JPH0441556B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an X-ray diagnostic apparatus, and particularly to an X-ray diagnostic apparatus using digital radiography.

[Technical background of the invention]

In recent years, in the field of X-ray diagnosis, particularly angiography, techniques called "digital fluorography," which applies time subtraction techniques and digital processing techniques, have come into use. This converts the X-ray television video signal into A/D (analog/digital), uses two digital memories, and integrates several frames of X-ray fluoroscopic images without contrast agent in the first memory. The first and second A subtraction image signal, which is an image of the difference obtained by performing a subtraction operation between the images stored in the memory, is created, and the subtraction image signal is converted to a D/A (digital/analog). This technique is used to create an analog video signal and display it on a CRT (cathode ray tube), or to create a film image using a multi-format camera that takes multiple frames on a single film. By using this method, it is possible to extract images, and by using this method, not only the conventional contrast agent injection method using an arterial catheter, but also
It is possible to use an intravenous injection method that does not use an arterial catheter, which enables safer, faster and more accurate cardiovascular system diagnosis.

By the way, conventional digital fluorography equipment sequentially A/D converts the video signal from the X-ray television camera to convert it into digital data.
A configuration as shown in FIG. 1 is used to collect image data.

That is, in the figure, 1 is an image intensifier (hereinafter referred to as I/I) that converts an X-ray image into an optical image.
2 is an X-ray television camera that captures an optical image displayed on the output surface of II1. This X-ray television camera 2 includes an image pickup tube 3 that captures an optical image and converts it into a video signal.
The electrical latent image of the optical image accumulated on the photoconductive surface of the composite is read out as a video signal by horizontally and vertically scanning the electron beam, and horizontal and vertical synchronization signals are added to this video signal for horizontal and vertical synchronization. It is equipped with a synchronization signal generation circuit 4 that generates horizontal and vertical synchronization signals for converting into a video signal (composite video signal) and outputting the same, and outputs the optical image of an X-ray image by converting it into a composite video signal.

This composite video signal is given to the synchronous separation circuit 6 of the digital fluorography device 5, where the video signal and the synchronous signal are separated, and the video signal is sent to the A/D converter 7. The data is converted into digital data at predetermined sampling intervals and sent as image data to an image processor (not shown) for image processing. Here, if the pixel configuration of the image memory on the image processor side is 512 x 512, the sampling interval is the time interval when one image screen on the X-ray television camera 2 is divided into 512 x 512 pixels.

Among the synchronization signals separated by the synchronization separation circuit 6, the vertical synchronization signal is sent to a phase matching circuit 8 that performs phase matching. A timing controller 9 that generates a timing control signal for controlling the timing of taking in the image memory is controlled for phase alignment.

That is, the timing controller 9 obtains a sampling signal and a timing control signal whose phases are aligned with the synchronization signal generated by the synchronization signal generation circuit 4 in the X-ray television camera 2, thereby generating image data at each pixel position on the screen. A/
The image data is obtained from the D converter 7 and is stored in a position corresponding to the pixel position of the image data on the image memory.

In other words, if the sampling signal of the A/D converter and the synchronization signal of the X-ray television camera 2 are not in phase, the captured image data will deviate from the pixel position of the image captured by the X-ray television camera 2. If this data is applied to the original pixel position and stored in the image memory, the image will be shifted by the amount of positional shift.

Therefore, in order to prevent this from happening, the phase is matched by the phase matching circuit 8, but the method for this phase matching is to divide the basic clock signal in the digital fluorography device 5 into several parts. Among them, the one that best matches the phase of the synchronization signal is selected and used as the basic clock, and the frequency of the basic clock is changed to match the phase of the synchronization signal. Thereby, the deviation can be suppressed to within one pixel.

