JPH0125439Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to control of a compensation filter for preventing halation provided on an input surface of an X-ray imaging apparatus, particularly an image intensifier.

Conventional X-ray imaging devices emit X-rays from an X-ray tube of an
The information obtained when the X-rays pass through the subject is amplified and output using an image intensifier (hereinafter simply referred to as .), which is installed in the center of the output lighting field. X of Hotomaru etc.
The intensity of the output is detected by a photodetector for controlling the radiation conditions (this example shows an example of controlling the X-ray tube voltage),
X-ray exposure was controlled by controlling the X-ray tube voltage according to the intensity. of the X-ray imaging device.
．． Since there is only one photodetector for controlling the X-ray conditions installed in the output light field, it is possible that the so-called X-ray dose may be excessive, such as X-rays that have passed through the lung field or direct X-rays that have passed through the air. The resulting halation is
In some cases, the light was incident on the photodetector. For this reason, the X-ray tube voltage has to be reduced, and the density of the desired area of the image projected on the X-ray photographic film is reduced, making it impossible to obtain an optimal X-ray photographic film. Recently, attempts have been made to control the X-ray dose by inserting a compensation filter, etc. into the lung field or the area where the X-rays are directly incident, in order to prevent such halation caused by an excessive X-ray dose. It is being however,
At present, compensation filters have the disadvantage that they must be operated manually.

The purpose of the present invention is to eliminate the above-mentioned drawbacks, detect the position of halation caused by lung field transmitted X-rays, direct X-rays, etc., and automatically insert a compensation filter at the position where the halation occurs, thereby improving the X-ray image. The purpose is to reduce density variations.

The features of this invention are: ．． A plurality of compensation filter control photodetectors are provided in the output lighting field, and means for comparing the output of each of the plurality of photodetectors with the output of the X-ray condition control photodetector; The present invention further includes means for controlling the compensation filter according to the output.

Hereinafter, the present invention will be described in detail along with one embodiment.

Figure 1 shows the structure of the present invention. ．． FIG. 2 is a diagram showing a schematic configuration of an embodiment of a control mechanism for a compensation filter provided on the input side of the controller. In the figure, 1 is the input of X-rays that have passed through the object and air. ．． This is the input screen. 2A to 2D are as described above. This is a compensation filter provided in the front stage of the input surface 1, and is connected to worms 4A to 4D by connecting rods 3A to 3D. 5A to 5D are the worms 4
It is a worm gear that meshes with A to 4D,
The worm gears 5A to 5D are servo motors MA to
Driven by MD. 6A to 6D are control lines for the servo motors MA to MD.

FIG. 2 is a block diagram of one embodiment of the control circuit for the compensation filter of the present invention.

In Figure 2, 21 is . ．． This is the output lighting field 21, and there is an X
A photodetector 22 for controlling X-ray conditions is provided, and a plurality of detectors 23A to 23D for controlling compensation filters are provided around the photodetector 22 for controlling X-ray conditions. 24, 25A to 25D are preamplifiers, 26 and 27A to 27D are sample and hold circuits, 28 is a compensation filter control level setter for setting a reference level for controlling the compensation filter, and 29A to 29D are the compensation filter control level setters. Comparison circuits 30A to 28 for comparing the level set in 28 and the output levels of the sample and hold circuits 27A to 27D;
30D is a motor drive circuit, and MA to MD are servo motors. 31 is an X-ray gate circuit, 32 is an X-ray tube voltage setting circuit for X-ray fluoroscopy, and 33 is an X-ray tube voltage setting circuit for X-ray photography.

FIG. 3 is a specific circuit configuration diagram of one embodiment of the compensation filter control level setter 28 shown in FIG. Potentiometer, R is resistance, E is ground.

FIG. 4 shows comparison circuits 29A to 29A shown in FIG.
29D is a specific circuit configuration diagram of an example,
291 is a comparator, R is a resistor, and E is a ground.

Next, the operation of this embodiment will be explained with reference to FIGS. 1 and 2.

