JPS6044873B2 - Intermittent X-ray television equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intermittent X-ray television apparatus.

For example, in X-ray diagnostic equipment used in the medical field,
Efforts have been made for a long time to reduce the radiation dose to which patients are exposed during X-ray examinations, and one means of doing so is the use of intermittent solar radiation type X-ray television equipment.

This intermittent sunlight method provides a blanking period for the image pickup tube,
During this blanking period, pulse X is applied to the subject.
The rays are irradiated with sunlight, and the transmitted X-ray image is captured using, for example, an X-ray fluorescence multiplier
I, I) converts it into an optical image and introduces it into the image pickup tube, where it is converted into a video signal and then sent to a recording device (video recorder, etc.)
The recording device reads the recorded signal of the recording device and displays it on the monitor until a new video signal is obtained by irradiating pulsed X-rays according to the next X-ray radiation command signal. The radiation dose to the subject is reduced by intermittent sunlight exposure.

FIG. 1 shows an example of an intermittent X-ray television apparatus.

In the figure, 1 is an X-ray tube, 2 is an object, 3 is an image intensifier (hereinafter abbreviated as 1, 1) that captures the X-rays that have passed through the object 2 and converts them into an optical image, and 4 is an image intensifier (hereinafter abbreviated as 1, 1). A lens system that guides an optical image; 5 is an image pickup tube (visicon) that converts the optical image guided by the lens system 4 into a video signal; 6 is a television camera controller; 7 is a video signal from the image pickup tube 5; A magnetic recording device (magnetic sheet recorder); 8 is a television monitor; 9 is an X-ray high-voltage generator that generates high voltage to be applied to the X-ray tube 1; 10 is an X-ray controller that controls X-ray radiation; 11 is a television Vertical synchronization signal VD output from camera controller 6
This is an intermittent X-ray television unit that counts down and creates sampling pulses synchronized with this countdown. Second
The figure is a time chart of the apparatus having the configuration shown in FIG. 1, and the operation will be explained using these. Single-phase X-ray device 7 for simplicity
I will explain as follows. In FIG. 2, a is a vertical synchronization signal VD generated by the television camera controller 6, and the intermittent television unit 11 counts down this vertical synchronization signal D and synchronizes with this at a certain fixed interval (for example, 1
0 times/second, 5 times/second, etc.) to create a sampling pulse (Figure 2b). This pulse becomes the source of the recording command signal and the X-ray control signal. When this sampling pulse is applied as an X-ray control signal to the X-ray controller 10, the X-ray controller 10 receives the sampling pulse (FIG. 2b) from the AC power supply voltage (FIG. 2c). , one cycle of AC power supply voltage (FIG. 2 d) is taken out and applied to the primary side of the X-ray high voltage generator 9 in synchronization with the first zero phase. Then this X
The line high voltage generator 9 generates a high voltage during one cycle when the AC power supply voltage is applied, and this is applied to the X-ray tube 1.
The X-ray tube 1 emits X-rays as shown in FIG. 2e. on the other hand,
As shown in FIG. 2f, when the sampling pulse (FIG. 2b) is output to the image pickup tube 5 of the television camera, blanking is applied for two fields. As mentioned above, X-ray exposure is performed for two cycles in synchronization with the zero phase, and since the vertical synchronization frequency of the television is lower than the power supply frequency, the blanking is performed after the image pickup tube 5 enters the blanking period. X-ray exposure is performed until the ranking period ends. Therefore, the X-rays emitted from the X-ray tube 1 and transmitted through the subject 2 are transmitted to the imaging tube 5 via I, I3 and the lens system 4.
When the light is incident on the image pickup tube 5, the image pickup tube 5 is always in a blanking period, and the image is accumulated on the target of the image pickup tube 5 as an image. When the blanking period ends, the television camera controller 6 unblanks the image pickup tube 5 again and begins reading out the image stored on the target. 5
As shown in Figure 2g, the first field for reading, that is, the first field that is unblanked, is set to -BlV, and the next field is read by applying a cathode potential of -B2V, which is even lower than -BlV. The first field and the next field. The level of the video signal from the image pickup tube 5 in the field is made almost equal. The next two fields are at a cathode potential of zero volts. Therefore, the output video signal from the image pickup tube 5 is read out as shown in FIG. and the video signal level decreases. Ordinary television uses an interlaced scanning system, so the video signals of Al and A2 with the same level are recorded on the magnetic recording device 7, and this is recorded until the recording of the next frame is finished and playback begins. It is played back and displayed on the television monitor 8. That is, after frame recording is performed, images are continuously displayed on the television monitor 8 by continuing to reproduce the frame until the next recording is completed. Since the levels of the video signals Al and A2 of the first field and the second field are equal, the reproduced image displayed on the monitor 8 is a stable image without flickering or the like. Here, in the first field of readout, set the cathode potential of the image pickup tube to 1 Kg.
The reason why the next field is set to -B2 is because the cathode potential is set to a positive potential for two fields and an X-ray charge image is accumulated on the target, and the video signal level tends to be high in the first field read out. This is because in the next field, the signal from the previous field is read out, and the level of the target charge image tends to be low.In order to equalize the video signal level in both fields, the cathode potential at the time of the first readout must be made slightly shallower. This is to make the next part a little deeper for balance.

