JP3896641B2 - X-ray fluoroscopic equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an X-ray fluoroscopic apparatus equipped with a compensation filter used when cutting unnecessary X-rays so as not to cause halation or the like in an X-ray fluoroscopic image, and in particular, adjusting an opening degree (opening degree) of the compensation filter. The present invention relates to a technique for reducing the X-ray exposure dose of a subject (patient) when performing a test.
[0002]
[Prior art]
In the conventional fluoroscopic imaging apparatus, as shown in FIG. 10, when X-ray exposure is performed from the X-ray tube 92 through the collimator 93 to the subject M placed on the top 91, the subject A transmitted X-ray image is formed on the output surface of an image intensifier (hereinafter abbreviated as “I / I tube” where appropriate) 94 by the transmitted X-rays that have passed through M. After being photographed, the image is finally projected as an X-ray fluoroscopic image on the screen of a TV monitor (not shown).
[0003]
However, if there is a large density difference in the transmitted X-rays from the subject, halation occurs in the X-ray fluoroscopic image displayed on the TV monitor, making it difficult to see the image of the important part of interest. Therefore, in the X-ray fluoroscopic apparatus, a compensation filter 97 for cutting unnecessary X-rays that cause halation and the like is provided in the collimator 93 in addition to the diaphragm 96 that defines the irradiation field of the X-ray tube 92. When halation occurs in the X-ray fluoroscopic image, the compensation filter 97 is set so as to advance into the X-ray irradiation field to cut the X-ray causing halation, thereby preventing the halation in the X-ray fluoroscopic image. The compensation filter 97 appears in the X-ray fluoroscopic image to hide the halation.
[0004]
[Problems to be solved by the invention]
However, when the position of the compensation filter 97 is adjusted under fluoroscopy in order to prevent halation, the subject M is exposed to extra X-rays. The X-ray fluoroscopic image is displayed on the screen of the TV monitor, and the compensation filter 97 adjusts so as to hide the halation and not the image of the region of interest. During this adjustment, the subject M He continues to take X-rays. Needless to say, it is necessary to avoid X-ray exposure as much as possible.
[0005]
In view of the above circumstances, an object of the present invention is to provide an X-ray fluoroscopic apparatus capable of greatly reducing the X-ray exposure amount of a subject when adjusting the opening degree of a compensation filter.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an X-ray tube for X-ray exposure and a transmission X-ray image detection arranged so as to face a subject-mounted top plate with the top plate interposed therebetween. An image intensifier, an imaging means for transmission X-ray imaging provided at a subsequent stage of the image intensifier, an image storage means for capturing and storing a video signal output from the imaging means as an X-ray fluoroscopic image, X-ray having an image display means for reading out the X-ray fluoroscopic image stored in the image storage means and displaying the X-ray fluoroscopic image on the monitor screen, and having a compensation filter whose degree of opening can be adjusted in front of the X-ray tube In a fluoroscopic imaging device, the current position of the inner edge of the compensation filter is detected by optical imaging means for obtaining an optical image of the opening portion of the compensation filter and signal processing on the optical image obtained by the optical imaging means. Optical image processing means, edge image extraction means for extracting the inner edge image in the optical image according to the current position of the inner edge recognized by the optical image processing means, and the inner edge image at the magnification of the fluoroscopic image. Image magnification adjusting means for adjusting to a corresponding magnification, and image combining means for combining the inner edge image and the X-ray fluoroscopic image whose magnification have been adjusted so that their image centers coincide with each other are provided. .
[0007]
[Action]
Subsequently, an operation when the adjustment of the opening degree of the compensation filter is executed in the X-ray fluoroscopic apparatus of the present invention will be described.
First, the subject is placed on the top, and the degree of opening of the compensation filter is set sufficiently large (opening is widened), and a fluoroscopic image is taken for a short time to store an X-ray fluoroscopic image. In other words, a transmission X-ray image is formed in the image intensifier along with the X-ray exposure to the subject by the X-ray tube, and this transmission X-ray image is taken by the imaging device at the subsequent stage, and then by the image storage unit. It is stored as an X-ray fluoroscopic image.
