JPH0620270B2 - X-ray television imaging device - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention belongs to the technical field of diagnostic medical devices, and in particular,
It belongs to the technical field of an X-ray television imaging apparatus such as a digital fluorography apparatus and an X-ray fluoroscopic imaging apparatus.

[Technical Background of the Invention and Problems Thereof] Conventionally, in an X-ray television imaging apparatus, an X-ray fluoroscopic image of a target region of a subject to be imaged is displayed on a display device, for example, a monitor, and the object is obtained by monitoring. It is common to identify the site. For example, in the digital fluorography apparatus, as shown in FIG. 3, X-rays emitted from the X-ray tube 12 can be obtained by transmitting X-rays through the subject P.
The line image is converted into a fluorescent image on the input fluorescent screen of the image intensifier (hereinafter, also referred to as I / I) 1, and the fluorescent image is appropriately amplified and converted to the output fluorescent screen of I / I1. An optical image is output, this optical image is photographed by a television camera 3 via an optical system (tandem lens system) 2, and a video signal output from the television camera 3 is passed through a camera controller 4 to a digital holography processor 5 The video signal and the TV scanning signal, which are stored in the internal memory and then processed by the digital fluorography processor 5, are output to the TV monitor 6 to display an X-ray fluoroscopic image on the TV monitor 6 and to display an image. The X-ray fluoroscopic image is recorded on the recording device 7, or the multi-format camera 8 captures the X-ray fluoroscopic image on an X-ray film.

In addition, the digital fluorography device uses continuous X-rays by the X-ray tube 12 in both a simple fluoroscopy mode and a fluoroscopy mode in which a video signal obtained by continuous X-ray exposure is digitally processed. The line exposure is performed as follows. That is, the digital fluorography processor 5 outputs a control signal for controlling continuous X-ray exposure to the X-ray controller 10, and a high voltage is generated from the high voltage generator 11 by the control signal output from the X-ray controller 10. By continuously applying to the X-ray tube 12, the X-ray tube 12
X-rays are continuously emitted from.

Moreover, in the digital fluorography device, the intermittent X
In the case of the fluoroscopic imaging mode that requires radiation and digital signal processing, intermittent X-ray radiation is performed as follows. That is, the digital fluorography processor 5 outputs a control signal for controlling intermittent X-ray exposure to the X-ray controller 10, and the high voltage generator 11 intermittently outputs a high voltage according to a rate signal output from the X-ray controller 10. By applying the X-ray tube 12 to the X-ray tube 12, the X-ray tube 12 intermittently emits X-rays.

Furthermore, in the digital fluorography device,
Similarly, as shown in FIG.
I / I indirect photography may be performed by the I / I indirect spot camera 15 and the I / I indirect cine camera 14,
The fluoroscopic image is observed by the television camera 3 and the television monitor 6 even during the I / I indirect photography.

Therefore, in the digital fluorography device, a simple fluoroscopic mode, a fluoroscopic imaging mode for I / I indirect imaging, a fluoroscopic imaging mode that requires continuous X-ray exposure or intermittent X-ray exposure and digital signal processing, etc. Therefore, the amount of light incident on the television camera 3 per unit time is different, and therefore the image output level from the television camera 3 is also different.

In addition, the amount of light incident on the television camera 3 per unit time also differs due to variations in conversion coefficients of I / I of the same type or differences in conversion coefficients of I / I of different types. Further, the amount of light incident on the television camera 3 per unit time also varies due to a decrease in the conversion coefficient with the aging of I · I and a change in the conversion coefficient due to switching of the input field diameter of I · I.

In order to perform optimum monitoring, the output level of the video signal from the TV camera 3 must always be constant. However, since the optimum X-ray exposure condition is determined according to the surgical method, it is not preferable to finely adjust the X-ray exposure condition in order to maintain the output of the television camera 3 at a constant level.

Therefore, regarding a conventional digital fluorography apparatus or X-ray fluoroscopic imaging apparatus, as shown in FIG. 5, in the X-ray optical system, a diaphragm 16 for varying the amount of light incident on the television camera 3 of an optical image, and the diaphragm. Aperture controller 1 for controlling 16
3 (same as shown by the same number in FIG. 3), a method of adjusting the diaphragm 16 by the diaphragm controller 13 so that the amount of incident light on the television camera 3 per unit time becomes constant. It has been proposed by the applicant (see Japanese Patent Laid-Open No. 198473/1983).