The method of adjusting the cathode potential in this way to equalize the video signal level of the first field and the next field for reading out the image stored in the image pickup tube 5 is called the cathode bias method, which is different from the conventional intermittent X-ray method. By using this cathode bias method in television equipment, frame recording became possible. However, in reality, when the frame recording method is implemented in this way, the γ (gamma) of the video signal differs between the first field and the next field, which causes flickering in the image on the television monitor 8. Therefore, it was difficult to suppress fritsuka.

The present invention has been made in view of the above circumstances, and when recording the video signal read out from the image pickup tube on a recording device using the cathode bias method, when recording the second read field, the first read field is recorded. The recorded signal of each field is read out one by one, compared with the video signal of the second field, and the difference signal is fed back to the cathode of the image pickup tube, and the cathode potential is corrected to be equal to the signal level of the first field. Accordingly, an object of the present invention is to provide an intermittent X-ray television apparatus that can provide a flicker-free monitor image.

An embodiment of the present invention will be described below with reference to FIG.

Figure 3 is a block diagram showing the configuration of this device.
1 is an image pickup tube; 22 is a television camera preamplifier circuit that amplifies the video signal output from the target of the image pickup tube 21; 23 is a television camera process amplifier circuit that further amplifies the video signal amplified by this circuit 22; 24; is a magnetic recording device using a magnetic sheet recorder that records the video signal output from the television camera process amplifier circuit 23. This magnetic recording device 24 uses a disc-shaped magnetic sheet 24a, rotates this magnetic sheet 24a in one direction, and attaches a recording head 24b to one end of the recording surface of the magnetic sheet 24a, and from this recording head 24b the magnetic sheet 24a is rotated in one direction. A reproducing head 24c is provided at a position shifted by 1800 degrees in terms of the rotation angle of the magnetic sheet 24a, and the first field,
The video of the second film is recorded between 1800 and 3600. 25 is the playback head 2 of this magnetic recording device 24.
a differential amplifier that compares the recorded and reproduced signal of the magnetic sheet 24a reproduced at 4c and the video signal output from the television camera process amplifier circuit 23 and outputs a difference signal;
26 is a gate circuit which extracts the output of the differential amplifier 25 at the timing of the second field of image pickup tube readout and supplies it to the cathode of the image pickup tube 21; 27 is a recording playback circuit reproduced and output from the playback head 24c of the magnetic recording device 24; A television monitor that receives signals and displays reproduced images.

Next, the operation of this device will be explained.

The principle of generating sampling pulses and pulsed X-rays in synchronization with the vertical periodic signal of the television camera is the same as that of the apparatus shown in FIG. 1, and its operation is also the same as that of FIG. 2. Also,
Blanking of the television camera is performed as shown in FIG. 2(f), and after cut-off for the cathode potential of the image pickup tube, -E in FIG. 2(g) is adjusted and fixed at an appropriate value in the first field of readout. Regarding the adjustment of b1, the total level of the output video signal (Fig. 2 h (:1) Al, A2, A3, A4
A signal of 112 or 1n or less of the sum of For the second field of readout, the cathode bias of the image pickup tube 21 is adjusted by the method according to the invention. In FIG. 3, as described above, with the cathode bias adjusted for the first field read out after cutoff, the output of the image pickup tube 21 is amplified through the preamplifier circuit 22 and the process amplifier circuit 23, and then taken out as a video signal. , is recorded on one half of the rotating magnetic sheet 24a through the recording head 24b.

