JPS6044874B2 - 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 patients during X-ray examinations, and one way to do this is to use an intermittent solar radiation type X-ray television equipment. be.

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
(hereinafter abbreviated as 1.1), it is converted into an optical image and introduced into the image pickup tube, where it is converted into a video signal, and then recorded in a recording device, and pulsed X-rays are generated by the next X-ray solar radiation command signal. The device reads out the recording signal of the recording device and displays it on a monitor until it is exposed to sunlight, and reduces the radiation dose of the subject by intermittently exposing and emitting X-rays. This is how it was done. 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.I) that captures the X-rays that have passed through the object and converts them into an optical image, and 4 is the A lens system that guides an optical image, 5 an image pickup tube that converts the optical image guided by the lens system 4 into a video signal, 6 a television camera controller, and 7 a magnetic recording device that records the video signal of the image pickup tube 5. (magnetic sheet recorder, etc.), 8 is a TV monitor, 9
1 is an X-ray high voltage generator that generates a high voltage to be applied to the X-ray tube 1; 10 is an X-ray controller that controls X-ray exposure; and 11 is an X-ray controller that counts down the vertical synchronization signal output from the television camera controller 6. This is an intermittent X-ray television unit that generates sampling pulses synchronized with this. Figure 2 is the first
This is a time chart of the device configured as shown in the figure, and its operation will be explained using these.

For the sake of simplicity, the description will be made assuming a single-phase X-ray apparatus that uses single-phase alternating current. FIG. 2a shows a vertical synchronizing signal a generated by the television camera controller 6, and the intermittent X-ray television unit 11 counts down this signal at a certain interval (for example, 1 time/Sec15 times/Sec, etc.). A sampling pulse (Figure 2b) is generated. This pulse becomes the source of the recording command signal and the X-ray control signal. When this sampling pulse is applied to the X-ray controller 10 as an X-ray control signal,
This X-ray controller 10 synchronizes the sampling pulse (Fig. 2 b) with the AC power supply voltage (Fig. 2 c) to the first zero phase, and adjusts the power supply voltage for one cycle or half cycle. (Fig. 2 d) was taken out and the X-ray height. It is applied to the primary side of the pressure generator 9.

Then, this X-ray high voltage generator 9 generates a high voltage during one cycle (half cycle in the case of a half cycle) to which the AC power supply voltage is applied, and applies this to the X-ray tube 1. As a result, the X-ray tube 1 has a 2-inch diameter as shown in FIG. 2e. A pulse of X-rays (one impulse in the case of a half cycle) is emitted. On the other hand, as shown in FIG. 2f, the image pickup tube 5 of the television camera has a
When the sampling pulse (FIG. 2b) is output, blanking is applied for, for example, two fields.

As mentioned above, X-ray exposure is performed for one cycle or half a cycle in synchronization with the zero phase, and since the frequency of the vertical synchronization signal of a television is generally lower than the power supply frequency, the image pickup tube 5 X-ray exposure ends after the blanking period begins and before the blanking period ends. Therefore, when the X-rays emitted from the X-ray tube 1 and transmitted through the subject 2 enter the image pickup tube 5 via I, I3 and the lens system, the image pickup tube 5 is always in the blanking period. The image is stored as an image on the target of the image pickup tube 5. When the blanking period ends, the television camera controller 6 unblanks the image pickup tube 5 again and starts reading out the image accumulated on the target. is at a high level, but as reading progresses to the second field A2 and the third field, the level rapidly decreases. Therefore, the video of the first read field A1 with the highest level is recorded on the magnetic recording device 7, and this recorded video is played back and displayed on the TV monitor 8 until the next X-ray exposure video is obtained. do. However, in the conventional apparatus, since the television camera is of a power supply asynchronous type, there is no synchronous relationship between the vertical synchronization signal (FIG. 2a) and the power supply voltage (FIG. 2c).

However, after obtaining the sampling pulse (Fig. 2b), one cycle (
(or half cycle) X-ray exposure is performed, so as a result,
The exposure timing of the obtained X-rays (Fig. 2 e) falls within the blanking period (Fig. 2 f) for two fields of the television camera, that is, the image pickup tube 5, but within the blanking period. The timing of X-ray exposure will be shifted little by little. That is, the time τ from the start of X-ray exposure to the first reading of the video signal after blanking for two fields (Fig. 2e) is exaggerated in the figure for clarity.

