JPH0795824B2 - X-ray diagnostic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to an X-ray diagnostic apparatus that collects X-ray transmission information of a subject to be used for diagnosis.

(Prior Art) FIG. 4 shows a conventional X-ray diagnostic apparatus. This apparatus uses an image intensifier (hereinafter, referred to as I · I) for an X-ray fluoroscopic image of the subject P by X-rays from the X-ray tube 1.
It is converted into a visible light image by the input phosphor screen 2 and is appropriately amplified and then led out to the output phosphor screen of I / I2. This visible image is taken into the TV camera 4 through the optical system 3, , And send the video signal to the CRT monitor 5.
It is designed to be visualized above. The TV camera 4
Has an image pickup tube (for example, Sachicon, Carnicon, Plumbicon, etc.). However, in the conventional X-ray diagnostic apparatus, since the TV camera 4 has a narrow dynamic range, the display screen of the CRT monitor 5 corresponding to the portion of the I / I2 where the X-ray is strongly hit becomes blank (this is "Halation"), there is a drawback that the image display is difficult to interpret.

(Problems to be Solved by the Invention) As described above, the conventional device has a drawback that halation occurs.

Therefore, the present invention eliminates the above-mentioned drawbacks, and an object of the present invention is to provide an X-ray diagnostic apparatus capable of preventing the occurrence of halation.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, the present invention converts an X-ray fluoroscopic image of a subject into a visible light image, and captures this visible light image with a solid-state image sensor. In the X-ray diagnostic apparatus provided for diagnosis, the solid-state imaging device includes an overflow drain terminal, and halation detection means for detecting the occurrence of halation by detecting charges emitted from the overflow drain terminal, Halation reducing means for reducing halation by controlling the knee characteristic of the solid-state image pickup device based on the detection output so as to eliminate the charge discharge from the overflow drain terminal is provided.

(Operation) FIG. 2 shows the input / output characteristics of the solid-state image sensor. Usually, as shown by the characteristic curve 7, the output voltage is saturated at a certain input level (light incident level) or more. The same applies to the image pickup tube. However, in the solid-state image sensor, the input / output characteristics can be changed as shown by characteristic curves 8 and 9.
The characteristic that the slope of the input / output characteristic curve changes before saturation as shown by these characteristic curves 7 and 8 is called the knee characteristic, and the movement control of this slope change point (P ₁ , P ₂ ) is the negative characteristic control. Called.

Here, even at the input level L where the output voltage is saturated in the characteristic curve 7, the saturation of the output voltage can be avoided in the case of the characteristic curves 8 and 9. That is, by controlling the knee characteristic, it is possible to prevent the occurrence of halation due to the output voltage saturation. In the present invention, the halation detection means detects the occurrence of halation, and the halation reduction means detects a negative (kne) based on the detection output.
e) Halation is reduced by performing characteristic control.

Note that the steeper the slope of the input / output characteristic curve, the better the density resolution of the image, so the density resolution will be slightly reduced by the above-mentioned knee characteristic control, but halation prevention has priority over density resolution in the interpretation diagnosis.

(Examples) Hereinafter, the present invention will be specifically described with reference to Examples.

FIG. 1 shows an embodiment of the present invention.

This X-ray diagnostic device operates under the control of the X-ray controller 13.
The X-ray fluoroscopic image of the subject P by the X-rays emitted from the radiation tube 1 is converted into a visible light image by I · I2, and this visible light image is taken into the solid-state camera 10 via the optical system 3, Solid-state camera 10
And the video signal is visualized on the CRT monitor 5.

The solid-state camera 10 is a solid-state image sensor such as a CCD (charge couple).
d device) 10a. Reference numeral 11 denotes a camera controller, and the solid-state camera 10 is under the control of this camera controller 11. The camera controller 11 functionally has camera control means 11a, halation detection means 11b, and halation reduction means 11c.

The camera control means 11a controls a series of imaging operations of the CCD 10a in the solid-state camera 10. The halation detection means 11b is the overflow drain (OFD) of the CCD 10a.
The occurrence of halation is detected by detecting the electric charge emitted from the terminal. The discharge of electric charge from the OFD terminal means that the CCD is in a saturated state, and therefore the presence or absence of halation can be determined by monitoring this OFD terminal. Halation reduction means 11c
Is the CCD based on the detection output of the halation detection means 11b.
The halation is reduced by controlling the knee characteristics of 10a.