On the other hand, the image you want to obtain may be at a specific synchronous position in the heartbeat cycle;
The test subject's electrocardiogram is detected using an ECG (electrocardiograph), a trigger signal synchronized with this electrocardiogram is obtained, and this activates the X-ray generator to generate an X-ray pulse. Although an X-ray image of the heart is obtained, the X-ray generator generates the X-rays in synchronization with the vertical synchronization signal outputted by the X-ray television camera 2. On the other hand, the heartbeat cycle is determined by the X-ray television camera 2. Since the X-ray pulse is asynchronous with the vertical synchronizing signal of the X-ray pulse, there is a shift of one vertical synchronizing signal generation cycle at most from when the trigger signal is applied until the X-ray pulse is generated.

That is, as shown in Fig. 2, the trigger signal from the ECG and the vertical synchronization signal of the X-ray television camera 2 are completely asynchronous, and one field is generated at the time when the first vertical synchronization signal is generated after receiving the trigger signal from the ECG. The X-ray television camera blanking is applied for 10 minutes to stop image reading for 1 field, and during this time, the X-ray generator generates 1 pulse of X-rays to obtain an X-ray image of the heart, and the trigger signal There is a time difference of τ ₁ from the time when the X-ray pulse is generated until the X-ray pulse is output. This τ ₁ reaches a maximum of one vertical synchronizing signal period (1V period in FIG. 2). After the X-ray television camera blanking is canceled, a video signal is obtained from the X-ray television camera 2, but
The image (captured image) based on this video signal ends up being an image of the state at the time τ ₁ hour has elapsed from the desired state of the heartbeat.

Moreover, when attempting to obtain a plurality of images synchronized with the heartbeat, τ ₁ and τ ₂ differ each time as shown in FIG. 2, and this does not result in images synchronized with the heartbeat.

[Purpose of the invention]

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an X-ray image diagnostic device that can capture X-ray transmission images that are accurately synchronized with biological signals such as electrocardiograms. .

[Summary of the invention]

That is, in order to achieve the above object, the present invention
an image converting means for converting a line image into an optical image; an imaging means for receiving the converted optical image and converting it into a video signal by scanning with an electron beam and outputting the image signal; and a detecting means for detecting a biological signal of the subject. , a means for receiving the detected biological signal and generating a trigger signal corresponding to a change in the biological signal, and a means for controlling the scanning timing of the electron beam of the imaging means in synchronization with the trigger signal. A trigger signal corresponding to the movement state of the living body is obtained from biological signals such as heartbeat, and the scanning timing of the electron beam of the imaging means is controlled in synchronization with this trigger signal, so that the readout timing of the optical image of the imaging means is adjusted to the timing of reading the optical image of the imaging means. By appropriately setting the timing difference during synchronization, it is possible to obtain a desired motion state.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained in Figures 3 to 6.
This will be explained with reference to the figures.

FIG. 3 is a block diagram showing an embodiment in which the present invention is applied to a digital fluorography device.

In the figure, 1 is II, 2' is an X-ray television camera, and 5' is a digital fluorography device. Said X
The line television camera 2' includes an image pickup tube 3' that captures an optically converted image of the X-ray image outputted by II1 and converts it into a video signal, and a synchronization signal generation circuit 4 that generates horizontal and vertical synchronization signals for this image pickup tube 3'. It has, and also,
The image pickup tube 3' has a photoconductive surface that accumulates an electric quantity, that is, an electric latent image, in accordance with the amount of light at the image formation position when receiving an optical image, and this photoconductive surface is aligned with an electron beam in accordance with the television scanning method. By performing a horizontal and vertical synchronized sweep, an electric signal corresponding to the amount of charge on the photoconductive surface at the sweep position can be extracted as a video signal.

The digital fluorography device 5' also includes an A/D converter 7, a timing controller 9', an electrocardiograph interface 13, an image processor 14, a D/A converter 15, and a system controller 16. Reference numeral 17 denotes an electrocardiograph, and this electrocardiograph 17 extracts an electrocardiogram, which is a signal corresponding to heartbeat, from the subject 22. The electrocardiograph interface 13 receives the electrocardiogram signal output from the electrocardiograph 17 and generates a trigger signal synchronized with, for example, the R wave.