However, in the above method, if the aperture diameter of the aperture 16 is opened to near the aperture diameter of the secondary lens 19 of the X-ray optical system,
There is a problem that the ratio of the peripheral light amount to the central light amount incident on the television camera 3 is significantly reduced. Further, if the aperture diameter of the aperture 16 is reduced too much than the aperture diameter of the secondary lens 19, the amount of light transmitted through the primary lens 18, which is inserted between the primary lens 18 and the secondary lens 19, is reduced. There is also a problem that a vignetting phenomenon occurs due to absorption and scattering of light by the photo pickup 20 to be detected, and a defect occurs in an optical image.

Further, there is a semi-transmissive mirror 17 as a light quantity correction means for the television camera 3 when switching from the simple fluoroscopic mode to the fluoroscopic imaging mode by the I / I indirect imaging.

However, since the light transmittance to the television camera 3 is limited to one type for the semi-transmissive mirror 17, even if the semi-transmissive mirror 17 can correct the light amount by mode switching, an indirect spot camera for gastric examination. , Indirect spot camera for circulatory organ and indirect cine camera for circulatory organ I
It is impossible to correct the amount of light incident on the television camera 3 per unit time based on the difference in each X-ray exposure condition in the indirect imaging. Therefore, even if a plurality of semi-transmissive mirrors 17 are arranged in order to enable such correction of the incident light amount, it is not practical due to the limitation of the capacity of the X-ray optical system, and the number of semi-transmissive mirrors 17 used. Is limited to two.

Further, in the digital fluorography device,
Conventionally, the correction of the amount of incident light on the television camera 3 per unit time for the fluoroscopic imaging mode by continuous X-ray exposure that requires digital signal processing and the fluoroscopic imaging mode by intermittent X-ray exposure that requires digital signal processing is conventionally performed. Semi-transparent mirror 1
It was done by attaching an optical attenuation filter to 7.

However, such a correction means has a drawback that the correction of the amount of light incident on the television camera 3 per unit time at the time of I / I indirect shooting must be sacrificed.

In addition, the variation of the conversion coefficient between I and I of the same model,
A unit for the TV camera 3 according to a difference in conversion coefficient between different types of I / I, a decrease in conversion coefficient due to aging of I / I, and a change in conversion coefficient due to switching of input field diameter of I / I. The amount of incident light per unit time is corrected by the auto iris control method.

However, in the digital fluorography apparatus, if the diaphragm 15 is changed by the auto iris control method and the diaphragm diameter is set near the upper limit or the lower limit of the usable range of the diaphragm diameter by switching between the two modes, I.
Proper light amount correction corresponding to the change in the conversion coefficient of I cannot be performed.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and an X of a digital fluorography apparatus, an X-ray fluoroscopic imaging apparatus, or the like.
In an X-ray television image capturing apparatus, the amount of light incident on the television camera per unit time is adjusted by adjusting the amount of light incident on the television camera, regardless of the difference in the operation method, the fluoroscopy, the fluoroscopy mode, and the various factors of the I · I conversion coefficient. It is an object of the present invention to provide an X-ray television photographing apparatus having an optical system capable of keeping the image output of the camera constant at all times.

[Outline of the Invention] An outline of the present invention for achieving the above object is to provide an image intensity converting an X-ray image obtained by transmitting X-rays emitted from an X-ray tube through a subject into an optical image. An X-ray television image capturing apparatus having a fire and a television camera for capturing an optical image from the image intensifier via an optical system having a primary lens and a secondary lens, in accordance with a change in the light amount of the optical image. Of the n optical filters that are controlled so that they can enter and leave the parallel rays formed by the primary lens, the optical transmittance of the optical filter having the maximum light transmittance of the n optical filters is When A, the light transmittances of the other n-1 optical filters are respectively It has n optical filters having a relationship of (m = 1, 2, ..., N−1), and a diaphragm arranged in a parallel light beam and having a diaphragm diameter variable according to a change in the light amount of an optical image. It is characterized by comprising an optical system.

[Embodiment of the Invention] FIG. 1 shows the configuration of an X-ray television imaging apparatus, for example, a digital fluorography apparatus, which is an embodiment of the present invention.

