JPH0229928Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an X-ray film for use in an X-ray imaging apparatus, such as one used for intraoral X-ray imaging for dental diagnosis.

When performing X-ray photography on two or three specific teeth in the above-mentioned intraoral X-ray photography, it is necessary to set a film in the oral cavity and irradiate it with X-rays from the outside. Conventionally, a light beam method or a film holder method with an optical sight has been used as a method for positioning the X-ray irradiation tube and the X-ray irradiation tube. The former light beam method provides the operator with information for determining positioning by emitting a light beam from the X-ray irradiation tube and brightly illuminating a point on the film surface or patient's surface that intersects with the X-ray central axis. However, since the light beam irradiation point is far from the center of the film, and the relationship between the position and direction of the light beam irradiation point and the point on the film or the film holder containing it cannot be easily determined by visual inspection, accurate positioning is difficult. It is impossible to do this, and requires the experienced intuition of the operator. In addition, the latter type of film holder with a sight device positions the irradiation tube of the sight device connected and fixed with a film holder, but in this case, the sight device, which spans from the inside of the oral cavity to the outside of the oral cavity, is placed on the patient's body. It has to be fixed by biting on the patient's mouth, placing a heavy burden on the patient and placing restrictions on the film set in the oral cavity.

The present invention aims to eliminate such difficulties, and features a film for an X-ray imaging apparatus in which a magnet is attached directly or indirectly to the film.

First, the principle of an X-ray imaging apparatus using a film according to the present invention will be explained with reference to FIGS. 1 and 2. That is, a magnet M is placed at a certain point on the coordinates, and this magnet M has an axially symmetrical shape (circle) with respect to its central axis m, and forms a symmetrical magnetic field around this central axis m. Corresponding to this, an X-ray irradiation tube A is provided, and this X-ray irradiation tube A has four magnetic detection sensors S... arranged at equal intervals in the circumferential direction around the X-ray central axis a, and each magnetic Detection sensor S...X
If the distance r from the line center axis a is made the same, then if you move the magnet M two-dimensionally or three-dimensionally to a position where the magnetic detection outputs of these sensors S... show the same value, the same value will be obtained. At the point indicated by , the central axes a and m of the X-ray irradiation tube A and the magnet M are positioned so that they are coaxial. In other words, in a coaxial state, the distance from the magnet M to each magnetic detection sensor S is the same, and each sensor is placed in an area with the same magnetic field strength of the symmetrical magnetic field formed by the magnet M, so the sensor outputs naturally match. That's what I do.

As the magnetic detection sensor, a magnetic modulation type sensor, a Hall element, a magnetoresistive element, a SOUID, etc. can be considered. Further, although the number of sensors is four in the above example, it may be two or more, and the number is selected according to the preferred usage pattern.

Next, one embodiment of the present invention will be explained with reference to FIGS. 3 and 4. The film holder 1 has three side edges 1b, 1c, and 1d excluding one side edge 1a. A presser edge 2 is formed by bending the film slightly toward the front side, and the film F is inserted into the front surface of the film holder 1 from the one side edge 1a side and held by the presser edge 2. The film F mentioned herein includes not only the film sheet itself, but also a so-called film pack in which the sheet is integrally backed with an intensifying screen. A magnet-fitting recess 3 is formed at the center of the rear surface of the film holder 1, that is, the X-ray non-incident side, and a disk-shaped magnet M is fitted and fixed in the recess 3. This fixation is carried out using an appropriate means such as adhesive or adhesive tape. In this case, the center position does not mean the center of the film F, but refers to the center of the range within the film holder 1 where the center of the film F is expected to be located, and this means that the film F moves slightly in the holder 1. This consideration was made to ensure that there was enough leeway to do so. In the case of a film used for X-ray photography using the parallel method, the virtual center of the film is adjusted so that the virtual center f of the film F and the central axis a of the X-rays incident on it are coaxial, as shown in Fig. 3. Similarly, f and the magnet center axis m are made to coincide. In addition, in the case of a film to be used for X-ray photography using the bisection method, the magnet M is positioned on an extended line where the X-ray central axis a intersects the virtual center f of the film F, as shown in FIG. In addition, the magnet center axis m is coaxially aligned with the X-ray center axis a. In the parallel method, the incident X-ray central axis a is a line passing through the virtual center of the film sheet F and perpendicular to the film surface, and in the bisection method, the incident X-ray central axis a is a line passing through the virtual center of the film F and relative to the film surface. An axis with a specific angle determined by . In the film 4 thus constructed, the incident X
A magnetic field that is symmetrical about the line center axis a can be obtained.

An example of an X-ray imaging method using a film with a magnet as described above will be explained with reference to FIG. 4. The film with a magnet is positioned inside the target tooth 4 to which X-rays are irradiated. On the other hand, a total of four magnetic detection sensors S are attached to the outer periphery of the tip of the X-ray irradiation tube A at equal intervals in the circumferential direction. Then, if the X-ray irradiation tube A is moved using the principles shown in Figs. and the central axis a of the X-ray irradiation tube A. Therefore, when X-ray photography is performed, the film F is completely placed within the X-ray irradiation field, and the X-ray irradiation target tooth 4 can be photographed. .

The above describes an X-ray imaging method for dental use, but it can of course be used in other fields.
It is suitable for photographing internal parts where the target cannot be seen from the outside in non-destructive tests, etc.

In the above embodiment, in order for the magnet center m and the central axis a of the X-ray irradiation tube A to always be coaxially aligned, the magnet M must be axially symmetrical with respect to its central axis m, or the X-ray irradiation tube A If the movement direction of the X-ray tube A is limited to one direction, it is necessary that the cross-sectional shape of the X-ray irradiation tube A be axially symmetrical or linearly symmetrical. In short, the magnetic detection sensor S is connected to the X-ray central axis a.
It is sufficient if they are all attached at equal diameter positions. Of course, it is also possible to rotate a single sensor and extract outputs from multiple positions for comparison.

Furthermore, although the magnet M is attached to the film holder 1 in FIGS. 2 and 3, it may also be attached directly to the film F.

As described above, if the film according to the present invention is used, by attaching a plurality of magnetic detection sensors sensitive to the magnetic field of the film-side magnet to the X-ray irradiation tube, or a single rotationally moving sensor, the detection of these sensors can be performed. The positioning of the film and the X-ray irradiation tube can be accurately and easily determined from the operation of determining the coincidence of outputs. Therefore, when this film is used, for example, in a dental X-ray imaging device,
All the drawbacks of conventional positioning methods such as the light beam method or the film holder method with sighting device described at the beginning can be eliminated. In addition, since accurate positioning can be performed, it is possible to narrow down the X-ray irradiation field and cut out excess X-rays, thereby reducing the exposure dose of the person being photographed.

[Brief explanation of the drawing]

Figures 1 and 2 are operational diagrams for explaining the principle of the X-ray imaging method using the film according to the present invention. One example is shown, and Fig. 3 is a rear view A, a vertical side view B, and a front view C in the case of parallel method photography, and Fig. 4 is the same view in the case of bisecting method photography. . Further, FIG. 5 is a schematic diagram showing an example of how to use the film of the present invention. Explanation of symbols: F...Film, M...Magnet.

Claims (1)

[Scope of utility model registration request] A film used in an X-ray imaging device that has a magnet attached directly or indirectly to the film.