The timing controller 9' also includes a synchronization signal generation circuit 10, a basic clock generation circuit 11,
It consists of a memory control circuit 12, among which a basic clock generation circuit 11 generates a predetermined clock signal, and a synchronization signal generation circuit 10 receives this clock signal and controls the image pickup tube 3'.
When it receives a trigger signal from the electrocardiograph interface 13, it is reset once and then generates horizontal and vertical synchronization signals again in synchronization with the clock signal. Further, this synchronizing signal generating circuit 10 is adapted to provide a reset output to a system controller 16. The memory control circuit 12 controls the storage address of the image data taken into the image processor 14, and when it receives the vertical synchronization signal output from the synchronization signal generation circuit 10, it outputs the clock output from the basic clock generation circuit 11. In synchronization with the signal, sequentially correspond to the sweep position of the electron beam of the image pickup tube 3', that is,
It generates an address corresponding to the pixel position of the video signal to be read out.

Further, the A/D converter 7 receives the video signal output from the image pickup tube 3', converts this video signal into digital data in synchronization with the clock signal output from the basic clock generation circuit 11, and converts the video signal into a digital signal for each pixel. image data.

The image processor 14 also includes an image memory that stores image data, and an arithmetic unit that performs image processing such as obtaining a subtraction image between images based on the image data stored in the image memory. The address is controlled by the output from the memory control circuit 12,
The image data output from the A/D converter 7 is stored in the image memory.

Further, the D/A converter 15 receives the processed image data output from the image processor 14 and converts it into an analog signal, and the system controller 16 controls the electrocardiograph interface. When receiving a trigger signal from 13, it generates an X-ray exposure signal after a predetermined time T has elapsed, and also controls the timing controller 9', image processor 14, and electrocardiograph interface 13 in general;
In addition to having the function of providing a predetermined television blanking signal to the line television camera 2', it is synchronized with the electrocardiogram.
In an ECG asynchronous X-ray pulse imaging mode other than the ECG synchronized mode, X
It generates a radiation exposure signal, and also controls to generate a continuous X-ray exposure signal so that X-ray exposure can be performed continuously in continuous X-ray acquisition mode and fluoroscopic mode.

Further, the digital fluorography device 5' includes a changeover switch 19 for selecting one of the outputs of the synchronizing signal generating circuit 10 or the synchronizing signal generating circuit 4 according to the mode and applying the selected output to the image pickup tube 3'. and a changeover switch 20 for selecting one of the outputs of the D/A converter 15 and the output of the image pickup tube 3'.
9 and 20 are switched and controlled under the control of the system controller 16 according to the mode.

18 is an X-ray controller; 21 is an X-ray tube; the X-ray controller 18 receives an X-ray exposure signal output from the system controller 16 and supplies tube voltage and tube current to the X-ray tube 21; This is to perform X-ray exposure. Further, 23 is a television monitor which receives the video signal given through the changeover switch 20 and displays it as an image.

FIG. 4 shows an example of the configuration of the synchronization signal generation circuit 10. In the figure, 10a is a delay circuit that delays and outputs the trigger signal output from the electrocardiograph interface 13, and can set a desired delay time. Also, 10
Reference numeral b designates a horizontal counter which receives and counts the clock signal output from the basic clock generating circuit 11 and outputs a synchronizing signal HD in the horizontal direction of the screen. 10c is this horizontal counter 1
This is a vertical counter that advances the count every time the count value of 0 reaches a predetermined number and outputs a synchronization signal VD in the vertical direction of the screen, and each of these counters 10b,
10c receives the output of the delay circuit 10a as a reset signal to clear the count value.

Next, the operation of this device having the above configuration will be explained. By specifying the mode from a console or keyboard (not shown), this device can perform continuous X-rays (1) ECG synchronized mode synchronized with the electrocardiogram (2) ECG asynchronous mode asynchronous with the electrocardiogram (3) The ECG asynchronous continuous acquisition mode (4) allows you to select one of the normal fluoroscopic modes. By making this selection, system controller 1
6 performs overall control so that the control corresponds to each mode.

