JP2692160B2 - X-ray fluoroscope - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

 The present invention relates to a fluoroscopic apparatus for medical diagnosis.

[Prior art]

When actually observing a subject with an X-ray fluoroscope, the image may be halated depending on the observation site and may be difficult to see. For example, when performing angiography of the heart, the lung field is displayed in addition to the heart portion on the screen of the monitor, but there is a very large difference in the X-ray absorption amount between the heart and the lung field. Therefore, the intensity of the lung field portion of the output image becomes excessive and causes halation, and the image information of that portion is lost, and the heart image becomes difficult to see. Therefore, conventionally, the operator manually moves the compensation filter while observing the TV monitor in the fluoroscopic state to position the compensation filter so as to hide the lung field.

[Problems to be solved by the invention]

However, there is a problem in that such a manual operation imposes a heavy burden on the operator. The present invention eliminates the burden of manual operation by automatically detecting a halation region and automatically positioning a compensation filter based on the deflection so that the contrast of an output image automatically becomes appropriate. The purpose is to provide.

[Means for Solving the Problems]

In order to achieve the above object, in an X-ray fluoroscope according to the present invention, an X-ray tube device, two arc-shaped compensating filter plates, and a collimator device incorporating a drive mechanism for driving these in the circumferential direction and the radial direction. , An image intensifier, a TV camera device, a means for obtaining image data by A / D converting the image signal obtained from this TV camera device, and the image data at a predetermined threshold value corresponding to the halation level. An image control device including a means for converting the value, a means for detecting a displacement angle in a peripheral angle direction of a field of view of the pixel value "1", and a means for determining the area of the part of the pixel value "1"; The positions of the two circular arc-shaped compensation filter plates in the circumferential direction are determined based on the detected displacement angles, and then the filter plates are moved in the radial direction, and the area of the pixel value “1” before and after the movement. Increase or decrease And a control device for controlling the drive mechanism to monitor the position and determine a radial position.

[Action]

In the image processing device, image data obtained by A / D conversion of the image signal obtained from the TV camera device is obtained, and this image data is set at a predetermined threshold value corresponding to the halation level.
The value of the pixel value "1" is detected, and the displacement angle in the peripheral angle direction of the visual field of the part is detected, and the area of the pixel value "1" part is obtained. The collimator device contains two arc-shaped compensation filter plates and a drive mechanism for driving them in the circumferential direction and the radial direction, and the positions of the two arc-shaped compensation filter plates in the circumferential direction are as described above. Is determined based on the detected deviation angle of Then, the filter plate is moved in the radial direction, and the increase or decrease in the area of the pixel value "1" portion before and after the movement is monitored. If the area does not increase or decrease, the overstrength part is completely covered by the filter plate.Therefore, by determining the radial position accordingly, the overstrength part is exactly covered by the compensation filter plate. Can be positioned automatically. Therefore, by covering only the portion where the image intensity is excessive with the compensation filter plate, halation can be avoided and an image with proper contrast can be automatically obtained. The compensating filter consists of two arc-shaped plates,
The movement control in the circumferential direction and the radial direction is performed by obtaining the angle of the overstrength portion or the area of the overstrength portion on the image obtained by binarizing the image data with the threshold value corresponding to the halation level. Therefore, the processing is easy, and with a simple configuration, it is possible to easily and surely obtain an image free from halation.

