit 21 , a cathode detection unit 22 , and an irradiation region detection unit 23 .

The image processing unit 20 generates an X-ray image based on the electrical signal output from the X-ray detector 13 and performs necessary image processing such as gradation processing. The image storage unit 21 temporarily stores the X-ray image generated by the image processing unit 20 .

The cathode detection unit 22 detects cathode position information indicating the side on the cathode side of the X-ray tube among the four sides of the X-ray irradiation area in the generated X-ray image.

More specifically, for example, the cathode detection unit 22 obtains the setting information of the X-ray tube of the X-ray source 11 stored in the system information storage unit 28, which is a storage area of the system control unit 2 described later, and determines the X-ray tube set by the image based on the setting information. The processing unit 20 generates the cathode position on the X-ray image, and generates cathode position information. At this time, when the X-ray tube or X-ray detector 13 is rotating, since the relative positions of the cathodes on the generated X-ray image are different, the X-ray tube rotation mechanism 10 based on the X-ray tube rotation mechanism 10 is also obtained together. rotation information.

Here, the X-ray tube installation information is information stored in the system control unit 2 by, for example, an installer when installing the X-ray imaging device, and is acquired following the procedure shown in the flowchart of FIG. 2 , for example.

Hereinafter, the process of storing the setting information in the storage area of the system control unit will be described according to the flowchart of FIG. 2 .

In step S11 , when the X-ray imaging device is installed, an image is acquired by the X-ray imaging device in accordance with the operation of the installer in a state where there is no subject. In the next step S12, in the X-ray image acquired by step S11, as shown in FIG. The pixels of the linear readout region 32 constituted by a plurality of pixels determined in a predetermined manner are used to create a distribution of pixel values.

In step S13, the side located on the cathode side is detected based on the distribution result of the pixel values of the four sides of the X-ray irradiated area. For example, it is determined whether the slopes of the distributions each exceed a given threshold. Among the four sides of the X-ray irradiation area, the sharpness of the image is different between the vicinity of the side on the cathode side and the side near the side on the anode side, so as shown in FIG. In the case of the pixel value at the pixel position of the region 32, the inclination is greatly different between the cathode-side readout region and the anode-side region. Similarly, the inclination is largely different between the readout region on the cathode side and the readout region other than the cathode side.

Therefore, by comparing the distribution result (for example, the inclination of the graph in FIG. 3(B) ) of each readout area with a predetermined threshold, the side on the cathode side can be specified from the four sides of the X-ray irradiation area. Therefore, in step S13, it is determined whether the distribution results of the four sides of the X-ray irradiated area exceed a given threshold. The flag indicating the side is stored in the system information storage unit 28 . In the determination of step S13, if the distribution result is smaller than the threshold value, it is regarded as the edge on the cathode side, and the process proceeds to step S15, and a flag indicating the cathode side is stored in the system information storage unit 28 . In this way, the positional information of the cathode and the anode of the X-ray source is stored in the system information storage unit 28 as the installation information, and the above-mentioned processing ends. In addition, the above-described processing may be performed only once when the X-ray imaging device is installed.

The irradiation area detection unit 23 detects the X-ray irradiation area in the image based on the cathode position information obtained by the cathode detection unit 22 . That is, the position of the boundary line of the X-ray irradiation area is detected. That is, the irradiation area detection unit 23 determines the side on the cathode side among the four sides of the X-ray irradiation area based on the output of the cathode detection unit 22, that is, the cathode position information, and emits X-rays on the side on the cathode side and the other three sides. The irradiated area detection process is different according to each characteristic, and thereby the X-ray irradiated area is accurately detected.

The system control unit 2 has a system information storage unit 28 that stores various information including the installation information of the above-mentioned X-ray source, controls the image processing unit 1 and the above-mentioned components, and makes the image generated by the image processing unit 1 displayed on display 3.

