JPH0544794B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention provides an input surface of an image intensifier (hereinafter referred to as "I・I") that uses X-rays that do not pass through the human body (direct The present invention relates to an X-ray photographing apparatus in which the density of photographic film does not decrease and remains appropriate even when X-rays or the like (hereinafter referred to as "excessive X-rays") are incident.

[Technical background of the invention]

An X-ray automatic exposure control device in an X-ray imaging device is provided with an I/I output photodetector that detects the amount of light at a predetermined portion of the output surface of the I/I, and the X-ray The X-ray generator is configured to control the X-ray generator so as to stop X-ray exposure when the X-ray dose necessary for the X-ray photograph to have an appropriate density has been emitted.

[Problems with background technology]

When an I/I output photodetector is used as the X-ray detection means of an automatic X-ray exposure control device, the I・X-rays are often directly incident on the I input surface, and due to this influence, the density of the X-ray photograph may be lower than the appropriate density, making it unsuitable for diagnosis. Furthermore, when the imaging unit includes a lung field, excessive X-rays similar to direct X-rays enter the I/I input surface, causing a similar adverse effect.

For this reason, excessive X-rays are determined from the video signal of the television system during fluoroscopy, and appropriate correction is made based on this determination result to prevent a decrease in density, or a large number of I/I output photodetectors are installed. A method has been implemented in which the influence of excessive X-rays is removed by selecting the I/I output photodetector to be used during imaging based on the strength of the output from each I/I output photodetector during fluoroscopy.

However, according to this method, excessive X-rays are determined only by the magnitude of the video signal during fluoroscopy or the strength of the output of the I/I output photodetector, so depending on the X-ray conditions, excessive X-rays may actually occur. There is a problem in that even if the X-ray is not an X-ray, it may be determined to be an excessive X-ray, and the X-ray photograph may not have the appropriate density.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and is an X-ray device that improves the accuracy of excessive X-ray determination compared to conventional devices and more reliably obtains X-ray photographs with appropriate density.
The object of the present invention is to provide a radiography device.

[Summary of the invention]

Summary of the present invention for achieving the above object includes: a bed on which a subject is placed; an X-ray tube that irradiates the subject with X-rays; An X-ray imaging apparatus having a television system that captures an image with a television camera and displays it on a television monitor, and an automatic exposure control system that controls the X-ray exposure conditions based on the light intensity of the optical image. , an imaging environment condition detection means for outputting a division size signal and a bed information signal, and an excessive X-ray detecting means for detecting a portion corresponding to excessive X-rays in the video signal from the television system and outputting an excessive X-ray detection signal. and a correction circuit for outputting a correction signal for correcting a change in density of photographic film due to excessive X-rays based on the division size signal, the bed information signal, and the excessive X-ray detection signal, the correction signal is used as a control signal for the automatic exposure control system.

[Embodiments of the invention]

Examples of the present invention will be described in detail below.

Figure 1 shows the configuration of the X-ray imaging device. In the figure, 1 is an X-ray fluoroscopy/photography bed on which the subject is placed, 2 is a spot shot device, and 3 is placed behind the spot shot device 2. I/I for converting an X-ray image into an optical image, 4 is I/I
An optical system including an output photodetector (for example, a photomultiplier tube), 5 a television camera that takes an X-ray image converted into an optical image by I.I.3, and 6 the aforementioned X-ray fluoroscope.
An X-ray tube 7 placed facing the photographing table 1 is a video signal processor that controls the sweeping of the television camera 5 and sends the video signal output from the television camera 5 to the television monitor 14. The television monitor 14 receives the video signal and a control signal for sweeping to display an X-ray image.

8 is an automatic exposure control circuit that obtains the output of the optical system 4 and controls the X-ray control device 10 so that the amount of light becomes a predetermined value, and 9 is an X-ray generator.

The X-ray control device 10 controls the tube voltage and tube current of the X-ray tube 6 during X-ray fluoroscopy according to the output of the automatic exposure control circuit 8, and controls the exposure time during imaging. control.

The I/I 3, optical system 4, television camera 5, video signal processor 7, and television monitor 1
4, the television system is connected to the optical system 4.
The I output photodetector and the automatic exposure control circuit 8 constitute an automatic exposure control system.

Reference numeral 11 denotes a photographing environment condition detection means, which includes a tilting angle determining circuit 23 for detecting a bed tilting angle from the X-ray fluoroscopy/photographing bed 1 and outputting a bed tilting angle signal as a bed information signal; and a division size determination circuit 24 that determines the division size of and outputs a division size signal.

The bed tilting angle signal is at a high level (“H”) when the bed tilting angle of the X-ray fluoroscopy/photography bed 1 is at a certain value or within a certain angle range (for example, around 90° suitable for esophagography). ``level'', and esophagography is performed when this is at a certain value or within a certain angle range.

Further, the division size signal becomes an "H" level when the division size of the imaging frame is a certain specific size, for example, when the division size is divided into left and right halves to prevent the influence of parts other than the esophagus of the human body.

Reference numeral 13 denotes excessive X-ray detection means, and an excessive X-ray dose calculation circuit 2 which takes in the video signal from the video signal processor 7 and generates a proportional signal proportional to the amount corresponding to the excessive X-ray in the video signal.
1, an excessive X-ray circuit 22 that outputs an "H" level excessive X-ray detection signal when excessive X-rays are included in the video signal, and this excessive X-ray detection signal and the photographing environment condition detection signal. and an AND circuit 25 that performs a logical product with the above and sends a switching control signal to a correction circuit 12, which will be described later.

