JPH0224070B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains] This invention belongs to the technical field of X-ray imaging devices,
Especially pulse-X using digital radiography.
The present invention relates to radiation diagnostic equipment.

[Technical background of the invention and its problems]

In recent years, with regard to X-ray diagnosis of the cardiovascular system, especially angiography, a technology called "digital radiography" or "digital fluorography" that applies time subtraction techniques and digital processing technology has been introduced into X-ray diagnostic equipment. It is applied to.

The outline of the digital radiography will be explained next.

First, after injecting an angiographic contrast agent into the patient's brachial vein, for example, when time T ₀ has elapsed, the first X-ray irradiation allows an X-ray television camera to scan the area to be examined before the angiographic contrast agent flows into the subject. A/D converts the X-ray television video signal output from the X-ray television camera into
The digital X-ray television video signal is converted and stored as a mask image in a first digital memory.
Next, after the injection of the angiographic agent, a second X-ray exposure is performed when the time T ₁ after mask uptake has elapsed, and thereafter, for example, X-ray exposure is intermittently performed at a predetermined rate per second. An X-ray television camera images the area being irradiated and the angiographic agent gradually flows into it over time, and the images are output from the X-ray television camera.
The A/D converted digital X-ray television video signal is stored in a second digital memory. Then, by subtracting the X-ray television video signal in the second digital memory with the X-ray television video signal in the first digital memory,
A subtraction video signal is synthesized, which is a subtraction image of a blood vessel into which a vascular contrast agent is flowing, and an analog subtraction video signal is obtained by D/A converting this subtraction video signal. The traction image is displayed on a CRT monitor, or the subtraction image is converted into a film image using a multi-format camera.

Digital radiography can be applied not only to conventional angiographic contrast injection using an arterial catheter, but also to intravenous injection without using an arterial catheter, making it possible to make safer, faster, and more accurate diagnoses. It has attracted a lot of attention in recent years because of its advantages.

Digital radiography also includes mask mode radiography.
Radiography (also known as Serial Imaging) and mask mode fluoroscopy (also known as Serial Imaging).
Mode Fluoroscopy (also called Continvous Mode). The former is suitable for diagnosing test areas with little movement, such as the head, kidneys, and peripheral vascular system, while the latter is suitable for diagnosing test areas with relatively large movement, such as the heart and the vascular system around the heart. Are suitable.

By the way, in conventional X-ray diagnostic equipment using mask mode fluoroscopy, the generation form of X-rays is not pulsed X-rays, but continuous X-rays similar to X-rays during fluoroscopy. Ta.
Continuous X-ray generation can display the movement of the area to be examined on a display device as smooth movement, but it produces so-called motion blur, so it is not suitable for the purpose of mask mode fluoroscopy, whose main purpose is dynamic observation. ,
Not necessarily suitable. Despite this, continuous X-rays are often generated for the following reasons.

In other words, X that adopts the generation form of pulsed X-rays
Due to the signal readout efficiency of the image pickup tube in the X-ray television camera that captures X-ray images and the afterimage phenomenon, for example, ray diagnostic equipment can process at most 10 X-ray images per second.
Since only line images can be obtained, it is not possible to display a test site that moves a lot as having smooth movement. In other words, in a pulsed X-ray diagnostic device, wide blanking for 1 to 2 fields is applied to a vidicon type image pickup tube, which is a general-purpose image pickup tube, and an X-ray pulse is emitted during that time.
After that, the X-ray image stored in the vidicon type image pickup tube is scanned to generate an X-ray video signal (hereinafter referred to as a video signal).
Read out. In that case, the video signals of the 1st field, 2nd field, 3rd field, etc. after the start of reading gradually decrease. In either the frame recording method, which uses the video signals of the first and second fields as one image, or the field recording method, which uses the video signal of the first field, the video signal is completely read out and erased. It takes time for several fields. In other words, pulse lines cannot be emitted between several fields to be erased (if
If pulsed X-rays are irradiated, the afterimage obtained from the previous irradiation and the video signal obtained from the current irradiation will mix, making it impossible to obtain an accurate image. ). Therefore, in the pulsed X-ray generation mode, only about 10 X-ray images can be obtained per second. In this case, X-ray television, which uses the standard television system that normally displays 30 images per second, complements the images stored in memory during periods when there is no X-ray exposure, creating animation-like images. An image with movement will be displayed. This makes it impossible to sufficiently observe the dynamics.