, τ2, etc., have a cycle equal to the heat cycle of the vertical synchronizing signal a and the power supply voltage c, and gradually fluctuate little by little with a half cycle of the power supply voltage c as the fluctuation width. This time τ from the start of X-ray exposure until readout.

, τ2 . . . (readout start time) are related to the readout efficiency of the image pickup tube 5 because they lead to a potential drop of the charge image itself due to spontaneous discharge of the charge image accumulated on the target. However, the charge accumulation efficiency is also related to the time constant determined by the capacitance of the target surface, and since it is better to wait a certain amount of time before reading out, it is usually
Even in the case of field-level blanking, the readout efficiency increases when τ is large. This reading start time τ. ,τ
2 (here, τ2<τ1), for example, the output video signal of the image pickup tube 5 of a television camera (Fig. 2g), and the voltage level Vl, 2 (here, 2<V1). This appears as a difference in level. In this state, the magnetic recording device 7 of the intermittent X-ray television system records the video signal of the first field read, and plays and outputs it until the next recording. The input video signals A1'' and B1'' are directly influenced by the level difference V1'' and 2'' between the images recorded by the magnetic recording device 7, as shown in FIG. The problem was that it was difficult to observe. The above has explained the case of the field recording method in which one image is composed of one field without interlaced scanning, but in the case of the frame recording method in which one image is composed of two field images by interlaced scanning. This has the disadvantage that the above-mentioned pulsation tends to further emphasize the discrepancy between the video signal levels of the first field and the second field, and therefore, flicker tends to occur in addition to the above-mentioned flicker, making it even more difficult to see. .

The present invention has been made in view of the above circumstances, and it creates a signal that is proportional to the elapsed time from the start of X-ray exposure to the start of reading from the image pickup tube, and uses this signal when reading the first field of the image pickup tube. An object of the present invention is to provide an intermittent X-ray television device which stabilizes a monitor image by matching the video signal levels by correcting the level of the video signal taken out by negative feedback to the cathode. .

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing an embodiment of the field recording method, in which 1 is an X-ray tube, 2 is an object, and 3 is a block diagram showing an embodiment of the field recording method.
converts the X-ray image transmitted through this object 2 into an optical image 1
．． I, 4 is a lens system that guides the optical image of 1.13, 5 is an image pickup tube that captures the optical image guided by this lens system 4 and converts it into a video signal, and 21 is an output from the target of this image pickup tube 5. A television camera preamplifier circuit 22 amplifies the video signal to be transmitted.
a process amplifier circuit that further amplifies the video signal output from the video signal and generates and adds a vertical synchronization signal that becomes a synchronization signal when displaying the image on the television monitor 8;
7 is a magnetic recording device that records and plays back the video signal output from the process amplifier circuit 22; 8 is a television monitor that displays the reproduced video signal of the magnetic recording device 7 as an image; 11 is the process amplifier circuit 22; Intermittent type
This is a line television unit, and the magnetic recording device 7 performs recording and playback using this sampling pulse. 10
9 is an X-ray controller which is driven by an X-ray exposure command generated by the intermittent X-ray television unit 11 in synchronization with the sampling pulse of the intermittent X-ray television unit 11 to control X-ray exposure; A high voltage generator 23 generates a high voltage to be applied to the X-ray tube 1 under the control of the
Synchronizing with the X-ray exposure command of the X-ray television unit 11, this pulse signal is used to generate a pulse signal of a predetermined voltage value during the generation period of the blanking signal, and this is integrated to obtain a readout start time value corresponding to the readout start time τ. 24 is a gate that is opened by the gate signal output from the integrating circuit 23 and passes the integrated signal of the integrating circuit 23 for one field. A circuit 25 is a mixing circuit which mixes the blanking signal output from the intermittent X-ray television unit 11 and the output signal from the gate circuit 24 and supplies the mixture to the cathode K of the image pickup tube 5.

