JPH08275935A - Radiography device - Google Patents

Abstract

PURPOSE: To move a compensating filter provided in an X-ray diaphragm to a proper position in a short time by detecting a halation area, and moving the compensating filter in response to this detected halation area. CONSTITUTION: An X-ray radiated from an X-ray tube 103 is irradiated to a subject through an X-ray diaphragm 20 containing a filter to a reduce an X-ray quantity, and the X-ray passing through the subject is received by an image intensifier 107, and is converted into an optical image, and this optical image is picked up by a TV camera 11. In this case, a halation detecting part is provided in the X-ray diaphragm 20 so as to detect an area higher than a preset level among image levels of respective picture elements of the picked-up image as a halation area. Operation is performed on a moving distance of the filter to a position corresponding to the detected halation area, and a built-in filter is moved in response to the moving distance of the filter by this operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray imaging apparatus for imaging an object using X-rays, and in particular, X-rays capable of preventing halation caused by X-ray energy exceeding an allowable value. The present invention relates to a photographing device.

[0002]

2. Description of the Related Art In recent years, various X-ray imaging apparatuses have been proposed for imaging the heart and blood vessels of a subject using X-rays. In such an X-ray imaging apparatus, in order to prevent halation that occurs in a portion having a large X-ray transmittance or to correct the state of the distribution of the thickness of the subject to be corrected, an X-ray tube that emits X-rays is used. A method of placing lead clay or the like that suppresses X-ray transmission on the X-ray output side has been adopted.

However, since the position where the lead clay or the like is placed is directly set by the operator's hand while checking the fluoroscopic image, it is troublesome. For this reason, there has been proposed a method in which a compensation filter provided on the X-ray exposure side of the X-ray tube and provided in an X-ray diaphragm for reducing the X-ray dose is remotely moved to a position corresponding to halation.

An external view of such an X-ray imaging apparatus is shown in FIG. As shown in FIG. 5, the X-ray imaging apparatus 101 includes an X-ray tube 103 that emits X-rays and an X-ray that is emitted from the X-ray tube 103.
X-ray diaphragm 105 that reduces the X-ray dose of X-rays, an image intensifier (hereinafter referred to as II) 107 that converts an X-ray image that has passed through the subject into an optical image, and I.I. An optical system 109 including a lens cemented to the optical image output side of I107 (the side facing the X-ray image incident side), and a TV camera 111 provided on the optical image output side of the optical system 109 for capturing an optical image.
And an X-ray tube 103 and an X-ray diaphragm 10 at one end, and an I.D. I. C arm 113 for holding 107, optical system 109, and TV camera 111, and C arm 11
It has a main body 115 supporting 3 and a display unit 117 displaying an optical image captured by the TV camera 111.

[0005]

However, since the operator sets the moving position of the compensation filter provided on the X-ray diaphragm, it is assumed that it takes time to set depending on the condition of the subject. Further, since the setting is performed while observing the fluoroscopic image, there is a possibility that the exposure dose to the subject may increase.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide an X-ray imaging apparatus capable of moving a compensation filter provided in an X-ray diaphragm to an appropriate position in a short time. To aim.

[0007]

To achieve the above object, the present invention comprises an X-ray tube for irradiating X-rays and a filter for reducing the X-ray dose, and this filter is provided at a desired position where X-rays pass. X exposed by the X-ray tube when inserted
X-ray diaphragm for reducing the X-ray dose of X-rays, X-ray-optical image conversion means for converting the X-rays emitted from the X-ray tube and passing through the X-ray diaphragm and the subject into an optical image, and this X-ray. In an X-ray imaging apparatus having an image pickup unit that picks up an optical image converted by a line-optical image conversion unit, the X-ray diaphragm has a halation level setting unit that sets a predetermined image level as a halation level, and the image pickup unit. Of the image levels of each pixel of the image picked up by the means, the halation detection means for detecting a region higher than the halation level set by the halation level setting means as a halation region, and the halation detected by the halation detection means. A filter control means for calculating a movement amount of the filter to a position corresponding to the area and outputting a control signal; And summarized in that having to have a filter moving means for moving the filter in correspondence to the amount of movement of the filter calculated by the motor control unit.

