JPH0321040Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to an X-ray television apparatus, and more particularly to an automatic X-ray television image brightness control device thereof.

2. Description of the Related Art Conventionally, X-ray television apparatuses have been equipped with automatic image brightness control devices. This automatic X-ray television image brightness control device changes the X-ray tube voltage so that the brightness of the image remains constant when viewing through the X-ray television. In other words, a voltage proportional to the brightness of the image is input from the X-ray television, this voltage is compared with a reference voltage, and a control voltage is applied to the X-ray tube voltage control circuit so that this voltage becomes equal to the reference voltage. This feedback loop ensures that the brightness of the image remains constant even if the thickness of the subject changes.

Problems to be Solved by the Invention However, with the conventional X-ray television image brightness automatic control device, inconveniences occur when a disconnection or poor contact occurs in a field bag system such as a television cable. When these abnormalities occur, the conventional
The automatic X-ray television image brightness control device determines that the X-ray dose is insufficient and increases the X-ray tube voltage, regardless of the thickness of the subject, so that the highest tube voltage is applied.

When the maximum tube voltage is applied in this way, strong light enters the image pickup tube of the television camera when the subject is thin, which not only causes adverse effects such as image burn-in, but also increases the radiation dose to the patient. .

This design is an improved X-ray TV that can detect abnormalities in the fieldback system not only during X-ray tube exposure but also before X-ray tube exposure, and prevents the tube voltage from increasing in the event of an abnormality. The object of the present invention is to provide an automatic image brightness control device.

Means for Solving the Problems According to this invention, the invention includes a comparison means for comparing a signal corresponding to the brightness of an image of an X-ray television with a reference signal, and the output of the comparison means is used to control the tube voltage of an X-ray tube. In an automatic X-ray television image brightness control device having a feedback means for changing the brightness so that the signal corresponding to the above brightness coincides with the reference signal by changing the tube voltage by inputting the It is provided with a manual adjustment means for generating an adjusted output, an alarm means, an abnormality detection means for detecting whether the signal corresponding to the luminance is outside a predetermined range, and a switching means. and,
The switching means switches the input of the tube voltage control means from the output of the comparison means to the output of the manual adjustment means in accordance with the output of the abnormality detection means, and operates the alarm means.

Function: If an abnormality such as a disconnection or poor contact occurs in a fieldback system such as a television cable, the signal corresponding to the brightness of the X-ray television image will be out of the normal range. Therefore, the abnormality can be detected by the abnormality detection means determining whether or not this signal is outside a predetermined range. When an abnormality is detected, the switching means is switched, manual adjustment is made, and the alarm means is activated, so that the X-ray tube voltage may become high and cause problems with the television camera or increase the exposure dose. It is safe and avoids the danger of

Example In the figure, a voltage proportional to the image brightness (hereinafter referred to as IBS voltage) is generated from the X-ray television 1, and this IBS voltage is converted into a reference voltage E1 proportional to the optimum image brightness in the differential amplifier 4. They are compared, and the output is sent to the tube voltage control circuit 12 via the contact 7 and the changeover switch 10, which are turned to the a side. In this way, a fieldback loop regarding image brightness is formed, and the IBS voltage is changed to the reference voltage E.
If the IBS voltage is higher than 1, the tube voltage is lowered to lower the IBS voltage, and if the IBS voltage is lower than the reference voltage E1, the tube voltage is increased to increase the IBS voltage. Control is performed so that there is no difference in voltage E1. As a result, even if the X-ray absorption changes due to changes in the thickness of the subject, a television image with optimal brightness can always be observed. The above is normal operation when no abnormality occurs.