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

FIG. 4 is a time chart showing the operation, and the explanation will be made with reference to this. TV camera vertical synchronization signal (
In this circuit, a sampling pulse (Fig. 4 b) is generated in synchronization with the output from the process amplifier circuit 22), and synchronized with the first zero phase of the power supply voltage (Fig. 4 c) after the output of the sampling pulse. The principle of applying one cycle or half a cycle to the X-ray tube 1 to emit X-rays (FIG. 4e) is the same as that described above. Therefore, the exposure
There is no synchronous relationship between the line (FIG. 4e) and the blanking period of the image pickup tube 5 (FIG. 4f), and after the start of X-ray exposure, the image pickup tube 5 does not receive the video signal until after the blanking period ends. The time it takes to read out (readout start time) τ is shown in Figure 4 f as τ1 and τ2.
The same is true for the fact that it is not constant as shown in .

Therefore, in the apparatus of the present invention, the X-ray exposure command output from the intermittent X-ray television unit 11 is also sent to the integrating circuit 23. Figure 4g) is output and integrated (Figure 4h).

Therefore, the integral value output of the integrating circuit 23 (FIG. 4h) is the readout start time τ of the image pickup tube 5. , τ2. This integrated value output is sent to the mixing circuit 25 via the gate circuit 24 which is opened for one field at the end of the blanking period, and is mixed here with the blanking signal output from the intermittent X-ray television unit 11. A signal as shown in FIG. 1 is formed. This mixed signal is applied to the cathode K of the image pickup tube 5, and the intensity of the beam for reading out the video signal emitted from this cathode to the target of the image pickup tube 5 is controlled. That is, as shown in FIG. 4, in order to bring the image pickup tube 5 into a blanking state, the cathode potential can be increased to suppress the beam directed toward the target, and in order to read out the video signal from the target at a high level, it is sufficient to increase the cathode potential. Since it is sufficient to lower the cathode potential to increase the potential difference with the target and apply a strong beam, during the blanking period, the gate circuit 24, which is a signal extraction circuit, is closed and only the blanking signal is transmitted to the cathode K. After the blanking period ends, the gate circuit 24 is opened and the integral value output (Fig. 4 h) output from the integrating circuit 23 is sent to the mixing circuit 25, and this integral value output is set as a negative potential and used as a blanking signal. Mix with.

This blanking signal after the blanking period for 2 fields has ended. During each subsequent field period, the potential becomes zero, and the cathode potential is lowered to zero so that the video signal of the image pickup tube 5 can be read out. field, the integral value output is sent and the output of the mixing circuit 25 is further lowered in the negative direction by this integral value output.

Therefore, the cathode potential is lowered by that amount in the negative direction.

In the example of FIG. 4, the voltage -B2, -' is lowered by the remaining voltage after subtracting the values B1, b''1, which are proportional to the readout start times τ1 and τ2, respectively, from the constant via filter value 1a. Therefore, the level difference in the read video signal due to the time difference in the read start time τ is corrected by 1B2, -B2'' by the cathode potential, and the video signal of the first field Al, 2, etc. Level 4
They are equal as shown in Figure j.

Here, for example, in FIG. 4, the readout start time τ.

, τ2 is τ. 〉If τ2 is assumed, and the cathode bias value at τ1 is 1, the readout efficiency will be lower at τ2 than at τ1, so the cathode bias value must be set to 1'', which is deeper in the negative direction than 1. On the other hand, since the signals Bl, bl'' proportional to τ1, τ2, etc. are generated by the integrating circuit 23 in FIG. B2, -B2'' are output as correction biases (of course, the levels of -a and -Bi, -b1'' are set as appropriate) and applied to the cathode K, and then read out from the image pickup tube 5. The video signals (Fig. 4j) 1 and 2 are at the same level, and are recorded on the magnetic recording device 7 and played back and displayed on the monitor 8 until the next video is obtained after the end of the X-ray exposure. If this is done, the reproduced video signals will have the same level as shown in FIG. 4k, so that a high-quality image without flickering can be obtained.

The above is about the case of the field recording method, but next, the case of the frame recording method will be explained. In an intermittent X-ray television apparatus using a frame recording method, the video signal levels of the first field and the second field are generally not the same (the latter is usually extremely low).

Further, even if some means is taken to make the peak levels of both frames equal, the levels with other frames cannot be made equal.For two reasons, severe frizz occurs on the screen, making it impractical. Therefore, in this system, a circuit is constructed as shown in FIG.