Reference numeral 12 denotes a system controller, and the operation of the entire apparatus of this embodiment is controlled by this system controller 12.

Next, the operation of the embodiment apparatus configured as described above will be described.

X-rays are emitted from the X-ray tube 1 under the control of the X-ray controller 13, and the X-ray transparent image of the subject P due to the X-rays is converted into a visible light image by I · I2, and this visible light image is solid. The image is taken by the camera 10. The video signal obtained by this imaging is taken into the CRT monitor 5, and an X-ray fluoroscopic image of the subject P is displayed on this monitor 5.

On the other hand, when the charge is discharged from the OFD terminal of the CCD 10a, the charge is detected by the halation detecting means 11b, and the detection output is transmitted to the halation reducing means 11c. Then, the halation reducing means 11c becomes the halation detecting means 1
Based on the detection output of 1b, the knee characteristic of the CCD 10a can be quickly controlled so that the electric charge is not discharged from the OFD terminal. According to this knee characteristic control, the input / output characteristics of the CCD are rapidly changed from the characteristic curve 7 to the characteristic curves 8 and 9 in FIG. 2, so that the saturation of the output voltage is avoided and the occurrence of halation is prevented. To be done. Therefore, the image displayed on the CRT monitor 5 does not cause halation, which is good for diagnostic interpretation.

FIG. 3 shows another embodiment.

In FIG. 3, those having the same functions as those shown in FIG. 1 are designated by the same reference numerals.

In the X-ray diagnostic apparatus shown in FIG. 3, the A / D converter 14 arranged at the subsequent stage of the solid-state camera 10 converts a video signal into a digital signal, and then the image processing unit 17 performs appropriate image processing. It is a thing. Output data (image data) from the A / D converter 14 is written in the image memory 15. The halation detecting means 16 is arranged at the subsequent stage of the image memory 15. The halation detecting means 16 detects the occurrence of halation by monitoring each pixel value of the digital image in the image memory 15. Since the saturation of the pixel value means the occurrence of halation, the occurrence of halation can be detected by the pixel value monitor. The detection output of the halation detecting means 16 is taken in by the halation reducing means 11c functionally realized by the camera controller 11. The function of this halation reducing means 11c is the same as that of FIG.

In the above configuration, the video signal output from the solid-state camera 10 is A / D converted by the A / D converter 14 and then written in the image memory 15. The image data in the image memory 15 is transferred to the halation detecting means 16 and the image processing section 17. The image data transferred to the image processing unit 17 is sent to the D / A converter 19 via the display memory 18 after being subjected to appropriate image processing here, and this D / A converter 19 outputs an analog signal. After being converted into, the image is taken into the CRT monitor 5 and displayed.

On the other hand, when the occurrence of halation is detected by the pixel value monitor of the halation detecting means 16, the detected output is transmitted to the halation reducing means 11c, and the halation reducing means 11c controls the knee characteristic of the CCD 10a. This prevents halation from occurring.

Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above embodiments and various modifications can be made.

[Effects of the Invention] As described in detail above, according to the present invention, since the knee characteristic of the solid-state imaging device can be quickly controlled based on the presence or absence of the charge discharge from the overflow drain terminal, the occurrence of halation can be prevented. A line diagnostic device can be provided.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an X-ray diagnostic apparatus according to the present invention, FIG. 2 is an input / output characteristic diagram for explaining a knee characteristic of a solid-state image sensor, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a block diagram of an example device, and FIG. 4 is a block diagram of a conventional device. 10a ... CCD (solid-state image sensor), 11b, 16 ... halation detection means, 11c ... halation reduction means.

Claims (1)

[Claims] 1. An X-ray fluoroscopic image of a subject is converted into a visible light image,
X for imaging this visible light image with a solid-state image sensor for diagnosis
In the line diagnostic device, the solid-state imaging device includes an overflow drain terminal, and halation detection means for detecting the occurrence of halation by detecting charges emitted from the overflow drain terminal,
An X-ray diagnostic apparatus comprising: a halation reducing means for reducing halation by controlling a knee characteristic of the solid-state image pickup device so as to eliminate charge discharge from the overflow drain terminal based on the detection output.