The digital fluorography device shown in FIG. 1 is different from the digital fluorography device shown in FIG. 3 in the following points.

That is, the primary lens 18 and I · I of the primary lens 18
In addition to the photo pickup 20 that is disposed on the side opposite to the position 1 and that detects the amount of light that passes through the primary lens 18, the secondary lens 19, and a diaphragm 21 that changes the amount of light of an optical image.
And an optical system 23 having a plurality of optical filters F-1, F-2, ..., F-n capable of entering and exiting the parallel rays formed by the primary lens 18 and attenuating the light quantity of the parallel rays.
A diaphragm controller 24 that outputs a diaphragm drive signal that controls the diaphragm diameter of the diaphragm 21 by a control signal that is output from the digital holography processor 27; and a control signal that is output from the digital holography processor 27. Optical filters F-1, F-2, ..., F
A filter drive controller 25 that outputs a filter drive control signal for moving -n into and out of a parallel light beam, and a filter drive control signal that is output from the filter drive controller 25 causes the optical filters F-1, F-2, .., F-n in and out of the parallel rays of filter drive devices 26-1, 26-
2, 26-n, automatic exposure controller 9 and X-ray controller 10
According to the information about the amount of light passing through the primary lens 18 detected by the photo pickup 20, which is input via the aperture controller 24 and the filter drive controller 2.
5 and a digital fluorography processor 27 having a function of outputting the command signal.

The optical filters F-1, F-2, ... F-n have the following relationships. That is, the optical filter F-
When the light transmittance of the optical filter having the maximum light transmittance among 1, F-2, ... F-n is A, the light transmittances of the other optical filters are (M is a positive integer). Here, A is the diaphragm 21
In consideration of the variable range of the attenuation amount due to, the ratio is set equal to the ratio of the minimum value to the maximum value of the attenuation rate adjustable by the diaphragm 21. That is, the optical filters F-1, F-2, ...
It is assumed that the light transmittance decreases in the order of F-n, and that the variable range of the attenuation rate by the diaphragm 21 is from 1.0 (opening the diaphragm) to 0.1 (1/10 of the opening of the diaphragm). The light transmittance of the filter F-1 is 0.1, and the optical filter F typified by the optical filters F-2 and F-n.
The light transmittances of -3, F-4 ... Relationship than 0.1 ² and ^0.1 4, a 0.1 8 ^....

In this way, by setting the light transmittances of the optical filters F-1, F-2, ... F-n, the light quantity of the parallel rays is set by the minimum number of optical filters and the diaphragm 21 as described later. Can be continuously attenuated.

It is to be noted that, in FIG. 1, those denoted by the same reference numerals as in FIG. 3 have the same functions as those shown in FIG.

Next, the above operation will be described.

First, the diaphragm 21 and the optical filters F-1, F-2 and F-
The variable range of the optical attenuation rate by combining with a total of three optical filters of F-3 represented by n will be described with reference to FIG.

FIG. 2 is an explanatory diagram showing the variable range of the light transmittance that can be realized by the diaphragm and the optical filter.

The optical filter F-1, F-2, F-3 of the light transmission respectively 0.1, 0.1 ^2, 0.1 ^4.

A Com1 in the figure is a variable range of the light attenuation rate only by the diaphragm 21, and has a variable range of the attenuation rate of 1.0 to 10 ^-1 . Also,
Com2 is variable width of the light attenuation factor can be realized in combination with the diaphragm 21 and the optical filter F-1, the light attenuation ratio of 10 ^-1 to
It has a variable range of 10 ^-2 . Similarly, Com3 is a variable range of the optical attenuation factor that can be realized by combining the diaphragm 21 and the optical filter F-2, and Com4 is the diaphragm 21 and the optical filters F-1 and F-2.
-2, the variable range of the optical attenuation factor that can be realized in combination with
5 is a variable width of the optical attenuation rate that can be realized by the combination of the diaphragm 21 and the optical filter F-3, and Com 6 is a variable width of the optical attenuation rate that can be realized by the combination of the diaphragm 21 and the optical filters F-1 and F-3. Com7 is a diaphragm 21 and optical filters F-2, F
Variable width of optical attenuation factor that can be realized in combination with -3, Com
Reference numeral 8 denotes a variable width of the optical attenuation factor that can be realized by combining the diaphragm 21 and the optical filters F-1, F-2, F-3. Therefore, by combining the three optical filters F-1, F-2, and F-3 with the diaphragm 21, the optical attenuation factor 1.
You can change continuously from 0 to 10 ^-8 .