Further, the halation detecting means sets the image picked up by the image pickup means to 1 for each predetermined plurality of pixels.
After reducing by averaging to pixels, it is desirable to detect, as the halation region, an image level higher than the image level set by the halation level setting means among the image levels of the respective pixels of the reduced image. .

[0009]

The X-ray imaging apparatus of the present invention is provided with an X-ray tube for irradiating X-rays and a filter for reducing the X-ray dose, and by inserting this filter at a desired position through which the X-rays pass. An X-ray diaphragm that reduces the X-ray dose of X-rays emitted from the tube, and an X-ray-optical system that converts the X-rays that are emitted from the X-ray tube and that have passed through the X-ray diaphragm and the subject into an optical image. In an X-ray imaging apparatus having an image conversion means and an image pickup means for picking up an optical image converted by the X-ray-optical image conversion means, in an image level of each pixel of an image picked up by the image pickup means, A region higher than the halation level that can be changed by the halation level setting means is detected as a halation region. Then, the moving amount of the filter to the position corresponding to the detected halation region is calculated, and the filter is moved in correspondence with the calculated moving amount of the filter. Thereby, the compensation filter provided in the X-ray diaphragm is moved to an appropriate position in a short time.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an X-ray imaging apparatus according to the present invention. Since the external configuration of the X-ray imaging apparatus of this embodiment is the same as that of the conventional X-ray imaging apparatus 101 shown in FIG. 5, its illustration is omitted. Further, the same parts as those of the conventional X-ray imaging apparatus 101 shown in FIG. 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 1, an X-ray imaging apparatus 1 of this embodiment controls an X-ray tube 103 for irradiating X-rays, an X-ray dose emitted from the X-ray tube 103, and an exposure time. X-ray controller 1
0, an X-ray diaphragm 20 that reduces the X-ray dose of the X-rays emitted from the X-ray tube 103, and an image intensifier (hereinafter referred to as I.I.
107), and I. An optical system 109 including a lens cemented to the optical image output side of I107 (the side facing the X-ray image incident side), a TV camera 111 provided on the optical image output side of the optical system 109 for capturing an optical image, and a TV Camera 111
And a display unit 117 that displays the optical image captured by.

In particular, the X of the X-ray imaging apparatus 1 of this embodiment is
As shown in FIG. 2, the line diaphragm 20 includes an image holding unit 21, an image reducing unit 23, a halation level setting unit 25, a halation detecting unit 27, a filter control unit 29, and a filter moving unit 31. ing.

The image holding unit 21 has an image memory (not shown), and holds the image output from the TV camera 111 in the image memory at regular timings, for example, at one second intervals.

The image reduction unit 23 applies the image held by the image holding unit 21 to a predetermined pixel group, for example, 4 in 2 rows and 2 columns.
A pixel group of pixels is averaged and each pixel group is reduced to one pixel to create a reduced image. The reduction of the image is performed because the number of data is large when the data is handled as it is, and the halation region is treated evenly in consideration of the influence of noise and the like.

The halation level setting unit 25 includes a data input unit (not shown) including a keyboard and the like, and sets a pixel value to be a halation as a halation level to a value input by an operator using the data input unit. .

The halation detecting section 27 includes an image reducing section 2
Each pixel value of the reduced image created in 3 is compared with the halation level set by the halation level setting unit 25. When the pixel value of the reduced image exceeds the halation level, the pixel area is detected as halation. , The pixel coordinates of the halation are filtered by the filter control unit 2
Supply to 9.

The filter control unit 29 calculates the movement amount of the compensation filter based on the coordinates of the halation pixel supplied from the halation detection unit 27 and supplies it to the filter movement unit 31.