The display 3 displays the X-ray image generated by the image processing unit 1 and subjected to predetermined image processing according to the instruction of the system control unit 2 .

In addition, the image processing unit 1 and the system control unit 2 can be partially or entirely constructed as a system including a CPU (central processing unit), a memory, etc., and the CPU loads and executes a program previously stored in a storage unit into the memory, thereby The functions of the respective units constituting the image processing unit 1 and the system control unit 2 can be realized. In addition, part or all of the functions can also be configured by hardware such as ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array).

The X-ray irradiation area detection process in the X-ray imaging device configured as described above and storing the position information of the cathode and the anode in the system information storage unit 28 as setting information will be described in accordance with the flowchart of FIG. 4 .

In step S41, the irradiation area detection part 23 takes in the X-ray image generated by the image processing part 20 and stored in the image storage part 21, and it progresses to step S42. In step S42 , the irradiation area detection unit 23 determines whether the vicinity of four sides of the boundary of the X-ray irradiation area in the acquired X-ray image is a side on the cathode side based on the cathode position information acquired from the cathode detection unit 22 . If it is determined in step S42 that it is the side on the cathode side, the process proceeds to step S43, and when it is determined that it is not the side on the cathode side, the process proceeds to step S44.

Here, the determination of whether or not the irradiated area detection unit 23 is a side on the cathode side is performed based on the cathode position information acquired from the cathode detection unit 22 . The cathode position information in the cathode detection unit 22 is generated following the cathode position information generation process. An example of a flowchart related to the cathode position information generation process is shown in FIG. 5 .

In step S51 of FIG. 5 , the cathode detection unit 22 acquires the setting information from the system information storage unit 28 . In the next step S52, rotation information of the X-ray source 11 and the X-ray detector 2 is acquired. In step S53 , cathode position information on the X-ray image is generated based on the installation information and the rotation information, and is output to the irradiation area detection unit 23 .

Returning to FIG. 4 , in step S43 , a first thinned image is generated for detecting the boundary line of the side on the cathode side. In step S44, a second thinned image is generated for detecting the boundary lines of the sides other than the side located on the cathode side.

As shown in FIG. 6 , referring to the graph obtained by plotting the readout area near each side, the result for the readout area near the side on the cathode side and the readout area near the other side In the results of , the slopes on the graphs are different. For example, when the difference in inclination is three times, the number of thinning of the first thinned image is equal to the number of thinning of the second thinned image so that the accuracy of the sides other than the cathode is apparently consistent. 3 times.

In the flowchart of FIG. 4 , the number of thinning of the first thinned image is set to 30, and the number of thinning of the second thinned image is set to ten. By performing the thinning process in this way, the inclinations of both can be apparently matched as shown in the right diagram of FIG. 6 and the process can be advanced.

In step S45, a high-frequency image is generated for each of the first thinned image and the second thinned image. This is to detect the boundary of the X-ray irradiation region by generating a high-frequency image from which low-frequency components are removed using a differential filter or the like to extract edges. In step S46, the two high-frequency images are respectively subjected to line detection through Hough transform, the length of the line and the density difference of the boundary value are detected, and whether it is the boundary line of the X-ray irradiation area is determined to determine the coordinates of the X-ray irradiation area. In the next step S47, the coordinates of the identified X-ray irradiation area are converted into coordinates of the X-ray image before thinning image generation to finally detect the X-ray irradiation area, and the above processing ends.

Thus, according to the present embodiment, an image is obtained based on X-rays generated in the X-ray tube and transmitted through the subject through the X-ray diaphragm, and the X-ray irradiation region is determined in the image. In such a case, when it is determined that Whether or not each side of the X-ray irradiated area is located on the cathode side of the X-ray tube, the process is different between the side located on the cathode side and the other sides to detect the X-ray irradiated area. Therefore, by performing image processing according to the characteristics of the side on the cathode side whose sharpness is lower than that of the other sides, it is possible to detect the boundary line of the X-ray irradiation area with high precision. On the other hand, since the edge other than the cathode side is sharper than the edge on the cathode side, the boundary line of the X-ray irradiation area can be detected with high accuracy by processing according to the characteristics of the edge other than the cathode side . As a result, the X-ray irradiation area on the X-ray image can be accurately detected.