【Example】

Next, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, the X-rays generated from the X-ray tube device 1 are focused by a collimator device 2 and irradiated toward a subject 3. The X-rays that have passed through the subject 3 are incident on the image intensifier 4, are converted into visible light images, and a video signal is obtained by the TV camera device 5. This video signal is digitized by the A / D converter 6, sent to the image processing device 7, and further returned to an analog video signal via the D / A converter 8 to be used as a TV monitor device 9.
Sent to As shown in FIG. 2, the collimator device 2 includes a compensating filter plate 22 in addition to the diaphragm plate 21, and a driving mechanism for the compensating filter plate 22 is built in although not shown. The filter plate 22 is formed in an arc shape as shown in FIG. 3 and can be moved in the radial direction and the circumferential direction. The image processing device 7 detects a portion where the level of the video signal is large enough to cause halation (hereinafter referred to as an overstrength portion), and obtains the angle thereof or the area of the overstrength portion. Based on the processing result of the image processing device 7, the compensation filter control device 10 controls the drive mechanism incorporated in the collimator device 2 to position the filter plate 22. First, the video signal obtained from the TV camera device 5 is A /
By being digitized by the D converter 6, the screen is divided into a matrix, and the image intensity is converted into an integer value represented by each small portion (pixel). This image data is binarized by the image processing device 7 with a certain threshold value. This threshold is for distinguishing between the overstrength part and the non-strength part. For example, if a TV monitor device causes halation at 0.7V input, 0.7V is set as the threshold value and the video signal Output level is binarized by this threshold value (this explanation is performed in analog, but in actuality, digital processing corresponding to this is performed). In this way, as shown in FIG. 4, in the area corresponding to the visual field 91 of the TV monitor screen, an image composed of the shaded signal "1" portion and the other signal "0" portion is obtained. This shaded portion is an overstrength portion, and the other portions are portions other than the overstrength portion. Next, the value is examined by scanning the field circle of this binary image. First, a suitable point such as the highest point U and the lowest point L
When the value of the point U is "0", the value of the pixel on the visual field circle is sequentially checked from the point U in the clockwise direction, and the first pixel having the value "1" is set as A1. Similarly, the pixel A2 which becomes "1" first is found by examining from the point L in the counterclockwise direction. When the U point and the L point are "1", the pixels are scanned in the clockwise direction and the opposite direction to find the pixels whose "1" becomes "0" and determine A1 and A2. In this way, A1 (X1, Y1), A2 (X2, Y2) is calculated, and A
The slope of line segment 1 connecting 1 and A2 can be expressed as (Y2-Y1) / (X2-X1). Therefore, the inclination of the vertical bisector l2 of this line segment 1 is − (X2-X1) / (Y2-Y1) = (X2-X1) / (Y1-Y2). Angle θ formed by this line l2 with the horizontal direction (Y direction)
Is θ = tan ⁻¹ {(X2-X1) / (Y1-Y2)}, the angle θ can be obtained from this. The compensation filter control device 10 controls the compensation filter plate 22 to rotate so that the angle becomes θ. Next, the compensation filter control device 10 moves the compensation filter plate 22 toward the irradiation field 23 by one step in the radial direction. The image processing device 7 obtains the area of the overstrength portion of the pixel value "1", and compares this area before and after one step movement. At first, when the filter plate 22 does not cover the irradiation field, the area is the same before and after the movement, but when it hits the irradiation field 23, the overstrength part is hidden, so the area after the movement is smaller than before the movement. Will become. When the entire overstrength part is covered with the filter plate 22, the area does not change. Therefore, if the step is returned by one step, the inner edge of the overstrength part and the inner edge of the filter plate 22 will be exactly the same. Other parts are not covered by the filter plate 22. Such positioning is performed by the image processing device 7 and the compensation filter control device 10 for the filter plates 22 on both sides. As a result, only the overstrength portion is covered with the compensation filter plate 22, so that the contrast of the output image is automatically maintained to be appropriate.

【The invention's effect】

According to the X-ray fluoroscope of the present invention, the compensation filter is
It is composed of two arc-shaped plates, which are moved in the circumferential direction and the radial direction, and the overstrength part that causes halation on the image binarized with the threshold corresponding to the halation level Since the movement is controlled by obtaining the angle or the area of that portion, the processing for control is easy, and the simple configuration makes it possible to obtain an appropriate contrast that does not easily and reliably cause halation. The image can be automatically obtained without bothering the operator.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a schematic view seen from the side of a collimator device, FIG. 3 is a schematic diagram seen from the front of the collimator device, and FIG. 4 is a binarized image. FIG. 1 ... X-ray tube device, 2 ... Collimator device, 3 ... Subject, 4 ... Image intensifier, 5 ... TV camera device, 6 ... A / D converter, 7 ... Image processing device, 8 ...
... D / A converter, 9 ... TV monitor, 10 ... Compensation filter controller, 21 ... Aperture plate, 22 ... Filter plate, 23 ...
… Irradiation field, 91 …… Field of view.

Claims (1)

(57) [Claims] 1. An X-ray tube device, two arc-shaped compensating filter plates, and a collimator device incorporating a drive mechanism for driving these in the circumferential and radial directions, an image intensifier, and a TV camera device. A means for obtaining image data by A / D converting the image signal obtained from this TV camera device, a means for binarizing the image data with a predetermined threshold value corresponding to the halation level, and a portion having a pixel value "1". For detecting the deviation angle in the direction of the peripheral angle of the field of view and the pixel value "1"
And an image processing device including means for obtaining the area of the portion, and positions of the two arcuate compensation filter plates in the circumferential direction are determined based on the detected deviation angle, and then the filter plates are radiused. And a controller for controlling the drive mechanism so as to determine the position in the radial direction by monitoring the increase and decrease in the area of the pixel value "1" before and after the movement.