JPH08107891A - Radioscopic image display in digital x-ray apparatus - Google Patents

Abstract

PURPOSE: To enable the lowering of exposure dose while increasing extraction capacity of a percutaneous inspection jig by displaying a radioscopic image of a part to be inspected under successively covering an area other than a display area of the percutaneous inspection jig being inserted, by automatically controlling the X-ray stop. CONSTITUTION: A controller 11 feeds a position control information of an X-ray stop 2 to the X-ray stop 2 to move the X-ray stop 2 to the positions of the maximum block and the minimum block of a tip block of a catheter. As a result, the X-ray stop 2 moves to cover a part outside an area and a radioscopic image is displayed during the insertion of a catheter. Thus, the displaying of a part of a subject to be inspected under covering a display area other than the tip part of the catheter with the X-ray stop 2 during the inserting operation is enabled thereby enabling the upgrading of the extraction capacity of a percutaneous inspection jig while allowing the lowering of exposure does to the subject and an operating person.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
In a digital X-ray apparatus that irradiates a ray and digitizes a detection signal thereof and then performs image calculation to collect and display a fluoroscopic or photographed image as digital data, a catheter or an endoscope while fluoroscopically examining a target site of a subject. When inserting a percutaneous inspection jig such as the above into the target site, the present invention relates to a fluoroscopic image display method capable of improving the visualizing ability of the percutaneous inspection jig and reducing the exposure dose.

[0002]

2. Description of the Related Art In recent years, percutaneous inspection jigs such as catheters and endoscopes have been used without performing surgical operations on patients.
BACKGROUND ART A technique called IVR (Interventional Radiology) for examining or treating a vascular lesion, a digestive lesion, and the like has been actively performed. According to this IVR, since no laparotomy is performed, physical risk or mental burden on the subject is reduced. However, this catheter or the like has to be inserted percutaneously from the outside of the body of the subject to the lesion area of the subject, and this insertion operation has been difficult.

Conventionally, the insertion operation of the subject such as the catheter into the body is carried out, for example, by using a digital X-ray device while seeing through the target site to reach the target lesion by following the path of the blood vessel. It was However, since the X-ray dose is low under fluoroscopy, it is difficult to see the catheter or the like during insertion. Further, in order to advance the catheter or the like to the target lesion, it is necessary to know the anatomical position of the lesion. Therefore, conventionally, a target region of a subject is imaged in advance, and the captured image (for example, a blood vessel map image) is superimposed and displayed on the current fluoroscopic image while the target region is fluoroscopically displayed. The insertion operation was performed while seeing the image and the fluoroscopic image of the catheter.

[0004]

However, when inserting a catheter or the like while observing the display of a conventional fluoroscopic image as described above, since the catheter or the like is a thin rod, the image is not visible under fluoroscopy with a low dose. The contrast of
The images of the catheter etc. were very difficult to see and the insertion operation was not easy. In addition, since X-ray irradiation for fluoroscopy is frequently performed during the insertion operation of the catheter or the like, the exposure dose to the subject or the operator is large.

Therefore, the present invention addresses such problems, and when inserting a percutaneous inspection jig such as a catheter into the target site while seeing through the target site of the subject,
It is an object of the present invention to provide a fluoroscopic image display method in a digital X-ray device that can improve the visualization capability of the percutaneous inspection jig and reduce the exposure dose.

[0006]