Furthermore, when a field recording method is adopted in a pulse On the other hand, when using the frame recording method, there is a difference in the output level between the first and second fields, so flicker appears on the screen of the X-ray television monitor, which again results in poor quality images. I can't get it.

[Purpose of the invention]

This invention was made in view of the above-mentioned circumstances.
Pulse X using digital radiography can be displayed as a high-quality image.
The purpose is to provide a radiation diagnostic device.

[Summary of the invention]

The outline of this invention for achieving the above object is as follows:
An X-ray tube, an image intensifier arranged opposite to the X-ray tube, a plurality of X-ray television cameras inputting output fluorescence images of the image intensifier through an optical device, and a plurality of X-rays. A mixing circuit that mixes each video signal from the TV camera, and an A/D converter for the video signal output from the mixing circuit.
a digital processor that performs conversion and subtraction processing; a display device that displays an X-ray image using a video signal output from the digital processor; and at least the X-ray tube, image intensifier, and X-ray television camera. In a pulsed X-ray diagnostic apparatus equipped with a system controller that controls according to the sequence of a plurality of X-ray television cameras are controlled by a wide blanking signal and a cathode bias signal to accumulate fluorescence images from the image intensifier during the wide blanking period; The stored image is read out within the same period. It is characterized by this.

[Embodiments of the invention]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention.

In the figure, 1 is the X-ray tube that irradiates the subject 2 with pulsed X-rays, and 3 is the X-ray image transmitted through the subject by the X-rays irradiated by the X-ray tube 1. This is an image intensifier (I/I) that converts the incident X-ray image into an optical image.

4 is an optical system device. More specifically, the optical system device 4 includes a primary lens 4a placed in front of the output phosphor screen of the I/I 3, and a primary lens 4a placed in front of the input surfaces of the image pickup tubes of the two X-ray television cameras 5 and 6. The secondary lenses 4c and 4d, and the
Next, there is a fixed half mirror 4b for distributing the output fluorescent images of I and I3 transmitted through the lens 4a into a light intensity of, for example, 50:50 and guiding them to the image pickup tube input surfaces of the two X-ray television cameras 5 and 6. , secondary lens 4
Optical diaphragms (auto iris) 4e, 4f are arranged in front of the lenses 4c, 4d and automatically adjust the amount of light of the output fluorescent image incident on the secondary lenses 4c, 4d.
and automatic light-shielding elements 4g, 4h, for example, liquid crystal shutters, for conducting and cutting off light incident on the input surfaces of the image pickup tubes of the two X-ray television cameras 5, 6. The output fluorescent images of the X-ray television cameras 5 and 6 are alternately input to the two X-ray television cameras 5 and 6. Two X-ray cameras 5, 6
The image pickup tubes 5a and 6a each equipped with can be a vidicon type image pickup tube, such as vidicon, plumbicon, carnicon, silicon vidicon, nubicon, or sachicon (trade name). It is said that a bidicon that does this is preferable.

7 and 8 are video amplifiers that amplify the video signals output from the two X-ray television cameras 5 and 6, respectively, and 9 is a television camera timing controller that amplifies the video signals output from the two X-ray television cameras 5 and 6, respectively. Controls all sequences of television cameras 5 and 6. 10A and 10B are cathode bias circuits that apply cathode bias to the image pickup tubes 5a and 6a in the two X-ray television cameras 5 and 6, and 11 is an I/I blanking circuit. The grid voltages in I and I3 are controlled to cut off output fluorescent images other than X-ray pulses. 12
A video mix circuit shown in numeral 2 combines video signals output from two X-ray television cameras 5 and 6, respectively. Reference numeral 13 denotes a sync generator, which generates synchronizing signals for the two X-ray television cameras 5 and 6, as well as video amplifiers 7 and 8, a television camera timing controller 9, a video mix circuit 12, and a digital processor 14, which will be described later. generates a pulse signal that is the basis of the synchronization signal.

