JPH0224000B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an
This invention relates to an automatic line exposure control device.

[Technical Background of the Invention] The structure and operation of a conventional device will be explained with reference to FIG.

In FIG. 1, 1 is an X-ray tube, 2 is a collimator provided at the X-ray emission port of this X-ray tube 1, and 3
4 is a collimator control circuit for determining the opening degree of the collimator 3; 4 is a bed on which the subject 5 is placed; 6 is a tilting controller for raising and lowering the bed 4; and 7 is a final controller for controlling the X-ray irradiation field. The divided mask to be controlled, 8, is a divided mask control circuit that determines the size of the divided mask 7, and is configured to operate in conjunction with the collimator control circuit 3.

9 connects the X-ray tube 1 via the bed 4 and the subject 5.
10 is a spot shot device 9 for taking an X-ray photograph, which is placed opposite to the spot shot device 9.
An image intensifier (hereinafter referred to as "I.
11 is a television camera that captures the X-ray image converted into an optical image by I.I 10, 12
13 is a light amount detection element (for example, a photomultiplier tube) for detecting the light amount of the optical image, and 13 is the I/I1
0 and the television camera 11; an optical system for distributing an optical image to the television camera 11 and the light amount detection element 12; 14 is the television camera 11;
The video signal output from the television camera 11 is transmitted to the television monitor 15.
A television camera control circuit and a television monitor 15 are configured to obtain the video signal and a control signal for sweeping to display an X-ray image.

16 is an automatic exposure control circuit that obtains the output of the light amount detection element 12 and controls the X-ray controller 17 so that the amount of light becomes a predetermined value; and 18 is an X-ray generator.

The X-ray controller 17 controls the tube voltage and tube current of the X-ray tube 1 during X-ray fluoroscopy according to the output of the automatic exposure control circuit 16 via the X-ray generator 18, and controls the exposure time during imaging. control.

The raising/lowering controller 6 controls the drive system of the bed 4, the spot shot device 9 controls the X-ray photography system, the I/I 10, the television camera 11, and the optical system 1.
3. The television camera control circuit 14 and television monitor 15 constitute a television system, and the light amount detection element 12 and automatic exposure control circuit 16 constitute an automatic exposure control system.

Next, the operation of the device having the above configuration will be explained.

By activating the X-ray controller 17 and sending a control signal to the X-ray generator 18,
A preset tube voltage and tube current are applied to the wire tube 1.

The X-ray tube 1 emits X-rays with an intensity corresponding to the tube voltage and tube current.

The emitted X-rays are collimated by the collimator 2 and transmitted through the subject 5 on the bed 4.
10.

X of subject 5 by transmitted X-rays by I・I10
The line image is converted into an optical image and appears as a visible image on the output surface of this I/I 10.

This visible image is transmitted to the television camera 1 by the optical system 13.
1 and the light amount detection element 12.

The visible image input to the television camera 11 is converted into a video signal here, and further sent to the television monitor 15 via the television camera 14.
Here, it is displayed as an X-ray transmission image of the subject 5.

On the other hand, the light amount of the optical image displayed on the output surface of the I/I 10 is detected by the light amount detection element 12, and this detection output is guided to the automatic exposure control circuit 16.

In order to optimize the X-ray image displayed on the television monitor 15 during fluoroscopic diagnosis, the automatic exposure control circuit 16 sends a control signal to the X-ray controller 17 in accordance with the detection output.
Control is performed so that the output of the light amount detection element 12 approaches a preset reference value.

As a result, X-rays are emitted from the X-ray tube 1 with such intensity that an X-ray transmitted image is displayed on the television monitor 15 at optimal brightness.

Through the above control process, the television monitor 15
An X-ray transmission image can be obtained with optimal brightness.

In addition, when performing X-ray photography of subject 5,
The spot shot device 9 is operated, and at the same time the automatic exposure control circuit 16 is operated as an integrator, the reference value of the light amount detection element 12 is switched to the value necessary for photographing, and the X-ray controller 17 is operated under predetermined photographing conditions. .