In order to achieve the above object, a method for displaying a fluoroscopic image in a digital X-ray apparatus according to the present invention is an X-ray tube for irradiating a subject lying on a subject table with X-rays. A sphere, an X-ray diaphragm arranged on the front surface of the X-ray tube to limit the area of the irradiated X-rays, and a transmission from the object which is arranged to face the X-ray tube with the object interposed therebetween. An X-ray detector for converting an X-ray image into a visible light image, and this X-ray detector
An imaging device that captures an output optical image from the line detector and converts it into an electrical signal, an A / D converter that converts the output signal from this imaging device into a digital signal, and this A / D converter or a later-described An arithmetic unit for inputting a digital signal from the storage unit to perform image arithmetic, and a storage unit for storing image data as input data or output data of the arithmetic unit,
From the D / A converter, a look-up table for converting the gradation of the image data read from the storage device for display, a D / A converter for converting the output data from the look-up table into an analog signal, A digital X-ray apparatus comprising a display device for displaying an image based on the analog signal of, a control device for controlling the operation of each of the above components, and a console connected to the control device for inputting operation. The target site of the subject is photographed in advance and the captured image is recorded in the storage device, and when the percutaneous inspection jig is inserted into the target site while seeing through the target site, The fluoroscopic image is read out while being fluoroscopically displayed and superimposed on the current fluoroscopic image to be displayed, and the X-ray diaphragm is used for the region other than the display region of the percutaneous inspection jig being inserted. It is for displaying the fluoroscopic images of the target site while sequentially covered with the X-ray diaphragm by turning control.

Further, the irradiation X-rays may be limited by the X-ray diaphragm so as to cover the display area other than the tip of the percutaneous inspection jig being inserted.

[0008]

Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a digital X-ray apparatus used for implementing the fluoroscopic image display method according to the present invention. This digital X-ray apparatus irradiates a target region of a subject with X-rays, digitizes a detection signal thereof, and then performs image calculation to collect and display a fluoroscopic or photographed image as digital data, and is shown in FIG. Like X
A ray tube 1, an X-ray diaphragm 2, an image intensifier (hereinafter abbreviated as "II") 3, an image pickup device 4, and an A
/ D converter 5, arithmetic unit 6, and frame memory 7a-
7n, look-up table 8, and D / A converter 9
And a display device 10, a control device 11, and a console 12.

The X-ray tube 1 irradiates a subject 14 placed on a subject table 13 with X-rays, and an X-ray controller 15 and a high-voltage generator 16 controlled by a controller 11 are provided.
A high voltage is applied to emit X-rays. The X-ray diaphragm 2 emits X rays emitted from the X-ray tube 1.
The X-ray tube 1 has, for example, four rectangular blades arranged on the front surface of the X-ray tube 1 to limit the irradiation area of the rays, and each blade can be inserted and retracted from the top, bottom, left, and right of the screen of the display device 10. There is.

II3 serves as an X-ray detector for converting an X-ray image emitted from the X-ray tube 1 and transmitted through the subject 14 into a visible light image, with the subject 14 in between. It is arranged so as to face the X-ray tube 1 while sandwiching it. The image pickup device 4 is for photographing the output optical image from the above II3 and converting it into an electric signal. The image pickup device 4 is composed of, for example, a television camera, and the light polarized by the distributor 17 provided on the optical output surface of II3 is made incident. It is connected to the. A / D converter 5
Is for converting the output signal from the image pickup device 4 into a digital signal. In addition, the arithmetic unit 6 is the A / D
An image calculation is performed by inputting a digital signal from the converter 5 or digital image data read from frame memories 7a to 7n described later. For example, addition / subtraction between images or multiplication / division calculation with a constant is performed in real time. It has become. Further, the frame memories 7a to 7n serve as storage devices for storing image data as input data to the arithmetic device 6 or output data from the arithmetic device 6, and a plurality of frame memories 7a to 7n are provided via the input / output switcher 18. Are connected in parallel, and by the operation of this input / output switch 18,
The image data read from any of the frame memories 7a to 7n is sent to the arithmetic unit 6, and the output data calculated by the arithmetic unit 6 is output to the frame memories 7a to 7n.
It is designed to be recorded in any of.

The look-up table 8 is used for gradation conversion of the image data read from the frame memories 7a to 7n for display. For example, black-and-white brightness data for image display corresponding to the data value of the image data. It is stored as a table. The D / A converter 9 converts the output data from the look-up table 8 into an analog signal. The display device 10 displays an image based on the analog signal output from the D / A converter 9, and is composed of, for example, a television monitor.

The control device 11 controls the operation of each of the above-mentioned components, and is composed of, for example, a CPU (central processing unit). Further, the console 12 is the control device 11 described above.
An operator inputs various kinds of operations by connecting to, for example, an instruction such as fluoroscopic or imaging mode discrimination, imaging site selection, and image analysis.