As shown in FIG. 3, the filter moving unit 31 is provided on a disk-shaped table 33 having a round hole 33a through which X-rays pass in the central portion thereof, and reduces the X-ray dose toward the round hole 33a. A female thread is provided on the annular body 37 in which the compensation filter 35 is detachably held via the fixing portion 37a, and a female thread is provided on the male thread provided on the rod-shaped lead screw 43 to which rotation is transmitted from the motor 41 via the gear 39. The motor 41 is rotated according to the movement amount of the compensation filter 35 supplied from the filter control unit 29 to move the compensation filter 35 to a desired position. A gear (not shown) is provided on the outer circumference of the disk-shaped table 33, and is rotated by the table motor 45 via a gear (not shown) provided on the rotation shaft of the table motor 45. The disk-shaped table 33 is rotatably fixed by a fixing member (not shown) joined to the cover of the X-ray diaphragm 20.

Although not shown, the filter moving unit 31
Is usually provided in parallel with the disk-shaped table 33. That is, two compensating filters 35 are provided, and the filter moving unit 31 is provided for each compensating filter 35. Further, the number of filter moving units 31 is not limited to two, and three or more may be provided.

Next, the operation of the X-ray imaging apparatus 1 of this embodiment will be described.

First, the operator uses the data input section of the halation level setting section 25 to input the pixel value into which the compensation filter 35 is to be inserted as the halation level.
For example, when performing X-ray fluoroscopy with the pixel value 4096 being the maximum, approximately the pixel value 4000 is input as the halation level. Further, when performing X-ray fluoroscopy with the pixel value 4096 being the maximum, about 2000 is input as the halation level. The halation level may be automatically switched in accordance with the switching between the fluoroscopic mode and the photographing mode such that the halation level is 2000 in the fluoroscopic mode and 4000 in the photographing mode.

Then, the halation level setting unit 25
Sets the input value as the halation level.

In this state, when performing fluoroscopy in which weak X-rays are exposed for a long time during the examination, fluoroscopy is started using an operation console (not shown) connected to the X-ray controller 10. This makes X
X-rays are emitted from the ray tube 103.

The X-rays that have been exposed and passed through the subject are I.D.
I. It is converted into an optical image by 107, and TV camera 111
Is converted into an image by.

The X-ray exposure timing is notified from the X-ray control unit 10 to the image holding unit 21. Upon receiving this notification, the image holding unit 21 holds the image in the image memory periodically, for example, at an interval of 1 second.

When the image is held, the image reduction unit 23
In the stored image, for each predetermined pixel group, for example, a pixel group consisting of 4 pixels in 2 rows and 2 columns is averaged, and each pixel group is reduced to 1 pixel to create a reduced image.

Next, the halation detecting unit 27 compares each pixel value of the reduced image created by the image reducing unit 23 with the halation level set by the halation level setting unit 25, and the pixel value of the reduced image is the halation level. When it exceeds the value, the pixel area is detected as halation, and the coordinates of the pixel of the halation are supplied to the filter control unit 29.

When the coordinates of the pixel of the halation are supplied, the filter control unit 29 calculates the moving amount of the compensation filter 35 based on the coordinates of the pixel of the halation and supplies it to the filter moving unit 31.

The amount of movement of the compensating filter 35 is obtained by first obtaining straight lines L1 and L2 connecting the ends of the halation region on the most center side when the shaded region of the reduced image shown in FIG. The rotation amount of the disk-shaped table 33 is calculated so that the straight lines L1 and L2 and the side of the compensation filter 35 on the round hole 33a side are parallel to each other. Next, the distances r1 and r from the centers of the straight lines L1 and L2 to the outer periphery of the image
Calculate 2 A position slightly from the center of the image from the distances r1 and r2 is set as the amount of movement of the compensation filter 35 toward the center of the image. The filter control unit 29 controls the rotation amount of the disk-shaped table 33 and the image center of the compensation filter 35 (the circular hole 3).
The amount of movement toward the (center of 3a) side is supplied to the filter moving unit 31 as the amount of movement of the compensation filter 35.