The X-ray fluoroscopic image held in the image storage means is read by the image display means and displayed on the monitor screen. However, since the opening degree of the compensation filter is set large, the monitor screen The compensation filter has not yet appeared in the X-ray fluoroscopic image displayed in FIG. However, if halation occurs in the X-ray fluoroscopic image on the monitor screen, the operator adjusts the compensation filter.
[0008]
In the fluoroscopic imaging apparatus according to the present invention, after the current position of the inner edge of the compensation filter is detected by signal processing on the optical image of the opening portion of the compensation filter, the inner side from the optical image is detected according to the detected current position of the inner edge. Edge images are extracted. Subsequently, after the inner edge image is adjusted to a magnification corresponding to the magnification of the X-ray fluoroscopic image, the inner edge image and the X-ray fluoroscopic image are combined so that their image centers coincide with each other. The virtual projection position of the inner edge is projected overlapping the X-ray fluoroscopic image. As the degree of opening of the compensation filter changes due to the operator's adjustment operation, the display position of the inner edge of the compensation filter changes on the monitor screen. You can find out at
[0009]
What is important here is that neither the detection of the current position of the inner edge of the compensation filter nor the superimposed display of the X-ray fluoroscopic image and the virtual projection position of the inner edge of the compensation filter is accompanied by X-ray exposure. is there. In the case of the X-ray fluoroscopic imaging apparatus of the present invention, even one X-ray fluoroscopic image used for superimposed display is sufficient, and the initial fluoroscopic imaging time is very short. It is only exposed to X-rays for a very short time in the early stage of the process, and it does not continue to be exposed to X-rays for the entire duration of the compensation filter adjustment process as before.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of an X-ray fluoroscopic apparatus according to the embodiment, and FIG. 2 is an explanatory diagram showing the movement of a compensation filter provided in the embodiment apparatus.
The X-ray fluoroscopic apparatus according to the embodiment includes a top plate 1 for mounting a subject M, an X-ray exposure X-ray tube 2 disposed so as to face the top plate 1 and a transmission X-ray. An I / I tube 3 for image detection, and a TV camera (imaging means) 4 that photoelectrically converts a transmission X-ray image formed on the output surface of the I / I tube 3 and outputs it as a video signal, and an X-ray tube 2 is an undertube type apparatus configuration located below the subject M.
[0011]
The top board 1 moves back and forth (in the direction of the body axis Z), up and down, and left and right with the subject M mounted according to the drive control of the top board control unit 11, and the X-ray tube 2 is an X-ray including a high voltage power source. The X-ray is exposed to the subject M according to the drive control of the exposure control unit 12, and the I / I tube 3 moves in the vertical direction according to the drive control of the I / I tube drive control unit 13. The magnification of the X-ray fluoroscopic image is changed due to the effect and electronic processing. Command signals corresponding to the imaging conditions and the like input and set on the console 14 are sent from the computer (CPU) 15 to the respective control units 11 to 13, and the top board 1, the X-ray tube 2 and the I / I tube 3 are imaged. Perform necessary movements according to conditions.
[0012]
In the embodiment apparatus, a collimator 5 is disposed in front of the X-ray tube 2, and a diaphragm 6 for defining an X-ray irradiation field is installed in the collimator 5. The diaphragm 6 is an X-ray shield such as lead, and the irradiation field is enlarged and reduced by adjusting the degree of opening. In the embodiment apparatus, the irradiation field is square.
Further, in the collimator 5, a compensation filter 7 used when cutting unnecessary X-rays is installed in front of the diaphragm 6 so as not to cause halation or the like in the transmitted X-ray image. The compensation filter 7 is also an X-ray shield such as lead, and the opening of the compensation filter 7 is enlarged or reduced by adjusting the degree of opening.
[0013]
As shown in FIG. 2, the compensation filter 7 includes two open / close leaves 7A and 7B, and the open / close leaves 7A and 7B are left and right as shown by a one-dot chain line in accordance with forward / reverse rotation of the motor 8. As shown in the solid line, the opening and closing leaves 7A and 7B approach from the left and right, and the opening degree decreases. The motor 8 is rotated by the compensation filter driving unit 16. That is, a command signal corresponding to an operator instruction input from the console 14 is sent from the computer 15 to the compensation filter driving unit 16, the motor 8 rotates, the open / close leaves 7A and 7B move, and the compensation filter 7 is moved by the operator. Set to the indicated opening degree.
