JPS5815920B2 - X-ray irradiation dose control device for dental intraoral X-ray photography - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION In general, dental intraoral X-ray imaging devices are used in a restricted manner in which a film is inserted into the oral cavity to take images. This is done indirectly by adjusting the voltage, tube current, and imaging time.

Therefore, variations in the irradiation dose due to changes in tube voltage etc. are likely to occur, and therefore, it is necessary to redo the X-ray due to too much or too little irradiation dose, or to expose the patient to excessive X-rays, or to obtain a reproducible X-ray image. It was difficult to carry out.

In addition, instead of adjusting the tube voltage, tube current, and imaging time, the amount of X-rays that have passed through the object is detected as an amount of electricity, and electrical feedback is applied to compare the detected amount of electricity with the set amount of electricity. Some attempts have been made to stop the X-ray irradiation from the X-ray tube only when the two match, but as mentioned above, in this type of imaging where the film is held in the mouth, Holding the device is painful for the person being photographed, and when photographing molars, the molars and the inside of the cheek are particularly close, so even holding the film is difficult and it is probably difficult to include the detector. It forces the photographed person to suffer.

In addition, even if holding is possible, it is extremely difficult to support the detection surface of the detector so that it can perform its original function sufficiently, and it is also inappropriate from the viewpoint of accuracy.

To avoid this, place the detector outside the mouth (close to the back of the head).
In this case, a sufficient amount of X-rays is required to perform the detection function, which results in unnecessary and excessive X-ray exposure, which imposes another burden on the person to be imaged.

The present invention has been made in view of the above, and detects the dose of X-rays during the process of irradiation, and makes it possible to irradiate an appropriate amount of X-rays through electrical feedback control. In the case of a hollow cylindrical tube with an X-ray detector installed inside), its tip is placed to face the subject's cheek surface, and the other end is placed to face the X-ray tube. There is no need to hold a detector in the mouth in addition to the film, and there is no need for a large amount of X-rays to pass through the head structure, and the control can be extended to conventional intraoral X-ray photography.

Hereinafter, one embodiment of the present invention will be described based on the drawings. In the block diagram shown in FIG.
3 is a main controller for an X-ray diagnostic device connected to the primary side of the high voltage transformer 2, 4 is an X-ray dose detector including a preamplifier, 5 is an amplifier, 6 is an integrator, 7 is a comparator, 8 is an X-ray irradiation dose setting device, of which elements 3 to 8
constitutes a feedback loop.

In the above configuration, when X-rays are irradiated from the X-ray tube 1 now, in the process of irradiating the X-rays before reaching the subject (teeth) of the subject (specifically, the cheek of the subject). Before the arrival of the X-rays), the irradiated X-ray dose is detected by the X-ray detector 4 and converted into an electrical output.

The output is amplified by an amplifier 5, integrated by an integrator 6, and input to a comparator 7.

This comparator 7 is supplied with X
Since the radiation dose value has been input, the comparator 7 compares both values.

As the X-ray irradiation continues, a feedback signal is input to the main controller 3 when the integral value and the X-ray irradiation dose set value match, and the energization to the primary side of the high voltage transformer 2 is stopped.

Therefore, an accurate amount of X-ray irradiation can be performed even if the tube voltage etc. change due to fluctuations in the power supply voltage.

The X-ray dose detector 4 described above is installed in a cover tube 9 as shown in FIG.

This cover tube 9 is used with one end facing the subject and the other end facing the X-ray tube 1. A pair of filters (aluminum plates) 10 are placed close to the other end inside the cover tube 9. A lead washer 11 serving as a diaphragm for the X-ray beam, a printed circuit board 12 and a fluorescent plate 13 are interposed between the two filters 10 and 10 to block the X-ray beam incident on the cover tube 9. A wire is applied to the fluorescent plate 13 to cause it to emit light, and a photoelectric converter 14 on the printed circuit board 12 outputs an electric signal corresponding to the luminance of the emitted light.

15 is a collar for defining the distance between the printed circuit board 12 and the fluorescent plate 13, and 16 is a collar for defining the distance between the printed circuit board 12 and the lead washer 11.

Reference numeral 17 denotes a cylindrical lid that serves to hold down the elements 10 to 13, and is fixed to the cover tube 9 with a screw connection 18.

Furthermore, 19 is an electric wire for taking out the above-mentioned electric signal.

In this way, in the present invention, in photography in which a film is held in the mouth and X-rays are irradiated from outside the mouth, the X-ray dose is controlled using the actually measured X-ray dose during the irradiation process before reaching the subject as a media. Because the detector is held outside the mouth, there is no problem of pain for the photographed person or inaccuracy of holding the detector, and at the same time, there is no problem of large amounts of light being caused by setting the detector outside the mouth and transmitting the head structure. There is no need to worry about X-ray exposure, and the X-ray dose can be controlled in the same way as with conventional intraoral X-ray photography, which brings good news to the patient.

Furthermore, since accurate X-ray irradiation is possible for each imaging session, it is also possible to obtain the desired X-ray photograph.

In addition, in the present invention, when the detector is installed outside the area of the main radiation inside the cover tube as in the embodiment, the X-ray dose is increased because the detector does not interfere with the main radiation dose. Therefore, it is preferable to adopt this method because it does not impair the benefit of reducing the X-ray dose obtained by detecting the X-ray dose during the X-ray irradiation process.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention; FIG. 1 is a block diagram, and FIG. 2 is an enlarged longitudinal cross-sectional view of an X-ray dose detection device. Explanation of symbols, 1...X-ray tube, 2...High voltage transformer, 3...
Main controller for X-ray diagnostic equipment, 4...X-ray dose detector, 5...
Amplifier, 6... Integrator, 7... Comparator, 8... X-ray irradiation dose setting device, 9... Cover tube.

Claims (1)

[Claims] 1. An X-ray film is held in the oral cavity, and an X-ray tube is provided outside the oral cavity, and an X-ray image is projected on the X-ray film using X-rays that have passed through the facial area and the teeth of the subject from the X-ray tube. In the dental intraoral X-ray device to be delivered, a cover tube with one end facing the subject and the other end facing the X-ray tube, and an incident X-ray dose detector installed inside the cover tube; It consists of a comparator that compares the integral value of this X-ray dose detector output with the X-ray dose set value, and when the above-mentioned integral value and the X-ray dose set value match, the X-ray tube is connected to the secondary side. 1. An X-ray irradiation dose control device for dental intraoral X-ray photography, characterized in that the primary side voltage supply to a high voltage transformer is stopped.