In FIG. 5, the same parts as in FIG. 3 are denoted by the same reference numerals, and their explanation will be omitted. In the figure, 1 is an X-ray tube, 2 is an object, 3 is 1.I, 4 is a lens system, 5 is an imaging tube, 7 is a magnetic recording device using a magnetic sheet recorder, 8 is a television monitor, 9 is a high-voltage generator, 10 is an X-ray controller, 1 is an intermittent X-ray television unit, 21 is a television camera preamplifier circuit, 22 is a process amplifier circuit, and 23 is an integrating circuit.The magnetic recording device 7 is a disc-shaped magnetic sheet. 7
a, rotate this magnetic sheet 7a in one direction, and attach the recording head 7b to one end of the recording surface of the magnetic sheet 7a.
Also, a reproducing head 7c is provided at a position shifted from the recording head 7b by 1800 degrees in terms of rotation angle of the magnetic sheet 7a, and one half of the magnetic sheet 7a, that is, at a rotation angle of 0 to 180 degrees, is provided.
1st field 1F 1180th to 360th until 0
0, the video of the second field i is recorded. 3
1 compares the video signal recorded and played back from the magnetic sheet 7a played back by the playback head 7c of the magnetic recording device 7 and the video signal sent from the process amplifier circuit 22 to the recording head 7b, and outputs a difference signal. a dynamic amplifier; 32 is a gate circuit which receives the blanking signal for two fields outputted through the integrating circuit 23 as a gate signal when it disappears; and passes the integrated signal of the integrating circuit 23 for one field; 33 is a gate circuit for passing the integrated signal of the integrating circuit 23 for one field; A gate circuit 34 is opened during the second field after the end of the blanking period of 10 minutes and passes the output of the differential amplifier 31, and a gate circuit 34 mixes the blanking signal and the outputs of these gate circuits 32 and 33 and outputs the mixture. This is a mixing circuit that is applied to the cathode K of the image pickup tube 5.

FIG. 6 is a time chart showing the operation of the circuit shown in FIG. 5, and this example shows an example of X-ray exposure of one impulse. Since the principle is exactly the same as in steps a to h, the explanation will be omitted.

The feature here is that although it is a frame recording method, the method explained in Figures 3 and 4 is applied exactly as is for the first readout field after blanking for two fields. . Therefore, at the time of the first field read, the integral value output is proportional to the read start times τ1 and τ2 (Fig. 6h), as explained earlier.
are obtained, and in the same manner as described above, values -B2, -B2'' (-Bll, 1 piece'' in FIG. 6i) proportional to these τ1 and τ2 are obtained via the gate circuit 32, and this signal is It is mixed with the blanking signal in the mixing circuit 34 and applied to the cathode K of the image pickup tube 5. Therefore, in the first fields Al and Bl that are read out, the levels of the read video signals are all the same as explained in FIGS. 3 and 4. The first field after the blanking period of two fields is corrected in this way, is read out from the image pickup tube 5, and is sent to the recording head 7b of the magnetic recording device 7 via the preamplifier circuit 21 and the process amplifier circuit 22, where it is magnetically recorded. The video is recorded on half of the sheet 7a.

Next, when the second field is reached, the first recorded portion of this magnetic sheet 7a comes to the position of the playback head 7c, so the recorded signal of this first field is played back (Fig. 6 KAl'', b''1). The signal is sent to the television monitor 8 for reproduction and display, and is also sent to the differential amplifier 31. At this time,
The second field video signal begins to be read out from the image pickup tube 5, is sent to the recording head 7b, and is recorded on the remaining half of the recording sheet 7a. This second field video signal (FIG. 6 JA2, B.) is also applied to the differential amplifier 31, so this differential amplifier 31 is connected to the recorded and played video signal of the first field that is applied. A difference signal from the second read video signal is extracted. The output signal of this differential amplifier 31 is applied to a gate circuit 33, through which the output signal of the differential amplifier 31 is sent to a mixing circuit 34, which is opened only during the readout period of the second field. It will be done. Then, this difference signal is sent to the mixing circuit 34 as a blanking signal (the signal level at this time is a normal unblank level), the above-mentioned correction signal -Bll, -Paste'' corresponding to the integral value output of the integrating circuit 23, and a pulse. Cathode bias correction signal for each rate (1/Sec, 5
(each of which is corrected for each pulse rate such as 3 times/Sec) and is added to the cathode K of the image pickup tube 5. As a result, the cathode potential is corrected, and as shown in FIG. Adjustment and polarity selection are performed as follows to ensure proper correction.