Next, the procedure of the fluoroscopic image display method executed by using the digital X-ray apparatus constructed as described above will be described with reference to the flow charts of FIGS. First, a target portion into which a catheter as a percutaneous inspection jig is inserted into the subject is specified, and the subject table 13 shown in FIG. 1 is moved to align the target portion of the subject 14 with the fluoroscopic and imaging positions. Then, an image to be referred to when inserting the catheter while seeing through the target region is photographed in advance by the procedure shown in FIG. For example, when a catheter is inserted into a certain blood vessel of the target site, the target site is irradiated with X-rays and photographed while injecting a contrast agent into the blood vessel of the subject.
Captured images of the target region are collected (step in FIG. 2). Then, the collected captured image is recorded in, for example, the second frame memory 7b (not shown) shown in FIG. 1 as a blood vessel map image (step).

Next, FIG. 3 shows a procedure for displaying a fluoroscopic image when the catheter is inserted into the target site while seeing through the target site. That is, first, the digital X-ray device shown in FIG. 1 is switched to the fluoroscopic mode, the target region of the subject is irradiated with X-rays for fluoroscopy, and a fluoroscopic image of the target region is collected (step in FIG. 3). Next, while seeing through the target area as described above, the second frame memory 7
The photographed image recorded in b is read out, the present perspective image collected by the arithmetic unit 6 shown in FIG. 1 is added to the read photographed image, and the image data after this addition is, for example, 1
The data is recorded in the th frame memory 7a (step).
Next, the image data is read from the frame memory 7a, and the perspective image after the addition is displayed on the screen of the display device 10 (step). At this time, the current perspective image is superimposed and displayed on the captured image as the blood vessel map image, and the catheter is inserted into the target site while watching the blood vessel map image and the perspective image. Then, in step, it is determined whether or not the fluoroscopy of the target part is finished. If it is not finished yet, go to the “NO” side and return to step, repeat each step →→→, and if the fluoroscopy is finished, “YES” Go to the side and end.

Next, with reference to FIGS. 4 and 5, for the procedure of automatic control of the X-ray diaphragm 2 shown in FIG. 1 when inserting the catheter into the target site while seeing through the target site of the subject. And explain. First, in the state in which the perspective image is displayed in the steps shown in FIG. 3, the display device 10 shown in FIG.
The display screen is divided into M × N blocks (step A in FIG. 4). That is, as shown in FIG. 6, the display screen of the display device 10 is divided into M blocks in the X direction and N blocks in the Y direction, and each of these blocks is used as a region of interest for identifying the insertion position of the catheter. Next, the frame addition image at the start of fluoroscopy is recorded as a reference fluoroscopic image in, for example, the third frame memory 7c (not shown) shown in FIG. 1 (step B). In this state, the current fluoroscopic images are sequentially collected (step C). Then, the difference between the current perspective images sequentially collected and the reference perspective image is calculated to obtain a differential perspective image (step D).

Next, for each pixel of the (m, n) block (m≤M, n≤N) of the differential perspective image obtained as described above, it is included within the specified threshold range. The pixel values to be counted are counted (step E). That is, it counts how many pixel values fall between the specified lower threshold value and upper threshold value. Next, it is judged whether or not the count of the pixel value is larger than a designated number (pixel number threshold value) (step F). "NO" when less than the specified number
Go to the side, jump to step H, and (m, n) of the differential perspective image
It is determined whether the block has reached the maximum. If the process has not reached the maximum yet, step H advances to the "NO" side, returns to step E, and repeats steps E->F-> H. If the pixel value count exceeds the specified number in step F during this repetition, the process proceeds to the "YES" side and step G is entered. Then, in this step G, the (m, n) block is determined as a catheter display block and registered. This catheter display block E ₁
This is the shaded portion in FIG. 7, and the position of the maximum block Xmax of this catheter display block E _{1 in} the X direction,
An area other than the area surrounded by the minimum block position Xmin, the maximum block position Ymax in the Y direction, and the minimum block position Ymin (within the range surrounded by the thick line in FIG. 7) is covered with the X-ray diaphragm 2 shown in FIG. It becomes a part.