If the ECG synchronization mode is selected now, the system controller 16 switches the changeover switch 19 to the output side of the synchronization signal generation circuit 10 and the changeover switch 20 to the output side of the D/A converter 15. As a result, the output of the synchronizing signal generating circuit 10 is applied to the image pickup tube 3', and the image pickup tube 3' is controlled to perform horizontal and vertical scanning of the electron beam in synchronization with this output.

Further, an electrocardiogram is detected from the subject 22 by an electrocardiograph 17, and this detected electrocardiogram signal is provided to an electrocardiograph interface 13. Further, the system controller 16 operates the timing controller 9' in response to an activation command given from an operation console (not shown).

When an electrocardiogram signal is applied, the electrocardiograph interface 13 generates a trigger signal in synchronization with, for example, an R wave. This can be obtained, for example, by a threshold method or by A/D converting and processing the electrocardiogram signal.

This trigger signal is given to the synchronization signal generation circuit 10.

Here, the synchronization signal generation circuit 10 has horizontal and vertical counters 10b and 10c, and the clock signal output from the basic clock generation circuit 11 is inputted to the horizontal counter 10b to be counted, and this count value is a predetermined value. By outputting a signal every time the signal reaches a predetermined value, this output signal is used as the horizontal synchronizing signal HD of the image pickup tube 3'. This output is used as a vertical synchronization signal. Then, the trigger signal is sent to the horizontal and vertical counters 10 via the delay circuit 10a of the synchronization signal generation circuit 10.
b, 10c, and therefore, after the trigger signal is generated, the delay circuit 10
Horizontal after delaying by the delay time set in a.
Vertical counters 10b and 10c are reset and their count values are cleared. Therefore, each time a trigger signal is generated, these counters 10b and 10c return to their initial states after a predetermined period of time, and the outputs of the horizontal and vertical counters 10b and 10c are transferred to X-rays via the changeover switch 19. This is given as a horizontal and vertical synchronizing signal to the image pickup tube 3' of the television camera 2', and the image pickup tube 3' sweeps the electron beam horizontally and vertically in synchronization with this signal. This allows for synchronized sweeps.

In addition, the trigger signal is the system controller 16
is also given, and the system controller can perform a sweep in synchronization with the trigger signal.

In addition, the trigger signal is the system controller 16
The system controller 16 generates an X-ray exposure signal after a predetermined time T has elapsed from this trigger signal, and supplies it to the X-ray controller 18 to control the X-ray tube 21.
Expose more X-ray pulses.

This X-ray pulse passes through the object 22 and II1
enters the input surface of the input plane, and an X-ray image is formed here. Then, II1 converts this X-ray image into an optical image and outputs it to the output surface. This optical image is guided to an image pickup tube 3' provided on the output surface side, and is focused on the photoconductive surface thereof to form an electric latent image.

In this device, the trigger signal and the synchronization signal generation circuit 10 are synchronized, so the first vertical synchronization signal after reset provided by the synchronization signal generation circuit 10 generates a TV camera blanking signal for one field, and The system controller 16 is configured to feed the tube 3'. As a result, when the image pickup tube 3' is reset by the generation of the trigger signal, television camera blanking is applied for one field from the time when the first vertical synchronization signal is generated, and the image pickup tube 3' outputs the electron beam only during this period. It stops and images are accumulated.

Therefore, the system controller 16 sets the predetermined time T so that the X-ray exposure signal is generated within this television camera blanking period. As a result, as shown in Fig. 5, when a trigger signal is generated, the vertical synchronization signal is reset after a predetermined time delay from the trigger signal, and in line with this, the vertical synchronization signal is reset at a predetermined timing within the television camera blanking period for one field. An X-ray pulse will be output. When the television camera blanking is completed, the electron beam of the image pickup tube 3' is swept in the next field, and a video signal is extracted as shown in Fig. 5e.
This signal is applied to the A/D converter 7 and is sequentially digitized into image data.