As a result, the X-ray controller 17 applies the tube voltage and tube current under predetermined imaging conditions to the X-ray tube 1, and therefore, the X-ray tube 1 emits X-rays corresponding to the tube voltage and tube current. be exposed to radiation.

Then, the X-rays transmitted through the subject 5 enter the spot shot device 9, the X-ray film is exposed, and an X-ray photograph of the subject 5 is taken.

At this time, the X-rays transmitted through the X-ray film are also incident on I.I.10, and an optical image appears on its output surface.

This optical image is also input to the light amount detection element 12 via the optical system 13, and its light amount is detected.

The output of the light amount detection element 12 is sent to the automatic exposure control circuit 1.
6, where integration is performed.

When the integral value reaches a required value, the automatic exposure control circuit 16 sends an X-ray stop signal to the X-ray controller 17.

Based on this X-ray stop signal, a control signal is sent from the X-ray controller 17 to the X-ray generator 18, and imaging ends.

At this point, the X-ray film of the spot shot device 9 is moved out of the X-ray irradiation field, and the state is again changed to the state for fluoroscopic diagnosis.

In this way, the automatic exposure control circuit 16 functions as a brightness control means for the display image on the television monitor 15 during fluoroscopic diagnosis, so that the optimum brightness is displayed, and also functions so that the X-ray film is properly exposed during radiography. Optimal control is performed.

[Problems with Background Art] By the way, in the above device, if the I/I 10 output image D is shown in FIG. The light amount detection element 12 detects the average light within this effective area A and controls the automatic exposure control circuit 16.
is under control.

That is, the light amount detection element 12 detects the amount of transmitted X-rays within the effective area A, and detects the intensity of the signal from the subject 5.
It is processed as an excess or deficiency of the X-ray conditions.

Considering an example of the use of this device, when the observation target is the stomach, X-rays are taken using a negative contrast agent C such as barium to clarify the condition of the stomach wall surface, as shown in Figure 2b. Increase image contrast.

In this case, a part B of the effective area A, which is the photometric field of the light amount detection element 12 described above, is covered with the negative contrast medium C, making it difficult for X-rays to pass through this part. The resulting optical image will be dark in that area.

The above-mentioned state may further change depending on the photographing or fluoroscopy situation.

If the rate at which the negative contrast agent C covers the photometric field of the light amount detection element 12 changes for the same subject thickness, the actual area of the photometric field will change.

As a result, the detection output of the light amount detection element 12 changes despite the same object thickness.

When such a phenomenon occurs, automatic brightness control during fluoroscopy is performed so that the average brightness of the entire photometric field becomes a predetermined value. The brightness of other parts other than that part is increased, and as a result, the increased brightness part causes halation on the television monitor 15.

In addition, when controlling the degree of darkening of an X-ray photograph at the time of imaging, there is a risk that the degree of darkening of the X-ray photograph becomes excessive, and furthermore, the degree of influence depends on the coverage rate of the negative contrast medium C in the photometric field of view. Change and obtain X
There is a risk that the density of the line photograph and the brightness of the image on the television monitor 15 will vary, which will reduce the diagnostic ability of doctors and the like.

That is, the above-mentioned apparatus does not fully perform the automatic exposure control function.

Covering with the negative contrast medium C as described above is particularly common in gastric imaging, compression imaging, and contrast medium-filled imaging.

As a countermeasure against this problem, it has been proposed to extract a video signal corresponding to the entire detection field from the television camera control circuit 14, calculate the actual detection field area from this video signal, and correct the automatic control function based on the ratio. However, with such a method, it is difficult to perform complete correction if the proportion of negative contrast agent coverage is large.

[Object of the Invention] The present invention has been made in view of the above circumstances, and provides an X-ray that can prevent the occurrence of inappropriate exposure phenomena such as overexposure caused by the covering of the photometric field of view with a negative contrast agent. The purpose of this invention is to provide an automatic exposure control device.