At this time, if the number of halation regions exceeds the number of compensation filters 35, the movement amount of the compensation filters 35 is calculated so that the halation regions are inserted in order from the larger region.

When the moving amount of the compensating filter 35 is supplied, the filter moving unit 31 rotates the table motor 45 to rotate the disk-shaped table 33 and rotates the motor 41 according to the moving amount to compensate. The filter 35 is moved to the center side of the round hole 33a. In this way, the compensation filter 35 is inserted in the halation region.

If the compensating filter 35 is moved, the TV
Although the image obtained by the camera 111 also changes, the image is periodically held while the X-ray is exposed to control the movement amount of the compensation filter 35, so that the optimum position is compensated. A filter 35 can be inserted.

As described above, in the X-ray imaging apparatus 1 of the present embodiment, an area higher than the halation level set by the halation level setting unit 25 is selected from the pixel values of the pixels of the image obtained by the TV camera 111. The amount of movement of the compensation filter 35 is detected as halation, and the movement amount of the compensation filter 35 to the position corresponding to this halation region is calculated.
5 is moved, the compensation filter 35
The patient can be moved to an appropriate position in a short time, and the dose to the patient can be reduced. Furthermore, since the compensation filter 35 can be moved to an appropriate position, halation can be suppressed, and S / S of the entire image can be suppressed.
The N ratio can also be improved.

In the above embodiment, the case of application to an X-ray imaging apparatus has been described as an example, but the present invention is not limited to this and can be applied to, for example, an X-ray TV apparatus.

[0035]

As described above, according to the present invention, the area of halation is detected and the compensation filter is moved in correspondence with the detected area of halation. It is possible to move the existing compensation filter to an appropriate position in a short time.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing a configuration of an X-ray diaphragm of the X-ray imaging apparatus shown in FIG.

FIG. 3 is a filter moving unit 3 of the X-ray imaging apparatus shown in FIG.
It is the figure which showed 1.

FIG. 4 is a diagram showing a reduced image for explaining an example of calculating a movement amount of a compensation filter by a filter control unit.

FIG. 5 is a diagram showing an appearance of a conventional X-ray imaging apparatus.

[Explanation of symbols]

 1 X-ray imaging apparatus 10 X-ray control unit 20 X-ray diaphragm 21 Image holding unit 23 Image reduction unit 25 Halation level setting unit 27 Halation detection unit 29 Filter control unit 31 Filter moving unit 103 X-ray tube 107 Image intensifier 109 Optical System 111 TV camera 117 display

Claims (2)

[Claims] 1. An X-ray tube for irradiating X-rays and a filter for reducing the X-ray dose are provided, and the X-rays for irradiation from the X-ray tube are inserted by inserting this filter at a desired position through which the X-rays pass. X-ray diaphragm for reducing the X-ray dose of X-rays, X-ray-optical image conversion means for converting the X-rays emitted from the X-ray tube and passing through the X-ray diaphragm and the subject into an optical image, and this X-ray. In an X-ray imaging apparatus having an image pickup unit that picks up an optical image converted by a line-optical image conversion unit, the X-ray diaphragm includes a halation level setting unit that sets a predetermined image level as a halation level, and the imaging unit. Halation detection means for detecting, as a halation area, an area higher than the halation level set by the halation level setting means among the image levels of each pixel of the image picked up by the means, A filter control means for calculating a movement amount of the filter to a position corresponding to the halation region detected by the halation detection means and outputting a control signal, and the filter according to the control signal output from the filter control means. An X-ray imaging apparatus having a filter moving means for moving. 2. The halation detection means reduces the image picked up by the image pickup means by averaging every one of a plurality of predetermined pixels to one pixel, and then reduces the image level of each pixel of the reduced image. The X-ray imaging apparatus according to claim 1, wherein an area having an image level higher than the image level set by the halation level setting means is detected as a halation area.