The digital processor 14 converts the video signals output from the two X-ray television cameras 5 and 6 into A/
Image processing such as subtraction processing and image enhancement processing is performed based on the digital signal obtained by D conversion. More specifically, 14a is a log compressor (log Amp), and 14b is a log compressor (log Amp).
14c is an A/D converter, and 14c is an algorithm that performs subtraction processing on two images. Reference numeral 14d designates the first digital memory for storing the mask image;
Denoted by e is a second digital memory that can sequentially store subtraction images obtained by performing subtraction processing between the mask image and subsequent images. Reference numeral 14f indicates a switch for selecting whether to display a mask image or a subtraction image, and reference numeral 14j indicates a D/A converter. 14g indicates post-processing that enhances the accumulated subtraction image. 14h is an image synthesizer that synthesizes the subtraction image after image enhancement, and 14i
1 is a D/A converter, which outputs an analog subtraction video signal. The digital processor 14 configured above operates, for example, as follows. Converting the video signal before the angiographic agent flows into the test site into a digital signal via the log compressor 14a and the A/D converter 14b and storing it in the first digital memory 14d,
Next, the video signal after the vascular contrast agent has flowed is converted into a digital signal via the A/D converter 14b, and in algorithm 14c, a mask image is obtained from the digital video signal after the vascular contrast agent has flowed. subtract the digital video signal,
Digital subtraction images (instantaneous subtraction images) are sequentially output. At the same time, it is also possible to integrate and store instantaneous subtraction images in the second digital memory 14e. Then,
Depending on the switching operation of the switch 14f, the digital video signal in the first digital memory 14d is converted into an analog video signal by the D/A converter 14j to display a mask image on the television monitor 15, or Display the subtraction image.
It is also possible to display a subtraction image on the television monitor 16 via the D/A converter 14i after the digital video signal in the second digital memory 14e is image-enhanced by the post-processing 14g. be.

Reference numeral 17 indicates a system controller that controls the entire system of the pulse X-ray diagnostic device, such as X-ray exposure timing, exposure control of the X-ray tube 1,
Control of the digital processor 14 (described later), control of the vascular contrast agent injection device 20 (described later), control of the optical apertures 4e and 4f installed in the optical system device 4, control of the light shielding elements 4g and 4h, and I/I blanking. A system command signal for controlling the circuit 11, etc. is output to each part.

Reference numeral 18 indicates an X-ray controller for controlling X-ray exposure, reference numeral 19 indicates an X-ray high voltage generator for generating high voltage to be applied to the X-ray tube 1, and reference numeral 20 indicates an is a vascular contrast agent injection device, which is equipped with at least a cylinder for injecting into a blood vessel of the subject 2 and a drive device for driving the syringe, and is configured to inject the blood vessel into the subject 2 according to a command signal from the total system controller 17. It is configured to be able to automatically inject an X-ray contrast agent.

Next, the operation of the pulse X-ray diagnostic apparatus having the above configuration will be explained with reference to FIG. 2.

In FIG. 2, a indicates a TV vertical synchronization signal (VD) of, for example, 60 frames/sec generated by the synchro generator 13, and b indicates a TV camera control output from the TV camera timing controller 9. The command signal, indicated by c, is an X-ray pulse emitted from the X-ray tube 1, and its pulse width is, for example, about 0.3 to 17 msec. d is the I/I blanking signal output from the I/I blanking circuit 11, and e
The symbol indicated by is a wide blanking signal input to the X-ray television camera 5, the symbol f is a cathode bias signal applied to the image pickup tube 5a of the X-ray television camera 5, and the symbol g is a wide blanking signal input to the X-ray television camera 5. The video signal output from the television camera 5 is indicated by h, and the wide blanking signal input to the X-ray television camera 6 is indicated by i.
j is the cathode bias signal applied to the image pickup tube 6a, j is the video signal output from the X-ray television camera 6, and k is the various system commands output from the total system controller 17. The signal indicated by l is a light shielding element close signal that operates the light shielding element 4g so that the output fluorescent images of I and I3 are not input to the X-ray television camera 5, and the signal indicated by m is the light shielding element closing signal for operating the light shielding element 4g so that the output fluorescent images of I and I3 are not input to the X-ray television camera 5. This is a light shielding element close signal that operates the light shielding element 4h so that the output fluorescent images of I and I3 are not input.N is a video signal used for recording, and O is an integration example of a mask image. , p is a video signal for displaying a subtraction image, and q is a video signal subjected to pseudo-interlacing to display a subtraction image on a television monitor. .