[Summary of the Invention] The summary of the present invention for achieving the above object is to convert an image of a subject by X-rays emitted from an X-ray tube into an optical image, capture this optical image with a television camera, and display it on a television monitor. In an X-ray automatic exposure control device, the X-ray automatic exposure control system includes a television system for displaying a video image on a television camera, and an automatic exposure control system for controlling the X-ray exposure conditions based on the light intensity of the optical image. A correction signal generating means for extracting a video signal and outputting a correction signal corresponding to the ratio of the contrast agent covered area of the subject based on the video signal of a specific portion, and a standard for an automatic exposure control system that is set in advance to an optimal value. A reference correction signal generating means that generates a correction signal, and based on the fluoroscopic X-ray conditions of the X-ray and the imaging environment conditions, determine whether the contrast agent covered area during gastrointestinal imaging is large, and based on this determination result, the The apparatus is characterized in that it comprises a correction signal generating means and a switching control means for controlling the output of the reference correction signal generating means to be cut off, and the correction signal or the reference 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 below with reference to FIGS. 3 and 4.

In FIGS. 3 and 4, the same parts as those in the apparatus shown in FIG. 1 are designated by the same reference numerals, and detailed explanation thereof will be omitted.

The device shown in FIG. 3 differs from the device shown in FIG. 1 in that it receives a video signal from the television camera control circuit 14, extracts a video signal of a specific part of the subject 5 (photometric field of view) from this video signal, and sends it out. In addition, a correction signal generating means 31 generates a correction signal to the automatic exposure control circuit 16 from the ratio of the area covered by the negative contrast agent in the subject based on the video signal of a specific portion.
interface circuits 41 and 43 that take in the imaging environment conditions (in this embodiment, the division size signal from the division mask control circuit 8 and the tilting angle signal from the tilting angle controller 6), and the X-ray control Vessel 17
an interface circuit 42 that takes in the fluoroscopic X-ray condition signal from the fluoroscopic X-ray condition signal; and an interface circuit 40 that takes in the correction signal from the correction signal generating means 31.
and the interface circuits 41, 42, 43
an AND circuit 44 which takes the AND of the outputs of the outputs of the reference correction signal generating means 45 which generates a reference correction signal set to an optimal value in advance, and an output of the interface circuit 40 and an output of the reference correction signal generating means 45. This is because a switching control means 32 is provided which includes a switching means 46 for switching the output of the AND circuit 44 based on the output of the AND circuit 44.

Next, the operation of the apparatus having the above configuration will be explained in the case of compression imaging of the subject 5.

As explained in the conventional example, it is possible to correct the coverage of a specific portion by the negative contrast medium C to some extent by providing the correction signal generating means 31, but if the coverage ratio increases, the correction effect becomes insufficient.

In general, in the case of compression imaging, the coverage of the negative contrast medium C within a specific portion increases.

In the case of compression imaging, the division size by the division mask 7 is set to four, and the bed 4 is set in the standing position.

Therefore, a division size signal of four divisions is sent from the division mask control circuit 8 to the switching control means 32 as follows.
Further, the up/down angle signals for the standing position are sent from the up/down controller 6 to the switching control means 32, respectively.

On the other hand, when most of the specific area is covered with the negative contrast agent C, the output of the light amount detection element 12 decreases, and therefore the automatic exposure control circuit 16 and the X-ray controller 17 function, causing the exposure from the X-ray generator 18. The fluoroscopic X-ray conditions emitted increase.

This fluoroscopic X-ray condition is sent to the switching control means 32 as a fluoroscopic X-ray condition signal having a predetermined value or more.

The AND circuit 44 of the switching control means 32 outputs the division size signal, the fluoroscopic X-ray condition signal, and the tilting angle signal to the interface circuits 41 and 4, respectively.
2 and 43, the logical product of these signals is taken, and the result is sent to the switching means 46 as a switching signal.

That is, the AND circuit 44 determines that compression imaging of the subject 5 is being performed based on the 4-division size signal, the fluoroscopic X-ray condition signal of a predetermined value or more, and the standing position angle signal, and sends out a switching signal. .