The correction circuit 12 includes a correction signal generation circuit 2 that outputs a correction signal when determining excessive X-rays based on the proportional signal.
8, a constant value signal generation circuit 26 that outputs a constant value correction signal, and a switching means 27 that switches the outputs of the correction signal generation circuit 28 and the constant value signal generation circuit 26 based on the switching control signal. Either of the two correction signals is output as a control signal to the automatic exposure control circuit 8.

Next, the operation of the apparatus having the above configuration will be explained. The tilting angle of the X-ray fluoroscopy/imaging bed 1 is determined by the tilting angle determination circuit 23, and is input to the AND circuit 25 as a bed tilting angle signal.

Similarly, the division size signal of the photographic film is also determined by the division size determination circuit 24, and is inputted to the AND circuit 25 as a division size signal.

On the other hand, a video signal during X-ray fluoroscopy is input from the video signal processor 7 to an excessive X-ray dose calculation circuit 21 and an excessive X-ray circuit 22.

The excessive X-ray dose calculation circuit 21 sends a proportional signal proportional to the amount of excessive X-rays included in the video signal to the correction signal generation circuit 28.

On the other hand, when the excessive X-ray circuit 22 determines that there is a high-level video signal component corresponding to excessive X-rays in the video signal, the excessive
The line detection signal is sent to the AND circuit 25.

The AND circuit 25 determines that the X-ray fluoroscopy/imaging bed 1 is in a state where excessive X-rays are incident on the input surfaces of I and I3 based on the bed tilting angle signal, division size signal, and direct X-ray detection signal. , sends a switching control signal to the switching means 27.

The switching means 27 switches to the correction signal generation circuit 28 side based on this switching control signal, and as a result, the correction signal for direct X-ray determination is sent to the automatic exposure control circuit 8 as a control signal.

If there is no direct X-ray in the video signal, no X-ray detection signal is directly sent from the excessive X-ray circuit 22 to the AND circuit 25, and therefore,
In this case, the switching control signal sent from the AND circuit 25 to the switching means 27 changes, and as a result, a correction signal from the constant value signal generating circuit 26 is sent as a control signal to the automatic exposure control circuit 8.

As mentioned above, if it is determined during X-ray fluoroscopy that straight X-rays are incident on the input surface of I/I3 based on the division size of the imaging film, the tilting angle of the bed, and the state of the video signal. A correction signal for correcting the amount of decrease in photographic film density due to direct X-rays is input from the correction signal generation circuit 28 to the automatic exposure control circuit 8, and as a result, appropriate correction is performed.

During X-ray photography that follows X-ray fluoroscopy, the output from the I/I output photodetector of the optical system 4 is input to the automatic exposure control circuit 8, and after being corrected by the above-mentioned correction signal, X-ray exposure is performed. Since the radiation stop signal is output from the automatic exposure control circuit 8 to the X-ray control device 10, X-ray imaging can be performed under conditions such that direct X-rays or X-rays that have passed through the lung field are incident on the input surface of I/I3. Even if X-ray imaging is performed, it is possible to automatically perform X-ray imaging at an appropriate density.

The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the invention.

For example, in the embodiment described above, a case was explained in which excessive X-rays are determined based on a video signal.
The detection may be performed based on the output signal of the I/I output photodetector. Further, as the bed information signal, in addition to the bed tilting angle, information such as the rolling of the top board can also be used. In this case, both the bed tilting angle and the top rolling information may be used as the bed information signal, or either one of them may be used as the bed information signal.

〔Effect of the invention〕

According to the present invention described in detail above, X-ray automatic exposure control can be performed even in X-ray imaging when X-rays that do not pass through the human body or X-rays that pass through the lung field are incident on the input surface of the image intensifier. Since the division size signal and bed information signal from the X-ray fluoroscopy/photography bed, etc. are also used for system correction,
It is possible to provide an X-ray automatic exposure control device that can improve the accuracy of determining excessive X-rays and improve the stability of automatic exposure control.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing the configuration of an imaging environment condition detecting means, an excessive X-ray detecting means, and a correction circuit in the apparatus shown in FIG. 1... X-ray fluoroscopy/photography bed, 2... Spotshot device, 3... I/I, 4... Optical system, 5...
...Television camera, 6...X-ray tube, 7...Video signal processor, 8...Automatic exposure control circuit, 9...
X-ray generator, 10... X-ray control device, 11... Imaging environment condition detection means, 12... Correction circuit, 13...
...Excessive X-ray detection means.

Claims (1)

[Scope of Claims] 1. A bed on which a subject is placed, an X-ray tube that irradiates the subject with X-rays, and an X-ray tube that converts the X-rays transmitted through the subject into an optical image, and this optical image is captured by a television camera. An X-ray imaging apparatus comprising: a television system that displays images on a television monitor; and an automatic exposure control system that controls exposure conditions for the X-rays based on the light intensity of the optical image. photographing environment condition detection means for outputting an information signal; excessive X-ray detection means for detecting a portion corresponding to excessive X-rays in the video signal from the television system and outputting an excessive X-ray detection signal; a correction circuit that outputs a correction signal for correcting a change in density of photographic film due to excessive X-rays based on the size signal, the bed information signal, and the excessive X-ray detection signal; An X-ray imaging device characterized in that the control signal is