If an abnormality occurs such as a disconnection of the television cable, an incorrect connection of a connector terminal, or a poor contact, the comparator 2 detects this. That is, if there is no abnormality, the IBS voltage is in the range of, for example, 3 to 9 volts, but if a disconnection occurs, it drops to 0 volts, which is outside the normal range. Therefore,
This comparator 2 compares the IBS voltage with a reference voltage E2 for abnormality detection, and detects that the IBS voltage is abnormally low. Comparator 2
When detecting an abnormality, current flows through the relay coil 3, and the relay contacts 7, 8, and 9 are pushed from the a side to the b side. Therefore, the output of the inverting amplifier 6 is input to the tube voltage control circuit 12 instead of the output of the differential amplifier 4. This inverting amplifier 6 generates a control signal proportional to the voltage set by the manual setting device 5 such as a variable resistor, and this signal is sent to the tube voltage control circuit 12, so that manual brightness adjustment is possible. It will be in a state of being carried out. Therefore,
No matter what the IBS voltage is, the tube voltage is manually adjusted and the image brightness is determined, so there is no inconvenience that the tube voltage is set to the maximum.

At this time, the relay contacts 8 and 9 are simultaneously switched from the a side to the b side, so that the indicator lamp 14 is turned off and the indicator lamps 15 and 13 are turned on. The indicator light 13 is an alarm indicator light and displays, for example, "FAULT" to notify that an abnormality has occurred in the IBS voltage field back system. The indicator light 14 is an indicator light that indicates "AUTO" when the tube voltage is being controlled automatically, and when "AUTO" is turned off, the indicator light 15 indicates that the tube voltage is being manually controlled. This will light up as an indicator light labeled as ``MANUAL''.

The changeover switch 10 is a switch for switching between automatic control and manual adjustment of the tube voltage, and when automatic is selected, the contact is on the a side and the above operation is performed. If manual is selected from the beginning and the contact is set to the b side, the "MANUAL" indicator light 15 is lit and the "AUTO" indicator light 14 is off.

In the above embodiment, in order to prevent an abnormal rise in tube voltage, it was detected that the IBS voltage became lower than the constant voltage E2, but it was detected that the IBS voltage did not simply become abnormally low, but also that it became abnormally high. It may also be possible to detect this, turn on the "FAULT" indicator light 13 to warn of the abnormality, and switch to manual adjustment of the tube voltage. Also, to alert you to an abnormality,
In addition to the "FAULT" indicator light 13, a buzzer or the like may be used.

Effects of the invention According to this invention, IBS can be detected not only during fluoroscopy using X-ray television, but also before fluoroscopic X-ray tube exposure.
Even if the voltage is abnormal, it can be detected and image pickup tube burnout and unnecessary radiation exposure to the patient can be prevented. In addition, if the IBS voltage is abnormal, it can be immediately switched to manual adjustment, so the tube voltage can be adjusted manually thereafter without any problems. Since an abnormality is alerted, it is easy to deal with it.

[Brief explanation of drawings]

The figure is a circuit diagram of one embodiment of this invention. 1...X-ray television, 2...Comparator, 3...Relay coil, 4...Differential amplifier, 5
...Manual setting device, 6...Inverting amplifier, 10...Auto/manual changeover switch, 12...Tube voltage control circuit, 13...Alarm indicator light, 14, 15...Indicator light.

Claims (1)

[Scope of utility model registration request] It includes a comparing means for comparing a signal corresponding to the brightness of the image of the X-ray television with a reference signal, and the output of the comparing means is inputted to the tube voltage control means of the X-ray tube to change the tube voltage, thereby adjusting the brightness as described above. An X-ray television image brightness automatic control device comprising a fieldback means for changing the brightness so that a signal corresponding to the reference signal coincides with a reference signal, a manual adjustment means for generating a manually adjusted output, and an alarm. means, abnormality detection means for detecting whether the signal corresponding to the luminance is out of a predetermined range, and manual control of the input of the tube voltage control means from the output of the comparison means according to the output of the abnormality detection means. 1. An automatic X-ray television image brightness control device comprising switching means for switching to the output of the adjusting means and operating the alarm means.