This switching signal activates the switching means 46, and the reference correction signal from the reference correction signal generating means 45 is sent as a control signal to the automatic exposure control circuit 16.

If any of the three types of signals is not input to the AND circuit 44, the switching means 46 switches to output the correction signal from the correction signal generation means 31 to the automatic exposure control circuit 16, and this correction signal is output to the automatic exposure control circuit 16. Sent as a control signal.

In this way, correction is normally performed on the automatic exposure control circuit 16 using a correction signal according to the coverage ratio of a specific portion by the negative contrast medium C, and when the coverage ratio increases extremely, the correction signal is applied accordingly. Correction will be performed using the reference correction signal.

Next, we will explain the case of contrast agent-filled imaging of the subject 5. In this case, the division size by the division mask 7 is not limited to 4 divisions, but it is often the case of 4 divisions that X-ray photography is overexposed. Furthermore, the bed 4 is also in a standing position in most cases.

Furthermore, the fluoroscopic X-ray conditions also increase as in the case of compression imaging.

Therefore, in this case as well, correction can be made by the device as in the case of compression imaging described above.

It goes without saying that the present invention is not limited to the embodiments described above, and that various modifications can be made within the scope of the invention.

For example, by sending only the reference correction signal to the automatic exposure control circuit 16 based on the division size signal, the fluoroscopic X-ray condition signal, and the tilting angle signal, without using the correction signal from the correction signal generation means 31,
It is also possible to prevent extreme overexposure in X-ray photography.

Further, although the description has been made using the division size and the tilting angle as the imaging environment conditions, it can also be implemented by inputting a compression tube signal etc. from the compression tube.

Further, the combination of these photographing environment conditions is not limited to two.

[Effects of the Invention] According to the present invention described in detail above, coating with a negative contrast agent is determined based on imaging environment conditions such as the tilting angle signal of the bed or the division size signal of the division mask and the fluoroscopic X-ray condition signal of a predetermined value or more. The system determines whether the image is a compression exposure or a contrast agent-filled image, and uses this determination result to correct the automatic exposure control system. It is possible to provide an X-ray automatic exposure control device that can prevent inappropriate exposure phenomena such as overexposure during X-ray photography from occurring.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional X-ray automatic exposure control device, Fig. 2 a and b are explanatory diagrams showing the relationship between the output image of the image intensifier and the photometric field of view by the light amount detection element, respectively, and Fig. 3 4 is a block diagram showing an embodiment of the device of the present invention, and FIG. 4 is a block diagram showing the configuration of the switching control means of the device shown in FIG. 3. DESCRIPTION OF SYMBOLS 1... X-ray tube, 5... Subject, 7... Division mask, 8... Division mask control circuit, 10... Image intensifier, 11... Television camera,
12... Light amount detection element, 14... Television camera control circuit, 15... Television monitor, 16...
Automatic exposure control circuit, 17... X-ray controller, 18...
... X-ray generator, 31 ... Correction signal generating means, 32
...Switching control means, 40, 41, 42, 43...
Interface circuit, 44...AND circuit, 4
5... Reference correction signal generation means, 46... Switching means.

Claims (1)

[Claims] 1. A television system that converts the image of a subject by X-rays emitted from an X-ray tube into an optical image, photographs this optical image with a television camera, and displays it on a television monitor; and an automatic exposure control system that controls the exposure conditions of the X-rays.
In an automatic line exposure control device, a correction signal that extracts a specific portion of the video signal from a television camera and outputs a correction signal corresponding to the ratio of the contrast agent covered area of the subject based on this specific portion of the video signal. a reference correction signal generating means for generating a reference correction signal for an automatic exposure control system set to an optimum value in advance; switching control means for determining whether the area coated with the agent is large and switching and controlling the outputs of the correction signal generation means and the reference correction signal generation means according to the determination result; An automatic X-ray exposure control device characterized in that it is used as a control signal for an exposure control system.