Control of aperture size of the aperture 21 and the optical filter F
Insertion of -1, F-2, and F-3 into the parallel light beam is performed by the aperture controller 24 and the filter drive controller 25, for example, as follows.

In the optimum state of the digital fluorography apparatus shown in FIG. 1, the aperture diameter of the aperture 21 is set to an aperture value intermediate between the upper and lower limit values in the usable range, and the light attenuation filter 22 appropriately sets the parallel light rays. It is assumed that the output level of the output video signal of the television camera 3 is 1 with respect to the amount of light 100 transmitted through the primary lens 18 by being disposed inside.

In the case of the fluoroscopic imaging mode by continuous X-ray exposure which requires digital signal processing, when the amount of light transmitted through the primary lens 18 is 10 times that of the optimum state, that is, 1000, the optical filter F-1 having a light transmittance of 0.1. Is inputted to the filter driving controller 25 from the digital fluorography processor 27, and the filter driving control signal is outputted from the filter driving controller 25 to the filter driving device 26-1 to obtain the light transmittance. An optical filter F-1 of 0.1 is placed in the parallel rays. For this reason, even if the amount of light transmitted through the primary lens 18 is 1000, it is attenuated to 1/10 by the optical filter F-1 having a light transmittance of 0.1. The video signal of level 1 is output from the camera 3.

Also, due to the secular change of I / I1, the change is 4 /
When it is reduced to 5, the photo pickup 20 detects that the amount of light passing through the primary lens 18 is reduced from 1000 to 800, and the detection signal is digitally transmitted via the automatic exposure control unit 9 and the X-ray controller 10. When output to the fluorography processor 27, a command signal is output from the digital fluorography processor 27 to the aperture controller 24, and the aperture drive signal output from the aperture controller 24 causes the aperture diameter of the aperture 21 to fall between its upper and lower limit values. By opening to 1.118 times the set value, the amount of light passing through the diaphragm 21 is set to 1000, and then the amount of light is attenuated to 100 by the optical filter F-1 having a light transmittance of 0.1. As in the case of the optimum state, the TV camera 3 outputs the level 1 video signal.

Also, I / I1 has two kinds of input visual field diameters (9 inches and 7 inches), and the conversion coefficient is 4/5 due to aging.
In a digital fluorography device equipped with a dual I / I that has been reduced to a minimum, in the case of a fluoroscopic imaging mode by continuous X-ray exposure that requires the digital signal processing, a 9-inch input field diameter is changed to a 7-inch input field diameter. When switching is performed, the conversion coefficient of I · I1 drops to 49/81, so the photo pickup 20 detects that the amount of light passing through the primary lens 18 has decreased to 800 × 49/81, and the detection signal The digital fluorography processor 27
Output to the digital fluorography processor 2
The aperture drive signal output from the aperture controller 24 for inputting the command signal output from 7 opens the aperture of the aperture 21 to 1.437 times which is set to the middle of the upper and lower limit values. Is set to 1000, and then the light amount is attenuated to 100 by the optical filter F-1 having the light transmittance of 0.1. As a result, the television camera 3 outputs the level 1 video signal.

The ratio of the maximum intensity to the minimum intensity of the optical image on the output surface of I · I1 is usually about 10 ⁶ ; 1 under various shooting conditions, but as described above, the diaphragm 21 and the optical filter F-
The input level to the television camera 3 becomes the optimum level by the action of 1, F-2, and F-3.