When the power to the X-ray imaging device (not shown) is turned on and X-rays are emitted from the X-ray generator (not shown), the emitted X-rays pass through the subject. ．． The signal is input to the input surface 1 of the . ．． The output is output to the lighting field 21. This output optical signal is transmitted through the X
It is detected by the line condition control photodetector 22. This detection signal is amplified by a preamplifier 24 and input to a sample hold circuit 26. There is no problem if this input signal is a continuous signal, but if the X-ray is a pulse, the sample and hold circuit 26 converts it into a continuous signal at the level when the X-ray is output. The output signal of the sample hold circuit 26 controls the X-ray tube voltage setting circuit 32 during fluoroscopy or the X-ray tube voltage setting circuit 33 during imaging to control the irradiation X-ray dose and perform exposure.

On the other hand, halation caused by X-rays that penetrate the lung field or direct X-rays is... ．． are independently detected by a plurality of compensation filter control photodetectors 23A to 23D provided in the output lighting field 21,
The detected signals are amplified by preamplifiers 25A to 25D, and output as continuous signals by sample and hold circuits 27A to 27D. Each signal output from the sample and hold circuits 27A to 27D is
The compensation filter control level setter 28 sets the level according to the output of the sample and hold circuit 26, and the set level signal and each signal output from the sample and hold circuits 27A to 27D are compared by comparison circuits 29A to 29D. After comparison, if a signal higher than the level signal set by the compensation filter control level setter 28 is input, a control signal is output from the comparison circuits 29A to 29D. This control signal output is input to motor drive circuits 30A to 30D, and servo motors MA to MD are controlled according to the control signal. The servo motors MA to MD are connected to the worm gears 5A to 5D shown in Fig. 1, and when the servo motors MA to MD rotate, the worm gears 5A
The worm is driven through the compensation filter 2A.
~2D are opened and closed in response to the control signal.

It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without changing the gist thereof.

As explained above, according to the present invention.
．． A compensation filter is installed in front of the input screen to reduce density variations in the X-ray film.
．． ．． An X-ray imaging apparatus is provided with a photodetector for controlling X-ray conditions in the light field of the output of the above-mentioned.
．． A plurality of compensation filter control photodetectors are provided in the light field of the output of the plurality of compensation filter control photodetectors, and the output of each of the plurality of compensation filter control photodetectors is compared with the output of the X-ray condition control photodetector. By providing a comparison means and a control means for controlling the setting position of the compensation filter according to the output of the comparison means, halation caused by X-rays transmitted through the lung field region or direct X-rays can be prevented. Since a compensating filter is inserted into the detected position and appropriate X-ray exposure conditions are automatically set, variations in the density of the X-ray photographic film can be reduced. This makes it possible to obtain high-quality X-ray images and improve operability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an embodiment of the control mechanism of the compensation filter of the present invention, FIG. 2 is a diagram showing the block configuration of an embodiment of the control circuit of the compensation filter of the present invention, and FIG. is a specific circuit configuration diagram of one embodiment of the compensation filter control level setter shown in FIG. 2, and FIG. 4 is a specific circuit configuration diagram of one embodiment of the comparison circuit shown in FIG. 2. . 1.... ．． input surface, 2A to 2D...compensation filter, 3A to 3D...connecting rod, 4A to 4D...
...Worm, 5A-5D...Gear, 6A-6D...
...Control line, 21.... ．． Output lighting field, 22
...Photodetector for controlling X-ray conditions, 23A to 23D...
...Compensation filter control photodetector, 24, 25A~
25D...Preamplifier, 26,27A~27D...
...Sample hold circuit, 28...Compensation filter control level setter, 29A to 29D...
Comparison circuit, 30A to 30D...Motor drive circuit, 31...X-ray gate circuit, 32...X-ray tube voltage setting circuit during fluoroscopy, 33...X-ray tube voltage setting circuit during imaging, MA~ MD... Servo motor.

Claims (1)

[Scope of utility model registration request] A compensation filter is installed in front of the input surface of the image intensifier to reduce variations in the density of the X-ray photographic film, and a photodetector for controlling the X-ray conditions is installed in the light field of the output of the image intensifier. The imaging device is provided with a plurality of compensation filter control photodetectors in a lighting field of the output of the image intensifier, and the output of each of the plurality of compensation filter control photodetectors and the X-ray conditions are determined. X equipped with a halation prevention mechanism, characterized in that a comparison means is provided for comparing the output of the control photodetector, and a control means is provided for controlling the setting position of the compensation filter according to the output of the comparison means. Ray imaging device.