On the other hand, the vertical synchronizing signal output from the synchronizing signal generating circuit 10 is also given to the memory control circuit 12, and the memory control circuit 12 is reset at the time of inputting this signal. Then, in synchronization with the clock signal output from the basic clock generation circuit 11, the memory control circuit 12 sequentially generates storage addresses for image data and supplies them to the image processor 14. The image processor 14 then takes in the image data output from the A/D converter 7 to the address of the image memory corresponding to the given storage address.

In this way, when one screen worth of video signals outputted from the X-ray television camera 2' is captured, the image processor 14 finishes capturing the image data. Then, when the next trigger signal is generated, the above-mentioned operation is repeated, and when the image data capture is finished again, the image processor 14 processes the data of the two images (one is the mask image) at the same pixel position. Subtraction is performed for each pixel to obtain subtraction image data.

Thereafter, subtraction between the mask image data and the next acquired image data is performed in the same manner. The data of the obtained subtraction image is sequentially sent to the D/A converter 15 and converted into an analog signal, converted into a video signal, and then applied to the television monitor 23 to be displayed as an image.

In this way, synchronization generates horizontal and vertical synchronization signals for the X-ray television camera by generating trigger signals based on biological signals corresponding to the movement state of biological movements that do not have perfect periodicity, such as heartbeats. A reset signal is given to the signal generation circuit to cause it to reset, and after this reset, the synchronization signal is started to be generated again, so that the synchronization signal generation circuit is synchronized with the biological signal, and the first vertical By giving television blanking for one field from the synchronization signal and generating an X-ray pulse at a predetermined timing after the trigger signal is generated so as to enter this period, the X-ray pulse can be synchronized with biological movements such as heartbeat. X of the subject
It becomes possible to obtain line images.

This allows the delay circuit 10 to
Delay time of a and time T after trigger signal generation
By appropriately determining , it becomes possible to obtain an image in a desired phase state.

Furthermore, there are cases where it is desired to generate X-ray pulses at a shorter period than the above-mentioned mode to continuously observe changes in motion, and in such a case, the above-mentioned ECG asynchronous mode is selected.

In this case, the electrocardiograph interface 13 is stopped, and the system controller 16 gives a reset signal to the synchronization signal generation circuit 10 after a predetermined period of time for each output of the X-ray exposure signal.

That is, a vertical synchronization signal is given to the system controller from the synchronization signal generation circuit 10, and based on this, the system controller 16 sequentially generates an X-ray exposure signal at a predetermined timing.
X-ray pulses are generated by an X-ray tube as shown in FIG. Then, each time the system controller 16 generates an X-ray exposure signal, the synchronization signal generation circuit 10
so that a reset signal is given to the

In this way, the synchronizing signal generating circuit 10 is reset every time it receives a reset signal, so that the vertical synchronizing signal is generated at a timing as shown in FIG. 6c. Then, when the X-ray exposure signal is generated, the system controller 16 performs television camera blanking for one field in synchronization with the vertical synchronization signal.
It is controlled so that it is given as shown in Figure b. As a result, the television camera blanking period can be shortened, and the generation cycle of X-ray pulses can be shortened accordingly.

Next, when the continuous acquisition mode is selected, the system controller 13 connects the electrocardiograph interface 1
3 is stopped and the X-ray exposure signal is continuously output. As a result, the X-ray tube continuously transmits
A line occurs.

In this mode, the synchronizing signal generating circuit 10 is not reset, and therefore generates horizontal and vertical synchronizing signals at regular intervals. The image pickup tube 3' sweeps horizontally and vertically in a normal state and outputs a video signal. Therefore, in this case, normal imaging is performed and the image data is sequentially input to the image processor 14.
After sequential subtraction with the image data of the mask image, it is D/A converted and displayed on the television monitor 2.
3.