As described above, in the apparatus of the present embodiment, the input level to the television camera 3 is set to the optimum level regardless of, for example, the difference in the photographing mode, the exposure condition, the difference in the I / I mode, the type of the subject, and the like. Therefore, it is possible to obtain a fluoroscopic image having no deterioration and excellent diagnostic ability. Also, if the width of the attenuation amount that needs to be adjusted increases, an optical filter with a small light transmittance is needed, which inevitably increases the number of optical filters. Aperture 2 where the ratio of the minimum value to the maximum value of the ratio is 0.1
1 and their light transmittances of 0.1, 0.1 ² , 0.
The combination of 1 ⁴ comprising three optical filters F-1, F-2, F-3, can be varied continuously light attenuation factor of 1.0 to 10 ^-8. That is, when the light transmittance of the optical filter having the maximum light transmittance is A, the light transmittances of other optical filters are If (m is a positive integer), there is no waste in the optical filter, and the light quantity of the parallel rays can be continuously attenuated by the minimum number of optical filters and the diaphragm 21. Therefore, it is extremely advantageous in terms of downsizing of the optical system 23 and cost of the device.

Although one embodiment of the present invention has been described above, it is needless to say that the present invention is not limited to the above embodiment and can be appropriately modified within the scope of the gist of the present invention.

For example, in the above embodiment, the optical filter having the maximum light transmittance is F-1, and the optical filter F-
Although the light transmittance of 1 is set equal to the ratio of the minimum value to the maximum value of the attenuation rate that can be adjusted by the diaphragm 21, it may be set to be slightly higher than this ratio. With this setting, for example, a portion that overlaps the variable width of the optical attenuation rate due to each combination of Com1 to Com8 in FIG. 2 can be provided. In an actual device, it is preferable to provide some portions that overlap the variable width of the light attenuation rate by each combination as described above in order to perform more reliable light amount adjustment.

There is no limitation on the arrangement order of the plurality of optical filters.

Further, the mode switching in the above-described embodiment was a switching from the simple fluoroscopic mode to the fluoroscopic imaging mode by continuous X-ray exposure, but the fluoroscopic imaging mode by I / I indirect imaging and the intermittent X-ray requiring digital signal processing. Even when switching to the fluoroscopic imaging mode due to exposure, the optical filters F-1, F-2, ..., F-n or the diaphragm 21 is used.
Fine adjustment of the light quantity by the optical filters F-1, F-2,
The output level of the video signal from the television camera 3 can be made constant by the coarse adjustment of Fn.

[Effects of the Invention] According to the present invention described in detail above, even if the amount of light transmitted through the primary lens changes in a wide range due to switching of shooting modes under which X-ray exposure conditions are significantly different, The amount of light incident on the image pickup tube per unit time can be made constant, the image output of the TV camera can be made constant, and there is no waste of optical filters. It is possible to continuously attenuate the amount of light. Further, since a plurality of optical filters and diaphragms are combined, it is possible to prevent the amount of ambient light incident on the television camera from being significantly reduced, or from causing a loss of an optical image or the like. As a result, it is possible to properly perform digital image processing in the digital fluorography processor and obtain a perspective image without deterioration.
It can greatly contribute to the improvement of medical diagnostic ability.

[Brief description of drawings]

FIG. 1 is a block diagram of an X-ray television imaging apparatus as an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing a variable range of the optical attenuation factor that can be realized by an aperture and an optical filter provided in the apparatus of this embodiment. FIG. 3 is a block diagram showing a conventional digital fluorography device, FIG. 4 is a block diagram showing a main part of a conventional digital fluorography device for performing I / I indirect imaging, and FIG. 5 is a conventional X-ray television. It is a block diagram which shows the optical system of an imaging device. 1 ... Image intensifier, 3 ... TV camera, 12 ... X-ray tube, 18 ... Primary lens, 19 ... Secondary lens, 21 ... Aperture, F-1, F-2, ..., Fn ... Optical filter, 23 ... Optical system.

Claims (1)

[Claims] 1. An image intensifier for converting an X-ray image obtained by transmitting X-rays emitted from an X-ray tube through a subject into an optical image, and an optical image from the image intensifier. X having a television camera for photographing through an optical system having a primary lens and a secondary lens
In a line television photographing device, there are n optical filters which are controlled so as to be able to enter and leave each of parallel rays formed by the primary lens in accordance with a change in the light amount of an optical image, of the n optical filters. When the light transmittance of the optical filter having the maximum light transmittance is A, the light transmittances of the other n-1 optical filters are respectively It has n optical filters having a relationship of (m = 1, 2, ..., N−1), and a diaphragm arranged in a parallel light beam and having a diaphragm diameter variable according to a change in the light amount of an optical image. An X-ray television imaging apparatus, which is equipped with an optical system.