JPH0337008Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a marker for X-ray electrophotography.

[Background of the idea]

In X-ray photography, which is effective for medical diagnosis, when the subject is one of two parts, such as the breast, limbs, etc., the position of such part,
That is, in order to be able to identify the right and left sides even on the photographed film, a marker with a letter, such as "R" or "L", is placed in the X-ray irradiation field, and this is simultaneously photographed together with the subject, and the film is The method used is to record the information above. This marker was developed for use in so-called silver halide film X-ray photography, and conventionally consists of a synthetic resin plate with identification characters "R" or "L" made of lead embedded in it.

By the way, in recent years, in the field of X-ray photography,
Line electrophotography devices are in the spotlight. This device uses an electrophotographic photosensitive plate instead of a silver halide film, and by irradiating the photosensitive plate with an X-ray image that has passed through the subject, a potential difference image matching the X-ray image is formed on the photosensitive plate. A permanent visible X-ray image is obtained by developing and transferring the image. According to this device, a development called an edge effect, which is unique to electrophotography, makes it possible to obtain a clearer image with emphasized image edges compared to conventional silver halide film.

Such X-ray electrophotography devices have the above-mentioned special effects, but on the other hand, because the photoreceptor is used repeatedly, the potential difference image formed on the photoreceptor plate is used before the next image is formed. It is necessary to erase the data. Conventionally, as a means for erasing the image, there is known a method of applying an alternating current electric field to the surface of the photosensitive plate and/or irradiating the surface with light. By the way, in such an X-ray electrophotography device, when the markers with lead characters mentioned above are used to identify the left and right parts of the subject, the difference in X-ray absorption between the characters and the non-character parts is extremely large. , the potential difference between the text and non-text areas formed on the photosensitive plate is correspondingly large, and as a result, even if the above-mentioned erasing means is used, the history of the text from the previous photograph remains on the photosensitive plate. This caused the inconvenience of appearing as an afterimage in the next photograph taken.

[Purpose of invention]

An object of the present invention is to provide a marker for X-ray electrophotography that does not cause the above-mentioned antecedent history and has a simple and suitable configuration.

[Structure of the idea]

The marker according to the present invention uses a synthetic resin member as a substrate, and characters made of barium sulfate are formed on the surface of the substrate, and silk screen printing, for example, is used as the forming method.

[Effect of idea]

According to the present invention, with the above configuration, the radiation dose range (X-ray tube voltage approximately
(20 kVp to about 120 kVp), no marker history was observed on the photosensitive plate.

[Example of idea]

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 and 2 show an example of an X-ray electrophotographic method in which the marker according to the present invention can be suitably used, and reference numeral 1 in the figures indicates an X-ray electrophotographic photosensitive plate. The photosensitive plate 1 includes a support plate 2 made of an X-ray transparent material such as carbon fiber reinforced resin (C-FRP), an electrode layer 3, and an insulating layer 4 when viewed from above, that is, from the X-ray irradiation side described later. It has a multilayer structure in which a photoconductor layer 5 and a surface insulating layer 6 made of materials such as , Se-Te, etc. are laminated in sequence. Furthermore, if necessary, a phosphor layer excited by X-rays may be formed between the support plate 2 and the electrode layer 3, in which case the electrode layer 3 and the insulating layer 4 may be made transparent.

In the photosensitive plate 1 having such a configuration, as a first process,
The insulating layer 6 is charged to a specific polarity (positive polarity in this example for convenience of explanation) from the side of the insulating layer 6 by a suitable external discharge means. As a result, positive charges are trapped in the photoconductor layer 5 as shown in FIG.
A P (persistent internal polarization) charge layer is formed.

In the second process, as shown in FIG. 2, after placing the subject 8 and the identification marker 9 on the support plate 2 side, X-rays are irradiated at an X-ray tube voltage of about 20 kVp to about 120 kVp, thereby forming a The X-ray image is transferred to photosensitive plate 1.
At the same time, a uniform direct current (or alternating current) electric field of opposite polarity, that is, negative polarity, is applied from the surface insulating layer 6 side. The reference numeral 10 in the figure is a corona discharge device for applying an electric field. Through this process, most of the PIP charges that had been captured in the photoconductor layer in the first process are removed by excitation of the photoconductor layer in the area of the photosensitive plate where the X-rays were projected. opened,
At the same time as the surface charges recombine and disappear, the layer 6 is charged with charges of new polarity, that is, negative polarity.
On the other hand, for areas that are not exposed to X-rays, P.
Since the IP charge is not rapidly released, the positive charge remains retained. In this way, an electrostatic latent image matching the X-ray image is formed.