First, the patient is placed on a bed for X-ray photography, and the X-ray photography conditions, delay time, X-ray exposure interval, for example, 15 frames/sec, and the total number of seconds until the end of X-ray photography are set. After setting on the operation panel (not shown), when the start button on the operation panel is pressed by the setup of the total system controller 17, the angiography is performed inside the body of the patient 2 by the angiography contrast agent injection device 20, as shown in FIG. After time T ₀ has elapsed since the agent was injected, the first pulsed X-ray is emitted from the X-ray tube 1 .

As shown in Figure 2, the first X-ray pulse c
From the falling edge of 1 to the rising edge of the second X-ray pulse c, the I.I blanking signal d output from the I.I blanking circuit 11 causes the I.I.3
The fluorescent image is not affected by external influences, and there is no unnecessary interference outside the pulsed X-ray exposure period due to afterglow on the I/I3 input surface and Light emission is cut off. In addition, blanking of I and I3 is, for example,
During the period specified by the focus voltage of I and I3,
This can be achieved by applying a reverse bias in a direction that cancels out the focus voltage and cutting off the focusing of I and I3. Also, the first
During the period of one frame (1/60 sec) from the rise of the first X-ray pulse, the image pickup tube 5 of the X-ray television camera 5
Apply wide blanking e to a, and set the image pickup tube 5.
Fluorescent images output from I and I3 are sufficiently accumulated on the photoconductive surface of a. Note that during the one-frame period, the light shielding element close signal m is output, so that the output fluorescent images of I and I3 are not input to the image pickup tube 6a of the X-ray television camera 6. Then the first
After the first X-ray pulse is irradiated, the output of the wide blanking signal is stopped, and the optical image accumulated on the photoconductive surface of the imaging tube 5a of the X-ray television camera 5 is read out using an interlace scanning method. At that time, the bias potential of the second field (third frame) is
A cathode bias signal f is input to the image pickup tube 5a so that it is more negative than that of the field (second frame). By applying cathode bias to the image pickup tube 5a in this way, all optical images are read out in the first field and the second field and output as a video signal g, and the third field (4
It is possible to prevent afterimages from occurring after the frame. Therefore, the period for capturing the output fluorescent images of I and I3 on the photoconductive surface of the image pickup tube 5a, in other words, the exposure interval of X-ray pulses can be shortened.
The image pickup tube 5a can output a large number of images per second as a video signal.

A video signal output from the X-ray television camera 5 is input to a video mix circuit 12 via a video amplifier 7.

Next, a second pulsed X-ray is emitted at the fifth frame of the television vertical synchronization signal a when the first pulsed X-ray is emitted. When irradiating the second pulsed X-ray, the I/I3 input plane is blanked by the I/I blanking signal d,
The fact that wide blanking h is performed on the image pickup tube 6a of the X-ray television camera 6 and the input to the X-ray television camera 5 is blocked by the output of the light shielding element close signal l means that the first pulsed X-ray The same is true for exposure. Further, by applying a cathode bias signal i to the image pickup tube 6a, all optical images are read out in the first field and the second field, and a video signal j is obtained.
This is also the same as in the case of the first pulsed X-ray exposure.

Thereafter, as shown in Fig. 2, pulsed X-rays are irradiated once every four frames of the TV vertical synchronization signal a, and the X-ray image of the object transmitted through the pulsed X-rays is captured by two cameras. X-ray television camera 5, 6
The video signals g and j are alternately converted into video signals g and j, which are input to the video mix circuit 12.

The input video signals are mixed by a video mix circuit 12 and input to a digital processor 14.

The digital processor 14 A/D converts the first field video signal n of the first field and second field video signals output from the two X-ray television cameras 5 and 6, and converts it into a digital video signal. Let signal n be system command signal k
n video signals n (Ae...Ce) during the mask image capture period specified by are stored in the first digital memory 14d, and averaged to form a mask image. Next, the video signal n (Ee, Ge...) of the subtraction capture period specified by the system command signal k is A/D converted and then read out from the first digital memory 14d by algorithm 14c as a mask image. Subtraction processing is performed on the video signal and the video signals read out from Ee, Ge, etc., which are input sequentially, and the video signal P for the obtained subtraction image is outputted to the television monitor 15 after D/A conversion, and instantaneously subtracted. Display the traction image. In addition, the instantaneous subtraction image is
It is also possible to add the data to the digital memory 14e. Note that when displaying the subtraction image, a pseudo-interlace method is used to prevent flickering on the screen. The addition section for instantaneous subtraction images cannot be applied to moving subjects, but it has a function. In this case, the television monitor 16
will be displayed.

in one second using the pulse X-ray diagnostic device with the above configuration.
Since 15 images can be displayed on the television monitor 15, a predetermined part of the subject can be displayed as a smoothly moving image.