Of course, when the open / close leaves 7A and 7B advance into the irradiation field defined by the diaphragm 6, the X-ray cutting function is exhibited. For example, in the case of the compensation filter 7 shown by the solid line in FIG. 2, only the X-rays in the opening H surrounded by the inner edges 7a and 7b of the open / close leaves 7A and 7B are irradiated to the subject M, and the outside of the opening H X-rays are shielded by the opening and closing leaves 7A and 7B.
[0014]
On the other hand, an AD conversion unit 17 that converts an analog video signal into a digital signal and an image storage unit 18 that captures and stores the digitized video signal as an X-ray fluoroscopic image are provided at the subsequent stage of the TV camera 4. For example, a frame memory having a matrix configuration of 1024 (10 bits) × 1024 (10 bits) is used as the image storage unit 18. The X-ray fluoroscopic image stored in the image storage unit 18 is read at any time and displayed on the screen of the TV monitor 19 as an X-ray fluoroscopic image. FIG. 3 shows an example of a fluoroscopic image displayed on the screen of the TV monitor 19. Since the reading of the X-ray fluoroscopic image from the image storage unit 18 and the image display on the TV monitor 19 are controlled by the computer 15, in the case of the embodiment apparatus, the image display is centered on the TV monitor 19, the computer 15 and its control program. Means are configured.
[0015]
Next, as a characteristic component related to adjusting the opening degree of the compensation filter 7 of the embodiment apparatus, an edge for recognizing the current position of the inner edges 7a and 7b of the compensation filter 7 without X-ray exposure. Current position recognition means and a current position at which the compensation filter 7 is recognized by the edge current position recognition means when the X-ray fluoroscopic image of the subject M stored in the image storage unit 18 is captured. The superimposing display means for superimposing images indicating the virtual projection positions of the inner edges 7a and 7b of the compensation filter 7 in the X-ray fluoroscopic image when it is assumed to be on the screen of the TV monitor 19 will be specifically described. To do.
[0016]
First, the edge current position recognition means will be described. As shown in FIG. 1, a reflection mirror 9 and a CCD camera 10 for optical photographing means for obtaining an optical image of an opening portion of the compensation filter 7 are installed in a collimator 5 and an inner edge 7a of the compensation filter 7 is also provided. , 7b, an optical image processing unit (optical image processing means) 20 for detecting the current position is provided at the rear stage of the CCD camera 10. In the embodiment apparatus, the optical photographing means and the optical image processing means constitute the edge current position recognition means.
[0017]
An image of the compensation filter 7 reflected on the reflection mirror 9 is taken by the CCD camera 10 and sent to the optical image processing unit 20 as an optical image. The optical image processing unit 20 AD-converts the optical image and temporarily holds it in the built-in frame memory MA. For example, in the case of the compensation filter 7 shown by a solid line in FIG. 2, an optical image as shown in FIG. 4 is held in the built-in frame memory MA. In the built-in frame memory MA, a range indicated by a circle C in FIG. 4 is an effective area corresponding to the display area of the TV monitor 19, and the optical image processing unit 20 uses a compensation filter for the effective area of the built-in frame memory MA. 7 performs signal processing for detecting the current positions of the inner edges 7a and 7b.
[0018]
For the horizontal line Li in which memory pixels having the same address Yi in the Y-direction address in the built-in frame memory MA are arranged, the change in pixel signal intensity from the address in the X-direction address located on the center line CL toward both sides (for example, differential processing is performed). And the address of the X direction address when the pixel signal intensity first changes greatly is associated with the address Yi of the Y direction address as addresses HRi and HLi indicating one point of the current position of the inner edges 7a and 7b. To detect. That is, when the signal level changes greatly from the inner edges 7a and 7b of the compensation filter 7 and the change in the pixel signal intensity from the center line CL toward both the left and right sides, the pixel signal intensity is always the first. Since the points that have changed significantly are located at the inner edges 7a and 7b, the signal processing as described above is performed for all the horizontal lines by the optical image processing unit 20, and each point of the current position of the inner edges 7a and 7b is indicated. If all the addresses are detected, the current positions of the inner edges 7a and 7b of the compensation filter 7 are recognized.