Next, at step H, it is judged again whether or not the (m, n) block of the differential perspective image has reached the maximum,
If it has reached the maximum, it proceeds to the "YES" side and enters step J of FIG. 5 through the connector. In this step J,
Of the catheter display blocks E ₁ shown in FIG. 7, the block 1 determined as the latest catheter display block
9 is registered as a block including the tip of the catheter 20, and, for example, 8 blocks adjacent to the latest catheter display block 19 are registered as the catheter tip block.
For example, as shown in FIG. 8, a total of 9 blocks centering on the latest catheter display block 19 (see FIG. 8).
(Within the thick line) is the catheter tip block E ₂
And Next, with respect to the catheter tip block E ₂ , the maximum block position Xmax in the X direction, the minimum block position Xmin, and the maximum block position Ymax in the Y direction and the minimum block position Ymin are obtained (step K). The catheter tip block E whose position is obtained in this way
₂ not only interferes with the insertion of the X-ray diaphragm 2 shown in FIG. 1 in the advancing direction of the catheter 20, but also hinders the movement detection of the catheter 20, so that this area is not covered by the X-ray diaphragm 2. It is a non-insertion area.

Next, the control device 11 shown in FIG. 1 sends the position control information of the X-ray diaphragm 2 obtained as described above to the X-ray diaphragm 2, and the X-ray diaphragm 2 is fed to the catheter tip block E. ₂ maximum blocks Xmax, Ymax and minimum block Xm
It is moved to the positions of in and Ymin (step L). As a result, the X-ray diaphragm 2 moves so as to cover the outer portion of the area surrounded by the thick line in FIG. Then, in this state, a fluoroscopic image when the catheter 20 is inserted is displayed (step P). As a result, the fluoroscopic image of the target site of the subject can be displayed while sequentially covering the display area other than the distal end portion of the catheter 20 during the insertion operation with the X-ray diaphragm 2. After that, in step Q, it is determined whether or not the fluoroscopy of the target region is finished, and if it is not finished yet, "NO"
And go back to step C of FIG. 4 through the connector,
Each step C → D → E → F → G → H → J → K → L → P →
If Q is repeated, and if the fluoroscopy is completed, proceed to the "YES" side and end.

Next, FIG. 9 shows the timing of various controls in the procedure of the above-mentioned perspective image display method. FIG. 9A shows a sync signal which is a reference signal for controlling the entire digital X-ray apparatus shown in FIG.
For example, it is a pulse signal every 1/30 seconds. FIG. 3B shows the timing of collecting the fluoroscopic image in accordance with the above-mentioned synchronization signal (see the step in FIG. 3). Further, FIG. 7C shows the perspective image collected as described above, superimposed on the photographed image previously photographed in the step of FIG. 2 (see step of FIG. 3), and after the addition. The timing at which a perspective image is displayed (see steps in FIG. 3) is shown. Then, in FIG. 7D, the reference perspective image is subtracted from the current perspective image added as described above (see step D in FIG. 4), and the catheter display block E is displayed.
₁ is identified (see step G in FIG. 4), the catheter tip block E ₂ is identified (see step J in FIG. 5), and position control information is sent to the X-ray diaphragm 2 to transmit the position control information.
7 shows the timing for moving the (see step L in FIG. 5). At this time, since the operating speed of the X-ray diaphragm 2 is very slow, it is desirable to set the control interval of the moving operation to about 1 second.

In the flow charts shown in FIGS. 4 and 5, the limitation of the irradiation X-rays by the X-ray diaphragm 2 is shown in FIG.
As described above, the procedure realized by covering the display area other than the display area (E ₂ ) at the distal end portion of the catheter 20 being inserted into the target site of the subject has been shown, but the present invention is not limited to this. As shown in FIG. 7, it may be realized by covering a region other than the entire display region (E ₁ ) of the catheter 20 being inserted into the target site of the subject with the X-ray diaphragm 2. In this case, the step J shown in FIG. 5 is skipped, the step H shown in FIG. 4 is directly entered to the step K shown in FIG. 5, and the catheter display block E ₁ shown in FIG. , The position of the minimum block may be obtained.