The rotation of the magnetic sheet 24a is synchronized with each field of the television camera, and one rotation corresponds to the time of two fields.
As the rotation of a continues, the other half of the recording head 24b
At the beginning of the process, the image pickup tube 21 is in the process of reading out the second field, and the video signal of the second field sent from the image pickup tube 21 is recorded on the magnetic sheet 24b. When this second field is recorded, the playback head 24c is shifted from the recording head 24b by 1800 degrees based on the rotation angle of the magnetic sheet 24a.
Since the recording portion of the first field of the magnetic sheet 24a has arrived, the reproduction signal of the first field is outputted from the reproduction head 24c and sent to the differential amplifier 25 and the television monitor 2.
Sent to 7. Then, the recorded and reproduced image of the first field is displayed on the television monitor 27 in interlaced scanning.
On the other hand, the video signal of the second field applied to the recording head 24b is also applied to the differential amplifier 25, and the differential amplifier 25 outputs a difference signal between the two and applies it to the gate circuit 26.

Since this gate circuit 26 is synchronized with the second field of video signal readout, the difference signal between the reproduction signal of the first field and the video signal of the second field passes through this gate circuit 26. is applied to the cathode of the image pickup tube 21, and the cathode potential is corrected by this difference signal. Therefore, the video signal level read out from the image pickup tube 21 is corrected and read out to be the video signal level of the first field, so that the first field and the second field recorded on the magnetic recording device 24 are The recording levels of the second field become equal, and when the image of the second field is reproduced and interlaced scanned on the monitor 27 and the image is reproduced and displayed, the levels of the displayed images are equal, so a stable image without flicker can be observed. can. 2 recorded on the magnetic sheet 24a
Thereafter, the images of one field are played back and displayed until the recording of the next frame of images is completed.

The same operation as described above is performed when recording the next field. It goes without saying that the input of the video signal to the recording head 24b is stopped until the recording of two fields is completed and the next recording is started. Here, the adjustment of the amount of feedback to the cathode potential of the image pickup tube 21 and the selection of its polarity will be explained.

That is, when the video signal level of the next field (hereinafter referred to as the second field) is lower than that of the first field (hereinafter referred to as the first field) to be read, the cathode potential of the second field is further increased. The reading efficiency of the image pickup tube 21 is increased to raise the video signal level of the second field so that it becomes the same as the video signal level of the first field. Moreover, when the video signal level of the second field is higher than that of the first field, the cathode potential of the second field is increased, lowering the readout efficiency of the image pickup tube 21, and reducing the - of the first field.
Try to match it to the video level.

As described above, according to the present invention, the video signal of the first field read out from the image pickup tube is recorded and played back by the cathode bias fixed in the recording device that records and plays back the video signal of the first field read out from the image pickup tube. Record as is, and when recording the second field, play back the recording of the first field recorded earlier and compare this playback signal with the video signal of the second field sent to the recording device. Differential amplifier so that the level is the same as the reproduced signal! During the readout of the second field, the difference signal was generated and the cathode bias of the image pickup tube was corrected using this difference signal to equalize the video signal level of the first field and the second field. You can get a high quality monitor image.

It should be noted that the present invention is not limited to the embodiments described above and shown in the drawings, and can be implemented with appropriate modifications within the scope of the gist thereof. For example, in the text, a single-phase X-ray apparatus is used, Although we have shown an example of two-impulse X-ray exposure, this can be one-impulse or pulsed X-ray using another X-ray device.Also, we have shown an example of a magnetic recording device as a recording device, It can also be implemented using other recording and reproducing media such as tubes and IC memories.

In this way, according to the present invention, the cathode potential of the image pickup tube is adjusted moment by moment in accordance with changes in the recording and playback signal level of the first field to be read out, so that the video signal of the second field is equal to the signal of the first field. Since the levels are equal to each other, there is no problem with the gamma difference between the video signals of the first and second fields, and the reproduced image on the monitor does not flicker, making it extremely easy to observe. An intermittent X-ray television device can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a conventional device, FIG. 2 is a time chart thereof, and FIG. 3 is a block diagram showing an embodiment of the present invention. 21... Image pickup tube, 24... Magnetic recording device, 25...
-Differential amplifier, 26...gate circuit.

Claims (1)

[Claims] 1 A blanking period is set in the image pickup tube, and an X-ray image obtained by irradiating pulsed X-rays during that period is accumulated in the image pickup tube, and after the blanking period has elapsed, two fields are read out and recorded, and this recorded image is In the device that is reproduced and displayed on a monitor, a recording device that can record the X-ray image accumulated in the image pickup tube and simultaneously reproduce the recorded image of one field before, and a reproduction signal and a recording signal of this recording device are input. It is equipped with a comparison circuit that outputs a difference signal between both signals, and a selection output circuit that outputs the difference signal in synchronization with the field signal, and the output signal of this selection output circuit is negatively fed back to the cathode of the image pickup tube to create a cathode bias. An intermittent X-ray television device characterized by correcting.