[0019]
Next, the superimposed display means will be described. The superimposed display means of the embodiment apparatus includes an edge image extraction unit 21, an image magnification adjustment unit 22, and an image composition unit 24. At the subsequent stage of the optical image processing unit 20, an edge image extraction unit 21 that extracts an inner edge image from the optical image according to the current position of the inner edges 7a and 7b recognized by the optical image processing unit 20 is provided. The image extraction unit 21 includes a frame memory MB having the same address system as the frame memory MA, and addresses indicating the current positions of the inner edges 7a and 7b detected by the optical image processing unit 20 (addresses Yi and addresses HRi and HLi). Each memory cell of the frame memory MB corresponding to each address) is stored with an H level signal, and the other memory cells are configured to store an L level signal. When the signal storage in the frame memory MB is completed, an image (inner edge image) obtained by extracting the inner edges 7a and 7b of the compensation filter 7 from the optical image is obtained as shown in FIG.
[0020]
Furthermore, an image magnification adjustment unit 22 that adjusts the inner edge image to a magnification corresponding to the magnification of the fluoroscopic image is provided after the edge image extraction unit 21. That is, the optical image taken by the CCD camera 10 always has the same magnification, but the magnification of the image obtained by X-ray photography varies depending on the vertical position of the I / I tube 3 and electronic processing. Before the inner edge image obtained by optical imaging is combined with the X-ray fluoroscopic image obtained by X-ray imaging, magnification correction is performed to match the X-ray imaging magnification.
[0021]
Note that the image magnification (magnification due to geometric effect) MP by X-ray imaging of the compensation filter 7 is MP = LA / LB as shown in FIG. Here, LA is the distance between the exposure center of the X-ray tube 2 and the incident surface of the I / I tube 3, and LB is the distance between the exposure center of the X-ray tube 2 and the compensation filter 7. The distance LA changes as the I / I tube 3 moves up and down, but the distance LB is always constant. Therefore, the distance LA is detected, and the magnification of the image accompanying the vertical movement of the I / I tube 3 is corrected. The image magnification adjustment unit 22 obtains a deviation from the magnification at the reference position of the I / I tube 3 based on the distance detection signal corresponding to the distance LA output from the SID (source image distance) detection unit 23. In addition to adjusting the magnification of the edge image in accordance with the amount of deviation, the magnification by electronic processing is also adjusted and stored in the built-in frame memory MC included in the image magnification adjustment unit 22 as shown in FIG. In the inner edge image after the magnification adjustment in FIG. 6, the magnification is slightly increased, and the inner edges 7a and 7b are slightly increased.
[0022]
After the image magnification adjustment unit 22, an image synthesis unit 24 that synthesizes the inner edge image whose magnification has been adjusted and the X-ray fluoroscopic image held in the image storage unit 18 is provided. For example, the X-ray fluoroscopic image shown in FIG. 3 and the magnification-adjusted inner edge image shown in FIG. 6 are synthesized by the image synthesis unit 24 and sent to the TV monitor 19. The image synthesizing unit 24 synthesizes images so that the centers of both images coincide. The I / I tube 3 and the compensation filter 7 are installed so that the center of the I / I tube 3 and the center of the compensation filter compensation filter 7 coincide. In addition, the CCD camera 10 is set so that the center of the compensation filter 7 is the center of the optical image, and the center of the inner edge image and the center of the optical image are coincident. Of course, the center of the X-ray fluoroscopic image is configured to coincide with the center of the I / I tube 3. Therefore, when image synthesis is performed so that the center of the inner edge image and the fluoroscopic image coincide with each other, the compensation filter 7 is displayed at the correct position on the screen of the TV monitor 19.