The formed electrostatic latent image is applied with electrostatic powder called toner and developed into a powder image, and then the developed image is transferred onto a suitable support, such as a transparent resin film, and fixed to match the subject and marker. A permanently visible image is obtained. On the other hand, the photosensitive plate after the transfer is subjected to AC corona discharge and light irradiation to erase the formed electrostatic latent image for the next X-ray imaging.

The marker 9 according to the present invention uses a thin plate-like member 11 as a substrate, as shown in FIG. Member 11
It consists of integrally molded or laminated plates made of synthetic resin material, such as acrylic resin, polycarbonate resin or phenolic resin.
The illustrated example shows a substrate for forming six markers, and a notch 12 is formed in the dividing part between each marker, so that each marker can be separated individually and used as desired by hand. . On the member 11, identification characters 13, for example, characters "L" or "R" to indicate the left and right sides of the imaging site, are formed mainly of barium sulfate. Here, "mainly" means that only barium sulfate may be used, but a synthetic resin material or the like may also be mixed therein. As a means for forming the character portion 13, necessary identification characters are engraved on the substrate 11.
Barium sulfate added with a suitable binder may be embedded in the indented portion, but a simpler method of formation is to print a barium sulfate solution onto the substrate by silk screen printing.
When carrying out such printing, barium sulfate powder is mixed into an aqueous emulsion, the mixture is printed by silk screen printing in the form of the desired identifying characters, and the printed character areas are then naturally or forcefully applied. Just let it dry. Such aqueous emulsions are preferably vinyl acetate emulsions, acrylic emulsions, alkyd resin emulsions, etc., but are not limited thereto. Furthermore, the finer the barium sulfate powder, the clearer the character image formed on the film.

Example: Mix 5 g of barium sulfate powder with 3 to 4 g of vinyl acetate-based aqueous emulsion (manufactured by Turner Color Co., Ltd., product name Neocolor, Gold and Silver "Medium"), and spread this mixture on an acrylic resin substrate approximately 1 mm thick. An identification character portion having a thickness of approximately 50 μm (thickness after drying) was formed by silk screen printing, and then air-dried at room temperature to form a marker.
When such a marker was used for X-ray electrophotography using the photosensitive plate and process described above, the characters of the marker were clearly recorded on the film after the image was taken, and moreover, During X-ray irradiation at a tube voltage of about 20 kVp to about 120 kVp, no previous history of such text remained at all. The voltage of the electric field applied to the photosensitive plate during photographing was +6700 VDC in the first process, -7000 VDC in the second process, and 4800 VAC for static elimination.

As described above, according to the present invention, it is possible to provide a marker for X-ray electrophotography that does not cause any previous history even when the photosensitive plate is used repeatedly.

Furthermore, the marker according to the present invention can be used in other X-ray electrophotography methods that include photosensitive plates or processes other than those described above, such as xerography, and can produce similar effects.

[Brief explanation of the drawing]

1 and 2 are explanatory diagrams showing an example of X-ray electrophotography in which the marker according to the present invention can be used, and FIG. 3 is a perspective view of the marker according to the present invention. 9... Marker, 11... Board, 13... Character portion.

Claims (1)

[Scope of utility model registration request] By irradiating a charged electrophotographic photoreceptor with an X-ray image that has passed through the subject, a potential difference image corresponding to the transmitted X-ray latent image is formed, and this is developed and transferred to form a visible image. A marker for X-ray electrophotography that is repeatedly used to photograph the next subject after cleaning and neutralizing the photoreceptor, and comprising a character part mainly made of barium sulfate and a synthetic resin substrate supporting the character part. characterized in that the character part and the substrate have an X-ray absorption difference that does not cause a previous history of the character part on the photosensitive plate in X-ray photography with an X-ray irradiation amount of X-ray tube voltage of 20 kVp to 120 kVp. A marker for X-ray electrophotography.