JP2513236B2 - X-ray detector - Google Patents

Description

The present invention relates to an X-ray detector used in an X-ray automatic exposure control device.

The X-ray automatic exposure control device is a device that automatically and properly sets the film density during X-ray photography.

(B) Prior Art FIG. 3 is a block diagram of the configuration of an X-ray automatic exposure control device. In the figure, 1 is an X-ray tube, 2 is its diaphragm, 3 is a subject, 4 is a bed top plate, 5 is a grid, 6 is a quick-shooting section, 7
Is an intensifying screen, 8 is a film, 9 is an intensifying screen, 10 is a crimping machine, 11
Is a lead plate, 12 is an image intensity (II), 13
Is a prism, 14 is a TV camera, 15 is a TV monitor, 16 is a detector or photomultiplier, 17 is a phototimer controller, and 18 is an X-ray high-voltage device.

According to this illustrated example, the image intensity shifter 12
A part of the output of the
Photo-current conversion is carried out at, the photocurrent of the photomultiplier 16 is integrated at the phototimer controller 17, and when the integrated value reaches a certain reference value, an X-ray cutoff signal is sent to the X-ray high voltage device 18. Then, the X-ray exposure is controlled to be appropriate.

(C) Problems to be Solved by the Invention In such automatic exposure control, the following two problems are major problems.

The light that the aX-ray film 8 sensitizes is the phosphor used in the intensifying screen, while the light that the Photomar 16 shines is the output light of II12, so that the X-ray tube voltage is high and low. By the difference, that is, by the quality of the X-ray,
The intensity of the light emission of II12 is different, and even if the amount of light from II12 is constant, the film density greatly varies depending on the X-ray tube voltage. That is, the film concentration depends on the tube voltage.

b. The intensity of X-rays incident on the phosphor 7 of the intensifying screen and the intensity of X-rays incident on II12 are between the intensifying screen crimping device 10, the lead plate 11 for removing backscattered rays, and the quick-shooting section 6. The case of
Different from these absorptions.

The ratio of the two incident X-ray intensities differs depending on the thickness of the subject and the tube voltage. The thinner the subject and the lower the tube voltage, the larger the ratio, and the smaller the X-ray intensity incident on II. this is,
This is because the subject is thin and the soft X-ray dose increases relative to the lower tube voltage and is absorbed by the crimping machine or the like.

Similar to the first point, even if the amount of light from II is constant, the film density will differ depending on the subject thickness. There is so-called subject dependency.

In view of the above circumstances, it is an object of the present invention to provide an X-ray detector for an X-ray automatic exposure control device that does not depend on the tube voltage and the subject thickness of the X-ray film concentration.

(D) Means for Solving the Problem In order to achieve the above-mentioned object, the X-ray detector for an X-ray automatic exposure control device of the present invention is a fluorescent light which emits light upon incidence of X-rays on one side surface of a semiconductor photodetector. It is characterized in that films are laminated, a film is arranged so as to face the fluorescent film, and the semiconductor photodetecting element is made sensitive by the emission of the fluorescent film and the film is exposed.

(E) Action The fluorescent film laminated on one side surface of the semiconductor photodetector element emits light upon incidence of X-rays. The light emission of the fluorescent film makes the semiconductor detection element having the fluorescent film laminated thereon sensitive and exposes the film facing the fluorescent film.

Therefore, the emission of the fluorescent film that exposes the film itself sensitizes the semiconductor photodetection element having the fluorescent film laminated thereon, and the X-ray absorber does not exist between the film and the semiconductor photodetection element. An X-ray detector for an X-ray automatic exposure control device that does not depend on the tube voltage and the subject thickness of the film density can be obtained.

The electric signal photoelectrically converted by the semiconductor photodetector is given to the phototimer controller.

(F) Embodiment A preferred embodiment of the present invention will be described with reference to the drawings.

 FIG. 1 is a vertical sectional view showing the first embodiment.

As in the illustrated example, on a substrate material 19 such as glass, a semiconductor photodetection element 21 having electrodes 20 and 22 on both surfaces, for example, a photodiode is supported, and a fluorescent film is further provided thereon.
23 are stacked.

It is desirable to use a transparent conductive film for the electrode 22 so as to transmit the light of the fluorescent film 23. The fluorescent film 23 emits fluorescence due to incident X-rays, but since light emission is emitted to both sides of the film,
As shown in the drawing, the film 8 is exposed and the photodetector
The same light as the light that has exposed the film 8 is incident on 21 as well, and it is sensed.

The photo-detecting element 21 can convert light into an electric current and take out the electric current to the outside through the electrodes 20 and 22.

The current drawn is the phototimer controller shown in FIG.
It is input to 17, and the current is integrated as described in the conventional embodiment. If the integrated current reaches a preset reference value, X
Break the line.

As will be apparent from the above description, the detector according to the illustrated embodiment is used in place of the intensifying screens 7 and / or 9 shown in FIG.

FIG. 2 is a vertical cross-sectional view showing another embodiment, in which the semiconductor photodetecting element 21 is divided in the vertical direction, and each divided portion is connected to the phototimer controller 17 via a lead wire. By such divided lighting, more accurate control such as selection of lighting for each imaging region or deletion of the high light emitting portion from direct X-rays is possible.

A feature of the X-ray detector of the present invention is that the same light emission as that of the phosphor exposed to the X-ray film is simultaneously taken by the semiconductor photodetector element in a position close to the phosphor.

Therefore, the film density according to the present invention is constant regardless of whether the tube voltage is high or low. Further, in the present invention, the film density is not related to the subject thickness because the semiconductor photodetector directly collects the light without an X-ray absorber.

It is obvious that the X-ray detector according to the present invention can be used not only as the II lighting type automatic X-ray exposure mechanism illustrated in FIG. 3 but also as an X-ray detector for a direct phototimer.

(G) Effect According to the X-ray detector for the X-ray automatic exposure control device of the present invention, the light emission itself of the phosphor that exposes the film is detected by the semiconductor photodetection element. Therefore, the tube voltage dependence of the X-ray film concentration. Also, there is no subject thickness dependence of the X-ray film density.

In addition, divided lighting can be performed and selection can be made for each imaging region. In addition, the optical system such as the photomultiplier and the prism is unnecessary in the configuration, the X-ray detector of the conventional direct phototimer is deleted, the number of parts of the device is reduced, and the X-ray automatic exposure control device including the X-ray detector is reduced. The configuration is simple.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing one embodiment of the present invention, FIG. 2 is a vertical sectional view showing another embodiment, and FIG.
It is a block diagram of a configuration of an automatic line exposure control device. Reference numerals 7 and 9 are intensifying screens, 8 is a film, 16 is a photomal, 19 is a substrate material, 20 and 22 are electrodes, and 23 is a phosphor.

Claims (1)

(57) [Claims] 1. A semiconductor photodetector comprising a semiconductor photodetector and a fluorescent film laminated on one side surface of the semiconductor photodetector so as to face the film. The film is exposed to light by X-ray incidence on the fluorescent film. An X-ray detector for an X-ray automatic exposure control device, characterized in that the semiconductor light detecting element is made sensitive.