[0023]
The composite image shown in FIG. 7 is displayed on the screen of the TV monitor 19 that has received the image composition from the image composition unit 24. The positions of the inner edges 7a and 7b in the composite image shown in FIG. 7 indicate the virtual projection positions of the inner edges of the compensation filter 7 in the X-ray fluoroscopic image when it is assumed that the compensation filter 7 is at the current position. If the X-ray exposure is performed as it is, only the portion surrounded by the inner edges 7a and 7b of the compensation filter 7 is displayed on the screen of the TV monitor 19, and the rest is the open / close leaf of the compensation filter 7. It will be in the state cut by 7A, 7B.
[0024]
Subsequently, the operation of the apparatus when the opening degree of the compensation filter 7 in the X-ray fluoroscopic apparatus described above is adjusted will be described.
First, the subject M is placed on the top 1, the opening degree of the compensation filter 7 is set sufficiently large (opening is widened), and fluoroscopic imaging is performed as usual to obtain an X-ray fluoroscopic image as an image storage unit 18. To remember. Since one X-ray fluoroscopic image may be stored in the image storage unit 18, the imaging time is extremely short. When the X-ray fluoroscopic image stored in the image storage unit 18 is read and the X-ray fluoroscopic image is displayed on the screen of the TV monitor 19, as shown in FIG. 3, the halation IH is generated around the organ I as the target site. As a result, the operator adjusts the compensation filter 7 to prevent halation IH.
[0025]
The operator inputs a command to reduce the degree of opening of the compensation filter 7 (narrow the opening) from the console 14. The image of the compensation filter 7 with a reduced degree of aperture is taken by the CCD camera 10, and the optical image shown in FIG. 4 is sent to the image processing unit 20 for signal processing, and the current positions of the inner edges 7 a and 7 b of the compensation filter 7. 5 is recognized, the inner edge image shown in FIG. Thereafter, the magnification adjustment by the image magnification adjustment unit 22 is performed, and the inner edge image after the magnification adjustment shown in FIG. 6 is obtained. Then, the image synthesis unit 24 combines the X-ray fluoroscopic image shown in FIG. The composite image shown in FIG. 7 is displayed on the screen of the monitor 19.
[0026]
The display position of the inner edges 7a and 7b of the compensation filter 7 on the screen of the TV monitor 19 changes as the degree of opening of the compensation filter 7 changes due to the operator's adjustment operation. The adjustment status of the degree of opening can be known. If X-ray exposure is performed as it is, only the portion surrounded by the inner edges 7a and 7b of the compensation filter 7 in the composite image in FIG. 7 is displayed on the screen of the TV monitor 19, and the other portions. Is cut by the opening and closing leaves 7A and 7B of the compensation filter 7, the operator can arrange that the organ I which is the target site is between the opening and closing leaves 7A and 7B, and the surrounding halation IH is outside the inner edges 7a and 7b. The degree of opening of the compensation filter 7 is adjusted.
[0027]
After the adjustment of the opening degree of the compensation filter 7 is completed, when an X-ray fluoroscopic image is projected on the screen of the TV monitor 19 while actually performing X-ray exposure, as shown in FIG. It is cut at 7B, and the organ I which is the target region is clearly displayed without being disturbed by halation.
The adjustment process of the compensation filter of the above embodiment is collectively shown in the flowchart of FIG.
[0028]
As described above, in the embodiment apparatus, the current position of the inner edges 7a and 7b of the compensation filter 7 is recognized, and the X-ray fluoroscopic image and the superimposed display of the image indicating the virtual projection positions of the inner edges 7a and 7b of the compensation filter 7 are also provided. No X-ray exposure is required, and even one X-ray fluoroscopic image used for superimposed display is sufficient, and as a result, the initial imaging is extremely short. As a result, the subject M is very short in the initial stage of the compensation filter adjustment process. Just get an X-ray.
[0029]
The present invention is not limited to the above embodiment, and can be modified as follows, for example.
(1) In the above embodiment, the X-ray tube has an under-tube type apparatus configuration located below the subject. However, the X-ray tube has an over-tube type apparatus configuration above the object. Is given as a modification.
[0030]
(2) In the above-described embodiment, only the image of the inner edge of the compensation filter is superimposed on the X-ray fluoroscopic image, but the configuration in which the entire image of the compensation filter is superimposed on the X-ray fluoroscopic image is a modified example. As mentioned. However, in this modification, the surrounding area of the composite image is hidden behind the compensation filter and cannot be seen. On the other hand, in the case of the embodiment, the adjustment can be performed while viewing the surrounding area of the composite image.