Furthermore, when the fluoroscopy mode is selected, the system controller 16 switches the changeover switches 19 and 20 to select the output of the synchronization signal generation circuit 4 of the X-ray television camera 2', and 20 selects the output of the synchronization signal generation circuit 4 of the X-ray television camera 2', contrary to the case of the three modes described above. Switching is performed to select the output of the image pickup tube 3'. Then, the system controller 16 generates a continuous X-ray exposure signal. As a result, X-ray tube 2
Continuous X-rays are emitted from 1, and the X-ray image is II.
1, the image is captured by an image pickup tube 3', and the image is provided to a television monitor 23 for display.

As a result of the above, according to this device, the synchronization signal generation timing can be controlled by resetting the synchronization signal generation circuit for generating the synchronization signal of the X-ray television camera, so it can be synchronized with biological signals such as electrocardiograms. It is now possible to generate a synchronization signal. Therefore, by blanking the X-ray television camera at predetermined timings according to the synchronization signal, and by emitting X-ray pulses during this period, it can be synchronized with biological signals. It is possible to perform X-ray exposure and imaging at the same time, which makes it possible to obtain X-ray images that match the phase of biological movement.
By making it possible to control the generation timing of the synchronization signal from the system controller, the generation timing of the vertical synchronization signal can be arbitrarily adjusted, and the television camera blanking period can also be arbitrarily adjusted.
If X-ray pulses are generated during this period, the generation cycle of the X-ray pulses can be changed arbitrarily, continuous X-ray images can be obtained in continuous X-ray exposure mode, and fluoroscopic images can be obtained in fluoroscopy mode. is also possible.

The purpose of the present invention is to make it possible to obtain an image that is in phase with the movement of a desired moving part such as the heart of a living body, and for this purpose, a digital fluorograph may be used. It is not limited to the following devices.

〔Effect of the invention〕

As described in detail above, the present invention includes an image converting means for converting an X-ray image into an optical image, an imaging means for receiving the converted optical image, converting it into a video signal by scanning with an electron beam, and outputting the image signal, a detection means for detecting a biological signal of the specimen; a means for receiving the detected biological signal and generating a trigger signal corresponding to a change in the biological signal; and a means for generating an electron beam of the imaging means in synchronization with the trigger signal. A trigger signal corresponding to the movement state of the living body is obtained from biological signals such as heartbeat, and the scanning timing of the electron beam of the imaging means is controlled in synchronization with this trigger signal. , the readout timing of the optical image of the imaging means can be made to correspond to the movement state of the living body, and by setting the timing difference when synchronizing appropriately, it is possible to obtain an image in a desired movement state. It is possible to provide an X-ray diagnostic apparatus that can collect an X-ray image of a desired region in a desired state of movement in a living body with low accuracy.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the main part configuration of a conventional device, Fig. 2 is a time chart for explaining its operation, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a block diagram showing the present invention. FIG. 5 is a block diagram showing an example of the configuration of a synchronizing signal generating circuit of the apparatus, FIG. 5 is a time chart for explaining the operation of the apparatus of the present invention, and FIG. 6 is a time chart for shortening the X-ray pulse interval. 1...Image intensifier, 2,2'...
X-ray television camera, 3, 3'...Image tube, 4, 10
...Synchronization signal generation circuit, 5,5'...Digital fluorography device, 7...A/D converter, 11...Basic clock generation circuit, 12...Memory control circuit, 13...Electrocardiograph interface, 14...Image processor Setsa, 15...D/A converter, 16...
System controller, 17...electrocardiograph, 18...X
Line controller, 19, 20...changeover switch, 21...X
Ray tube, 22...subject, 23...television monitor.

Claims (1)

[Scope of Claims] 1. Image converting means for converting an X-ray image into an optical image; Imaging means for receiving the converted optical image and converting it into a video signal by scanning with an electron beam and outputting the image signal; a detection means for detecting a biological signal; a means for receiving the detected biological signal and generating a trigger signal corresponding to a change in the biological signal; and an imaging means in synchronization with the trigger signal and with a set delay time. An X-ray diagnostic apparatus comprising: means for controlling scanning timing of an electron beam.