By accurately detecting the X-ray irradiated area, the X-ray irradiated area can be used in subsequent image processing such as gradation processing and frequency processing, thereby improving image quality.

When inserting the X-ray diaphragm obliquely, or when injecting the X-ray tube so that the X-ray irradiation area on the X-ray image becomes a trapezoid, the position on the cathode side is also determined, and the sides on the cathode side and Other than these, the detection processing is different, thereby improving the detection accuracy of the X-ray irradiated area.

<Second Embodiment>

In the X-ray imaging apparatus according to the first embodiment described above, the position of the cathode on the X-ray image is determined based on information contained in the system information storage unit such as installation information and rotation information. In the present embodiment, the position of the cathode for each shot is determined based on the acquired X-ray images. Since the configuration of the X-ray imaging device and the processing other than determination of the cathode position are the same as those of the first embodiment, description thereof will be omitted, and a cathode position determination process for determining the cathode position by image processing will be described below following the flow chart of FIG. 7 .

In step S71, the irradiated region detection unit 23 takes in the X-ray image generated by the image processing unit 20 and stored in the image storage unit 21, and proceeds to step S72. In the following step S72, in the image acquired by step S71, as shown in FIG. The pixels of the linear readout area 32 constituted by a plurality of pixels are distributed.

In step S73, it is determined whether or not the distribution results of the four sides of the X-ray irradiation area exceed predetermined thresholds. Among the four sides of the X-ray irradiation area, the sharpness of the image is different between the vicinity of the side on the cathode side and the side near the side on the anode side, so as shown in FIG. In the case of the pixel value at the pixel position of the region 32, the inclination is greatly different between the cathode-side readout region and the anode-side region. Similarly, the inclination is largely different between the readout region on the cathode side and the readout region other than the cathode side. In addition, when the X-ray diaphragm is not used during imaging, that is, the X-ray irradiation area is not limited by the X-ray diaphragm, the inclination becomes approximately 0 when the pixel value for the pixel position is plotted on the readout region 32 .

Therefore, by comparing the distribution result of each readout area (for example, the inclination of the graph in FIG. 3(B) ) with a predetermined threshold A, it can be determined whether or not the X-ray aperture is used. In step S72, it is determined whether or not the distribution results of the four sides of the X-ray irradiated area exceed a predetermined threshold A, and if the result exceeds the threshold A, it is deemed that there is an X-ray aperture, and the process proceeds to step S74. When the distribution results of the four sides of the X-ray irradiated area are each lower than the predetermined threshold value A, it is assumed that there is no X-ray aperture, and the process proceeds to step S77.

In step S74, based on the distribution result of each readout area, the side located on the cathode side is specified from the four sides of the X-ray irradiation area. That is, in step S74, it is determined whether the distribution results of the four sides of the X-ray irradiated area exceed a predetermined threshold B, and if it exceeds the threshold B, it is regarded as a side not located on the cathode side, and the process proceeds to step S75, where A flag not meaning the cathode side is stored in the storage area of the cathode detection unit 22 .

In the determination of step S74, if the distribution result is smaller than the threshold value B, it is regarded as the edge on the cathode side, and the process proceeds to step S76, and a flag indicating the cathode side is stored in the storage area of the cathode detection unit 22. In this way, the cathode position information indicating the position of the cathode of the X-ray source is stored in the storage area of the cathode detection unit 22 . In step S77, it is judged whether the processing of all four sides has been completed. If not, the process returns to step S73, and the above processing is repeated. When the processing of all four sides is completed, the above processing is terminated.