[0031]
(3) In the above-described embodiment, the open / close leaves 7A and 7B of the compensation filter 7 are configured to move to the left and right, but the configuration in which the open / close leaves 7A and 7B also rotate in addition to the left and right movements is a modified example. Can be mentioned.
[0032]
【The invention's effect】
According to the X-ray fluoroscopic apparatus according to the present invention, the optical position of the opening portion of the compensation filter and the image signal processing are used to recognize the current position of the inner edge of the compensation filter, and the X-ray fluoroscopic image and the compensation filter. The virtual projection position of the inner edge is superimposed on the monitor, and the display position of the inner edge of the compensation filter changes as the degree of opening of the compensation filter changes due to the operator's adjustment operation. The adjustment status of the degree of opening can be known without X-ray exposure. Thus, according to the present invention, the subject is exposed to X-rays only in the very short initial period of the compensation filter adjustment process, and as before, during the entire period of the compensation filter adjustment process, There is no continuous exposure, and the X-ray exposure dose of the subject during adjustment of the opening degree of the compensation filter is greatly reduced.
[0033]
Furthermore, according to the present invention, since the opening part of the compensation filter is optically imaged, even if the opening part of the compensation filter is changed to a complicated shape according to the form of the part of interest, the shape of the opening part It is possible to easily superimpose and display the inner edge position corresponding to the X-ray fluoroscopic image.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an overall configuration of an X-ray fluoroscopic apparatus according to an embodiment.
FIG. 2 is an explanatory diagram showing the movement of a compensation filter provided in the embodiment apparatus;
FIG. 3 is a plan view showing an X-ray fluoroscopic image obtained by the example apparatus.
FIG. 4 is a schematic diagram illustrating a storage state of an optical image of a compensation filter.
FIG. 5 is a schematic diagram illustrating a storage state of an inner edge image.
FIG. 6 is a schematic diagram showing a storage state of an inner edge image whose magnification has been corrected.
FIG. 7 is a plan view showing a composite image of an X-ray fluoroscopic image and an inner edge image.
FIG. 8 is a plan view showing an X-ray fluoroscopic image after adjusting the opening degree of the compensation filter.
FIG. 9 is a flowchart illustrating a compensation filter adjustment process according to the embodiment.
FIG. 10 is a block diagram showing a main configuration of a conventional X-ray fluoroscopic apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Top plate 2 ... X-ray tube 3 ... I * I tube 4 ... TV camera 7 ... Compensation filter 7a, 7b ... Inner edge 9 ... Reflection mirror 10 ... CCD camera 18 ... Image storage part 19 ... TV monitor 20 ... Optical image Processing unit 21 ... Edge image extraction unit 22 ... Image magnification adjustment unit 24 ... Image composition unit 25 ... Position sensor unit 26 ... Edge image forming unit M ... Subject

Claims (1)

An object-mounted top plate, an X-ray tube for X-ray exposure and an image intensifier for transmission X-ray image detection arranged to face each other across the top plate, and a subsequent stage of the image intensifier An imaging means for transmissive X-ray imaging provided in the apparatus, an image storage means for capturing and storing a video signal output from the imaging means as an X-ray fluoroscopic image, and an X-ray fluoroscopic image stored in the image storage means In an X-ray fluoroscopic apparatus comprising an image display means for reading out and displaying on a monitor screen and having a compensation filter whose degree of opening can be adjusted on the front side of the X-ray tube, Optical imaging means for obtaining an image, optical image processing means for detecting the current position of the inner edge of the compensation filter by signal processing on the optical image obtained by the optical imaging means, and the optical image processing Edge image extraction means for extracting an inner edge image in the optical image according to the current position of the inner edge recognized by the means; and image magnification adjustment means for adjusting the inner edge image to a magnification corresponding to the magnification of the fluoroscopic image. An X-ray fluoroscopic imaging apparatus comprising: an image synthesizing unit that synthesizes an inner edge image whose magnification has been adjusted and an X-ray fluoroscopic image so that their image centers coincide with each other.

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