Although one embodiment of this invention has been described in detail above, this invention is not limited to the above embodiment, and it goes without saying that it can be implemented with appropriate modifications within the scope of the gist of this invention. Nor.

In the embodiment described above, 15 X-ray images were displayed on the television monitor per second, but in another embodiment, the system time chart shown in FIG. 2 was compressed to 1/2, X-ray pulse c is emitted once every two frames, and two television cameras 5 and 6
If each of them outputs a video signal alternately at a rate of once every four frames, 30 X-rays can be displayed on a TV monitor per second.

Further, in the embodiment described above, a field recording method is employed, but in other embodiments, a frame recording method may be employed. In that case, it goes without saying that a gamma value correction circuit must be added in order to make the γ value of the video signal of the first field and the video signal of the second field the same.

In the above embodiment, the TV vertical synchronization signal (VD) was 60 frames/sec (60Hz), but in other embodiments, the TV vertical synchronization signal may be larger than 60Hz, in which case three or more X A line television camera may also be used.

Further, in the embodiments described above, the mask images used for subtraction processing were all the same, but in another embodiment, the video signals sequentially input to the digital processor 14 are used as mask images, and the next The subtraction processing may be performed between the video signal and the input video signal.

〔Effect of the invention〕

According to this invention, the following effects can be achieved. That is, after blanking I and I to cut off unnecessary light emission outside of the X-ray exposure period, wide blanking the image pickup tube to accumulate a sufficient optical image, and then applying cathode bias to the After the third field, the optical images of the first and second fields are read out efficiently so that no afterimage remains, and moreover, multiple X-ray television cameras, for example, two X-ray television cameras, are operated alternately, and the video Since it outputs a signal,
It is capable of displaying 15 X-ray images per second on a television monitor, and has the possibility of displaying 30 images per second. Therefore, the pulse X according to the present invention
In the X-ray diagnostic apparatus, the movement of the image displayed on the television monitor becomes smooth, and X-ray diagnosis can be performed accurately.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram showing one embodiment of the present invention, and FIG. 2 is a system time chart showing the sequence in the embodiment. DESCRIPTION OF SYMBOLS 1... X-ray tube, 3... Image intensifier, 4... Optical device, 4g, 4h... Light blocking means (light blocking element), 5, 6... X-ray television camera, 12... Mixing circuit (video mix circuit), 14... Digital Processor, 17... System controller (total system controller).

Claims (1)

[Scope of Claims] 1. An X-ray tube, an image intensifier placed opposite to the X-ray tube, and a plurality of X-ray televisions into which fluorescent images output from the image intensifier are inputted via optical devices. The camera, a mixing circuit that mixes each video signal from multiple X-ray television cameras, and an A/
A digital processor that performs D conversion and subtraction processing, a display device that displays an X-ray image using a video signal output from the digital processor, and at least the X-ray tube, image intensifier, and X-ray television camera. In a pulse X-ray diagnostic apparatus equipped with a system controller that controls according to a certain sequence, the image intensifier fires a fluorescent image only during the X-ray exposure period by blanking outside the X-ray exposure period. a plurality of X-ray television cameras are controlled by a wide blanking signal and a cathode bias signal to accumulate fluorescence images from the image intensifier during the wide blanking period and to form the cathode bias A pulse X-ray diagnostic apparatus characterized in that the accumulated image is read out within a period. 2. The pulse X-ray diagnostic apparatus according to claim 1, wherein blanking of the image intensifier is performed by applying a reverse bias that cancels the focus voltage during the focus voltage designation period. 3. The optical device is equipped with a light shielding means at its input section, and by opening and closing the light shielding means according to a certain sequence, the output fluorescence of the image intensifier is transmitted to the light input sections of the plurality of X-ray television cameras in a certain order. A pulse X-ray diagnostic apparatus according to claim 1, which inputs an image.