(Modification)

In the X-ray imaging apparatuses according to the first embodiment and the second embodiment described above, an example in which the number of thinning is set with a fixed value at the time of thinning processing has been described. As shown in the graph of Fig. 8, in the case where the X-ray tube is located at the center of the X-ray detector, the thinning number can be changed according to the position of the X-ray aperture from the center of the X-ray detector, so that the accuracy can be improved. good detection.

In addition, when the X-ray tube is not located at the center of the X-ray detector (for example, when the X-ray tube has a swing angle and incident imaging is performed), the number of thinning can be set variably according to the geometrical position. .

Furthermore, the result of the distribution varies with the tube voltage applied to the X-ray tube during X-ray imaging. That is, the higher the tube voltage, the more influenced by the X-ray transmittance and scattered rays, and the gentler the inclination of the distribution. Therefore, in this case, as shown in FIG. 9, the proportional relationship between the number of thinning and the tube voltage depends not only on the geometrical position but also on the tube voltage. By changing the number of thinning, it is possible to accurately perform detection.

Furthermore, in the above-mentioned example, an example was described in which the number of thinning is different between the side where the cathode is located and the other sides based on the cathode position information, but it is not necessarily necessary to generate a thinned image, and it is also possible to generate a high The coefficient K of the differential filter at the time of the video image is different between the side on the cathode side and the other sides. FIG. 10 shows an example in which the coefficient of the differential filter increases along the peripheral portion from the center of the X-ray detector. The gradient of the distribution at the boundary line of the X-ray irradiation area on the cathode side can also be made gentle by increasing the coefficient of the differential filter used when generating a high-frequency image on the cathode side (Yn direction side) Make corrections.

In addition, this invention is not limited to the said Example, Various modification examples are included. For example, the above-mentioned embodiments are described in detail for better understanding of the present invention, and are not necessarily limited to having all the configurations described. For example, addition, deletion, and replacement of other configurations can be performed on a part of the configuration of each embodiment.

Claims (6)

1. a kind of X-ray filming apparatus, has：

X-ray source with the X-ray tube to subject X-ray irradiation；

The X-ray aperture that x-ray irradiation area to being irradiated to subject from the x-ray source is limited；

The X-ray detector of the X-ray of the subject is irradiated and is penetrated in detection via the X-ray aperture；

The image processing part of radioscopic image is generated based on the electric signal exported from the X-ray detector；

It is penetrated positioned at the X among 4 sides of the x-ray irradiation area in the radioscopic image generated by the image processing part to expression The cathode test section that the cathode site information on the side of the cathode side of spool is detected；With

The x-ray bombardment area in the radioscopic image is detected based on the cathode site information obtained by the cathode test section The irradiation area test section in domain.

2. X-ray filming apparatus according to claim 1, wherein

The cathode test section detects the letter of the cathode site on the radioscopic image based on the location information of the X-ray tube Breath.

3. X-ray filming apparatus according to claim 1, wherein

The cathode test section is examined based on the rotation information of the location information of the X-ray tube and the X-ray detector Survey the cathode site information in described image.

4. X-ray filming apparatus according to claim 1, wherein

The irradiation area test section by the radioscopic image into processing is in the ranks taken, to generate for detecting the X-ray Image is taken between the 1st of the boundary line on the side of the cathode side positioned at the X-ray tube in image and for detecting the X-ray In image be located at cathode side other than while boundary line the 2nd between take image, and image and institute are taken between the described 1st State the irradiation area for being taken between the 2nd and detecting X-ray in image.

5. X-ray filming apparatus according to claim 1, wherein

The cathode test section is by handling the radioscopic image generated by described image processing unit, to detect described the moon Pole location information.

6. X-ray filming apparatus according to claim 5, wherein

The inclination of the distribution of the variation of the pixel value of the cathode test section based on the location of pixels for the radioscopic image Degree, to detect the cathode site information.