[0021]

Since the present invention is constructed as described above,
The target site of the subject is photographed in advance and the captured image is recorded in a storage device, and when the percutaneous inspection jig is inserted into the target site while seeing through the target site, the target site is seen through. Meanwhile, the captured image is read out and displayed by superimposing it on the current fluoroscopic image, and the area other than the display area of the percutaneous inspection jig being inserted is automatically controlled by the X-ray diaphragm. It is possible to display a perspective image of the target portion while sequentially covering it. Therefore, in a digital X-ray device, when a percutaneous inspection jig such as a catheter or an endoscope is inserted into the target portion while seeing through the target portion of the subject, the percutaneous inspection jig is depicted. The radiation dose to the subject and the operator can be reduced while improving the performance.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a digital X-ray apparatus used for carrying out a perspective image display method according to the present invention.

FIG. 2 is a flowchart showing a procedure of previously capturing an image to be referred when inserting a catheter while seeing through a target region of a subject.

FIG. 3 is a flowchart showing a procedure for displaying a fluoroscopic image when inserting the catheter into a target site.

FIG. 4 is a first half flowchart showing a procedure of automatic control of an X-ray diaphragm when inserting the catheter into a target site.

FIG. 5 is a second half flowchart showing a procedure of automatic control of the X-ray diaphragm.

FIG. 6 is an explanatory diagram showing a state in which the display screen of the display device is divided into M × N blocks.

FIG. 7 is an explanatory diagram showing formation of a catheter display block when inserting a catheter into a target site.

FIG. 8 is an explanatory view showing formation of a catheter tip block when inserting a catheter into a target site.

FIG. 9 is a timing diagram showing various control timings in the procedure of the perspective image display method of the present invention.

[Explanation of symbols]

1 ... X-ray tube 2 ... X-ray diaphragm 3 ... II 4 ... Imaging device 5 ... A / D converter 6 ... Arithmetic device 7a-7n ... Frame memory 8 ... Look-up table 9 ... D / A converter 10 ... Display Device 11 ... Control device 12 ... Operation table 13 ... Subject table 14 ... Subject 15 ... X-ray controller 16 ... High voltage generator 18 ... Input / output switch 20 ... Catheter E ₁ ... Catheter display block E ₂ ... Catheter tip block

Claims (2)

[Claims] 1. The X-ray is applied to the subject lying on the subject table.
X-ray tube for irradiating the X-ray tube, an X-ray diaphragm arranged in front of the X-ray tube for limiting the area of the X-ray to be irradiated, and opposed to the X-ray tube with the subject interposed therebetween. An X-ray detector arranged to convert a transmitted X-ray image from a subject into a visible light image, an imaging device for capturing an output optical image from the X-ray detector and converting it into an electric signal, and an imaging device A / D converter for converting the output signal of the above into a digital signal, an arithmetic unit for inputting a digital signal from this A / D converter or a storage device described later, and performing image arithmetic operation, input data of this arithmetic unit or A storage device for storing image data as output data, a look-up table for gradation conversion of the image data read out from the storage device for display, and a D for converting output data from the look-up table into an analog signal. / A converter A display device for displaying an image based on an analog signal from the D / A converter, a control device for controlling the operation of each of the above components, and a console connected to the control device for inputting an operation. In this digital X-ray apparatus, the target region of the subject is photographed in advance, the photographed image is recorded in the storage device, and the percutaneous inspection jig is inserted into the target region while seeing through the target region. In this case, the photographed image is read out while supervising the target region, and superimposed and displayed with the current fluoroscopic image, and the region other than the display region of the percutaneous inspection jig being inserted is the X-ray diaphragm. A method for displaying a fluoroscopic image of a digital X-ray device, wherein the fluoroscopic image of the target portion is displayed while being automatically controlled by the X-ray diaphragm. 2. The limitation of irradiation X-rays by the X-ray diaphragm is
2. The method for displaying a fluoroscopic image in a digital X-ray apparatus according to claim 1, wherein a display area other than the tip of the percutaneous inspection jig being inserted is covered.