That is, compared to the video signal of the first field read, 2
When the video signal of the second field is low, the cathode potential of the second field is further lowered to increase the readout efficiency of the image pickup tube 5 and the video signal level of the second field is raised, and the video signal of the first field is lowered. same as the signal level. In addition, 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 5, and Adjust to match the video signal level of the field. In this way, the adjustment of the cathode potential of the second read field is performed according to the change in the level of the reproduced video signal of the first field (during the 16.7 ms period of one field), which is reproduced from time to time. The video signal level is always aligned with the initial video signal level at all points on the screen as shown in FIG. 6k.

Therefore, the problem of the τ difference between the first field video signal and the second field video signal automatically disappears, so that the reproduced image on the TV monitor 8 is free from flickering in the intermittent X-ray television operation using the frame recording method. will no longer occur.

Further, even if the power supply phase and the vertical synchronization signal of the television camera are out of phase, the pulsation in the video signal level due to this is corrected, so the reproduced image on the television monitor is stabilized. Like this
Create a voltage signal proportional to the elapsed time from the start of radiation exposure to the start of reading out the video signal from the image pickup tube (readout start time τ), and use this signal as a correction signal at the time of the first field read out from the image pickup tube. Divine groan: 1=Shi? -= In the formula, the video signal of the first field obtained in this way is added to the correction signal and negative feedback is applied when reading the second field to equalize the level of the read video signal, so the monitor It is possible to provide an intermittent X-ray television apparatus that has excellent features such as being able to suppress pulsation in the reproduced image and also suppressing flickering in the case of the frame recording method, making it easy to observe.

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, an image storage tube or an IC memory may be used in place of the magnetic recording device. etc. may also be used.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing a conventional example, Fig. 2 is a time chart showing its operation, Fig. 3 is a block diagram showing an embodiment of the present invention using the field recording method, and Fig. 4 is a time chart showing its operation. FIG. 5 is a block diagram showing an embodiment of the present invention in a frame recording system, and FIG. 6 is a time chart showing its operation. 5... Image pickup tube, 7... Magnetic recording device, 8... Television monitor, 23... Integrating circuit, 24, 32, 33...
・Gate circuit, 25, 34...Mixed circuit, 31...
Differential amplifier.

Claims (1)

[Scope of Claims] 1. A blanking period is provided 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, it is read out and recorded, and this recording is performed. In an intermittent X-ray television device that reproduces and displays a captured image on a monitor, an integral signal is generated that is proportional to the elapsed time from the start of X-ray exposure to the start of reading out the video signal from the image pickup tube, and at the end of the blanking period. an integrating circuit that generates an extraction control signal for one field; and a signal that operates according to the extraction control signal, extracts the integrated signal, and feeds it back negatively to the cathode of the image pickup tube during the first field of reading the video signal of the image pickup tube. An intermittent X-ray television device characterized by comprising an extraction circuit. 2. A blanking period is set in the image pickup tube, and an X-ray image obtained by exposing the image pickup tube to pulsed X-rays during that period is accumulated in the image pickup tube, and after the blanking period has elapsed, it is read out and recorded, and the recorded image is displayed on a monitor. In an intermittent X-ray television device for reproducing and displaying, an integral signal proportional to the elapsed time from the start of X-ray exposure to the start of reading out the video signal of the image pickup tube is generated, and one field is extracted at the end of the blanking period. an integrating circuit that generates a control signal; a signal extraction circuit that operates according to the extraction control signal to extract the integrated signal and feed it negative feedback to the cathode of the image pickup tube during the first field of reading the video signal of the image pickup tube; a difference signal output circuit that sequentially outputs a difference signal between a video signal obtained during the first field of readout of the image pickup tube and a video signal obtained during the second field of readout; An intermittent X-ray television apparatus characterized by comprising a signal extraction and mixing circuit that provides negative feedback to the cathode of the image pickup tube during a second field.